mcast_set_if函数-白红宇

mcast_set_if函数

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发布时间：2019-06-06

本文共 1377 字，大约阅读时间需要 4 分钟。

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           int sockfd_to_family(int);int mcast_set_if(int sockfd, const char *ifname, u_int ifindex){ switch (sockfd_to_family(sockfd)) { case AF_INET: { struct in_addr inaddr; struct ifreq ifreq; if (ifindex > 0) { if (if_indextoname(ifindex, ifreq.ifr_name) == NULL) { errno = ENXIO; /* i/f index not found */ return(-1); } goto doioctl; } else if (ifname != NULL) { strncpy(ifreq.ifr_name, ifname, IFNAMSIZ); doioctl: if (ioctl(sockfd, SIOCGIFADDR, &ifreq) < 0) { return(-1); } memcpy(&inaddr, &((struct sockaddr_in *) &ifreq.ifr_addr)->sin_addr, sizeof(struct in_addr)); } else { /* remove prev. set default */ inaddr.s_addr = htonl(INADDR_ANY); } return(setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_IF, &inaddr, sizeof(struct in_addr))); }#ifdef IPV6 case AF_INET6: { u_int idx; if ( (idx = ifindex) == 0) { if (ifname == NULL) { errno = EINVAL; /* must supply either index or name */ return(-1); } if ( (idx = if_nametoindex(ifname)) == 0) { errno = ENXIO; /* i/f name not found */ return(-1); } } return(setsockopt(sockfd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &idx, sizeof(idx))); }#endif default: { errno = EAFNOSUPPORT; return(-1); } }}