u_int32_t Checksum(Packet *iPkt,u_int32_t pktlen)
{
if( (iPkt == NULL) ||
pktlen == 0)
{
/* XXX */
return 1;
}
if(iPkt->iph)
{
if(IS_IP4(iPkt))
{
ip_checksum((void *)iPkt->iph,
(pktlen - ((void *) iPkt->iph - (void *)iPkt->pkt)));
}
else if(IS_IP6(iPkt))
{
ip6_checksum((void *)iPkt->iph,
(pktlen - ((void *) iPkt->iph - (void *)iPkt->pkt)));
}
else
{
goto cksum_err;
}
}
return 0;
cksum_err:
printf("[%s()]: Encountered an error while running checksum against a packet \n",
__FUNCTION__);
return 1;
}
/*
* Check header option specified against packet
*
* Return 1 if check is true (e.g. data matches)
* Return 0 if check is not true.
*/
ENGINE_LINKAGE int checkHdrOpt(void *p, HdrOptCheck *optData)
{
SFSnortPacket *pkt = (SFSnortPacket *)p;
/* Header field will be extracted from its native
* 1 or 2 bytes, converted to host byte order,
* and placed in a 4 byte value for easy comparison
*/
uint32_t value = 0;
if ((optData->hdrField & IP_HDR_OPTCHECK_MASK) && (!pkt->ip4_header))
return RULE_NOMATCH;
if ((optData->hdrField & TCP_HDR_OPTCHECK_MASK) &&
(!pkt->ip4_header || !pkt->tcp_header))
return RULE_NOMATCH;
if ((optData->hdrField & ICMP_HDR_OPTCHECK_MASK) &&
(!IPH_IS_VALID(pkt) || !pkt->icmp_header))
return RULE_NOMATCH;
switch (optData->hdrField)
{
/* IP Header Checks */
case IP_HDR_ID:
value = IS_IP6(pkt) ? ntohl(GET_IPH_ID(pkt)) : ntohs((uint16_t)GET_IPH_ID(pkt));
break;
case IP_HDR_PROTO:
//value = pkt->ip4_header->proto;
value = GET_IPH_PROTO(pkt);
break;
case IP_HDR_FRAGBITS:
return checkBits(optData->value, optData->op, ((ntohs(GET_IPH_OFF(pkt)) & 0xe000) & ~optData->mask_value));
break;
case IP_HDR_FRAGOFFSET:
value = ntohs(GET_IPH_OFF((pkt))) & 0x1FFF;
break;
case IP_HDR_TOS:
//value = pkt->ip4_header->type_service;
value = GET_IPH_TOS(pkt);
break;
case IP_HDR_TTL:
//value = pkt->ip4_header->time_to_live;
value = GET_IPH_TTL(pkt);
break;
case IP_HDR_OPTIONS:
return checkOptions(optData->value, optData->op, pkt->ip_options, pkt->num_ip_options);
break;
/* TCP Header checks */
case TCP_HDR_ACK:
value = ntohl(pkt->tcp_header->acknowledgement);
break;
case TCP_HDR_SEQ:
value = ntohl(pkt->tcp_header->sequence);
break;
case TCP_HDR_FLAGS:
return checkBits(optData->value, optData->op, (pkt->tcp_header->flags & ~optData->mask_value));
break;
case TCP_HDR_WIN:
value = ntohs(pkt->tcp_header->window);
break;
case TCP_HDR_OPTIONS:
return checkOptions(optData->value, optData->op, pkt->tcp_options, pkt->num_tcp_options);
break;
/* ICMP Header checks */
case ICMP_HDR_CODE:
value = pkt->icmp_header->code;
break;
case ICMP_HDR_TYPE:
value = pkt->icmp_header->type;
break;
case ICMP_HDR_ID:
if ((pkt->icmp_header->code == ICMP_ECHO_REQUEST) ||
(pkt->icmp_header->code == ICMP_ECHO_REPLY))
