Running into a heap corruption with WinSock2 application - heap-memory

Question

I have a feeling it's a stupid error, but I am making a echo server to identify packets, and output the data, then resend it back. It works on some packets, but one I'm trying to echo is breaking and saying there is a heap being corrupted.
Vector class, just using as container for now:
class vec2
{
public:
vec2(){};
float x, y;
};
PlayerData struct:
struct PlayerData
{
vec2 pos;
int health;
float rotation;
char moveflags;
short playerID;
};
Packet I'm trying to send:
struct ServerPacket_SyncGame //5
{
short packetID;
PlayerData data[8];
};
The next part is messy, but I'll comment it to try to make sense.
ServerPacket_SyncGame* SP_SG = new ServerPacket_SyncGame; //creates packet pointer
for(int i = 0; i < 8; i++) //assigns the eight playerdata structs in the packet array
{
SP_SG->data[i].playerID = i;
SP_SG->data[i].health = rand() % 30;
SP_SG->data[i].moveflags = 'D';
SP_SG->data[i].pos.x = rand() % 1000;
SP_SG->data[i].pos.y = rand() % 1000;
SP_SG->data[i].rotation = rand() % 360;
}
SP_SG->packetID = 5; //assigns the packet id
cout << "\n\nSent data: \n"; ////Outputting the data to be sent
for(int i = 0; i < 8; i++)
cout << "\nPlayer ID: " << SP_SG->data[i].playerID << "\nPosition: ("
<< SP_SG->data[i].pos.x << ", " << SP_SG->data[i].pos.y
<< ")\nHealth: " << SP_SG->data[i].health << "\nRotation: "
<<SP_SG->data[i].rotation << "\nMove Flags: "
<< SP_SG->data[i].moveflags << endl;
void* SP_SG_DAT = (void*)SP_SG; //casting the packet into a void*
char* SP_SG_BUFF = (char*)SP_SG_DAT; //casting from a void* to a char*
send(Socket, SP_SG_BUFF, sizeof(ServerPacket_SyncGame), 0); //sends the char*
char* SP_SG_RCVBUFF = new char; //new buffer for recv
recv(Socket, SP_SG_RCVBUFF, sizeof(ServerPacket_SyncGame), 0); //recv new buffer
void* SP_SG_RCVDAT = (void*) SP_SG_RCVBUFF; //casts char* to void* again
ServerPacket_SyncGame* RCVSP_SG = (ServerPacket_SyncGame*) SP_SG_RCVDAT;
//casts from void* to packet*
cout << "\n\nRecieved Data:\n\n"; //outputs converted received information
for(int i = 0; i < 8; i++)
cout << "\nPlayer ID: " << SP_SG->data[i].playerID << "\nPosition: ("
<< SP_SG->data[i].pos.x << ", " << SP_SG->data[i].pos.y
<< ")\nHealth: " << SP_SG->data[i].health << "\nRotation: "
<<SP_SG->data[i].rotation << "\nMove Flags: "
<< SP_SG->data[i].moveflags << endl;
I've used this method with other packets, and it's worked perfectly, server side this is how it echos:
for(;;)
{
char* buffer = new char;
char* temp = new char;
int size = recv(Socket, buffer, sizeof(ServerPacket_SyncGame), 0);
memcpy(temp, buffer, size);
send(Socket, (char*)InterpretInfo((void*)temp), size, 0);
};
InterpretInfo accepts the void* that you cast out of the char* you recieve, it deals with it like this:
void* InterpretInfo(void* data)
{
short* tempsht = static_cast<short*>(data);
cout << "\n\nRecieved packet ID: " << *tempsht;
switch(*tempsht)
{
This particular packet's ID is 5, this is it's case:
case 5:
//ServerPacket_SyncGame
{
cout << " which is ServerPacket_SyncGame\n";
ServerPacket_SyncGame* decoded = (ServerPacket_SyncGame*)data;
for(int i = 0; i < 8; i++)
{
cout << "Player ID: " << decoded->data[i].playerID ;
cout << "\nPosition: (" << decoded->data[i].pos.x << ", "
<< decoded->data[i].pos.y << ")\n";
cout << "Health: " << decoded->data[i].health
<< "\nRotation: " << decoded->data[i].rotation
<< "\nMove Flags: " << decoded->data[i].moveflags << endl;
}
return(void*)decoded;
}
It only does it with this packet, and it breaks and says the heap is corrupted when I try to access anything from the packet, though in debug mode I can read all information in the packet clearly.
I need at least 10 rep to post a picture, so here is a link to what I'm talking about in the running code:
http://i.imgur.com/Dbyi0c3.png
Thank you in advanced for any help or insight to help me get this done, I'm still quite novice at C++ and love to learn.

Answer 1

You are allocating only 1 byte for the recv() buffer, but you are trying to read sizeof(ServerPacket_SyncGame) number of bytes into it. You need to change this:
char* SP_SG_RCVBUFF = new char; //new buffer for recv
To this:
char* SP_SG_RCVBUFF = new char[sizeof(ServerPacket_SyncGame)];
Same thing with your for loop:
for(;;)
{
//char* buffer = new char;
char* buffer = new char[sizeof(ServerPacket_SyncGame)];
//char* temp = new char;
char* temp = new char[sizeof(ServerPacket_SyncGame)];
...
};
I would suggest you clean up your code:
ServerPacket_SyncGame* SP_SG = new ServerPacket_SyncGame; //creates packet pointer
for(int i = 0; i < 8; i++) //assigns the eight playerdata structs in the packet array
{
SP_SG->data[i].playerID = i;
SP_SG->data[i].health = rand() % 30;
SP_SG->data[i].moveflags = 'D';
SP_SG->data[i].pos.x = rand() % 1000;
SP_SG->data[i].pos.y = rand() % 1000;
SP_SG->data[i].rotation = rand() % 360;
}
SP_SG->packetID = 5; //assigns the packet id
...
// don't forget to do error handling on this, and pay attention to the
// return value so you know if you actually sent the entire struct or not...
send(Socket, (char*)SP_SG, sizeof(ServerPacket_SyncGame), 0);
delete SP_SG;
SP_SG = new ServerPacket_SyncGame;
// don't forget to do error handling on this, and pay attention to the
// return value so you know if you actually received the entire struct or not...
recv(Socket, (char*)SP_SG, sizeof(ServerPacket_SyncGame), 0); //recv new buffer
...
delete SP_SG;
ServerPacket_SyncGame buffer;
for(;;)
{
// don't forget to do error handling on this, and pay attention to the
// return value so you know if you actually received the entire struct or not...
int size = recv(Socket, &buffer, sizeof(ServerPacket_SyncGame), 0);
if (size > 0)
{
// don't forget to do error handling on this, and pay attention to the
// return value so you know if you actually sent the entire struct or not...
send(Socket, (char*)InterpretInfo(&buffer), size, 0);
}
};