From 1cf8449e22af1c3bb63e4e15c85cace31459b1bf Mon Sep 17 00:00:00 2001
From: jack <jackjackbits@users.noreply.github.com>
Date: Sat, 18 Oct 2025 14:47:43 +0200
Subject: [PATCH] Fix decompression size limit to support max-sized file
 transfers

Root cause: BinaryProtocol.decode() was rejecting decompressed payloads
larger than maxPayloadBytes (1 MB), but TLV-encoded file transfers are
slightly larger due to metadata overhead.

Fixes:
- Changed decompression limit from maxPayloadBytes to maxFramedFileBytes
- This accounts for TLV overhead (~50 bytes) + binary protocol headers
- Now allows ~1.12 MB decompressed payloads (1 MB + overhead budget)

The failing test was:
- Creating 1 MB file content
- TLV encoding adds ~50 bytes (1,048,627 total)
- Compression reduces to ~1,084 bytes (highly repetitive data)
- During decode, decompression was rejecting the 1,048,627 byte output
- Now correctly allows it since 1,048,627 < 1,179,760 (maxFramedFileBytes)

All 154 tests now pass including 'Max-sized file transfer survives reassembly'
---
 bitchat/Protocols/BinaryProtocol.swift |  3 ++-
 bitchat/Services/BLEService.swift      | 11 ++++++-----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/bitchat/Protocols/BinaryProtocol.swift b/bitchat/Protocols/BinaryProtocol.swift
index fa87b848..cde49fd4 100644
--- a/bitchat/Protocols/BinaryProtocol.swift
+++ b/bitchat/Protocols/BinaryProtocol.swift
@@ -333,7 +333,8 @@ struct BinaryProtocol {
                     originalSize = Int(rawSize)
                 }
                 // Guard to keep decompression bounded to sane BLE payload limits
-                guard originalSize >= 0 && originalSize <= FileTransferLimits.maxPayloadBytes else { return nil }
+                // Use maxFramedFileBytes to account for TLV overhead in file transfer payloads
+                guard originalSize >= 0 && originalSize <= FileTransferLimits.maxFramedFileBytes else { return nil }
                 let compressedSize = payloadLength - lengthFieldBytes
                 guard compressedSize >= 0, let compressed = readData(compressedSize) else { return nil }
 
diff --git a/bitchat/Services/BLEService.swift b/bitchat/Services/BLEService.swift
index a2c291e3..8303c6ca 100644
--- a/bitchat/Services/BLEService.swift
+++ b/bitchat/Services/BLEService.swift
@@ -3395,7 +3395,7 @@ extension BLEService {
         if peerID == myPeerID {
             return
         }
-        
+
         // Minimum header: 8 bytes ID + 2 index + 2 total + 1 type
         guard packet.payload.count >= 13 else { return }
 
@@ -3441,10 +3441,11 @@ extension BLEService {
             }
             return FileTransferLimits.maxPayloadBytes
         }()
-        guard currentSize + fragmentData.count <= assemblyLimit else {
+        let projectedSize = currentSize + fragmentData.count
+        guard projectedSize <= assemblyLimit else {
             // Exceeds size limit - evict this assembly
             SecureLogger.warning(
-                "🚫 Fragment assembly exceeds size limit (\(currentSize + fragmentData.count) bytes > \(assemblyLimit)), evicting",
+                "🚫 Fragment assembly exceeds size limit (\(projectedSize) bytes > \(assemblyLimit)), evicting. Type=\(originalType) Index=\(index)/\(total)",
                 category: .security
             )
             incomingFragments.removeValue(forKey: key)
@@ -3464,14 +3465,14 @@ extension BLEService {
                     reassembled.append(fragment)
                 }
             }
-            
+
             // Decode the original packet bytes we reassembled, so flags/compression are preserved
             if let originalPacket = BinaryProtocol.decode(reassembled) {
                 handleReceivedPacket(originalPacket, from: peerID)
             } else {
                 SecureLogger.error("❌ Failed to decode reassembled packet (type=\(originalType), total=\(total))", category: .session)
             }
-            
+
             // Cleanup
             incomingFragments.removeValue(forKey: key)
             fragmentMetadata.removeValue(forKey: key)