Use writer instead of RawSocket in Client

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,
+    };
+}