Mailinglist Archive: proxy-suite (13 mails)

[Volker Wiegand <wiegand@xxxxxxx>]

Hi,

the following patch was posted from Rogier Wolff, but the Mailing List
Daemon refused to accept it.  We are crrently fixing the posting problem,
and here is his posting.

Volker

---------- Forwarded message ----------
Date: Fri, 10 Dec 1999 14:09:30 +0100 (MET)
From: Rogier Wolff <R.E.Wolff@xxxxxxxxxxxx>
To: proxy-suite-owner@xxxxxxxx
Subject: failure notice (fwd)


Hi,

When the data port for connections to the server is specified as 41000
- 41999, there will always be a data connection between realserver:20
and proxyserver:41000, as the ftp-proxy always uses the lowest
possible port. Some ftp-servers don't seem to like this. They end up
refusing to build a dataconnection half of the time. (i.e. first
request works, second request doesn't, and so forth).

I observed this on an old Red Hat system, probably still running a 2.0
kernel (just checked: Yes, its 2.0.32). Now you know why this system
should really be behind the firewall.

Anyway, I've modified the ftp-proxy to start looking for a free port
at a random position in the range. This reduces the problem from
occurring 50% of the time to 0.05% of the time. (range is 1000
entries). This is acceptable, as the retry will simply work.

					Roger. 

diff -ur proxy-suite-1.7.orig/common/com-misc.c proxy-suite-1.7/common/com-misc.c
--- proxy-suite-1.7.orig/common/com-misc.c	Fri Oct 22 11:29:01 1999
+++ proxy-suite-1.7/common/com-misc.c	Fri Dec 10 12:47:11 1999
@@ -643,6 +643,17 @@
 #endif
 }
 
+int misc_rand (int lrng, int urng)
+{
+	struct timeval t;
+
+	if (lrng == urng) return lrng;
+
+	gettimeofday (&t, NULL);
+	srand (t.tv_usec);
+	return (lrng + (rand () % (urng - lrng + 1)));
+}
+
 
 /* ------------------------------------------------------------
  * $Log: com-misc.c,v $
diff -ur proxy-suite-1.7.orig/common/com-socket.c proxy-suite-1.7/common/com-socket.c
--- proxy-suite-1.7.orig/common/com-socket.c	Fri Oct 22 11:29:01 1999
+++ proxy-suite-1.7/common/com-socket.c	Fri Dec 10 12:49:21 1999
@@ -1163,6 +1163,7 @@
 {
 	struct sockaddr_in saddr;
 	int sock;
+	int i;
 	u_int16_t port;
 
 	if (phls == NULL || ctyp == NULL)	/* Sanity check	*/
@@ -1181,17 +1182,22 @@
 	saddr.sin_addr.s_addr = htonl(addr);
 	saddr.sin_family      = AF_INET;
 
+	
 	/*
 	** Bind the socket, taking care of a given port range.
 	** Note: this function covers also lrng = urng = 0 ...
+	**
+	** Note: To prevent problems with reuseing portnos too quickly
+	** we start at a random point inside the range. 
 	*/
-	for (port = lrng; port <= urng; port++) {
+	for (i=0,port = misc_rand (lrng, urng);i < (urng-lrng); i++,port++) {
 		saddr.sin_port = htons(port);
 		if (bind(sock, (struct sockaddr *) &saddr,
 					sizeof(saddr)) == 0)
 			break;
 		if (errno != EADDRINUSE)
-			port = urng + 1;
+			i = urng-lrng + 1;
+		if (port >= urng) port = lrng;
 	}
 	if (port > urng) {		/* nothing found?	*/
 		close(sock);



-- 
** R.E.Wolff@xxxxxxxxxxxx ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
 "I didn't say it was your fault. I said I was going to blame it on you."