fix use after free

For some reason I am still getting this:

2025/05/10 16:37:06 Error decoding message: SGVsbG8gZGFya25lc3MgbXkgb2xkIGZyaWVuZA==::53475673624738675a4746796132356c63334d6762586b676232786b49475a79615756755a413d3daaaa

build.zig

@@ -1,121 +1,72 @@
 const std = @import("std");
 
-// 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.
 
-    // 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,
+        .optimize = optimize,
     });
 
-    mod.addImport("network", b.dependency("network", .{}).module("network"));
-    mod.addImport("gatorcat", b.dependency("gatorcat", .{}).module("gatorcat"));
+    // 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
-    // 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"));
+    lib_mod.addImport("gatorcat", b.dependency("gatorcat", .{}).module("gatorcat"));
+
+    exe_mod.addImport("zaprus", lib_mod);
+    exe_mod.addImport("clap", b.dependency("clap", .{}).module("clap"));
+
+    const lib = b.addLibrary(.{
+        .linkage = .static,
+        .name = "zaprus",
+        .root_module = lib_mod,
+    });
+
+    b.installArtifact(lib);
+
+    // 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 },
-                .{ .name = "clap", .module = b.dependency("clap", .{}).module("clap") },
-            },
-        }),
+        .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);
-    b.installArtifact(b.addLibrary(.{
-        .linkage = .static,
-        .name = "zaprus",
-        .root_module = mod,
-    }));
 
-    // 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
@@ -124,42 +75,21 @@ 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

@@ -37,16 +37,16 @@
     // internet connectivity.
     .dependencies = .{
         .network = .{
-            .url = "git+https://github.com/ikskuh/zig-network#7947237eec317d9458897f82089f343a05450c2b",
-            .hash = "network-0.1.0-Pm-Agl8xAQBmkwohveGOfTk4zQnuqDs0Ptfbms4KP5Ce",
+            .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#9cfa61596cd44ef7be35f8d2e108d2025e09868e",
-            .hash = "clap-0.10.0-oBajB_TnAQB0l5UdW9WYhhJDEswbedvwFOzzZwGknYeR",
+            .url = "git+https://github.com/Hejsil/zig-clap?ref=0.10.0#e47028deaefc2fb396d3d9e9f7bd776ae0b2a43a",
+            .hash = "clap-0.10.0-oBajB434AQBDh-Ei3YtoKIRxZacVPF1iSwp3IX_ZB8f0",
         },
         .gatorcat = .{
-            .url = "git+https://github.com/jeffective/gatorcat#db73d0f7780331d82e785e85773d1afaf154c2e6",
-            .hash = "gatorcat-0.3.11-WcrpTQn0BwArrCFVHy9FPBIPDJQqPrFdJlhiyH7Ng5x4",
+            .url = "git+https://github.com/kj4tmp/gatorcat#bb1847f6c95852e7a0ec8c07870a948c171d5f98",
+            .hash = "gatorcat-0.3.2-WcrpTf1mBwDrmPaIhKCfLJO064v8Sjjn7DBq4CKZSgHH",
         },
     },
     .paths = .{

src/Client.zig

@@ -1,82 +1,28 @@
 const base64Enc = std.base64.Base64Encoder.init(std.base64.standard_alphabet_chars, '=');
 const base64Dec = std.base64.Base64Decoder.init(std.base64.standard_alphabet_chars, '=');
 
-rand: Random,
-writer: *std.Io.Writer,
+var rand: ?Random = null;
 
-const Self = @This();
-
-const max_message_size = 2048;
-
-pub fn init(writer: *std.Io.Writer) !Self {
+pub fn init() !void {
     var prng = Random.DefaultPrng.init(blk: {
         var seed: u64 = undefined;
         try posix.getrandom(mem.asBytes(&seed));
         break :blk seed;
     });
-    const rand = prng.random();
-
-    return .{
-        .rand = rand,
-        .writer = writer,
-    };
+    rand = prng.random();
+    try network.init();
 }
 
-pub fn deinit(self: *Self) void {
-    self.writer.flush() catch {};
+pub fn deinit() void {
+    network.deinit();
 }
 
