(usagi-users 00512) Problem receiving the IPv6 headers

[SUPERJFG <SUPERJFG@xxxxxxxx>]

Hi.

I'm trying to receive the IPv6 headers of the incoming packets, and 
what I see is that the last header is always lost. As it's explained in 
the RFC, first the reception of these headers must be enabled. This 
corresponds to the following code:

#ifdef IPV6_RECVPKTINFO 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on, 
sizeof(on)); 
#else 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_PKTINFO, &on, 
sizeof(on)); 
#endif 
                                                                      
#ifdef IPV6_RECVHOPLIMIT 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on, 
sizeof(on)); 
#else 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_HOPLIMIT, &on, 
sizeof(on)); 
#endif 
                                                                      
#ifdef IPV6_RECVRTHDR 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_RECVRTHDR, &on, 
sizeof(on)); 
#else 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_RTHDR, &on, sizeof(on)); 
#endif 
                                                                      
#ifdef IPV6_RECVHOPOPTS 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_RECVHOPOPTS, &on, 
sizeof(on)); 
#else 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_HOPOPTS, &on, 
sizeof(on)); 
#endif 
                                                                      
#ifdef IPV6_RECVDSTOPTS 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_RECVDSTOPTS, &on, 
sizeof(on)); 
#else 
  setsockopt (socketDesc, IPPROTO_IPV6, IPV6_DSTOPTS, &on, 
sizeof(on)); 
#endif 


After thar, I try to see what my socket has received with the following 
code (I've simplified it just to show 
you):                                                                   
                                                                        
          
struct msghdr   msg;
struct cmsghdr  *cmsgptr;
                                                         

The variables are correctly initializated and the recvmsg call doesn't 
return any error, so in msg must be all the IPv6 headers.           

                                                           
for (cmsgptr = CMSG_FIRSTHDR(msg); cmsgptr != NULL;cmsgptr = 
CMSG_NXTHDR(msg, cmsgptr)) { 
                                                                      
    if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == 
IPV6_PKTINFO ) { 
      printf ("PKTINFO header\n"); 
    } 
    if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == 
IPV6_RTHDR ) { 
      printf ("RTHDR header\n"); 
    } 
    if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == 
IPV6_HOPOPTS ) { 
      printf ("HOPOPTS header\n"); 
    } 
    if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == 
IPV6_DSTOPTS ) { 
      printf ("DSTOPTS header\n"); 
    } 
    if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == 
IPV6_HOPLIMIT ) { 
      printf ("HOPLIMIT header\n"); 
    } 
                                                                      
   } 
                                                                      

It seems that the CMSG_NXTHDR macro ignores the last header (returns 
NULL while there's a header remaining), because I've tried to send 
several optional headers, and I always get all of them except for the 
last one. Someone knows something about this or has had a similar 
problem with this?

     I should be very grateful if someone could help.


                                        Thanks.
 

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