networks1/trace at master · SravanthiAshokKumar/networks1 · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<sys/socket.h>
#include<unistd.h>
#include<pthread.h>
#include<poll.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<fcntl.h>
#include<sys/stat.h>
#include<signal.h>
#include<sys/sem.h>
#include<poll.h>
#include<pthread.h>
#include<sys/select.h>
#include<sys/un.h>
#define SA (struct sockaddr*)
#include<netinet/ip.h>
#include<netinet/ip_icmp.h>
unsigned short
csum (unsigned short *buf, int nwords)
{
 unsigned long sum;
 for (sum = 0; nwords > 0; nwords--)
sum += *buf++;
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return ~sum;
}
int main (int argc, char *argv[])
{
 if (argc != 2)
 {
 printf ("need destination for tracert\n");
 exit (0);
 }
  int sfd = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);
char buf[4096] = { 0 };
struct ip *ip_hdr = (struct ip *) buf;
int hop = 0;
 int one = 1;
const int *val = &one;
if(setsockopt (sfd, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0)
printf ("Cannot set HDRINCL!\n");
struct sockaddr_in addr;
addr.sin_port = htons (7);
addr.sin_family = AF_INET;
inet_pton (AF_INET, argv[1], &(addr.sin_addr));
while (1)
{
ip_hdr->ip_hl = 5;
ip_hdr->ip_v = 4;
ip_hdr->ip_tos = 0;
ip_hdr->ip_len = 20 + 8;
ip_hdr->ip_id = 10000;
ip_hdr->ip_off = 0;
ip_hdr->ip_ttl = hop;
ip_hdr->ip_p = IPPROTO_ICMP;
inet_pton (AF_INET, "192.168.117.105", &(ip_hdr->ip_src));
inet_pton (AF_INET, argv[1], &(ip_hdr->ip_dst));
ip_hdr->ip_sum = csum ((unsigned short *) buf, 9);
struct icmphdr *icmphd = (struct icmphdr *) (buf + 20);
icmphd->type = ICMP_ECHO;
icmphd->code = 0;
icmphd->checksum = 0;
icmphd->un.echo.id = 0;
icmphd->un.echo.sequence = hop + 1;
icmphd->checksum = csum ((unsigned short *) (buf + 20), 4);
sendto (sfd, buf, sizeof(struct ip) + sizeof(struct icmphdr), 0, SA & addr, sizeof addr);
char buff[4096] = { 0 };
struct sockaddr_in addr2;
socklen_t len = sizeof (struct sockaddr_in);
recvfrom (sfd, buff, sizeof(buff), 0, SA & addr2, &len);
struct icmphdr *icmphd2 = (struct icmphdr *) (buff + 20);
 if (icmphd2->type != 0)
printf ("hop limit:%d Address:%s\n", hop, inet_ntoa (addr2.sin_addr));
 else
{
 printf ("Reached destination:%s with hop limit:%d\n",
 inet_ntoa (addr2.sin_addr), hop);
exit (0);
}
 hop++;
 }
 return 0;
}