-/// Used for relay messages and connection handshake.
-/// Assumes Client .init has been called.
-fn broadcastInitialInterestMessage(self: *Self, msg_bytes: []align(@alignOf(SaprusMessage)) u8) !void {
-    var packet_bytes: [max_message_size]u8 = comptime blk: {
-        var b: [max_message_size]u8 = @splat(0);
-
-        // Destination MAC addr to FF:FF:FF:FF:FF:FF
-        for (0..6) |i| {
-            b[i] = 0xff;
-        }
-
-        // Set Ethernet type to IPv4
-        b[0x0c] = 0x08;
-        b[0x0d] = 0x00;
-
-        // Set IPv4 version to 4
-        b[0x0e] = 0x45;
-
-        // Destination broadcast
-        for (0x1e..0x22) |i| {
-            b[i] = 0xff;
-        }
-
-        // Set TTL
-        b[0x16] = 0x40;
-
-        // Set IPv4 protocol to UDP
-        b[0x17] = 0x11;
-
-        // Set interest filter value to 8888.
-        b[0x24] = 0x22;
-        b[0x25] = 0xb8;
-        break :blk b;
-    };
-    var msg: *SaprusMessage = try .bytesAsValue(msg_bytes);
-    try msg.networkFromNativeEndian();
-    defer msg.nativeFromNetworkEndian() catch unreachable;
-
-    // The byte position within the packet that the saprus message starts at.
-    const saprus_start_byte = 42;
-    @memcpy(packet_bytes[saprus_start_byte .. saprus_start_byte + msg_bytes.len], msg_bytes);
-
-    const writer = self.writer;
-    _ = try writer.write(packet_bytes[0 .. saprus_start_byte + msg_bytes.len]);
-    try writer.flush();
-}
-
-// fn broadcastSaprusMessage(msg_bytes: []align(@alignOf(SaprusMessage)) u8) !void {}
-
-fn broadcastSaprusMessage(msg_bytes: []align(@alignOf(SaprusMessage)) u8, udp_port: u16) !void {
-    const msg: *SaprusMessage = try .bytesAsValue(msg_bytes);
+fn broadcastSaprusMessage(msg: *SaprusMessage, udp_port: u16) !void {
+    if (false) {
+        var foo: gcat.nic.RawSocket = try .init("enp7s0"); // /proc/net/dev
+        defer foo.deinit();
+    }
+    const msg_bytes = msg.asBytes();
     try msg.networkFromNativeEndian();
     defer msg.nativeFromNetworkEndian() catch unreachable;
 
@@ -98,41 +44,48 @@ fn broadcastSaprusMessage(msg_bytes: []align(@alignOf(SaprusMessage)) u8, udp_po
 
     try sock.bind(bind_addr);
 
-    std.debug.print("{x}\n", .{msg_bytes});
-
     _ = try sock.sendTo(dest_addr, msg_bytes);
 }
 
-pub fn sendRelay(self: *Self, payload: []const u8, dest: [4]u8) !void {
-    var buf: [max_message_size]u8 align(@alignOf(SaprusMessage)) = undefined;
-    const msg_bytes = buf[0..try SaprusMessage.calcSize(
-        .relay,
-        base64Enc.calcSize(payload.len),
-    )];
+pub fn sendRelay(payload: []const u8, dest: [4]u8, allocator: Allocator) !void {
+    const msg_bytes = try allocator.alignedAlloc(
+        u8,
+        @alignOf(SaprusMessage),
+        try SaprusMessage.lengthForPayloadLength(
+            .relay,
+            base64Enc.calcSize(payload.len),
+        ),
+    );
+    defer allocator.free(msg_bytes);
     const msg: *SaprusMessage = .init(.relay, msg_bytes);
 
     const relay = (try msg.getSaprusTypePayload()).relay;
     relay.dest = dest;
     _ = base64Enc.encode(relay.getPayload(), payload);
 
-    try self.broadcastInitialInterestMessage(msg_bytes);
+    try broadcastSaprusMessage(msg, 8888);
 }
 
-fn randomPort(self: Self) u16 {
-    return self.rand.intRangeAtMost(u16, 1024, 65000);
+fn randomPort() u16 {
+    var p: u16 = 0;
+    if (rand) |r| {
+        p = r.intRangeAtMost(u16, 1024, 65000);
+    } else unreachable;
+
+    return p;
 }
 
