void do_udp(void *p)
{
g.packet_udp++;
if(g.print_flag_udp)
print_udp(p);
}
void do_udp( char * data )
{
global.packet_udp ++;
struct udphdr * pudp = (struct udphdr *)data;
if( global.print_flag_udp )
print_udp( pudp );
}
static void print_ipv4(FILE* dst, const struct ip* ip, bool compact){
void* payload = ((char*)ip) + 4*ip->ip_hl;
fprintf(dst, ";IPv4[%d/", 4*ip->ip_hl);
if(!compact){
fprintf(dst, "%d/",(u_int16_t)ntohs(ip->ip_len));
fprintf(dst, "%d",(u_int8_t)ip->ip_ttl);
} else {
fprintf(dst, "Len=%d:",(u_int16_t)ntohs(ip->ip_len));
fprintf(dst, "ID=%d:",(u_int16_t)ntohs(ip->ip_id));
fprintf(dst, "TTL=%d:",(u_int8_t)ip->ip_ttl);
fprintf(dst, "Chk=%d:",(u_int16_t)ntohs(ip->ip_sum));
}
if(ntohs(ip->ip_off) & IP_DF) {
fprintf(dst, "DF");
}
if(ntohs(ip->ip_off) & IP_MF) {
fprintf(dst, "MF");
}
if(!compact){
fprintf(dst, "] ; ");
} else {
fprintf(dst, " Tos=%0x];\t",(u_int8_t)ip->ip_tos);
}
switch( ip->ip_p ) {
case IPPROTO_TCP:
print_tcp(dst, ip, (const struct tcphdr*)payload,compact);
break;
case IPPROTO_UDP:
print_udp(dst, ip, (const struct udphdr*)payload,compact);
break;
case IPPROTO_ICMP:
print_icmp(dst, ip, (const struct icmphdr*)payload,compact);
break;
case IPPROTO_IGMP:
fprintf(dst, "IGMP");
break;
default:
fprintf(dst, "Unknown transport protocol: %d \n", ip->ip_p);
break;
}
}
int main(int argc, char **argv) {
int raw_mode = 0;
struct GlobalHeader ghead;
// parameter check
if(argc == 1) {
raw_mode = 0;
} else if(argc == 2) {
if(0 != strcmp(argv[1], "-r")) {
usage();
return 0;
}
raw_mode = 1;
} else {
usage();
return 0;
}
// read global header
if(!raw_mode) {
// XXX Should check link type and record snapshot length.
fread(&ghead, sizeof(unsigned char), sizeof(struct GlobalHeader), stdin);
if(ghead.magic != MAGIC_NUMBER) {
printf("invalid file format\n");
return 0;
}
printf("PCAP format v%d.%d, ", ghead.majorver, ghead.minorver);
if(ghead.linklayertype != 1) {
printf("unsupported link layer type\n");
return 0;
}
printf("link layer type: Ethernet.\n");
}
// read each packet
while (1) {
int i;
struct PacketHeader phead;
struct EthernetHeader ehead;
printf("\n");
// packet header
if (!raw_mode) {
// XXX Should use length information in decoding below.
if(sizeof(struct PacketHeader) != fread(&phead, sizeof(unsigned char), sizeof(struct PacketHeader), stdin)) break;
if(phead.packetsize > ghead.snapshotlength) {
printf("wrong packet at 0x%08x\n", (int)ftell(stdin));
return 0;
}
printf("<<<PCAP packet\n");
printf(" packet size: %d\n", phead.packetsize);
printf(" payload size: %d\n", phead.payloadsize);
}
// data captured from wire
get_ether(&ehead);
print_ether(&ehead);
if (ehead.length_type <= 1500) {
// old style packet
printf("Old style packet, length = %d\n", ehead.length_type);
printf("We don't support this packet now\n");
if (!raw_mode) {
dump(phead.packetsize-sizeof(ehead), 1);
}
} else if (ehead.length_type == 0x0800) {
// ASSIGNMENT: MODIFY THIS TO PRINT INFORMATION ABOUT ENCAPSULATED PAYLOAD.
struct IPv4Header ipv4head;
get_ipv4(&ipv4head);
print_ipv4(&ipv4head);
if(ipv4head.protocol == 4) {
printf("IP packet\n");
printf("Wedon't support this packet now\n");
dump(ipv4head.datalen-sizeof(ipv4head), 1);
} else if(ipv4head.protocol == 6) {
struct TCPHeader tcphead;
get_tcp(&tcphead);
print_tcp(&tcphead);
// get payload in TCP packet
//dump(ipv4head.datalen-sizeof(ipv4head)-sizeof(tcphead), 2);
if(phead.packetsize >= sizeof(ehead)+ipv4head.datalen) {
dump(ipv4head.datalen-sizeof(ipv4head)-sizeof(tcphead), 0);
} else {
dump((ipv4head.datalen-sizeof(ipv4head)-sizeof(tcphead))-(sizeof(ehead)+ipv4head.datalen-phead.packetsize), 0);
}
} else if(ipv4head.protocol == 17) {
struct UDPHeader udphead;
get_udp(&udphead);
assert(udphead.size == ipv4head.datalen-sizeof(ipv4head));
print_udp(&udphead);
// get payload in UDP packet
if(phead.packetsize >= sizeof(ehead)+ipv4head.datalen) {
dump(udphead.size-sizeof(udphead), 0);
} else {
dump((udphead.size-sizeof(udphead))-(sizeof(ehead)+ipv4head.datalen-phead.packetsize), 0);
}
} else {
printf("Unexpected IP packet\n");
dump(ipv4head.datalen-sizeof(ipv4head), 1);
}
if(!raw_mode) {
if(phead.packetsize > sizeof(ehead)+ipv4head.datalen) {
printf("pad:\n");
dump(phead.packetsize-sizeof(ehead)-ipv4head.datalen, 1);
}
}
} else if(ehead.length_type == 0x0806) {
printf("ARP packet\n");
printf("We don't support this packet now\n");
if (!raw_mode) {
dump(phead.packetsize-sizeof(ehead), 1);
}
} else if(ehead.length_type == 0x86DD) {
printf("IPv6 packet\n");
printf("We don't support this packet now\n");
if (!raw_mode) {
dump(phead.packetsize-sizeof(ehead), 1);
}
} else {
printf("Unexpected Ethernet packet\n");
if (!raw_mode) {
dump(phead.packetsize-sizeof(ehead), 1);
}
}
}
return 0;
}
