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add compression bomb protection

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This commit is contained in:
callebtc
2026-01-07 17:32:38 +07:00
parent aabd0011df
commit cc09d35e40
1 changed files with 29 additions and 9 deletions
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app/src/main/java/com/bitchat/android/protocol/BinaryProtocol.kt
+29 -9
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@@ -202,12 +202,12 @@ object BinaryProtocol {
try {
// Try to compress payload if beneficial
var payload = packet.payload
var originalPayloadSize: UShort? = null
var originalPayloadSize: Int? = null
var isCompressed = false
if (CompressionUtil.shouldCompress(payload)) {
CompressionUtil.compress(payload)?.let { compressedPayload ->
originalPayloadSize = payload.size.toUShort()
originalPayloadSize = payload.size
payload = compressedPayload
isCompressed = true
}
@@ -217,7 +217,8 @@ object BinaryProtocol {
val headerSize = getHeaderSize(packet.version)
val recipientBytes = if (packet.recipientID != null) RECIPIENT_ID_SIZE else 0
val signatureBytes = if (packet.signature != null) SIGNATURE_SIZE else 0
val payloadBytes = payload.size + if (isCompressed) 2 else 0
val sizeFieldBytes = if (isCompressed) (if (packet.version >= 2u.toUByte()) 4 else 2) else 0
val payloadBytes = payload.size + sizeFieldBytes
val capacity = headerSize + SENDER_ID_SIZE + recipientBytes + payloadBytes + signatureBytes + 16 // small slack
val buffer = ByteBuffer.allocate(capacity.coerceAtLeast(512)).apply { order(ByteOrder.BIG_ENDIAN) }
@@ -247,7 +248,7 @@ object BinaryProtocol {
buffer.put(flags.toByte())
// Payload length (2 or 4 bytes, big-endian) - includes original size if compressed
val payloadDataSize = payload.size + if (isCompressed) 2 else 0
val payloadDataSize = payload.size + sizeFieldBytes
if (packet.version >= 2u.toUByte()) {
buffer.putInt(payloadDataSize) // 4 bytes for v2+
} else {
@@ -284,7 +285,11 @@ object BinaryProtocol {
if (isCompressed) {
val originalSize = originalPayloadSize
if (originalSize != null) {
buffer.putShort(originalSize.toShort())
if (packet.version >= 2u.toUByte()) {
buffer.putInt(originalSize.toInt())
} else {
buffer.putShort(originalSize.toShort())
}
}
}
buffer.put(payload)
@@ -398,13 +403,28 @@ object BinaryProtocol {
// Payload
val payload = if (isCompressed) {
// First 2 bytes are original size
if (payloadLength.toInt() < 2) return null
val originalSize = buffer.getShort().toInt()
val lengthFieldBytes = if (version >= 2u.toUByte()) 4 else 2
if (payloadLength.toInt() < lengthFieldBytes) return null
val originalSize = if (version >= 2u.toUByte()) {
buffer.getInt()
} else {
buffer.getShort().toUShort().toInt()
}
// Compressed payload
val compressedPayload = ByteArray(payloadLength.toInt() - 2)
val compressedSize = payloadLength.toInt() - lengthFieldBytes
val compressedPayload = ByteArray(compressedSize)
buffer.get(compressedPayload)
// Security check: Compression bomb protection
if (compressedSize > 0) {
val ratio = originalSize.toDouble() / compressedSize.toDouble()
if (ratio > 50_000.0) {
Log.w("BinaryProtocol", "🚫 Suspicious compression ratio: ${ratio}:1")
return null
}
}
// Decompress
CompressionUtil.decompress(compressedPayload, originalSize) ?: return null