-pub fn sendInitialConnection(
-    self: Self,
-    payload: []const u8,
-    output_bytes: []align(@alignOf(SaprusMessage)) u8,
-    initial_port: u16,
-) !*SaprusMessage {
-    const dest_port = self.randomPort();
-    const msg_bytes = output_bytes[0..try SaprusMessage.calcSize(
-        .connection,
-        base64Enc.calcSize(payload.len),
-    )];
+pub fn sendInitialConnection(payload: []const u8, initial_port: u16, allocator: Allocator) !*SaprusMessage {
+    const dest_port = randomPort();
+    const msg_bytes = try allocator.alignedAlloc(
+        u8,
+        @alignOf(SaprusMessage),
+        try SaprusMessage.lengthForPayloadLength(
+            .connection,
+            base64Enc.calcSize(payload.len),
+        ),
+    );
+
     const msg: *SaprusMessage = .init(.connection, msg_bytes);
 
     const connection = (try msg.getSaprusTypePayload()).connection;
@@ -140,13 +93,16 @@ pub fn sendInitialConnection(
     connection.dest_port = dest_port;
     _ = base64Enc.encode(connection.getPayload(), payload);
 
-    try broadcastSaprusMessage(msg_bytes, 8888);
+    try broadcastSaprusMessage(msg, 8888);
 
     return msg;
 }
 
-pub fn connect(self: Self, payload: []const u8) !?SaprusConnection {
-    const initial_port = self.randomPort();
+pub fn connect(payload: []const u8, allocator: Allocator) !?SaprusConnection {
+    var initial_port: u16 = 0;
+    if (rand) |r| {
+        initial_port = r.intRangeAtMost(u16, 1024, 65000);
+    } else unreachable;
 
     var initial_conn_res: ?*SaprusMessage = null;
 
@@ -163,17 +119,18 @@ pub fn connect(self: Self, payload: []const u8) !?SaprusConnection {
     try sock.setReadTimeout(1 * std.time.us_per_s);
     try sock.bind(bind_addr);
 
-    var sent_msg_bytes: [max_message_size]u8 align(@alignOf(SaprusMessage)) = undefined;
-    const msg = try self.sendInitialConnection(payload, &sent_msg_bytes, initial_port);
+    const msg = try sendInitialConnection(payload, initial_port, allocator);
+    defer allocator.free(msg.asBytes());
 
-    var response_buf: [max_message_size]u8 align(@alignOf(SaprusMessage)) = undefined;
+    var response_buf: [4096]u8 align(@alignOf(SaprusMessage)) = undefined;
     _ = try sock.receive(&response_buf); // Ignore message that I sent.
     const len = try sock.receive(&response_buf);
 
-    initial_conn_res = try .networkBytesAsValue(response_buf[0..len]);
+    std.debug.print("response bytes: {x}\n", .{response_buf[0..len]});
+    initial_conn_res = SaprusMessage.init(.connection, response_buf[0..len]);
 
     // Complete handshake after awaiting response
-    try broadcastSaprusMessage(msg.asBytes(), self.randomPort());
+    try broadcastSaprusMessage(msg, randomPort());
 
     if (false) {
         return initial_conn_res.?;
@@ -190,3 +147,6 @@ const posix = std.posix;
 const mem = std.mem;
 
 const network = @import("network");
+const gcat = @import("gatorcat");
+
+const Allocator = mem.Allocator;

src/RawSocketWriter.zig

@@ -1,45 +0,0 @@
-const std = @import("std");
-const gcat = @import("gatorcat");
-const Writer = @This();
-const assert = std.debug.assert;
-
-interface: std.Io.Writer,
-socket: gcat.nic.RawSocket,
-alloc: std.mem.Allocator,
-
-fn drain(io_w: *std.Io.Writer, data: []const []const u8, splat: usize) std.Io.Writer.Error!usize {
-    const w: *Writer = @alignCast(@fieldParentPtr("interface", io_w));
-    const buffered = io_w.buffered();
-    var res: usize = 0;
-    if (buffered.len > 0) {
-        w.socket.linkLayer().send(buffered) catch return error.WriteFailed;
-        _ = io_w.consumeAll();
-    }
-
-    for (data[0 .. data.len - 1]) |d| {
-        w.socket.linkLayer().send(d) catch return error.WriteFailed;
-        res += d.len;
-    }
-
-    if (splat > 0 and data[data.len - 1].len > 0) {
-        var splatBuffer: std.ArrayList(u8) = .empty;
-        defer splatBuffer.deinit(w.alloc);
-        for (0..splat) |_| {
-            splatBuffer.appendSlice(w.alloc, data[data.len - 1]) catch return error.WriteFailed;
-        }
-        w.socket.linkLayer().send(splatBuffer.items) catch return error.WriteFailed;
-    }
-
-    return res;
-}
-
-pub fn init(interface_name: [:0]const u8, buffer: []u8, alloc: std.mem.Allocator) !Writer {
-    return .{
-        .interface = .{
-            .vtable = &.{ .drain = drain },
-            .buffer = buffer,
-        },
-        .socket = try .init(interface_name),
-        .alloc = alloc,
-    };
-}

src/main.zig

@@ -37,37 +37,36 @@ pub fn main() !void {
         .allocator = gpa,
     }) catch |err| {
         // Report useful error and exit.
-        try diag.reportToFile(.stderr(), err);
+        diag.report(std.io.getStdErr().writer(), err) catch {};
         return err;
     };
     defer res.deinit();
 
