Use getaddrinfo() and add IPv6 support in startServer

This commit refactors startServer to use getaddrinfo() to
prepare the socket creation. Doing so, it also adds support for
IPv6 by using AF_UNSPEC as the address family.

radio/rfsimulator/simulator.c

@@ -547,30 +547,67 @@ static int rfsimu_vtime_cmd(char *buff, int debug, telnet_printfunc_t prnt, void
   return CMDSTATUS_FOUND;
 }
 
-static int startServer(openair0_device *device) {
-  rfsimulator_state_t *t = (rfsimulator_state_t *) device->priv;
+static int startServer(openair0_device *device)
+{
+  int sock = -1;
+  struct addrinfo *results = NULL;
+  struct addrinfo *rp= NULL;
+
+  rfsimulator_state_t *t = (rfsimulator_state_t *)device->priv;
   t->role = SIMU_ROLE_SERVER;
-  t->listen_sock = socket(AF_INET, SOCK_STREAM, 0);
-  if (t->listen_sock < 0) {
-    LOG_E(HW, "socket(SOCK_STREAM) failed, errno(%d)\n", errno);
+
+  char port[6];
+  snprintf(port, sizeof(port), "%d", t->port);
+
+  struct addrinfo hints = {
+   .ai_family = AF_INET6,
+   .ai_socktype = SOCK_STREAM,
+   .ai_flags = AI_PASSIVE,
+  };
+
+  int s = getaddrinfo(NULL, port, &hints, &results);
+  if (s != 0) {
+    LOG_E(HW, "getaddrinfo: %s\n", gai_strerror(s));
+    freeaddrinfo(results);
     return -1;
   }
+
   int enable = 1;
-  if (setsockopt(t->listen_sock, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) != 0) {
-    LOG_E(HW, "setsockopt(SO_REUSEADDR) failed, errno(%d)\n", errno);
-    return -1;
+  int disable = 0;
+  for (rp = results; rp != NULL; rp = rp->ai_next) {
+    sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+    if (sock == -1) {
+      continue;
+    }
+
+    if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &disable, sizeof(int)) != 0) {
+      continue;
+    }
+
+    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) != 0) {
+      continue;
+    }
+
+    if (bind(sock, rp->ai_addr, rp->ai_addrlen) == 0) {
+      break;
+    }
+
+    close(sock);
   }
-  struct sockaddr_in addr = {.sin_family = AF_INET, .sin_port = htons(t->port), .sin_addr = {.s_addr = INADDR_ANY}};
-  int rc = bind(t->listen_sock, (struct sockaddr *)&addr, sizeof(addr));
-  if (rc < 0) {
-    LOG_E(HW, "bind() failed, errno(%d)\n", errno);
+
+  freeaddrinfo(results);
+
+  if (sock <= 0) {
+    LOG_E(HW, "could not open a socket\n");
     return -1;
   }
+  t->listen_sock = sock;
+
   if (listen(t->listen_sock, 5) != 0) {
     LOG_E(HW, "listen() failed, errno(%d)\n", errno);
     return -1;
   }
-  struct epoll_event ev= {0};
+  struct epoll_event ev = {0};
   ev.events = EPOLLIN;
   ev.data.fd = t->listen_sock;
   if (epoll_ctl(t->epollfd, EPOLL_CTL_ADD, t->listen_sock, &ev) != 0) {