[SDL] Preparing a UDP packet with SDL_net

[James Buchwald]

I'm trying to write a client/server MMO using SDL_net for the networking on
both sides. However, I've run into a problem when using the SDLNet_WriteXX
family of functions. I'm trying to write a 16-bit packet type ID to a UDP
packet, but it always segfaults.

This is the code that I create my packets with:
// initialize packet to given size
    packet = SDLNet_AllocPacket(buffer_size + 1);
    if (!packet) {
        cout << "[error] failed to create packet" << endl;
        return;
    }
    // zero out the packet
    memset(packet->data, 0, buffer_size + 1);

And this is the code I use for writing data to the packet:
void AO_Packet::write16(Uint16 src) {
    if (read_only) return;
    if (position + sizeof(src) > packet->maxlen) {
        string error = "write16: not enough room in packet";
        cout << "[debug] " << error << endl;
        return;
    }
    SDLNet_Write16(src, packet->data[position]);
    position += sizeof(src);
}

Whenever my code runs, however, I get a segfault the first time
SDLNet_Write16 is called. The packet was successfully created, though, and
position is set to 0. Now I can't figure out what I'm doing wrong.

-- 
"If you see somebody who you don't know getting into a crop duster that
doesn't belong to you, report them." -- President George W. Bush
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