-    if (res.args.help != 0) {
-        return clap.helpToFile(.stderr(), clap.Help, &params, .{});
-    }
+    try SaprusClient.init();
+    defer SaprusClient.deinit();
 
-    var sock_buffer: [2048]u8 = undefined;
-    var rawSocketWriter: RawSocketWriter = try .init("enp7s0", &sock_buffer, gpa); // /proc/net/dev
-    var client = try SaprusClient.init(&rawSocketWriter.interface);
-    defer client.deinit();
+    if (res.args.help != 0) {
+        return clap.help(std.io.getStdErr().writer(), clap.Help, &params, .{});
+    }
 
     if (res.args.relay) |r| {
         const dest = parseDest(res.args.dest);
-        try client.sendRelay(
+        try SaprusClient.sendRelay(
             if (r.len > 0) r else "Hello darkness my old friend",
             dest,
+            gpa,
         );
         // std.debug.print("Sent: {s}\n", .{r});
         return;
     } else if (res.args.connect) |c| {
-        _ = client.connect(if (c.len > 0) c else "Hello darkness my old friend") catch |err| switch (err) {
+        _ = SaprusClient.connect(if (c.len > 0) c else "Hello darkness my old friend", gpa) catch |err| switch (err) {
             error.WouldBlock => null,
             else => return err,
         };
         return;
     }
 
-    return clap.helpToFile(.stderr(), clap.Help, &params, .{});
+    return clap.help(std.io.getStdErr().writer(), clap.Help, &params, .{});
 }
 
 fn parseDest(in: ?[]const u8) [4]u8 {
@@ -92,6 +91,5 @@ const ArrayList = std.ArrayList;
 const zaprus = @import("zaprus");
 const SaprusClient = zaprus.Client;
 const SaprusMessage = zaprus.Message;
-const RawSocketWriter = zaprus.RawSocketWriter;
 
 const clap = @import("clap");

src/message.zig

@@ -38,7 +38,7 @@ pub const Message = packed struct {
 
         pub fn getPayload(self: *align(1) Relay) []u8 {
             const len: *u16 = @ptrFromInt(@intFromPtr(self) - @sizeOf(u16));
-            return @as([*]u8, @ptrCast(&self.payload))[0 .. len.* - @bitSizeOf(Relay) / 8];
+            return @as([*]u8, @ptrCast(&self.payload))[0 .. len.* - @sizeOf(Relay)];
         }
     };
     const Connection = packed struct {
@@ -52,7 +52,7 @@ pub const Message = packed struct {
 
         pub fn getPayload(self: *align(1) Connection) []u8 {
             const len: *u16 = @ptrFromInt(@intFromPtr(self) - @sizeOf(u16));
-            return @as([*]u8, @ptrCast(&self.payload))[0 .. len.* - @bitSizeOf(Connection) / 8];
+            return @as([*]u8, @ptrCast(&self.payload))[0 .. len.* - @sizeOf(Connection)];
         }
 
         fn nativeFromNetworkEndian(self: *align(1) Connection) void {
@@ -79,8 +79,6 @@ pub const Message = packed struct {
 
     /// Takes a byte slice, and returns a Message struct backed by the slice.
     /// This properly initializes the top level headers within the slice.
-    /// This is used for creating new messages. For reading messages from the network,
-    /// see: networkBytesAsValue.
     pub fn init(@"type": PacketType, bytes: []align(@alignOf(Self)) u8) *Self {
         std.debug.assert(bytes.len >= @sizeOf(Self));
         const res: *Self = @ptrCast(bytes.ptr);
@@ -89,14 +87,14 @@ pub const Message = packed struct {
         return res;
     }
 
