Support joining multicast addresses (both ASM and SSM).
[cubemap] / udpinput.cpp
index 6b17799..5e39d66 100644 (file)
@@ -22,13 +22,91 @@ using namespace std;
 
 extern ServerPool *servers;
 
+namespace {
+
+// Similar to parse_hostport(), but only parses the IP address,
+// and does not use mapped-v4 addresses, since multicast seems
+// to not like that too much.
+bool parse_ip_address(const string &ip, sockaddr_storage *addr)
+{
+       memset(addr, 0, sizeof(*addr));
+
+       assert(!ip.empty());
+       if (ip[0] == '[') {
+               sockaddr_in6 *addr6 = (sockaddr_in6 *)addr;
+               addr6->sin6_family = AF_INET6;
+               if (ip[ip.size() - 1] != ']') {
+                       log(ERROR, "address '%s' is malformed; must be either [ipv6addr] or ipv4addr",
+                               ip.c_str());
+                       return false;
+               }
+               if (inet_pton(AF_INET6, ip.c_str(), &addr6->sin6_addr) != 1) {
+                       log(ERROR, "'%s' is not a valid IPv6 address");
+                       return false;
+               }
+       } else {
+               sockaddr_in *addr4 = (sockaddr_in *)addr;
+               addr4->sin_family = AF_INET;
+               if (inet_pton(AF_INET, ip.c_str(), &addr4->sin_addr) != 1) {
+                       log(ERROR, "'%s' is not a valid IPv4 address");
+                       return false;
+               }
+       }
+
+       return true;
+}
+
+bool maybe_join_multicast_group(int sock, const string &group, const string &source)
+{
+       if (group.empty()) {
+               // Not multicast.
+               return true;
+       }
+
+       // Join the given multicast group (ASM or SSM).
+       // TODO: Also support sources apart from multicast groups,
+       // e.g. udp://[::1]:1234 for only receiving from localhost.
+       if (!source.empty()) {
+               // Single-Source Multicast (SSM).
+               group_source_req gsr;
+               memset(&gsr, 0, sizeof(gsr));
+               if (!parse_ip_address(group, &gsr.gsr_group)) {
+                       return false;
+               }
+               if (!parse_ip_address(source, &gsr.gsr_source)) {
+                       return false;
+               }
+               int level = (gsr.gsr_group.ss_family == AF_INET) ? SOL_IP : SOL_IPV6;
+               if (setsockopt(sock, level, MCAST_JOIN_SOURCE_GROUP, &gsr, sizeof(gsr)) == -1) {
+                       log_perror("setsockopt(MCAST_JOIN_SOURCE_GROUP)");
+                       return false;
+               }
+       } else {
+               // Any-Source Multicast (ASM).
+               group_req gr;
+               memset(&gr, 0, sizeof(gr));
+               if (!parse_ip_address(group, &gr.gr_group)) {
+                       return false;
+               }
+               int level = (gr.gr_group.ss_family == AF_INET) ? SOL_IP : SOL_IPV6;
+               if (setsockopt(sock, level, MCAST_JOIN_GROUP, &gr, sizeof(gr)) == -1) {
+                       log_perror("setsockopt(MCAST_JOIN_GROUP)");
+                       return false;
+               }
+       }
+
+       return true;
+}
+
+}  // namespace
+
 UDPInput::UDPInput(const string &url)
        : url(url),
          sock(-1)
 {
        // Should be verified by the caller.
        string protocol;
-       bool ok = parse_url(url, &protocol, &host, &port, &path);
+       bool ok = parse_url(url, &protocol, &user, &host, &port, &path);
        assert(ok);
 
        construct_header();
@@ -46,7 +124,7 @@ UDPInput::UDPInput(const InputProto &serialized)
 {
        // Should be verified by the caller.
        string protocol;
-       bool ok = parse_url(url, &protocol, &host, &port, &path);
+       bool ok = parse_url(url, &protocol, &user, &host, &port, &path);
        assert(ok);
 
        construct_header();
@@ -108,6 +186,18 @@ void UDPInput::do_work()
                                usleep(200000);
                                continue;
                        }
+
+                       // The syntax udp://source@group (abusing the username field
+                       // to store the sender in SSM) seems to be a VLC invention.
+                       // We mimic it.
+                       if (!maybe_join_multicast_group(sock, host, user)) {
+                               log(WARNING, "[%s] Multicast join failed. Waiting 0.2 seconds and trying again...",
+                                            url.c_str());
+                               safe_close(sock);
+                               sock = -1;
+                               usleep(200000);
+                               continue;
+                       }
                }
 
                // Wait for a packet, or a wakeup.