Moved pick_port_bind() to the libcommon common code so both client and server can use it. Client can now specify a range of ephemeral ports (transaction id)

common/tftpsubs.c

@@ -272,3 +272,41 @@ synchnet(int f)		/* socket to flush */
 
   return pktcount;		/* Return packets drained */
 }
+
+
+int pick_port_bind(int sockfd, struct sockaddr_in *myaddr, unsigned int port_range_from, unsigned int port_range_to)
+{
+  unsigned int port, firstport;
+  int port_range = 0;
+
+  if (port_range_from != 0 && port_range_to != 0) {
+      port_range = 1;
+  }
+
+  firstport = port_range
+    ? port_range_from + rand() % (port_range_to-port_range_from+1)
+    : 0;
+
+  port = firstport;
+
+  do {
+    myaddr->sin_port = htons(port);
+    
+    if (bind(sockfd, (struct sockaddr *)myaddr, sizeof *myaddr) < 0) {
+      /* Some versions of Linux return EINVAL instead of EADDRINUSE */
+      if ( !(port_range && (errno == EINVAL || errno == EADDRINUSE)) )
+	return -1;
+
+      /* Normally, we shouldn't have to loop, but some situations involving
+	 aborted transfers make it possible. */
+    } else {
+      return 0;
+    }
+
+    port++;
+    if ( port > port_range_to )
+      port = port_range_from;
+  } while ( port != firstport );
+
+  return -1;
+}

common/tftpsubs.h

@@ -74,3 +74,6 @@ extern char *xstrdup(const char *);
 void (*bsd_signal(int, void (*)(int)))(int);
 
 #endif
+
+
+int pick_port_bind(int sockfd, struct sockaddr_in *myaddr, unsigned int from, unsigned int to);

tftp/main.c

@@ -102,6 +102,9 @@ const char *prompt = "tftp> ";
 sigjmp_buf	toplevel;
 void	intr(int);
 struct	servent *sp;
+int portrange = 0;
+unsigned int portrange_from = 0;
+unsigned int portrange_to   = 0;
 
 void	get (int, char **);
 void	help (int, char **);
@@ -241,6 +244,16 @@ main(int argc, char *argv[])
 	case 'c':
 	  iscmd = 1;
 	  break;
+    case 'R':
+      if ( ++arg >= argc )
+           usage(EX_USAGE);
+      if ( sscanf(argv[arg], "%u:%u", &portrange_from, &portrange_to) != 2 ||
+            portrange_from > portrange_to || portrange_to > 65535 ) {
+         fprintf(stderr, "Bad port range: %s\n", argv[arg]); 
+         exit(EX_USAGE);
+      }
+      portrange = 1;
+      break;
 	case 'h':
 	default:
 	  usage(*optx == 'h' ? 0 : EX_USAGE);
@@ -276,7 +289,7 @@ main(int argc, char *argv[])
   }
   bzero((char *)&s_in, sizeof (s_in));
   s_in.sin_family = AF_INET;
-  if (bind(f, (struct sockaddr *)&s_in, sizeof (s_in)) < 0) {
+  if (pick_port_bind(f, &s_in, portrange_from, portrange_to)) {
     perror("tftp: bind");
     exit(EX_OSERR);
   }

tftpd/tftpd.c

@@ -273,38 +273,6 @@ static int recv_time(int s, void *rbuf, int len, unsigned int flags,
   }
 }
 
-static int
-pick_port_bind(int sockfd, struct sockaddr_in *myaddr)
-{
-  unsigned int port, firstport;
-
-  firstport = portrange
-    ? portrange_from + rand() % (portrange_to-portrange_from+1)
-    : 0;
-
-  port = firstport;
-
-  do {
-    myaddr->sin_port = htons(port);
-    
-    if (bind(sockfd, (struct sockaddr *)myaddr, sizeof *myaddr) < 0) {
-      /* Some versions of Linux return EINVAL instead of EADDRINUSE */
-      if ( !(portrange && (errno == EINVAL || errno == EADDRINUSE)) )
-	return -1;
-
-      /* Normally, we shouldn't have to loop, but some situations involving
-	 aborted transfers make it possible. */
-    } else {
-      return 0;
-    }
-
-    port++;
-    if ( port > portrange_to )
-      port = portrange_from;
-  } while ( port != firstport );
-
-  return -1;
-}
 
 int
 main(int argc, char **argv)
@@ -750,7 +718,7 @@ main(int argc, char **argv)
   from.sin_family = AF_INET;
   
   /* Process the request... */
-  if (pick_port_bind(peer, &myaddr) < 0) {
+  if (pick_port_bind(peer, &myaddr, portrange_from, portrange_to) < 0) {
     syslog(LOG_ERR, "bind: %m");
     exit(EX_IOERR);
   }