-    /// Compute the number of bytes required to store a given payload size for a given message type.
-    pub fn calcSize(comptime @"type": PacketType, payload_len: usize) MessageTypeError!u16 {
-        const header_size = @bitSizeOf(switch (@"type") {
+    pub fn lengthForPayloadLength(comptime @"type": PacketType, payload_len: usize) MessageTypeError!u16 {
+        std.debug.assert(payload_len < std.math.maxInt(u16));
+        const header_size = @sizeOf(switch (@"type") {
             .relay => Relay,
             .connection => Connection,
             .file_transfer => return MessageTypeError.NotImplementedSaprusType,
             else => return MessageTypeError.UnknownSaprusType,
-        }) / 8;
+        });
         return @intCast(payload_len + @sizeOf(Self) + header_size);
     }
 
@@ -107,7 +105,6 @@ pub const Message = packed struct {
         return std.mem.bytesAsValue(Connection, &self.bytes);
     }
 
-    /// Access the message Saprus payload.
     pub fn getSaprusTypePayload(self: *Self) MessageTypeError!(union(PacketType) {
         relay: *align(1) Relay,
         file_transfer: void,
@@ -121,7 +118,6 @@ pub const Message = packed struct {
         };
     }
 
-    /// Convert the message to native endianness from network endianness in-place.
     pub fn nativeFromNetworkEndian(self: *Self) MessageTypeError!void {
         self.type = @enumFromInt(bigToNative(
             @typeInfo(@TypeOf(self.type)).@"enum".tag_type,
@@ -145,7 +141,6 @@ pub const Message = packed struct {
         }
     }
 
-    /// Convert the message to network endianness from native endianness in-place.
     pub fn networkFromNativeEndian(self: *Self) MessageTypeError!void {
         try switch (try self.getSaprusTypePayload()) {
             .relay => {},
@@ -160,27 +155,6 @@ pub const Message = packed struct {
         self.length = nativeToBig(@TypeOf(self.length), self.length);
     }
 
-    /// Convert network endian bytes to a native endian value in-place.
-    pub fn networkBytesAsValue(bytes: SelfBytes) MessageParseError!*Self {
-        const res = std.mem.bytesAsValue(Self, bytes);
-        try res.nativeFromNetworkEndian();
-        return .bytesAsValue(bytes);
-    }
-
-    /// Create a structured view of the bytes without initializing the length or type,
-    /// and without converting the endianness.
-    pub fn bytesAsValue(bytes: SelfBytes) MessageParseError!*Self {
-        const res = std.mem.bytesAsValue(Self, bytes);
-        return switch (res.type) {
-            .relay, .connection => if (bytes.len == res.length + @sizeOf(Self))
-                res
-            else
-                MessageParseError.InvalidMessage,
-            .file_transfer => MessageParseError.NotImplementedSaprusType,
-            else => MessageParseError.UnknownSaprusType,
-        };
-    }
-
     /// Deprecated.
     /// If I need the bytes, I should just pass around the slice that is backing this to begin with.
     pub fn asBytes(self: *Self) SelfBytes {
@@ -190,74 +164,43 @@ pub const Message = packed struct {
 };
 
 test "testing variable length zero copy struct" {
+    const gpa = std.testing.allocator;
+    const payload = "Hello darkness my old friend";
+
+    // Create a view of the byte slice as a Message
+    const msg: *Message = try .init(gpa, .relay, payload.len);
+    defer msg.deinit(gpa);
+
     {
-        // Relay test
-        const payload = "Hello darkness my old friend";
-        var msg_bytes: [try Message.calcSize(.relay, payload.len)]u8 align(@alignOf(Message)) = undefined;
-
-        // Create a view of the byte slice as a Message
-        const msg: *Message = .init(.relay, &msg_bytes);
-
+        // Set the message values
         {
-            // Set the message values
-            {
-                // These are both set by the init call.
-                // msg.type = .relay;
-                // msg.length = payload_len;
-            }
-            const relay = (try msg.getSaprusTypePayload()).relay;
-            relay.dest = .{ 1, 2, 3, 4 };
-            @memcpy(relay.getPayload(), payload);
+            // These are both set by the init call.
+            // msg.type = .relay;
+            // msg.length = payload_len;
         }
-
-        {
-            // Print the message as hex using the network byte order
-            try msg.networkFromNativeEndian();
-            // We know the error from nativeFromNetworkEndian is unreachable because
-            // it would have returned an error from networkFromNativeEndian.
-            defer msg.nativeFromNetworkEndian() catch unreachable;
-            std.debug.print("relay network bytes: {x}\n", .{msg_bytes});
-            std.debug.print("bytes len: {d}\n", .{msg_bytes.len});
-        }
-
-        if (false) {
-            // Illegal behavior
-            std.debug.print("{any}\n", .{(try msg.getSaprusTypePayload()).connection});
-        }
-
-        try std.testing.expectEqualDeep(msg, try Message.bytesAsValue(msg.asBytes()));
+        const relay = (try msg.getSaprusTypePayload()).relay;
+        relay.dest = .{ 1, 2, 3, 4 };
+        @memcpy(relay.getPayload(), payload);
     }
 
