srsenb: implement expert.sctp_nodelay

lib/include/srsran/common/network_utils.h

@@ -88,14 +88,16 @@ class unique_socket
   bool connect_to(const char* dest_addr_str, int dest_port, sockaddr_in* dest_sockaddr = nullptr);
   bool start_listen();
   bool reuse_addr();
+  bool nodelay(int enable);
   bool sctp_subscribe_to_events();
   bool sctp_set_rto_opts(int rto_max);
   bool sctp_set_init_msg_opts(int max_init_attempts, int max_init_timeo);
   int  get_socket() const { return sockfd; };
 
 protected:
-  sockaddr_in addr   = {};
-  int         sockfd = -1;
+  net_utils::protocol_type proto  = net_utils::protocol_type::NONE;
+  sockaddr_in              addr   = {};
+  int                      sockfd = -1;
 };
 
 namespace net_utils {

lib/include/srsran/interfaces/enb_s1ap_interfaces.h

@@ -44,6 +44,7 @@ struct s1ap_args_t {
   int32_t     max_s1_setup_retries;
   uint32_t    s1_connect_timer;
   bool        sctp_reuse_addr;
+  bool        sctp_nodelay;
   int32_t     sctp_rto_max;
   int32_t     sctp_init_max_attempts;
   int32_t     sctp_max_init_timeo;

lib/src/common/network_utils.cc

@@ -220,6 +220,34 @@ bool reuse_addr(int fd)
   return true;
 }
 
+bool tcp_nodelay(int fd, int enable)
+{
+  if (fd < 0) {
+    srslog::fetch_basic_logger(LOGSERVICE).error("Trying set nodelay for a closed socket. Socket=%d", fd);
+    return false;
+  }
+  if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &enable, sizeof(int)) < 0) {
+    srslog::fetch_basic_logger(LOGSERVICE).error("Failed to set TCP_NODELAY. Socket=%d", fd);
+    return false;
+  }
+  srslog::fetch_basic_logger(LOGSERVICE).debug("Successfully set TCP_NODELAY. Socket=%d", fd);
+  return true;
+}
+
+bool sctp_nodelay(int fd, int enable)
+{
+  if (fd < 0) {
+    srslog::fetch_basic_logger(LOGSERVICE).error("Trying set nodelay for a closed socket. Socket=%d", fd);
+    return false;
+  }
+  if (setsockopt(fd, IPPROTO_SCTP, SCTP_NODELAY, &enable, sizeof(int)) < 0) {
+    srslog::fetch_basic_logger(LOGSERVICE).error("Failed to set SCTP_NODELAY. Socket=%d", fd);
+    return false;
+  }
+  srslog::fetch_basic_logger(LOGSERVICE).debug("Successfully set SCTP_NODELAY. Socket=%d", fd);
+  return true;
+}
+
 bool sctp_subscribe_to_events(int fd)
 {
   if (fd < 0) {
@@ -338,6 +366,7 @@ bool unique_socket::open_socket(net_utils::addr_family   ip_type,
     return false;
   }
   sockfd = net_utils::open_socket(ip_type, socket_type, protocol);
+  proto = protocol;
   return is_open();
 }
 
@@ -376,6 +405,18 @@ bool unique_socket::reuse_addr()
   return net_utils::reuse_addr(sockfd);
 }
 
+bool unique_socket::nodelay(int enable)
+{
+  switch (proto) {
+  case net_utils::protocol_type::SCTP:
+    return net_utils::sctp_nodelay(sockfd, enable);
+  case net_utils::protocol_type::TCP:
+    return net_utils::tcp_nodelay(sockfd, enable);
+  default:
+    return false;
+  }
+}
+
 bool unique_socket::sctp_subscribe_to_events()
 {
   return net_utils::sctp_subscribe_to_events(sockfd);

srsenb/src/main.cc

@@ -287,6 +287,7 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     ("expert.max_s1_setup_retries", bpo::value<int32_t>(&args->stack.s1ap.max_s1_setup_retries)->default_value(-1), "Max S1 setup retries")
     ("expert.s1_connect_timer",  bpo::value<uint32_t>(&args->stack.s1ap.s1_connect_timer)->default_value(10), "Connection Retry Timer for S1 connection (seconds)")
     ("expert.sctp_reuse_addr",     bpo::value<bool>(&args->stack.s1ap.sctp_reuse_addr)->default_value(false), "Use SO_REUSE_ADDR on S1-C interface.")
+    ("expert.sctp_nodelay", bpo::value<bool>(&args->stack.s1ap.sctp_nodelay)->default_value(false), "Use SCTP_NODELAY on S1-C interface.")
     ("expert.sctp_rto_max", bpo::value<int32_t>(&args->stack.s1ap.sctp_rto_max)->default_value(6000), "SCTP maximum RTO.")
     ("expert.sctp_init_max_attempts", bpo::value<int32_t>(&args->stack.s1ap.sctp_init_max_attempts)->default_value(3), "Maximum SCTP init attempts.")
     ("expert.sctp_max_init_timeo)", bpo::value<int32_t>(&args->stack.s1ap.sctp_max_init_timeo)->default_value(5000), "Maximum SCTP init timeout.")

srsenb/src/stack/s1ap/s1ap.cc

@@ -533,6 +533,14 @@ bool s1ap::connect_mme()
     }
   }
 
+  // Set SCTP_NODELAY if necessary
+  if (args.sctp_nodelay) {
+    if (not mme_socket.nodelay(1)) {
+      mme_socket.close();
+      return false;
+    }
+  }
+
   // Subscribe to shutdown events
   if (not mme_socket.sctp_subscribe_to_events()) {
     mme_socket.close();