{
value = ntohs(pkt->icmp_header->icmp_header_union.echo.id);
}
else
{
return RULE_NOMATCH;
}
break;
case ICMP_HDR_SEQ:
if ((pkt->icmp_header->code == ICMP_ECHO_REQUEST) ||
(pkt->icmp_header->code == ICMP_ECHO_REPLY))
{
value = ntohs(pkt->icmp_header->icmp_header_union.echo.seq);
}
else
{
return RULE_NOMATCH;
}
break;
default:
return RULE_NOMATCH;
break;
}
return checkField(optData->op, value, optData->value);
}
/*--------------------------------------------------------------------
* Function: LogIPHeader(TextLog* )
*
* Purpose: Dump the IP header info to the given TextLog
*
* Arguments: log => TextLog to print to
*
* Returns: void function
*--------------------------------------------------------------------
*/
void LogIPHeader(TextLog* log, Packet * p)
{
if(!IPH_IS_VALID(p))
{
TextLog_Print(log, "IP header truncated\n");
return;
}
if(p->frag_flag)
{
/* just print the straight IP header */
TextLog_Puts(log, inet_ntoa(GET_SRC_ADDR(p)));
TextLog_Puts(log, " -> ");
TextLog_Puts(log, inet_ntoa(GET_DST_ADDR(p)));
}
else
{
if(GET_IPH_PROTO(p) != IPPROTO_TCP && GET_IPH_PROTO(p) != IPPROTO_UDP)
{
/* just print the straight IP header */
TextLog_Puts(log, inet_ntoa(GET_SRC_ADDR(p)));
TextLog_Puts(log, " -> ");
TextLog_Puts(log, inet_ntoa(GET_DST_ADDR(p)));
}
else
{
if (!BcObfuscate())
{
/* print the header complete with port information */
TextLog_Puts(log, inet_ntoa(GET_SRC_ADDR(p)));
TextLog_Print(log, ":%d -> ", p->sp);
TextLog_Puts(log, inet_ntoa(GET_DST_ADDR(p)));
TextLog_Print(log, ":%d", p->dp);
}
else
{
/* print the header complete with port information */
if(IS_IP4(p))
TextLog_Print(log, "xxx.xxx.xxx.xxx:%d -> xxx.xxx.xxx.xxx:%d", p->sp, p->dp);
else if(IS_IP6(p))
TextLog_Print(log, "x:x:x:x:x:x:x:x:%d -> x:x:x:x:x:x:x:x:%d", p->sp, p->dp);
}
}
}
if(!BcOutputDataLink())
{
TextLog_NewLine(log);
}
else
{
TextLog_Putc(log, ' ');
}
TextLog_Print(log, "%s TTL:%u TOS:0x%X ID:%u IpLen:%u DgmLen:%u",
protocol_names[GET_IPH_PROTO(p)],
GET_IPH_TTL(p),
GET_IPH_TOS(p),
IS_IP6(p) ? ntohl(GET_IPH_ID(p)) : ntohs((uint16_t)GET_IPH_ID(p)),
GET_IPH_HLEN(p) << 2,
GET_IP_DGMLEN(p));
/* print the reserved bit if it's set */
if((uint8_t)((ntohs(GET_IPH_OFF(p)) & 0x8000) >> 15) == 1)
TextLog_Puts(log, " RB");
/* printf more frags/don't frag bits */
if((uint8_t)((ntohs(GET_IPH_OFF(p)) & 0x4000) >> 14) == 1)
TextLog_Puts(log, " DF");
if((uint8_t)((ntohs(GET_IPH_OFF(p)) & 0x2000) >> 13) == 1)
TextLog_Puts(log, " MF");
TextLog_NewLine(log);
/* print IP options */
if(p->ip_option_count != 0)
{
LogIpOptions(log, p);
}
/* print fragment info if necessary */
if(p->frag_flag)
{
TextLog_Print(log, "Frag Offset: 0x%04X Frag Size: 0x%04X\n",
(p->frag_offset & 0x1FFF),
GET_IP_PAYLEN(p));
}
}
