static int rtadv_recv_packet (int sock, u_char *buf, int buflen, struct sockaddr_in6 *from, unsigned int *ifindex, int *hoplimit) { int ret; struct msghdr msg; struct iovec iov; struct cmsghdr *cmsgptr; struct in6_addr dst; char adata[1024]; /* Fill in message and iovec. */ msg.msg_name = (void *) from; msg.msg_namelen = sizeof (struct sockaddr_in6); msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = (void *) adata; msg.msg_controllen = sizeof adata; iov.iov_base = buf; iov.iov_len = buflen; /* If recvmsg fail return minus value. */ ret = recvmsg (sock, &msg, 0); if (ret < 0) return ret; for (cmsgptr = ZCMSG_FIRSTHDR(&msg); cmsgptr != NULL; cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)) { /* I want interface index which this packet comes from. */ if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == IPV6_PKTINFO) { struct in6_pktinfo *ptr; ptr = (struct in6_pktinfo *) CMSG_DATA (cmsgptr); *ifindex = ptr->ipi6_ifindex; memcpy(&dst, &ptr->ipi6_addr, sizeof(ptr->ipi6_addr)); } /* Incoming packet's hop limit. */ if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == IPV6_HOPLIMIT) { int *hoptr = (int *) CMSG_DATA (cmsgptr); *hoplimit = *hoptr; } } return ret; }
static void * getsockopt_cmsg_data (struct msghdr *msgh, int level, int type) { struct cmsghdr *cmsg; void *ptr = NULL; for (cmsg = ZCMSG_FIRSTHDR(msgh); cmsg != NULL; cmsg = CMSG_NXTHDR(msgh, cmsg)) if (cmsg->cmsg_level == level && cmsg->cmsg_type) return (ptr = CMSG_DATA(cmsg)); return NULL; }