static void process_udp(char *data)
{
struct proc_node *ipp = udp_procs;
struct ip *iph = (struct ip *) data;
struct udphdr *udph;
struct tuple4 addr;
int hlen = iph->ip_hl << 2;
int len = ntohs(iph->ip_len);
int ulen;
if (len - hlen < (int)sizeof(struct udphdr))
return;
udph = (struct udphdr *) (data + hlen);
ulen = ntohs(udph->UH_ULEN);
if (len - hlen < ulen || ulen < (int)sizeof(struct udphdr))
return;
if (my_udp_check
((void *) udph, ulen, iph->ip_src.s_addr,
iph->ip_dst.s_addr)) return;
addr.source = ntohs(udph->UH_SPORT);
addr.dest = ntohs(udph->UH_DPORT);
addr.saddr = iph->ip_src.s_addr;
addr.daddr = iph->ip_dst.s_addr;
while (ipp) {
ipp->item(&addr, ((char *) udph) + sizeof(struct udphdr),
ulen - sizeof(struct udphdr), data);
ipp = ipp->next;
}
}
static void process_udp(char *data, struct timeval* ts)
{
struct proc_node *ipp = udp_procs;
struct ip *iph = (struct ip *) data;
struct udphdr *udph;
struct tuple4 addr;
int hlen = iph->ip_hl << 2;
int len = ntohs(iph->ip_len);
int ulen;
if (len - hlen < (int)sizeof(struct udphdr))
return;
udph = (struct udphdr *) (data + hlen);
ulen = ntohs(udph->UH_ULEN);
if (len - hlen < ulen || ulen < (int)sizeof(struct udphdr))
return;
/* According to RFC768 a checksum of 0 is not an error (Sebastien Raveau) */
if (udph->uh_sum && my_udp_check
((void *) udph, ulen, iph->ip_src.s_addr,
iph->ip_dst.s_addr)) return;
addr.source = ntohs(udph->UH_SPORT);
addr.dest = ntohs(udph->UH_DPORT);
addr.saddr = iph->ip_src.s_addr;
addr.daddr = iph->ip_dst.s_addr;
while (ipp) {
ipp->item(&addr, ((char *) udph) + sizeof(struct udphdr),
ulen - sizeof(struct udphdr), data);
ipp = ipp->next;
}
}
int form_syn_response(char *data, int len)
{
struct ethhdr *ethh;
struct iphdr *iph;
struct udphdr *udph;
struct tcphdr *tcph;
uint8_t proto_in_ip = 0;
uint16_t checksum;
char tmp[6];
char *payload_ptr;
int payload_len;
ethh = (struct ethhdr *)data;
// FIXME: dest address of the server/client
memcpy(tmp, ethh->h_dest, 6);
memcpy(ethh->h_dest, ethh->h_source, 6);
memcpy(ethh->h_source, tmp, 6);
/* IP layer */
switch (ntohs(ethh->h_proto)) {
case ETH_P_IP:
iph = (struct iphdr *)(ethh + 1);
proto_in_ip = iph->protocol;
udph = (struct udphdr *)((uint32_t *)iph + iph->ihl);
tcph = (struct tcphdr *)((uint32_t *)iph + iph->ihl);
uint32_t tmp = iph->saddr;
iph->saddr = iph->daddr;
iph->daddr = tmp;
/* Do checksum */
iph->check = 0;
checksum = ip_fast_csum((unsigned char *)iph, iph->ihl);
iph->check = ~checksum;
break;
default:
fprint(ERROR, "protocol %04hx ", ntohs(ethh->h_proto));
goto done;
}
/* Transport layer */
switch (proto_in_ip) {
case IPPROTO_TCP:
payload_ptr = (char *)tcph + tcph->doff * 4;
payload_len = len - (payload_ptr - data);
/* TODO: there will be a mapping between sequence
number of p-c and s-p connection, the sequence difference
will be stored in the TCB, and code should be added, but not here
*/
tcph->ack_seq = htonl(ntohl(tcph->seq) + 1);
tcph->seq = 0;
uint16_t tmp_port = tcph->source;
tcph->source = tcph->dest;
tcph->dest = tmp_port;
tcph->ack = 1;
tcph->check = 0;
checksum = my_tcp_check((void *)tcph, len - ((char *)tcph - data),
iph->saddr, iph->daddr);
tcph->check = ~checksum;
break;
case IPPROTO_UDP:
fprint(ERROR, "a udp packet?\n");
payload_ptr = (char *)udph + 8;
payload_len = len - (payload_ptr - data);
udph->check = 0;
checksum = my_udp_check((void *)udph, ntohs(udph->len),
iph->saddr, iph->daddr);
udph->check = ~checksum;
break;
default:
fprint(ERROR, "protocol %d\n", proto_in_ip);
break;
}
done:
return 0;
}
