Add msgs with toBytes functions

src/main.zig

@@ -2,6 +2,40 @@
 //! you are building an executable. If you are making a library, the convention
 //! is to delete this file and start with root.zig instead.
 
+const SaprusPacketType = enum(u16) {
+    relay = 0x003C,
+    file_transfer = 0x8888,
+};
+
+const SaprusHeaderFrame = struct {
+    msg_type: SaprusPacketType,
+    payload: []u8,
+
+    const Self = @This();
+
+    fn toBytes(s: Self, allocator: Allocator) ![]u8 {
+        const buf = allocator.alloc(u8, 32 + s.payload.len);
+        std.mem.writeInt(u16, buf[0..2], s.msg_type, .big);
+        std.mem.writeInt(u16, buf[2..4], s.payload.len);
+        std.mem.copyForwards(u8, buf[4..], s.payload);
+        return buf;
+    }
+};
+
+const SaprusRelayMessage = struct {
+    dest: [4]u8,
+    payload: []u8,
+
+    const Self = @This();
+
+    fn toBytes(s: Self, allocator: Allocator) ![]u8 {
+        const buf = allocator.alloc(u8, 4 + s.payload.len);
+        std.mem.copyForwards(u8, buf[0..4], s.dest);
+        std.mem.copyForwards(u8, buf[4..], s.payload);
+        return buf;
+    }
+};
+
 pub fn main() !void {
     // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
     std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
@@ -37,3 +71,4 @@ test "fuzz example" {
 }
 
 const std = @import("std");
+const Allocator = std.mem.Allocator;