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.zon

@@ -45,8 +45,8 @@
             .hash = "clap-0.10.0-oBajB434AQBDh-Ei3YtoKIRxZacVPF1iSwp3IX_ZB8f0",
         },
         .gatorcat = .{
-            .url = "git+https://github.com/kj4tmp/gatorcat.git#0a97b666677501db4939e3e8245f88a19e015893",
-            .hash = "gatorcat-0.3.4-WcrpTcleBwCta_9TjomuIGb3bdg2Pke_FXI_WkMTEivH",
+            .url = "git+https://github.com/kj4tmp/gatorcat#bb1847f6c95852e7a0ec8c07870a948c171d5f98",
+            .hash = "gatorcat-0.3.2-WcrpTf1mBwDrmPaIhKCfLJO064v8Sjjn7DBq4CKZSgHH",
         },
     },
     .paths = .{

src/Client.zig

@@ -1,86 +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,
-socket: gcat.nic.RawSocket,
+var rand: ?Random = null;
 
-const Self = @This();
-
-const max_message_size = 2048;
-
-pub fn init(interface_name: [:0]const u8) !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();
-
-    const socket: gcat.nic.RawSocket = try .init(interface_name);
-
-    return .{
-        .rand = rand,
-        .socket = socket,
-    };
+    rand = prng.random();
+    try network.init();
 }
 
-pub fn deinit(self: *Self) void {
-    self.socket.deinit();
+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);
-
-    try self.socket.linkLayer().send(packet_bytes[0 .. saprus_start_byte + msg_bytes.len]);
-}
-
-// fn broadcastSaprusMessage(msg_bytes: []align(@alignOf(SaprusMessage)) u8) !void {}
-
-fn broadcastSaprusMessage(msg_bytes: []align(@alignOf(SaprusMessage)) u8, udp_port: u16) !void {
+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: *SaprusMessage = try .bytesAsValue(msg_bytes);
+    const msg_bytes = msg.asBytes();
     try msg.networkFromNativeEndian();
     defer msg.nativeFromNetworkEndian() catch unreachable;
 
@@ -102,41 +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;
@@ -144,13 +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;
 
@@ -167,17 +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.?;
@@ -195,3 +148,5 @@ const mem = std.mem;
 
 const network = @import("network");
 const gcat = @import("gatorcat");
+
+const Allocator = mem.Allocator;

src/main.zig

@@ -42,23 +42,24 @@ pub fn main() !void {
     };
     defer res.deinit();
 
+    try SaprusClient.init();
+    defer SaprusClient.deinit();
+
     if (res.args.help != 0) {
         return clap.help(std.io.getStdErr().writer(), clap.Help, &params, .{});
     }
 
-    var client = try SaprusClient.init("enp7s0");
-    defer client.deinit();
-
     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,
         };

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 {