NATMap: Reuse the same port unless it is unavailable (#126)

Fixes #120

src/hev-conf.c

@@ -245,21 +245,23 @@ hev_conf_baddr (void)
 }
 
 const char *
-hev_conf_bport (void)
+hev_conf_bport (int next)
 {
     static char port[16];
 
-    if (brand) {
-        int n = bport[1] - bport[0] + 1;
-        bport[2] = bport[0] + (rand () % n);
-    }
+    if (!port[0] || next) {
+        if (brand) {
+            int n = bport[1] - bport[0] + 1;
+            bport[2] = bport[0] + (rand () % n);
+        }
 
-    snprintf (port, sizeof (port) - 1, "%u", bport[2]);
+        snprintf (port, sizeof (port) - 1, "%u", bport[2]);
 
-    if (!brand) {
-        bport[2] = bport[2] + 1;
-        if (bport[2] > bport[1]) {
-            bport[2] = bport[0];
+        if (!brand) {
+            bport[2] = bport[2] + 1;
+            if (bport[2] > bport[1]) {
+                bport[2] = bport[0];
+            }
         }
     }
 

src/hev-conf.h

@@ -113,12 +113,13 @@ const char *hev_conf_baddr (void);
 
 /**
  * hev_conf_bport:
+ * @next: switch to the next port
  *
  * Get bind port for port mapping.
  *
  * Returns: returns string.
  */
-const char *hev_conf_bport (void);
+const char *hev_conf_bport (int next);
 
 /**
  * hev_conf_taddr:

src/hev-tnsk.c

@@ -26,6 +26,7 @@
 
 static struct sockaddr_storage saddr;
 static HevTask *task;
+static int port_next;
 static int timeout;
 static int fd;
 
@@ -98,13 +99,14 @@ tnsk_run (void)
     http = hev_conf_http ();
     tfwd = hev_conf_taddr ();
     addr = hev_conf_baddr ();
-    port = hev_conf_bport ();
+    port = hev_conf_bport (port_next);
     hport = hev_conf_hport ();
     iface = hev_conf_iface ();
     mark = hev_conf_mark ();
 
     fd = hev_sock_client_base (type, SOCK_STREAM, addr, port, http, hport,
                                iface, mark, &saddr, NULL);
+    port_next = (fd < 0);
     if (fd < 0) {
         LOGV (E, "%s", "Start TCP keep-alive service failed.");
         return;

src/hev-unsk.c

@@ -27,6 +27,7 @@
 static struct sockaddr_storage saddr;
 static struct sockaddr_storage daddr;
 static HevTask *task;
+static int port_next;
 static int timeout;
 static unsigned int cycle;
 
@@ -95,7 +96,7 @@ unsk_run (void)
     type = hev_conf_type ();
     ufwd = hev_conf_taddr ();
     addr = hev_conf_baddr ();
-    port = hev_conf_bport ();
+    port = hev_conf_bport (port_next);
     stun = hev_conf_stun ();
     sport = hev_conf_sport ();
     iface = hev_conf_iface ();
@@ -105,6 +106,7 @@ unsk_run (void)
 
     fd = hev_sock_client_base (type, SOCK_DGRAM, addr, port, stun, sport, iface,
                                mark, &saddr, &daddr);
+    port_next = (fd < 0);
     if (fd < 0) {
         LOGV (E, "%s", "Start UDP keep-alive service failed.");
         return;