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TCP HDR variables
hi
i m new to this network programming .i was supposed to work on raw sockets in my academics.i m trying to get familiar with it by goin thru some codes available on net i got one code which is as follows
main (void)
{
int s = socket (PF_INET, SOCK_RAW, IPPROTO_TCP); /* open raw socket */
char datagram[4096]; /* this buffer will contain ip header, tcp header,
and payload. we'll point an ip header structure
at its beginning, and a tcp header structure after
that to write the header values into it */
struct ip *iph = (struct ip *) datagram;
struct tcphdr *tcph = (struct tcphdr *) datagram + sizeof (struct ip);
struct sockaddr_in sin;
/* the sockaddr_in containing the dest. address is used
in sendto() to determine the datagrams path */
sin.sin_family = AF_INET;
sin.sin_port = htons (P);/* you byte-order >1byte header values to network
byte order (not needed on big endian machines) */
sin.sin_addr.s_addr = inet_addr ("127.0.0.1");
memset (datagram, 0, 4096); /* zero out the buffer */
/* we'll now fill in the ip/tcp header values, see above for explanations */
iph->ip_hl = 5;
iph->ip_v = 4;
iph->ip_tos = 0;
iph->ip_len = sizeof (struct ip) + sizeof (struct tcphdr); /* no payload */
iph->ip_id = htonl (54321); /* the value doesn't matter here */
iph->ip_off = 0;
iph->ip_ttl = 255;
iph->ip_p = 6;
iph->ip_sum = 0; /* set it to 0 before computing the actual checksum later */
iph->ip_src.s_addr = inet_addr ("1.2.3.4");/* SYN's can be blindly spoofed */
iph->ip_dst.s_addr = sin.sin_addr.s_addr;
tcph->th_sport = htons (1234); /* arbitrary port */
tcph->th_dport = htons (P);
tcph->th_seq = random ();/* in a SYN packet, the sequence is a random */
tcph->th_ack = 0;/* number, and the ack sequence is 0 in the 1st packet */
tcph->th_x2 = 0;
tcph->th_off = 0; /* first and only tcp segment */
tcph->th_flags = TH_SYN; /* initial connection request */
tcph->th_win = htonl (65535); /* maximum allowed window size */
tcph->th_sum = 0;/* if you set a checksum to zero, your kernel's IP stack
should fill in the correct checksum during transmission */
tcph->th_urp = 0;
iph->ip_sum = csum ((unsigned short *) datagram, iph->ip_len >> 1);
/* finally, it is very advisable to do a IP_HDRINCL call, to make sure
that the kernel knows the header is included in the data, and doesn't
insert its own header into the packet before our data */
{ /* lets do it the ugly way.. */
int one = 1;
const int *val = &one
if (setsockopt (s, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0)
printf ("Warning: Cannot set HDRINCL!\n");
}
while (1)
{
if (sendto (s, /* our socket */
datagram, /* the buffer containing headers and data */
iph->ip_len, /* total length of our datagram */
0, /* routing flags, normally always 0 */
(struct sockaddr *) &sin, /* socket addr, just like in */
sizeof (sin)) < 0) /* a normal send() */
printf ("error\n");
else
printf (".");
}
return 0;
}
the error that i m getting is that
testraw.c:58: error: ‘struct tcphdr’ has no member named ‘th_sport’
testraw.c:59: error: ‘struct tcphdr’ has no member named ‘th_dport’
testraw.c:60: error: ‘struct tcphdr’ has no member named ‘th_seq’
testraw.c:61: error: ‘struct tcphdr’ has no member named ‘th_ack’
testraw.c:62: error: ‘struct tcphdr’ has no member named ‘th_x2’
testraw.c:63: error: ‘struct tcphdr’ has no member named ‘th_off’
testraw.c:64: error: ‘struct tcphdr’ has no member named ‘th_flags’
testraw.c:64: error: ‘TH_SYN’ undeclared (first use in this function)
testraw.c:64: error: (Each undeclared identifier is reported only once
testraw.c:64: error: for each function it appears in.)
testraw.c:65: error: ‘struct tcphdr’ has no member named ‘th_win’
testraw.c:66: error: ‘struct tcphdr’ has no member named ‘th_sum’
testraw.c:68: error: ‘struct tcphdr’ has no member named ‘th_u
its working fine when i change the tcph->sport to tcph->source
and changing the remaining some variables but i couldnt able to change all as i m not very much familiar with the raw sockets
if some one can help me regarding this issue will b very helpful for me in my academics assignments...
thnx in advance
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