tiny.stun.Message

1pub const Message = struct {2    header: Header,3    bytes: []const u8,4    attribute_count: u14,56    pub fn decode(bytes: []const u8) DecodeError!Message {7        if (bytes.len < header_bytes) return error.MessageTooShort;8        const message_type = std.mem.readInt(u16, bytes[0..2], .big);9        if ((message_type & 0xc000) != 0) return error.InvalidMessageType;10        const payload_len = std.mem.readInt(u16, bytes[2..4], .big);11        if ((payload_len & 3) != 0) return error.InvalidMessageLength;12        const total = std.math.add(usize, header_bytes, payload_len) catch13            return error.InvalidMessageLength;14        if (total > bytes.len) return error.InvalidMessageLength;15        if (total < bytes.len) return error.TrailingBytes;16        if (std.mem.readInt(u32, bytes[4..8], .big) != magic_cookie) {17            return error.InvalidMagicCookie;18        }19        const header = Header{20            .class = decodeClass(message_type),21            .method = decodeMethod(message_type),22            .length = payload_len,23            .transaction_id = bytes[8..20].*,24        };25        const count = try validateAttributes(bytes, header.transaction_id);26        return .{ .header = header, .bytes = bytes, .attribute_count = count };27    }2829    pub fn attributes(self: Message) Iterator {30        return .{31            .bytes = self.bytes,32            .transaction_id = self.header.transaction_id,33        };34    }3536    pub fn verifyIntegrity(self: Message, key: []const u8) VerifyError!void {37        const item = try self.integrityItem() orelse return error.MissingIntegrity;38        const adjusted_len: u16 = @intCast(item.end - header_bytes);39        switch (item.attribute.value) {40            .message_integrity => |expected| {41                var actual: [integrity.sha1_bytes]u8 = undefined;42                integrity.hmacSha1Adjusted(43                    &actual,44                    self.bytes,45                    item.start,46                    adjusted_len,47                    key,48                );49                if (!integrity.equalSha1(actual, expected)) return error.IntegrityMismatch;50            },51            .message_integrity_sha256 => |expected| {52                var actual: [integrity.sha256_bytes]u8 = undefined;53                integrity.hmacSha256Adjusted(54                    &actual,55                    self.bytes,56                    item.start,57                    adjusted_len,58                    key,59                );60                if (!integrity.equalSha256(actual, expected)) return error.IntegrityMismatch;61            },62            else => unreachable,63        }64    }6566    pub fn verifyFingerprint(self: Message) VerifyError!void {67        var iterator = self.attributes();68        for (0..max_attribute_count) |_| {69            const item = try iterator.nextItem() orelse break;70            if (item.attribute.value == .fingerprint) {71                const expected = item.attribute.value.fingerprint;72                if (integrity.fingerprint(self.bytes[0..item.start]) != expected) {73                    return error.FingerprintMismatch;74                }75                return;76            }77        }78        return error.MissingFingerprint;79    }8081    fn integrityItem(self: Message) DecodeError!?Item {82        var iterator = self.attributes();83        var sha1: ?Item = null;84        for (0..max_attribute_count) |_| {85            const item = try iterator.nextItem() orelse break;86            switch (item.attribute.value) {87                .message_integrity_sha256 => return item,88                .message_integrity => if (sha1 == null) {89                    sha1 = item;90                },91                else => {},92            }93        }94        return sha1;95    }96};

1pub const Message = message_mod.Message;