source: lib/protocols_transport.c @ db161c0

#include "libtrace.h"
#include "protocols.h"
#include <assert.h>
#include <stdlib.h>
#include <stdio.h> // fprintf

DLLEXPORT void *trace_get_transport(const libtrace_packet_t *packet, 
                uint8_t *proto,
                uint32_t *remaining
                ) 
{
        uint8_t dummy_proto;
        uint16_t ethertype;
        uint32_t dummy_remaining;
        void *transport;

        if (!proto) proto=&dummy_proto;

        if (!remaining) remaining=&dummy_remaining;

        transport = trace_get_layer3(packet,&ethertype,remaining);

        if (!transport || *remaining == 0)
                return NULL;

        switch (ethertype) {
                case TRACE_ETHERTYPE_IP: /* IPv4 */
                        transport=trace_get_payload_from_ip(
                                (libtrace_ip_t*)transport, proto, remaining);
                        /* IPv6 */
                        if (transport && *proto == TRACE_IPPROTO_IPV6) {
                                transport=trace_get_payload_from_ip6(
                                 (libtrace_ip6_t*)transport, proto,remaining);
                        }
                        return transport;
                case TRACE_ETHERTYPE_IPV6: /* IPv6 */
                        return trace_get_payload_from_ip6(
                                (libtrace_ip6_t*)transport, proto, remaining);
                        
                default:
                        fprintf(stderr,"unknown ethertype=%04x\n",ethertype);
                        *proto=0;
                        return NULL;
        }

}

DLLEXPORT libtrace_tcp_t *trace_get_tcp(libtrace_packet_t *packet) {
        uint8_t proto;
        libtrace_tcp_t *tcp;

        tcp=(libtrace_tcp_t*)trace_get_transport(packet,&proto,NULL);

        if (!tcp || proto != TRACE_IPPROTO_TCP)
                return NULL;

        return (libtrace_tcp_t*)tcp;
}

DLLEXPORT libtrace_tcp_t *trace_get_tcp_from_ip(libtrace_ip_t *ip, uint32_t *remaining)
{
        libtrace_tcp_t *tcpptr = 0;

        if (ip->ip_p == 6)  {
                tcpptr = (libtrace_tcp_t *)
                        trace_get_payload_from_ip(ip, NULL, remaining);
        }

        return tcpptr;
}

DLLEXPORT libtrace_udp_t *trace_get_udp(libtrace_packet_t *packet) {
        uint8_t proto;
        libtrace_udp_t *udp;

        udp=(libtrace_udp_t*)trace_get_transport(packet,&proto,NULL);

        if (!udp || proto != 17)
                return NULL;

        return udp;
}

DLLEXPORT libtrace_udp_t *trace_get_udp_from_ip(libtrace_ip_t *ip, uint32_t *remaining)
{
        libtrace_udp_t *udpptr = 0;

        if (ip->ip_p == TRACE_IPPROTO_UDP) {
                udpptr = (libtrace_udp_t *)
                        trace_get_payload_from_ip(ip, NULL, remaining);
        }

        return udpptr;
}

DLLEXPORT libtrace_icmp_t *trace_get_icmp(libtrace_packet_t *packet) {
        uint8_t proto;
        libtrace_icmp_t *icmp;

        icmp=(libtrace_icmp_t*)trace_get_transport(packet,&proto,NULL);

        if (!icmp || proto != TRACE_IPPROTO_ICMP)
                return NULL;

        return icmp;
}

DLLEXPORT libtrace_icmp_t *trace_get_icmp_from_ip(libtrace_ip_t *ip, uint32_t *remaining)
{
        libtrace_icmp_t *icmpptr = 0;

        if (ip->ip_p == TRACE_IPPROTO_ICMP)  {
                icmpptr = (libtrace_icmp_t *)trace_get_payload_from_ip(ip, 
                                NULL, remaining);
        }

        return icmpptr;
}

DLLEXPORT void *trace_get_payload_from_udp(libtrace_udp_t *udp, uint32_t *remaining)
{
        if (remaining) {
                if (*remaining < sizeof(libtrace_udp_t)) {
                        *remaining = 0;
                        return NULL;
                }
                *remaining-=sizeof(libtrace_udp_t);
        }
        return (void*)((char*)udp+sizeof(libtrace_udp_t));
}

DLLEXPORT void *trace_get_payload_from_tcp(libtrace_tcp_t *tcp, uint32_t *remaining)
{
        unsigned int dlen = tcp->doff*4;
        if (remaining) {
                if (*remaining < dlen) {
                        *remaining = 0;
                        return NULL;
                }
                *remaining-=dlen;
        }
        return (void *)((char *)tcp+dlen);
}

DLLEXPORT void *trace_get_payload_from_icmp(libtrace_icmp_t *icmp, uint32_t *remaining)
{
        if (remaining) {
                if (*remaining < sizeof(libtrace_icmp_t)) {
                        *remaining = 0;
                        return NULL;
                }
                *remaining-=sizeof(libtrace_icmp_t);
        }
        return (char*)icmp+sizeof(libtrace_icmp_t);
}

/* Return the client port
 */
DLLEXPORT uint16_t trace_get_source_port(const libtrace_packet_t *packet)
{
        uint32_t remaining;
        const struct ports_t *port = 
                (const struct ports_t*)trace_get_transport((libtrace_packet_t*)packet,
                        NULL, &remaining);

        /* snapped too early */
        if (remaining<2)
                return 0;

        if (port)
                return ntohs(port->src);
        else
                return 0;
}

/* Same as get_source_port except use the destination port */
DLLEXPORT uint16_t trace_get_destination_port(const libtrace_packet_t *packet)
{
        uint32_t remaining;
        struct ports_t *port = 
                (struct ports_t*)trace_get_transport((libtrace_packet_t*)packet,
                        NULL, &remaining);
        /* snapped to early */
        if (remaining<4)
                return 0;

        if (port)
                return ntohs(port->dst);
        else
                return 0;
}