Use writer instead of RawSocket in Client

build.zig

@@ -1,72 +1,121 @@
 const std = @import("std");
 
-// Although this function looks imperative, note that its job is to
-// declaratively construct a build graph that will be executed by an external
-// runner.
+// 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).
 pub fn build(b: *std.Build) void {
-    // Standard target options allows the person running `zig build` to choose
+    // Standard target options allow 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.
 
-    const lib_mod = b.createModule(.{
+    // 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.
         .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,
     });
 
-    // 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,
-    });
+    mod.addImport("network", b.dependency("network", .{}).module("network"));
+    mod.addImport("gatorcat", b.dependency("gatorcat", .{}).module("gatorcat"));
 
-    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.
+    // 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.
     const exe = b.addExecutable(.{
         .name = "zaprus",
-        .root_module = exe_mod,
+        .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") },
+            },
+        }),
     });
 
     // This declares intent for the executable to be installed into the
-    // standard location when the user invokes the "install" step (the default
-    // step when running `zig build`).
+    // 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`.
     b.installArtifact(exe);
+    b.installArtifact(b.addLibrary(.{
+        .linkage = .static,
+        .name = "zaprus",
+        .root_module = mod,
+    }));
 
-    // 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.
+    // 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.
     const run_cmd = b.addRunArtifact(exe);
+    run_step.dependOn(&run_cmd.step);
 
-    // By making the run step depend on the install step, it will be run from the
+    // By making the run step depend on the default 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
@@ -75,21 +124,42 @@ pub fn build(b: *std.Build) void {
         run_cmd.addArgs(args);
     }
 
-    // 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,
+    // 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,
     });
 
-    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+    // A run step that will run the test executable.
+    const run_mod_tests = b.addRunArtifact(mod_tests);
 
-    // 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);
+    // 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.
 }

build.zig.zon

@@ -37,16 +37,16 @@
     // internet connectivity.
     .dependencies = .{
         .network = .{
-            .url = "https://github.com/ikskuh/zig-network/archive/c76240d2240711a3dcbf1c0fb461d5d1f18be79a.zip",
-            .hash = "network-0.1.0-AAAAAOwlAQAQ6zKPUrsibdpGisxld9ftUKGdMvcCSpaj",
+            .url = "git+https://github.com/ikskuh/zig-network#7947237eec317d9458897f82089f343a05450c2b",
+            .hash = "network-0.1.0-Pm-Agl8xAQBmkwohveGOfTk4zQnuqDs0Ptfbms4KP5Ce",
         },
         .clap = .{
-            .url = "git+https://github.com/Hejsil/zig-clap?ref=0.10.0#e47028deaefc2fb396d3d9e9f7bd776ae0b2a43a",
-            .hash = "clap-0.10.0-oBajB434AQBDh-Ei3YtoKIRxZacVPF1iSwp3IX_ZB8f0",
+            .url = "git+https://github.com/Hejsil/zig-clap#9cfa61596cd44ef7be35f8d2e108d2025e09868e",
+            .hash = "clap-0.10.0-oBajB_TnAQB0l5UdW9WYhhJDEswbedvwFOzzZwGknYeR",
         },
         .gatorcat = .{
-            .url = "git+https://github.com/kj4tmp/gatorcat.git#0a97b666677501db4939e3e8245f88a19e015893",
-            .hash = "gatorcat-0.3.4-WcrpTcleBwCta_9TjomuIGb3bdg2Pke_FXI_WkMTEivH",
+            .url = "git+https://github.com/jeffective/gatorcat#db73d0f7780331d82e785e85773d1afaf154c2e6",
+            .hash = "gatorcat-0.3.11-WcrpTQn0BwArrCFVHy9FPBIPDJQqPrFdJlhiyH7Ng5x4",
         },
     },
     .paths = .{

src/Client.zig

@@ -2,13 +2,13 @@ const base64Enc = std.base64.Base64Encoder.init(std.base64.standard_alphabet_cha
 const base64Dec = std.base64.Base64Decoder.init(std.base64.standard_alphabet_chars, '=');
 
 rand: Random,
-socket: gcat.nic.RawSocket,
+writer: *std.Io.Writer,
 
 const Self = @This();
 
 const max_message_size = 2048;
 
-pub fn init(interface_name: [:0]const u8) !Self {
+pub fn init(writer: *std.Io.Writer) !Self {
     var prng = Random.DefaultPrng.init(blk: {
         var seed: u64 = undefined;
         try posix.getrandom(mem.asBytes(&seed));
@@ -16,16 +16,14 @@ pub fn init(interface_name: [:0]const u8) !Self {
     });
     const rand = prng.random();
 
-    const socket: gcat.nic.RawSocket = try .init(interface_name);
-
     return .{
         .rand = rand,
-        .socket = socket,
+        .writer = writer,
     };
 }
 
 pub fn deinit(self: *Self) void {
-    self.socket.deinit();
+    self.writer.flush() catch {};
 }
 
 /// Used for relay messages and connection handshake.
@@ -70,16 +68,14 @@ fn broadcastInitialInterestMessage(self: *Self, msg_bytes: []align(@alignOf(Sapr
     const saprus_start_byte = 42;
     @memcpy(packet_bytes[saprus_start_byte .. saprus_start_byte + msg_bytes.len], msg_bytes);
 
-    try self.socket.linkLayer().send(packet_bytes[0 .. saprus_start_byte + msg_bytes.len]);
+    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 {
-    if (false) {
-        var foo: gcat.nic.RawSocket = try .init("enp7s0"); // /proc/net/dev
-        defer foo.deinit();
-    }
     const msg: *SaprusMessage = try .bytesAsValue(msg_bytes);
     try msg.networkFromNativeEndian();
     defer msg.nativeFromNetworkEndian() catch unreachable;
@@ -194,4 +190,3 @@ const posix = std.posix;
 const mem = std.mem;
 
 const network = @import("network");
-const gcat = @import("gatorcat");

src/RawSocketWriter.zig

@@ -0,0 +1,45 @@
+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

@@ -37,16 +37,18 @@ pub fn main() !void {
         .allocator = gpa,
     }) catch |err| {
         // Report useful error and exit.
-        diag.report(std.io.getStdErr().writer(), err) catch {};
+        try diag.reportToFile(.stderr(), err);
         return err;
     };
     defer res.deinit();
 
     if (res.args.help != 0) {
-        return clap.help(std.io.getStdErr().writer(), clap.Help, &params, .{});
+        return clap.helpToFile(.stderr(), clap.Help, &params, .{});
     }
 
-    var client = try SaprusClient.init("enp7s0");
+    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.relay) |r| {
@@ -65,7 +67,7 @@ pub fn main() !void {
         return;
     }
 
-    return clap.help(std.io.getStdErr().writer(), clap.Help, &params, .{});
+    return clap.helpToFile(.stderr(), clap.Help, &params, .{});
 }
 
 fn parseDest(in: ?[]const u8) [4]u8 {
@@ -90,5 +92,6 @@ 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/root.zig

@@ -1,4 +1,12 @@
 pub const Client = @import("Client.zig");
 pub const Connection = @import("Connection.zig");
+pub const RawSocketWriter = @import("RawSocketWriter.zig");
 
-pub usingnamespace @import("message.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;