rresvport() in terms of bind() & bindresvport()

2 files changed, 15 insertions, 14 deletions

diff --git a/src/lib/libc/net/rcmd.3 b/src/lib/libc/net/rcmd.3
index 8452e395db..add4faa314 100644
--- a/src/lib/libc/net/rcmd.3
+++ b/src/lib/libc/net/rcmd.3
@@ -134,6 +134,9 @@ by
 and several other functions.  Privileged Internet ports are those
 in the range 0 to 1023.  Only the super-user
 is allowed to bind an address of this sort to a socket.
+.Fn rresvport
+needs to be seeded with a port number; if that port
+is not available it will find another.
 .Pp
 The
 .Fn iruserok
diff --git a/src/lib/libc/net/rcmd.c b/src/lib/libc/net/rcmd.c
index 22a956cfb0..28420d20eb 100644
--- a/src/lib/libc/net/rcmd.c
+++ b/src/lib/libc/net/rcmd.c
@@ -228,21 +228,19 @@ rresvport(alport)
         s = socket(AF_INET, SOCK_STREAM, 0);
         if (s < 0)
                 return (-1);
-        for (;;) {
-                sin.sin_port = htons((u_short)*alport);
-                if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
-                        return (s);
-                if (errno != EADDRINUSE) {
-                        (void)close(s);
-                        return (-1);
-                }
-                (*alport)--;
-                if (*alport == IPPORT_RESERVED/2) {
-                        (void)close(s);
-                        errno = EAGAIN;         /* close */
-                        return (-1);
-                }
+        sin.sin_port = htons((u_short)*alport);
+        if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
+                return (s);
+        if (errno != EADDRINUSE) {
+                (void)close(s);
+                return (-1);
         }
+        if (bindresvport(s, &sin) == -1) {
+                (void)close(s);
+                return (-1);
+        }
+        *alport = (int)ntohs(sin.sin_port);
+        return (s);
 }
 
 int     __check_rhosts_file = 1;