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|
/// Type tag for Message union.
/// This is the first value in the actual packet sent over the network.
pub const PacketType = enum(u16) {
relay = 0x003C,
connection = 0x00E9,
_,
};
pub const MessageTypeError = error{
NotImplementedSaprusType,
UnknownSaprusType,
};
pub const MessageParseError = MessageTypeError || error{
InvalidMessage,
};
const message = @This();
pub const Message = union(PacketType) {
relay: Message.Relay,
connection: Message.Connection,
pub const Relay = message.Relay;
pub const Connection = message.Connection;
};
pub const relay_dest_len = 4;
pub fn parse(bytes: []const u8) MessageParseError!Message {
var in: Reader = .fixed(bytes);
const @"type" = in.takeEnum(PacketType, .big) catch |err| switch (err) {
error.InvalidEnumTag => return error.UnknownSaprusType,
else => return error.InvalidMessage,
};
const checksum = in.takeArray(2) catch return error.InvalidMessage;
switch (@"type") {
.relay => {
const dest: Relay.Dest = .fromBytes(
in.takeArray(relay_dest_len) catch return error.InvalidMessage,
);
const payload = in.buffered();
return .{
.relay = .{
.dest = dest,
.checksum = checksum.*,
.payload = payload,
},
};
},
.connection => {
const src = in.takeInt(u16, .big) catch return error.InvalidMessage;
const dest = in.takeInt(u16, .big) catch return error.InvalidMessage;
const seq = in.takeInt(u32, .big) catch return error.InvalidMessage;
const id = in.takeInt(u32, .big) catch return error.InvalidMessage;
const reserved = in.takeByte() catch return error.InvalidMessage;
const options = in.takeStruct(Connection.Options, .big) catch return error.InvalidMessage;
const payload = in.buffered();
return .{
.connection = .{
.src = src,
.dest = dest,
.seq = seq,
.id = id,
.reserved = reserved,
.options = options,
.payload = payload,
},
};
},
else => return error.NotImplementedSaprusType,
}
}
test parse {
_ = try parse(&[_]u8{ 0x00, 0x3c, 0x00, 0x17, 0xac, 0x12, 0x01, 0x1e, 0x72, 0x65, 0x6d, 0x6f, 0x76, 0x65, 0x20, 0x65, 0x76, 0x65, 0x6e, 0x74, 0x20, 0x6c, 0x6f, 0x67, 0x67, 0x65, 0x64 });
{
const expected: Message = .{
.connection = .{
.src = 12416,
.dest = 61680,
.seq = 0,
.id = 0,
.reserved = 0,
.options = @bitCast(@as(u8, 100)),
.payload = &[_]u8{ 0x69, 0x61, 0x6d, 0x64, 0x65, 0x66, 0x61, 0x75, 0x6c, 0x74 },
},
};
const actual = try parse(&[_]u8{ 0x00, 0xe9, 0x00, 0x18, 0x30, 0x80, 0xf0, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x64, 0x69, 0x61, 0x6d, 0x64, 0x65, 0x66, 0x61, 0x75, 0x6c, 0x74 });
try std.testing.expectEqualDeep(expected, actual);
}
}
const Relay = struct {
dest: Dest,
checksum: [2]u8 = undefined,
payload: []const u8,
pub const Dest = struct {
bytes: [relay_dest_len]u8,
/// Asserts bytes is less than or equal to 4 bytes
pub fn fromBytes(bytes: []const u8) Dest {
var buf: [4]u8 = @splat(0);
std.debug.assert(bytes.len <= buf.len);
@memcpy(buf[0..bytes.len], bytes);
return .{ .bytes = buf };
}
};
pub fn init(dest: Dest, payload: []const u8) Relay {
return .{ .dest = dest, .payload = payload };
}
/// Asserts that buf is large enough to fit the relay message.
pub fn toBytes(self: Relay, buf: []u8) []u8 {
var out: Writer = .fixed(buf);
out.writeInt(u16, @intFromEnum(PacketType.relay), .big) catch unreachable;
out.writeInt(u16, undefined, .big) catch unreachable; // Length field, but unread. Will switch to checksum
out.writeAll(&self.dest.bytes) catch unreachable;
out.writeAll(self.payload) catch unreachable;
return out.buffered();
}
test toBytes {
var buf: [1024]u8 = undefined;
const relay: Relay = .init(
.fromBytes(&.{ 172, 18, 1, 30 }),
// zig fmt: off
&[_]u8{
0x72, 0x65, 0x6d, 0x6f, 0x76, 0x65, 0x20, 0x65, 0x76, 0x65,
0x6e, 0x74, 0x20, 0x6c, 0x6f, 0x67, 0x67, 0x65, 0x64
},
// zig fmt: on
);
// zig fmt: off
var expected = [_]u8{
0x00, 0x3c, 0x00, 0x17, 0xac, 0x12, 0x01, 0x1e, 0x72,
0x65, 0x6d, 0x6f, 0x76, 0x65, 0x20, 0x65, 0x76, 0x65,
0x6e, 0x74, 0x20, 0x6c, 0x6f, 0x67, 0x67, 0x65, 0x64
};
// zig fmt: on
try expectEqualMessageBuffers(&expected, relay.toBytes(&buf));
}
};
const Connection = struct {
src: u16,
dest: u16,
seq: u32,
id: u32,
reserved: u8 = undefined,
options: Options = undefined,
payload: []const u8,
/// Reserved option values.
/// Currently unused.
pub const Options = packed struct(u8) {
opt1: bool = false,
opt2: bool = false,
opt3: bool = false,
opt4: bool = false,
opt5: bool = false,
opt6: bool = false,
opt7: bool = false,
opt8: bool = false,
};
/// Asserts that buf is large enough to fit the connection message.
pub fn toBytes(self: Connection, buf: []u8) []u8 {
var out: Writer = .fixed(buf);
out.writeInt(u16, @intFromEnum(PacketType.connection), .big) catch unreachable;
out.writeInt(u16, undefined, .big) catch unreachable; // Saprus length field, unread.
out.writeInt(u16, self.src, .big) catch unreachable;
out.writeInt(u16, self.dest, .big) catch unreachable;
out.writeInt(u32, self.seq, .big) catch unreachable;
out.writeInt(u32, self.id, .big) catch unreachable;
out.writeByte(self.reserved) catch unreachable;
out.writeStruct(self.options, .big) catch unreachable;
out.writeAll(self.payload) catch unreachable;
return out.buffered();
}
};
test "Round trip" {
{
const expected = [_]u8{ 0x0, 0xe9, 0x0, 0x15, 0x30, 0x80, 0xf0, 0xf0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x64, 0x36, 0x3a, 0x3a, 0x64, 0x61, 0x74, 0x61 };
const msg = (try parse(&expected)).connection;
var res_buf: [expected.len + 1]u8 = undefined; // + 1 to test subslice result.
const res = msg.toBytes(&res_buf);
try expectEqualMessageBuffers(&expected, res);
}
}
// Skip checking the length / checksum, because that is undefined.
fn expectEqualMessageBuffers(expected: []const u8, actual: []const u8) !void {
try std.testing.expectEqualSlices(u8, expected[0..2], actual[0..2]);
try std.testing.expectEqualSlices(u8, expected[4..], actual[4..]);
}
const std = @import("std");
const Allocator = std.mem.Allocator;
const Writer = std.Io.Writer;
const Reader = std.Io.Reader;
test {
std.testing.refAllDeclsRecursive(@This());
}
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