+#define IN6ADDR_ALL_DHCP_RELAY_AGENTS_AND_SERVERS_MC_INIT \
+ { { { 0xff,0x02,0,0,0,0,0,0,0,0,0,0,0,0x1,0,0x2 } } } /* ff02::1:2 */
+static const struct in6_addr in6addr_all_dhcp_relay_agents_and_servers_mc =
+ IN6ADDR_ALL_DHCP_RELAY_AGENTS_AND_SERVERS_MC_INIT;
+
+int dhcpv6_send_packet(int index, struct dhcpv6_packet *dhcp_pkt, int len)
+{
+ struct msghdr m;
+ struct iovec v;
+ struct in6_pktinfo *pktinfo;
+ struct cmsghdr *cmsg;
+ int fd, ret, opt = 1;
+ struct sockaddr_in6 src;
+ struct sockaddr_in6 dst;
+ void *control_buf;
+ size_t control_buf_len;
+
+ fd = socket(PF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
+ if (fd < 0)
+ return -errno;
+
+ if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
+ int err = errno;
+ close(fd);
+ return -err;
+ }
+
+ memset(&src, 0, sizeof(src));
+ src.sin6_family = AF_INET6;
+ src.sin6_port = htons(DHCPV6_CLIENT_PORT);
+
+ if (bind(fd, (struct sockaddr *) &src, sizeof(src)) <0) {
+ int err = errno;
+ close(fd);
+ return -err;
+ }
+
+ memset(&dst, 0, sizeof(dst));
+ dst.sin6_family = AF_INET6;
+ dst.sin6_port = htons(DHCPV6_SERVER_PORT);
+
+ dst.sin6_addr = in6addr_all_dhcp_relay_agents_and_servers_mc;
+
+ control_buf_len = CMSG_SPACE(sizeof(struct in6_pktinfo));
+ control_buf = g_try_malloc0(control_buf_len);
+ if (!control_buf) {
+ close(fd);
+ return -ENOMEM;
+ }
+
+ memset(&m, 0, sizeof(m));
+ memset(&v, 0, sizeof(v));
+
+ m.msg_name = &dst;
+ m.msg_namelen = sizeof(dst);
+
+ v.iov_base = (char *)dhcp_pkt;
+ v.iov_len = len;
+ m.msg_iov = &v;
+ m.msg_iovlen = 1;
+
+ m.msg_control = control_buf;
+ m.msg_controllen = control_buf_len;
+ cmsg = CMSG_FIRSTHDR(&m);
+ cmsg->cmsg_level = IPPROTO_IPV6;
+ cmsg->cmsg_type = IPV6_PKTINFO;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(*pktinfo));
+
+ pktinfo = (struct in6_pktinfo *)CMSG_DATA(cmsg);
+ memset(pktinfo, 0, sizeof(*pktinfo));
+ pktinfo->ipi6_ifindex = index;
+ m.msg_controllen = cmsg->cmsg_len;
+
+ ret = sendmsg(fd, &m, 0);
+ if (ret < 0) {
+ char *msg = "DHCPv6 msg send failed";
+
+ if (errno == EADDRNOTAVAIL) {
+ char *str = g_strdup_printf("%s (index %d)",
+ msg, index);
+ perror(str);
+ g_free(str);
+ } else
+ perror(msg);
+ }
+
+ g_free(control_buf);
+ close(fd);
+
+ return ret;
+}
+