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Log oversized compressed payloads before rejection #1682

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Log oversized compressed payloads before rejection #1682

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1b64bf4
fix: log oversized compressed payload rejection
qtjg Aug 18, 2026
d8a41fa
fix: correct UInt16 payload encoding line
qtjg Aug 18, 2026
e90fd38
test: cover oversized compressed payload rejection
qtjg Aug 18, 2026
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9 changes: 8 additions & 1 deletion localPackages/BitFoundation/Sources/BitFoundation/BinaryProtocol.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -366,7 +366,14 @@ public struct BinaryProtocol {
guard let rawSize = read16() else { return nil }
originalSize = Int(rawSize)
}
guard originalSize >= 0 && originalSize <= FileTransferLimits.maxFramedFileBytes else { return nil }
guard originalSize >= 0 else { return nil }
guard originalSize <= FileTransferLimits.maxFramedFileBytes else {
SecureLogger.warning(
"🚫 Compressed payload expanded size exceeds limit: \(originalSize) bytes > \(FileTransferLimits.maxFramedFileBytes) bytes",
category: .security
)
Comment on lines +371 to +374

@chatgpt-codex-connector chatgpt-codex-connector Bot Aug 18, 2026

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P2 Badge Avoid logging each oversized frame twice

When an oversized compressed frame is padded, decode(_:) first calls decodeCore on the padded data and then retries after MessagePadding.unpad; both attempts reach this warning before returning nil, so one received frame emits two identical security warnings and inflates any diagnostic count. Log the rejection only once across the two decode attempts, or propagate the rejection reason to the outer decoder.

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return nil
}
let compressedSize = payloadLength - lengthFieldBytes
guard compressedSize > 0, let compressed = readData(compressedSize) else { return nil }

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31 changes: 31 additions & 0 deletions localPackages/BitFoundation/Tests/BitFoundationTests/BinaryProtocolTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -349,6 +349,37 @@ struct BinaryProtocolTests {
let encoded = try #require(BinaryProtocol.encode(packet), "Failed to encode oversized packet")
#expect(BinaryProtocol.decode(encoded) == nil)
}

@Test("Log and reject compressed payloads above the expanded-size limit")
func compressedPayloadExpandedSizeAboveLimitIsRejected() {
var malformedData = Data()
malformedData.append(2) // v2
malformedData.append(MessageType.message.rawValue)
malformedData.append(1) // ttl
malformedData.append(contentsOf: Data(repeating: 0, count: 8)) // timestamp
malformedData.append(BinaryProtocol.Flags.isCompressed)

// The v2 payload length includes the four-byte original-size preamble.
let payloadLength: UInt32 = 6
malformedData.append(contentsOf: [
UInt8((payloadLength >> 24) & 0xFF),
UInt8((payloadLength >> 16) & 0xFF),
UInt8((payloadLength >> 8) & 0xFF),
UInt8(payloadLength & 0xFF)
])
malformedData.append(contentsOf: Data(repeating: 0x01, count: BinaryProtocol.senderIDSize))

let expandedSize = UInt32(FileTransferLimits.maxFramedFileBytes + 1)
malformedData.append(contentsOf: [
UInt8((expandedSize >> 24) & 0xFF),
UInt8((expandedSize >> 16) & 0xFF),
UInt8((expandedSize >> 8) & 0xFF),
UInt8(expandedSize & 0xFF)
])
malformedData.append(contentsOf: [0x78, 0x9C]) // compressed bytes are never reached

#expect(BinaryProtocol.decode(malformedData) == nil)
}

// MARK: - Message Padding Tests

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