Adds the outbound-side primitives acdream needs to send a LoginRequest
packet to an ACE server: a growable byte buffer writer with AC's two
length-prefixed string formats, plus the LoginRequest payload builder
and parser.
PacketWriter (Packets/PacketWriter.cs):
- Growable byte[] buffer with little-endian WriteByte/UInt16/UInt32/Bytes
- WriteString16L: u16 length + ASCII bytes + zero-pad to 4-byte boundary
(pad counted from start of length prefix, matching ACE's Extensions.cs)
- WriteString32L: u32 outer length (= asciiLen+1) + 1 marker byte (value
ignored by reader, we emit 0) + ASCII + pad. Reader decrements the
outer length by 1 when consuming the marker, so asciiLen is recovered
correctly. Asserts ≤255 chars (two-byte-marker variant not needed for
acdream's dev credentials).
- ASCII encoding used instead of Windows-1252 since dev account names
and passwords are ASCII-safe; can switch to CodePages later if a
non-ASCII identifier ever turns up.
LoginRequest (Packets/LoginRequest.cs):
- Build(account, password, timestamp, clientVersion="1802") produces
the login payload bytes that go into the body of a packet whose
header has the LoginRequest flag set
- Parse(bytes) for tests and diagnostics — server never calls this
in production, but round-trip tests make the writer self-verifying
- NetAuthType enum mirrors ACE: Account/AccountPassword/GlsTicket
- Wire layout per ACE's PacketInboundLoginRequest:
String16L ClientVersion
u32 bodyLength (bytes remaining after this field)
u32 NetAuthType (2 = AccountPassword)
u32 AuthFlags (0 for normal client)
u32 Timestamp
String16L Account
String16L LoginAs (empty for non-admin)
String32L Password (when AccountPassword)
- bodyLength field is back-patched after the full body has been
written (classic "write placeholder, come back and patch" flow)
Tests (17 new, 61 total in net project, 138 across both test projects):
PacketWriter (11):
- u32 little-endian
- String16L: empty, 1/2/3-char with correct padding
- String32L: 2-char short, empty, >255 throws
- AlignTo4 no-op when aligned, pads when not
- Buffer grows past initial capacity on big writes
LoginRequest (6):
- Build→Parse round-trip with realistic credentials (testaccount/
testpassword/timestamp)
- Empty account/password round-trip (padding edge case)
- BodyLength field reflects actual remaining bytes after itself
- Total wire size is multiple of 4 (sanity check on padding)
- Different credentials produce different bytes
- End-to-end: payload embedded in a full Packet with LoginRequest
header flag + correct unencrypted checksum, PacketCodec.TryDecode
parses it, BodyBytes round-trips back to the same credentials
through LoginRequest.Parse
This gives acdream everything needed to construct the first datagram
of the handshake. Phase 4.5c next: WorldSession state machine to drive
the handshake sequence.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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