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Enhance PrivateMessagePacket encoding and decoding for variable content lengths

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HAMZA OZTURK - Mobil Operasyonel Cozumler Mudurlugu 2025-10-10 09:52:48 +03:00 committed by Hamza Öztürk
parent 97fc21c23f
commit a83f0fa735
1 changed files with 47 additions and 16 deletions
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63
bitchat/Protocols/Packets.swift
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@ -114,20 +114,19 @@ struct PrivateMessagePacket {
}
func encode() -> Data? {
var data = Data()
data.reserveCapacity(2 + min(messageID.count, 255) + 2 + min(content.count, 255))
// TLV for messageID
guard let messageIDData = messageID.data(using: .utf8), messageIDData.count <= 255 else { return nil }
guard let contentData = content.data(using: .utf8), contentData.count <= 65535 else { return nil }
var data = Data()
let estimatedMessageLength = 1 + 1 + messageIDData.count
let estimatedContentLength = contentData.count > 255 ? 1 + 3 + contentData.count : 1 + 2 + contentData.count
data.reserveCapacity(estimatedMessageLength + estimatedContentLength)
data.append(TLVType.messageID.rawValue)
data.append(UInt8(messageIDData.count))
data.append(messageIDData)
// TLV for content
guard let contentData = content.data(using: .utf8), contentData.count <= 255 else { return nil }
data.append(TLVType.content.rawValue)
data.append(UInt8(contentData.count))
data.append(contentData)
appendContentTLV(value: contentData, into: &data)
return data
}
@ -141,17 +140,20 @@ struct PrivateMessagePacket {
guard let type = TLVType(rawValue: data[offset]) else { return nil }
offset += 1
let length = Int(data[offset])
offset += 1
guard offset + length <= data.count else { return nil }
let value = data[offset..<offset + length]
offset += length
switch type {
case .messageID:
guard offset < data.count else { return nil }
let length = Int(data[offset])
offset += 1
guard offset + length <= data.count else { return nil }
let value = data[offset..<offset + length]
offset += length
messageID = String(data: value, encoding: .utf8)
case .content:
guard let length = readContentLength(from: data, offset: &offset) else { return nil }
guard offset + length <= data.count else { return nil }
let value = data[offset..<offset + length]
offset += length
content = String(data: value, encoding: .utf8)
}
}
@ -159,4 +161,33 @@ struct PrivateMessagePacket {
guard let messageID = messageID, let content = content else { return nil }
return PrivateMessagePacket(messageID: messageID, content: content)
}
private func appendContentTLV(value: Data, into buffer: inout Data) {
buffer.append(TLVType.content.rawValue)
if value.count <= 255 {
buffer.append(UInt8(value.count))
} else {
buffer.append(0xFF)
buffer.appendUInt16(UInt16(value.count))
}
buffer.append(value)
}
private static func readContentLength(from data: Data, offset: inout Int) -> Int? {
guard offset < data.count else { return nil }
let firstByte = Int(data[offset])
offset += 1
if firstByte < 255 {
return firstByte
}
guard offset + 2 <= data.count else { return nil }
let high = Int(data[offset])
let low = Int(data[offset + 1])
offset += 2
let length = (high << 8) | low
return length <= 65535 ? length : nil
}
}