Set a hop limit on our DHCPv6 messages.

diff --git a/dhcp6.c b/dhcp6.c
index 63ca4418463d75ca0b00e466be43964f3d6e7a1c..5a1a40412c6595fe39a0b2c90c7eb59221407c9a 100644 (file)
--- a/dhcp6.c
+++ b/dhcp6.c
@@ -704,7 +704,7 @@ dhcp6_sendmessage(struct interface *ifp, void (*callback)(void *))
 {
        struct dhcp6_state *state;
        struct ipv6_ctx *ctx;
-       struct sockaddr_in6 to;
+       struct sockaddr_in6 dst;
        struct cmsghdr *cm;
        struct in6_pktinfo pi;
        struct timeval RTprev;
@@ -713,12 +713,13 @@ dhcp6_sendmessage(struct interface *ifp, void (*callback)(void *))
        uint8_t neg;
        const char *broad_uni;
        const struct in6_addr alldhcp = IN6ADDR_LINKLOCAL_ALLDHCP_INIT;
+       int hoplimit = HOPLIMIT;
 
-       memset(&to, 0, sizeof(to));
-       to.sin6_family = AF_INET6;
-       to.sin6_port = htons(DHCP6_SERVER_PORT);
+       memset(&dst, 0, sizeof(dst));
+       dst.sin6_family = AF_INET6;
+       dst.sin6_port = htons(DHCP6_SERVER_PORT);
 #ifdef SIN6_LEN
-       to.sin6_len = sizeof(to);
+       dst.sin6_len = sizeof(dst);
 #endif
 
        state = D6_STATE(ifp);
@@ -729,10 +730,10 @@ dhcp6_sendmessage(struct interface *ifp, void (*callback)(void *))
            (state->state == DH6S_REQUEST &&
            (!IN6_IS_ADDR_LINKLOCAL(&state->unicast) || !ipv6_linklocal(ifp))))
        {
-               to.sin6_addr = alldhcp;
+               dst.sin6_addr = alldhcp;
                broad_uni = "broadcasting";
        } else {
-               to.sin6_addr = state->unicast;
+               dst.sin6_addr = state->unicast;
                broad_uni = "unicasting";
        }
 
@@ -829,8 +830,8 @@ logsend:
        }
 
        ctx = ifp->ctx->ipv6;
-       to.sin6_scope_id = ifp->index;
-       ctx->sndhdr.msg_name = (caddr_t)&to;
+       dst.sin6_scope_id = ifp->index;
+       ctx->sndhdr.msg_name = (caddr_t)&dst;
        ctx->sndhdr.msg_iov[0].iov_base = (caddr_t)state->send;
        ctx->sndhdr.msg_iov[0].iov_len = state->send_len;
 
@@ -845,6 +846,15 @@ logsend:
        pi.ipi6_ifindex = ifp->index;
        memcpy(CMSG_DATA(cm), &pi, sizeof(pi));
 
+       /* Hop limit */
+       cm = CMSG_NXTHDR(&ctx->sndhdr, cm);
+       if (cm == NULL) /* unlikely */
+               return -1;
+       cm->cmsg_level = IPPROTO_IPV6;
+       cm->cmsg_type = IPV6_HOPLIMIT;
+       cm->cmsg_len = CMSG_LEN(sizeof(hoplimit));
+       memcpy(CMSG_DATA(cm), &hoplimit, sizeof(hoplimit));
+
        if (sendmsg(ctx->dhcp_fd, &ctx->sndhdr, 0) == -1) {
                syslog(LOG_ERR, "%s: %s: sendmsg: %m", ifp->name, __func__);
                ifp->options->options &= ~DHCPCD_IPV6;