going off the deep end with with generic message type

src/Client.zig

@@ -48,17 +48,15 @@ fn broadcastSaprusMessage(msg: *SaprusMessage, udp_port: u16) !void {
 }
 
 pub fn sendRelay(payload: []const u8, dest: [4]u8, allocator: Allocator) !void {
-    const msg: *SaprusMessage = try .init(
+    const msg: *SaprusMessageNew(.relay) = try .init(
         allocator,
-        .relay,
         @intCast(base64Enc.calcSize(payload.len)),
     );
     defer msg.deinit(allocator);
-    const relay = (try msg.getSaprusTypePayload()).relay;
+    msg.dest = dest;
-    relay.dest = dest;
+    _ = base64Enc.encode(msg.getPayload(), payload);
-    _ = base64Enc.encode(relay.getPayload(), payload);
 
-    try broadcastSaprusMessage(msg, 8888);
+    try broadcastSaprusMessage(try SaprusMessage.bytesAsValue(msg.asBytes()), 8888);
 }
 
 fn randomPort() u16 {
@@ -125,6 +123,7 @@ pub fn connect(payload: []const u8, allocator: Allocator) !?SaprusConnection {
 }
 
 const SaprusMessage = @import("message.zig").Message;
+const SaprusMessageNew = @import("message.zig").MessageNew;
 const SaprusConnection = @import("Connection.zig");
 
 const std = @import("std");

src/message.zig

@@ -26,6 +26,124 @@ pub const Error = error{
     InvalidMessage,
 };
 
+pub fn MessageNew(comptime packet_type: PacketType) type {
+    comptime {
+        if (packet_type == .file_transfer)
+            @compileError("File transfer not implemented");
+        if (packet_type != .relay and packet_type != .connection)
+            @compileError("Unkown message type");
+    }
+
+    return packed struct {
+        const Self = @This();
+        const SelfBytes = []align(@alignOf(Self)) u8;
+
+        const Relay = struct {
+            pub fn getPayload(self: *Self) []u8 {
+                return @as([*]align(@alignOf(Self)) u8, @ptrCast(&self.payload))[0 .. self.length - 4];
+            }
+        };
+        const Connection = packed struct {
+            pub fn getPayload(self: Self) []u8 {
+                return @as([*]u8, &self.payload)[0 .. self.length - 4];
+            }
+        };
+
+        type: PacketType = packet_type,
+        length: u16,
+
+        // Relay
+        dest: if (packet_type == .relay) @Vector(4, u8) else void,
+
+        // Connection
+        src_port: if (packet_type == .connection) u16 else void, // random number > 1024
+        dest_port: if (packet_type == .connection) u16 else void, // random number > 1024
+        seq_num: if (packet_type == .connection) u32 else void,
+        msg_id: if (packet_type == .connection) u32 else void,
+        reserved: if (packet_type == .connection) u8 else void,
+        options: if (packet_type == .connection) ConnectionOptions else void = if (packet_type == .connection) .{} else {},
+
+        // Relay or Connection
+        payload: switch (packet_type) {
+            .relay, .connection => void,
+            else => noreturn,
+        },
+
+        pub usingnamespace switch (packet_type) {
+            .relay => Relay,
+            .connection => Connection,
+            .file_transfer => @compileError("File Transfer message type not implemented"),
+            else => @compileError("Unknown message type"),
+        };
+
+        pub fn init(allocator: Allocator, payload_len: u16) !*Self {
+            const size = payload_len + @sizeOf(Self);
+            const bytes = try allocator.alignedAlloc(u8, @alignOf(Self), size);
+            const res: *Self = @ptrCast(bytes.ptr);
+            res.type = packet_type;
+            res.length = payload_len;
+            return res;
+        }
+
+        pub fn deinit(self: *Self, allocator: Allocator) void {
+            allocator.free(self.asBytes());
+        }
+
+        pub fn nativeFromNetworkEndian(self: *Self) void {
+            self.type = @enumFromInt(bigToNative(
+                @typeInfo(@TypeOf(self.type)).@"enum".tag_type,
+                @intFromEnum(self.type),
+            ));
+            self.length = bigToNative(@TypeOf(self.length), self.length);
+
+            if (packet_type == .connection) {
+                self.src_port = bigToNative(@TypeOf(self.src_port), self.src_port);
+                self.dest_port = bigToNative(@TypeOf(self.dest_port), self.dest_port);
+                self.seq_num = bigToNative(@TypeOf(self.seq_num), self.seq_num);
+                self.msg_id = bigToNative(@TypeOf(self.msg_id), self.msg_id);
+            }
+        }
+
+        pub fn networkFromNativeEndian(self: *Self) void {
+            self.type = @enumFromInt(bigToNative(
+                @typeInfo(@TypeOf(self.type)).@"enum".tag_type,
+                @intFromEnum(self.type),
+            ));
+            self.length = bigToNative(@TypeOf(self.length), self.length);
+
+            if (packet_type == .connection) {
+                self.src_port = nativeToBig(@TypeOf(self.src_port), self.src_port);
+                self.dest_port = nativeToBig(@TypeOf(self.dest_port), self.dest_port);
+                self.seq_num = nativeToBig(@TypeOf(self.seq_num), self.seq_num);
+                self.msg_id = nativeToBig(@TypeOf(self.msg_id), self.msg_id);
+            }
+        }
+
+        pub fn asBytes(self: *Self) SelfBytes {
+            const size = @sizeOf(Self) + self.length;
+            return @as([*]align(@alignOf(Self)) u8, @ptrCast(self))[0..size];
+        }
+    };
+}
+
+test MessageNew {
+    comptime for (@typeInfo(MessageNew(.connection)).@"struct".decls) |field| {
+        @compileLog(field);
+    };
+}
+
+// pub fn bytesAsMessage(bytes: []const u8) !*Self {
+//     const res = std.mem.bytesAsValue(Self, bytes);
+//     return switch (res.type) {
+//         .relay, .connection => if (bytes.len == res.length + @sizeOf(Self))
+//             res
+//         else
+//             Error.InvalidMessage,
+//         .file_transfer => Error.NotImplementedSaprusType,
+//         else => Error.UnknownSaprusType,
+//     };
+// }
+
 // ZERO COPY STUFF
 // &payload could be a void value that is treated as a pointer to a [*]u8
 /// All Saprus messages
@@ -216,45 +334,6 @@ const asBytes = std.mem.asBytes;
 const nativeToBig = std.mem.nativeToBig;
 const bigToNative = std.mem.bigToNative;
 
-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);
-}
-
 test {
     std.testing.refAllDeclsRecursive(@This());
 }