SessionDatagram redesign: add src_addr, reclassify error signals

Add src_addr to SessionDatagram envelope (34-byte header: msg_type + src_addr + dest_addr + hop_limit) so transit routers can route error signals back to the packet's originator. Reclassify CoordsRequired/PathBroken as link-layer error signals (plaintext inside SessionDatagram) rather than e2e encrypted session messages. Transit routers generate these when forwarding fails and route them to src_addr; if source is also unreachable, drop silently. Remove redundant src_addr/dest_addr/hop_limit from SessionSetup, SessionAck, and DataPacket (now in envelope). DataPacket header reduced from 36 to 4 bytes. Remove PathBroken.original_src. Fix routing loop vulnerability: gate bloom filter path on having cached dest_coords to prevent blind forwarding between peers. Simplify select_best_candidate() to require coordinates. Fix gossip protocol type codes (0x11->0x20, 0x12->0x30, 0x13->0x31) for consistency across all design docs. All 5 design docs updated and cross-checked for consistency. 335 tests pass, zero warnings.
2026-08-12 01:27:32 +00:00 · 2026-02-12 11:32:45 +00:00
parent 2f8e97c0ab
commit d41009b778
9 changed files with 535 additions and 349 deletions
@@ -892,11 +892,16 @@ Post-handshake data packets between authenticated peers.
 │  │   1    │ payload          │ variable  │ Message-specific payload      │  │
 │  └────────┴──────────────────┴───────────┴───────────────────────────────┘  │
 │                                                                             │
-│  Link message types:                                                        │
+│  Link message types (inside encrypted frame):                                │
 │    0x10 = TreeAnnounce       0x30 = LookupRequest                          │
 │    0x20 = FilterAnnounce     0x31 = LookupResponse                         │
 │    0x40 = SessionDatagram    0x50 = Disconnect                             │
 │                                                                             │
+│  SessionDatagram (0x40) carries session-layer payloads:                     │
+│    0x00 = SessionSetup       0x10 = DataPacket                             │
+│    0x01 = SessionAck         0x20 = CoordsRequired                         │
+│                               0x21 = PathBroken                             │
+│                                                                             │
 └─────────────────────────────────────────────────────────────────────────────┘
 ```