apollo/MessageDecode.cpp at master · gamefreak/apollo · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
#ifdef WIN32
#include "stdint.h"
#endif

#include <apollo/Net/MessageDecode.h>
#include <string.h>

namespace Net
{

namespace MessageEncoding
{

ENetPacket* Encode ( const Message& msg )
{
	size_t packetLength = 2 + msg.message.length() + 4 + msg.dataLength;
	unsigned char* packetData = (unsigned char*)malloc(packetLength);

	uint16_t messageIDLength = msg.message.length();
	messageIDLength = htons(messageIDLength);
	memcpy(packetData, &messageIDLength, 2);
	memcpy(packetData + 2, msg.message.data(), msg.message.length());
	uint32_t messagePayloadLength = msg.dataLength;
	messagePayloadLength = htonl(messagePayloadLength);
	memcpy(packetData + 2 + msg.message.length(), &messagePayloadLength, 4);
	if (messagePayloadLength)
		memcpy(packetData + 2 + msg.message.length() + 4, msg.data, msg.dataLength);

	ENetPacket* packet = enet_packet_create(packetData, packetLength, ENET_PACKET_FLAG_RELIABLE);

	free((void*)packetData);

	return packet;
}

Message* Decode ( ENetPacket* packet )
{
	const unsigned char* data = (const unsigned char*)packet->data;
	uint16_t messageIDLength;
	memcpy(&messageIDLength, data, 2);
	messageIDLength = ntohs(messageIDLength); //find supposed length of messageID
	uint32_t messageLength;
	memcpy(&messageLength, data + 2 + messageIDLength, 4); //find supposed length of message data
	messageLength = ntohl(messageLength);

	if (messageIDLength + messageLength == packet->dataLength && messageIDLength < (packet->dataLength - 6)) //if its a valid message, interpret
	{
		char* messageID = (char*)alloca(messageIDLength + 1);
		messageID[messageIDLength] = 0;
		memcpy(messageID, data + 2, messageIDLength);

		for (unsigned i = 0; i <= messageIDLength; i++) //check messageID contents
		{//......................0........9....||...................A........Z....||...................a.........z....||................ _

			if (!((messageID[i] >= 48 && messageID[i]<= 57)  ||  (messageID[i] >= 65 && messageID[i] <= 90)  ||  (messageID[i] >= 97 && messageID[i] <= 122)  ||  (messageID[i] == 95)))
			{
				return NULL;
			}
		}


		void* messageBuffer = NULL;
		if (messageLength)
		{
			messageBuffer = alloca(messageLength);
			memcpy(messageBuffer, data + 2 + messageIDLength + 4, messageLength);
		}
		std::string messageIDString = std::string(messageID, messageIDLength);
		Message* result = new Message(messageIDString, messageBuffer, messageLength);
		return result; //this is only reached if the message passes the tests
	}
	return NULL; // invalid format
}

}

}