     {
-        // Connection test
-        const payload = "Hello darkness my old friend";
-        var msg_bytes: [try Message.calcSize(.connection, payload.len)]u8 align(@alignOf(Message)) = undefined;
+        const bytes = msg.asBytes();
 
-        // Create a view of the byte slice as a Message
-        const msg: *Message = .init(.connection, &msg_bytes);
-
-        {
-            // Initializing connection header values
-            const connection = (try msg.getSaprusTypePayload()).connection;
-            connection.src_port = 1;
-            connection.dest_port = 2;
-            connection.seq_num = 3;
-            connection.msg_id = 4;
-            connection.reserved = 5;
-            connection.options = @bitCast(@as(u8, 6));
-            @memcpy(connection.getPayload(), payload);
-        }
-
-        {
-            // Print the message as hex using the network byte order
-            try msg.networkFromNativeEndian();
-            // We know the error from nativeFromNetworkEndian is unreachable because
-            // it would have returned an error from networkFromNativeEndian.
-            defer msg.nativeFromNetworkEndian() catch unreachable;
-            std.debug.print("connection network bytes: {x}\n", .{msg_bytes});
-            std.debug.print("bytes len: {d}\n", .{msg_bytes.len});
-        }
+        // Print the message as hex using the network byte order
+        try msg.networkFromNativeEndian();
+        // We know the error from nativeFromNetworkEndian is unreachable because
+        // it would have returned an error from networkFromNativeEndian.
+        defer msg.nativeFromNetworkEndian() catch unreachable;
+        std.debug.print("network bytes: {x}\n", .{bytes});
+        std.debug.print("bytes len: {d}\n", .{bytes.len});
     }
+
+    if (false) {
+        // Illegal behavior
+        std.debug.print("{any}\n", .{(try msg.getSaprusTypePayload()).connection});
+    }
+
+    try std.testing.expectEqualDeep(msg, try Message.bytesAsValue(msg.asBytes()));
 }
 
 const std = @import("std");
@@ -268,48 +211,42 @@ const nativeToBig = std.mem.nativeToBig;
 const bigToNative = std.mem.bigToNative;
 
 test "Round trip Relay toBytes and fromBytes" {
-    if (false) {
-        const gpa = std.testing.allocator;
-        const msg = Message{
-            .relay = .{
-                .header = .{ .dest = .{ 255, 255, 255, 255 } },
-                .payload = "Hello darkness my old friend",
-            },
-        };
+    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 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);
+    const from_bytes = try Message.fromBytes(to_bytes, gpa);
+    defer from_bytes.deinit(gpa);
 
-        try std.testing.expectEqualDeep(msg, from_bytes);
-    }
-    return error.SkipZigTest;
+    try std.testing.expectEqualDeep(msg, from_bytes);
 }
 
 test "Round trip Connection toBytes and fromBytes" {
-    if (false) {
-        const gpa = std.testing.allocator;
-        const msg = Message{
-            .connection = .{
-                .header = .{
-                    .src_port = 0,
-                    .dest_port = 0,
-                },
-                .payload = "Hello darkness my old friend",
+    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 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);
+    const from_bytes = try Message.fromBytes(to_bytes, gpa);
+    defer from_bytes.deinit(gpa);
 
-        try std.testing.expectEqualDeep(msg, from_bytes);
-    }
-    return error.SkipZigTest;
+    try std.testing.expectEqualDeep(msg, from_bytes);
 }
 
 test {

src/root.zig

@@ -1,12 +1,4 @@
 pub const Client = @import("Client.zig");
 pub const Connection = @import("Connection.zig");
-pub const RawSocketWriter = @import("RawSocketWriter.zig");
 
-const msg = @import("message.zig");
-
-pub const PacketType = msg.PacketType;
-pub const foo = msg.foo;
-pub const ConnectionOptions = msg.ConnectionOptions;
-pub const MessageTypeError = msg.MessageTypeError;
-pub const MessageParseError = msg.MessageParseError;
-pub const Message = msg.Message;
+pub usingnamespace @import("message.zig");