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feat(net): acdream enters the world — CharacterList parsed + CharacterEnterWorld sent + 68 CreateObject received (Phase 4.7)

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Drives the full post-handshake flow on a live ACE server. After the
3-way handshake completes, acdream:
  1. Reassembles CharacterList and parses out every character on the
     account (tested against testaccount which has two: +Acdream and
     +Wdw). Full field decode: GUIDs, names, delete-delta, slotCount,
     accountName, turbine chat, ToD flag.
  2. Picks the first character and builds a single-fragment
     CharacterEnterWorldRequest (opcode 0xF7C8, empty body beyond opcode)
     on the UIQueue, wraps it with EncryptedChecksum + BlobFragments,
     consumes one outbound ISAAC keystream word, and sends.
  3. Waits for CharacterEnterWorldServerReady (opcode 0xF7DF) to confirm
     the server accepted our encrypted outbound packet.
  4. Builds CharacterEnterWorld (opcode 0xF657, body = u32 guid +
     String16L accountName) and sends as a second fragment with
     fragment_sequence 2, packet sequence 3.
  5. Drains 10 seconds of post-login traffic: 101 GameMessages assembled,
     68 of which are CreateObject (0xF745) — the entities around
     +Acdream spawning into our session. Also saw DeleteObject (0xF746),
     ObjectDescription (0xF74C), SetState (0xF755), GameEvent (0xF7B0),
     LoginCharacterSet (0xF7E0), and a 0x02CD smaller opcode.

This is the Phase 4.7 win: acdream is authenticated, connected,
character-selected, logged in, and actively receiving the world state
stream, all with ZERO protocol errors. Every byte of every packet we
sent to the server was correct — the first bit wrong in our outbound
ISAAC math would have produced silent disconnect instead of 101
successful replies.

Added to AcDream.Core.Net:
  - Messages/CharacterList.cs: full parser for opcode 0xF658, ported
    from ACE's GameMessageCharacterList writer. Returns structured
    record with Characters[], SlotCount, AccountName, UseTurbineChat,
    HasThroneOfDestiny. Tested offline with hand-assembled bodies
    matching ACE's writer format.
  - Messages/CharacterEnterWorld.cs: outbound builders for
    CharacterEnterWorldRequest (0xF7C8, opcode-only) and
    CharacterEnterWorld (0xF657, opcode + guid + String16L account).
  - Messages/GameMessageFragment.cs: helper to wrap a GameMessage body
    in a single MessageFragment with correct Id/Count/Index/Queue and
    Sequence. Also a Serialize helper to turn a MessageFragment into
    packet-body bytes for PacketCodec.Encode. Throws on oversize
    (>448 byte) messages; multi-fragment outbound split is TBD.
  - GameMessageGroup enum mirroring ACE byte-for-byte (UIQueue = 0x09
    is the one we use for enter-world).

Fixed: FragmentAssembler was keying on MessageFragmentHeader.Id, but
ACE's outbound fragment Id is ALWAYS the constant 0x80000000 — the
unique-per-message key is Sequence, matching how ACE's own
NetworkSession.HandleFragment keys its partialFragments dict. Our
live tests happened to work before because every GameMessage we'd
seen was single-fragment (hitting the Count==1 shortcut), but
multi-fragment CreateObject bodies would have silently mixed. Fixed
now and all 7 FragmentAssembler tests still pass with the Sequence-key.

Tests: 9 new offline (4 CharacterList, 2 CharacterEnterWorld, 3
GameMessageFragment), 1 new live (gated by ACDREAM_LIVE=1). Total
77 core + 83 net = 160 passing.

LIVE RUN OUTPUT:
  step 4: CharacterList received account=testaccount count=2
    character: id=0x5000000A name=+Acdream
    character: id=0x50000008 name=+Wdw
  choosing character: 0x5000000A +Acdream
  sent CharacterEnterWorldRequest: packet.seq=2 frag.seq=1 bytes=40
  step 6: CharacterEnterWorldServerReady received
  sent CharacterEnterWorld(guid=0x5000000A): packet.seq=3 frag.seq=2 bytes=60
  step 8 summary: 101 GameMessages assembled, 68 CreateObject
  unique opcodes seen: 0xF7B0, 0xF7E0, 0xF746, 0xF745, 0x02CD,
                       0xF755, 0xF74C

Phase 4.7 next: start decoding CreateObject bodies to extract GUID +
world position + setup/GfxObj id, so these entities can flow into
IGameState and render in the acdream game window. The foundry statue
is waiting in one of those 68 spawns.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik 2026-04-11 15:14:31 +02:00
parent 0aea24c78e
commit 94da385ff4
8 changed files with 629 additions and 10 deletions
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22
src/AcDream.Core.Net/Packets/FragmentAssembler.cs
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@ -3,9 +3,11 @@ namespace AcDream.Core.Net.Packets;
/// <summary>
/// Reassembles multi-fragment GameMessages. UDP packets can arrive in any
/// order and individual fragments within a logical message can be split
/// across packets, so we buffer partial messages keyed by fragment Id and
/// only yield a complete byte stream once every <c>Count</c> fragment for
/// that Id has arrived.
/// across packets, so we buffer partial messages keyed by fragment
/// <b>Sequence</b> (the actual unique identifier — ACE's outbound fragment
/// <c>Id</c> field is always the constant <c>0x80000000</c>; the
/// per-message-unique value is the <c>Sequence</c>, matching how ACE's
/// own <c>NetworkSession.HandleFragment</c> keys its partialFragments dict).
///
/// <para>
/// <b>Correctness properties:</b>
@ -14,11 +16,11 @@ namespace AcDream.Core.Net.Packets;
/// the full message is released on the last fragment regardless of
/// its index.</item>
/// <item>Duplicate-fragment idempotence: receiving index N twice for the
/// same Id is harmless — the second copy is silently ignored.</item>
/// same Sequence is harmless — the second copy is silently ignored.</item>
/// <item>Single-fragment messages: Count=1 releases immediately on
/// that one fragment with no buffering.</item>
/// <item>Orphaned partials: if fragments for an Id arrive but the message
/// never completes, they stay buffered until
/// <item>Orphaned partials: if fragments for a Sequence arrive but the
/// message never completes, they stay buffered until
/// <see cref="DropAll"/> is called or the assembler is disposed.
/// A future phase will add a TTL-based eviction.</item>
/// </list>
@ -56,10 +58,12 @@ public sealed class FragmentAssembler
return fragment.Payload;
}
if (!_inFlight.TryGetValue(h.Id, out var partial))
// Key on Sequence, not Id — ACE's outbound Id is a constant and
// its own inbound assembler keys on Sequence for the same reason.
if (!_inFlight.TryGetValue(h.Sequence, out var partial))
{
partial = new PartialMessage(h.Count, h.Queue);
_inFlight[h.Id] = partial;
_inFlight[h.Sequence] = partial;
}
// Idempotent: receiving the same index twice is not an error.
@ -86,7 +90,7 @@ public sealed class FragmentAssembler
offset += p.Length;
}
_inFlight.Remove(h.Id);
_inFlight.Remove(h.Sequence);
messageQueue = partial.Queue;
return combined;
}