ref: 5b3b1bbab6c49148b9309d0a9de0ef33e1a63513
dir: /src/net_packet.c/
// // Copyright(C) 2005-2014 Simon Howard // // This program is free software; you can redistribute it and/or // modify it under the terms of the GNU General Public License // as published by the Free Software Foundation; either version 2 // of the License, or (at your option) any later version. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // DESCRIPTION: // Network packet manipulation (net_packet_t) // #include <ctype.h> #include <string.h> #include "m_misc.h" #include "net_packet.h" #include "z_zone.h" static int total_packet_memory = 0; net_packet_t *NET_NewPacket(int initial_size) { net_packet_t *packet; packet = (net_packet_t *) Z_Malloc(sizeof(net_packet_t), PU_STATIC, 0); if (initial_size == 0) initial_size = 256; packet->alloced = initial_size; packet->data = Z_Malloc(initial_size, PU_STATIC, 0); packet->len = 0; packet->pos = 0; total_packet_memory += sizeof(net_packet_t) + initial_size; //printf("total packet memory: %i bytes\n", total_packet_memory); //printf("%p: allocated\n", packet); return packet; } // duplicates an existing packet net_packet_t *NET_PacketDup(net_packet_t *packet) { net_packet_t *newpacket; newpacket = NET_NewPacket(packet->len); memcpy(newpacket->data, packet->data, packet->len); newpacket->len = packet->len; return newpacket; } void NET_FreePacket(net_packet_t *packet) { //printf("%p: destroyed\n", packet); total_packet_memory -= sizeof(net_packet_t) + packet->alloced; Z_Free(packet->data); Z_Free(packet); } // Read a byte from the packet, returning true if read // successfully boolean NET_ReadInt8(net_packet_t *packet, unsigned int *data) { if (packet->pos + 1 > packet->len) return false; *data = packet->data[packet->pos]; packet->pos += 1; return true; } // Read a 16-bit integer from the packet, returning true if read // successfully boolean NET_ReadInt16(net_packet_t *packet, unsigned int *data) { byte *p; if (packet->pos + 2 > packet->len) return false; p = packet->data + packet->pos; *data = (p[0] << 8) | p[1]; packet->pos += 2; return true; } // Read a 32-bit integer from the packet, returning true if read // successfully boolean NET_ReadInt32(net_packet_t *packet, unsigned int *data) { byte *p; if (packet->pos + 4 > packet->len) return false; p = packet->data + packet->pos; *data = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]; packet->pos += 4; return true; } // Signed read functions boolean NET_ReadSInt8(net_packet_t *packet, signed int *data) { if (NET_ReadInt8(packet,(unsigned int *) data)) { if (*data & (1 << 7)) { *data &= ~(1 << 7); *data -= (1 << 7); } return true; } else { return false; } } boolean NET_ReadSInt16(net_packet_t *packet, signed int *data) { if (NET_ReadInt16(packet, (unsigned int *) data)) { if (*data & (1 << 15)) { *data &= ~(1 << 15); *data -= (1 << 15); } return true; } else { return false; } } boolean NET_ReadSInt32(net_packet_t *packet, signed int *data) { if (NET_ReadInt32(packet, (unsigned int *) data)) { if (*data & (1 << 31)) { *data &= ~(1 << 31); *data -= (1 << 31); } return true; } else { return false; } } // Read a string from the packet. Returns NULL if a terminating // NUL character was not found before the end of the packet. char *NET_ReadString(net_packet_t *packet) { char *start; start = (char *) packet->data + packet->pos; // Search forward for a NUL character while (packet->pos < packet->len && packet->data[packet->pos] != '\0') { ++packet->pos; } if (packet->pos >= packet->len) { // Reached the end of the packet return NULL; } // packet->data[packet->pos] == '\0': We have reached a terminating // NULL. Skip past this NULL and continue reading immediately // after it. ++packet->pos; return start; } // Read a string from the packet, but (potentially) modify it to strip // out any unprintable characters which could be malicious control codes. // Note that this may modify the original packet contents. char *NET_ReadSafeString(net_packet_t *packet) { char *r, *w, *result; result = NET_ReadString(packet); if (result == NULL) { return NULL; } // w is always <= r, so we never produce a longer string than the original. w = result; for (r = result; *r != '\0'; ++r) { // TODO: This is a very naive way of producing a safe string; only // ASCII characters are allowed. Probably this should really support // UTF-8 characters as well. if (isprint(*r) || *r == '\n') { *w = *r; ++w; } } *w = '\0'; return result; } // Dynamically increases the size of a packet static void NET_IncreasePacket(net_packet_t *packet) { byte *newdata; total_packet_memory -= packet->alloced; packet->alloced *= 2; newdata = Z_Malloc(packet->alloced, PU_STATIC, 0); memcpy(newdata, packet->data, packet->len); Z_Free(packet->data); packet->data = newdata; total_packet_memory += packet->alloced; } // Write a single byte to the packet void NET_WriteInt8(net_packet_t *packet, unsigned int i) { if (packet->len + 1 > packet->alloced) NET_IncreasePacket(packet); packet->data[packet->len] = i; packet->len += 1; } // Write a 16-bit integer to the packet void NET_WriteInt16(net_packet_t *packet, unsigned int i) { byte *p; if (packet->len + 2 > packet->alloced) NET_IncreasePacket(packet); p = packet->data + packet->len; p[0] = (i >> 8) & 0xff; p[1] = i & 0xff; packet->len += 2; } // Write a single byte to the packet void NET_WriteInt32(net_packet_t *packet, unsigned int i) { byte *p; if (packet->len + 4 > packet->alloced) NET_IncreasePacket(packet); p = packet->data + packet->len; p[0] = (i >> 24) & 0xff; p[1] = (i >> 16) & 0xff; p[2] = (i >> 8) & 0xff; p[3] = i & 0xff; packet->len += 4; } void NET_WriteString(net_packet_t *packet, const char *string) { byte *p; size_t string_size; string_size = strlen(string) + 1; // Increase the packet size until large enough to hold the string while (packet->len + string_size > packet->alloced) { NET_IncreasePacket(packet); } p = packet->data + packet->len; M_StringCopy((char *) p, string, string_size); packet->len += string_size; }