Network Byte order not reached reading from a sock RAW

Pietro Paolini P.Paolini at ext.adbglobal.com
Fri Oct 12 12:04:41 EDT 2012


Hello,

I am struggling with the byte order question on a x86_32 arch, I am doing some modifications on a program which actually works fine on a MIPS arch.

I do a reading from a RAW socket in this way:

	/* Configure socket */
        if ((fd = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP)) < 0) {
                perror("Error on socket creation, exit");
                exit(1);
        }
	  ....
        if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, (void *)&va, sizeof(va))) {
                perror("Error on setsockopt, exit");
                exit(1);
        }
        va = 0;
	....
	....
	struct msghdr mhdr;
	struct __in_pktinfo *pktinfo = NULL;
	...
	...
	nrd = recvmsg(env->mrouter_fd, &mhdr, 0);	
	...
	ip = (struct iphdr *)iov.iov_base;

When I print the saddr (or daddr) of the received ip packet it is printed as host byte order instead of what I am expecting, the network byte order. I can just use the htonl() family functions for solve the problem but I would like understand if it is the normal behavior or if there is an issues on my code, or if the device driver of my NIC can influence the question.
Many thanks,
Pietro.




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