sd-radv: Receive Router Solicitations

Receive Router Solicitations and send a unicast Router Advertisment
in response. Refactor ICMPv6 packet handling code so that the common
ICMPv6 validation parts are reused between the existing router
discovery and the new functionality adding reception of Router
Solicitation messages.

1 files changed, 20 insertions, 73 deletions

diff --git a/src/libsystemd-network/sd-ndisc.c b/src/libsystemd-network/sd-ndisc.c
index 83e57d43f7..0437e0b0b7 100644
--- a/src/libsystemd-network/sd-ndisc.c
+++ b/src/libsystemd-network/sd-ndisc.c
@@ -222,23 +222,9 @@ static int ndisc_handle_datagram(sd_ndisc *nd, sd_ndisc_router *rt) {
 static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
         _cleanup_(sd_ndisc_router_unrefp) sd_ndisc_router *rt = NULL;
         sd_ndisc *nd = userdata;
-        union {
-                struct cmsghdr cmsghdr;
-                uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
-                            CMSG_SPACE(sizeof(struct timeval))];
-        } control = {};
-        struct iovec iov = {};
-        union sockaddr_union sa = {};
-        struct msghdr msg = {
-                .msg_name = &sa.sa,
-                .msg_namelen = sizeof(sa),
-                .msg_iov = &iov,
-                .msg_iovlen = 1,
-                .msg_control = &control,
-                .msg_controllen = sizeof(control),
-        };
-        struct cmsghdr *cmsg;
-        ssize_t len, buflen;
+        ssize_t buflen;
+        int r;
+        _cleanup_free_ char *addr = NULL;
 
         assert(s);
         assert(nd);
@@ -252,66 +238,27 @@ static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userda
         if (!rt)
                 return -ENOMEM;
 
-        iov.iov_base = NDISC_ROUTER_RAW(rt);
-        iov.iov_len = rt->raw_size;
-
-        len = recvmsg(fd, &msg, MSG_DONTWAIT);
-        if (len < 0) {
-                if (errno == EAGAIN || errno == EINTR)
-                        return 0;
-
-                return log_ndisc_errno(errno, "Could not receive message from ICMPv6 socket: %m");
-        }
-
-        if ((size_t) len != rt->raw_size) {
-                log_ndisc("Packet size mismatch.");
-                return -EINVAL;
-        }
-
-        if (msg.msg_namelen == sizeof(struct sockaddr_in6) &&
-            sa.in6.sin6_family == AF_INET6)  {
-
-                if (in_addr_is_link_local(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr) <= 0) {
-                        _cleanup_free_ char *addr = NULL;
-
-                        (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr, &addr);
-                        log_ndisc("Received RA from non-link-local address %s. Ignoring.", strna(addr));
-                        return 0;
-                }
-
-                rt->address = sa.in6.sin6_addr;
-
-        } else if (msg.msg_namelen > 0) {
-                log_ndisc("Received invalid source address size from ICMPv6 socket: %zu bytes", (size_t) msg.msg_namelen);
-                return -EINVAL;
-        }
-
-        /* namelen == 0 only happens when running the test-suite over a socketpair */
-
-        assert(!(msg.msg_flags & MSG_CTRUNC));
-        assert(!(msg.msg_flags & MSG_TRUNC));
-
-        CMSG_FOREACH(cmsg, &msg) {
-                if (cmsg->cmsg_level == SOL_IPV6 &&
-                    cmsg->cmsg_type == IPV6_HOPLIMIT &&
-                    cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
-                        int hops = *(int*) CMSG_DATA(cmsg);
-
-                        if (hops != 255) {
-                                log_ndisc("Received RA with invalid hop limit %d. Ignoring.", hops);
-                                return 0;
-                        }
+        r = icmp6_receive(fd, NDISC_ROUTER_RAW(rt), rt->raw_size, &rt->address,
+                     &rt->timestamp);
+        if (r < 0) {
+                switch (r) {
+                case -EADDRNOTAVAIL:
+                        (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &rt->address, &addr);
+                        log_ndisc("Received RA from non-link-local address %s. Ignoring", addr);
+                        break;
+
+                case -EMULTIHOP:
+                        log_ndisc("Received RA with invalid hop limit. Ignoring.");
+                        break;
+
+                case -EPFNOSUPPORT:
+                        log_ndisc("Received invalid source address from ICMPv6 socket.");
+                        break;
                 }
 
-                if (cmsg->cmsg_level == SOL_SOCKET &&
-                    cmsg->cmsg_type == SO_TIMESTAMP &&
-                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
-                        triple_timestamp_from_realtime(&rt->timestamp, timeval_load((struct timeval*) CMSG_DATA(cmsg)));
+                return 0;
         }
 
-        if (!triple_timestamp_is_set(&rt->timestamp))
-                triple_timestamp_get(&rt->timestamp);
-
         nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 
         return ndisc_handle_datagram(nd, rt);