ftpd passive port range patch

[Jason Tishler]

The attached patch (against inetutils 1.3.2-19) enables Cygwin ftpd to
support a restricted range of passive mode ports similar to ProFTPD's
PassivePorts option.  Using this version of Cygwin ftpd, I am able to
tunnel all ftp traffic (i.e., both control and all data connections)
through a ssh tunnel.  This is very useful in situations where sftp is
not an option.

Is the Cygwin inetutils maintainer willing to consider this patch for
inclusion in the standard Cygwin package?

Thanks,
Jason
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--- ftpd.c.orig	2002-10-01 15:39:24.000000000 -0400
+++ ftpd.c	2002-10-02 12:06:47.000000000 -0400
@@ -170,6 +170,8 @@ int	stru;			/* avoid C keyword */
 int	mode;
 int	usedefault = 1;		/* for data transfers */
 int	pdata = -1;		/* for passive mode */
+int	pasv_start_port = 0;	/* for passive mode */
+int	pasv_end_port = 0;	/* for passive mode */
 sig_atomic_t transflag;
 off_t	file_size;
 off_t	byte_count;
@@ -325,16 +327,28 @@ main(argc, argv, envp)
 	LastArgv = envp[-1] + strlen(envp[-1]);
 #endif /* SETPROCTITLE */
 
-	while ((ch = getopt(argc, argv, "dlt:T:u:v")) != EOF) {
+	while ((ch = getopt(argc, argv, "de:ls:t:T:u:v")) != EOF) {
 		switch (ch) {
 		case 'd':
 			debug = 1;
 			break;
 
+		case 'e':
+			pasv_end_port = atoi(optarg);
+			if (pasv_end_port < 0)
+				pasv_end_port = 0;
+			break;
+
 		case 'l':
 			logging++;	/* > 1 == extra logging */
 			break;
 
+		case 's':
+			pasv_start_port = atoi(optarg);
+			if (pasv_start_port < 0)
+				pasv_start_port = 0;
+			break;
+
 		case 't':
 			timeout = atoi(optarg);
 			if (maxtimeout < timeout)
@@ -370,6 +384,9 @@ main(argc, argv, envp)
 			break;
 		}
 	}
+	if (pasv_end_port < pasv_start_port)
+		pasv_end_port = pasv_start_port;
+
 	(void) freopen(PATH_DEVNULL, "w", stderr);
 	(void) signal(SIGPIPE, lostconn);
 	(void) signal(SIGCHLD, SIG_IGN);
@@ -1582,6 +1599,7 @@ void
 passive()
 {
 	int len;
+	int pasv_port;
 	char *p, *a;
 
 	pdata = socket(AF_INET, SOCK_STREAM, 0);
@@ -1589,12 +1607,16 @@ passive()
 		perror_reply(425, "Can't open passive connection");
 		return;
 	}
-	pasv_addr = ctrl_addr;
-	pasv_addr.sin_port = 0;
 	(void) seteuid(getuid ());
-	if (bind(pdata, (struct sockaddr *)&pasv_addr, sizeof(pasv_addr)) < 0) {
-		(void) seteuid((uid_t)pw->pw_uid);
-		goto pasv_error;
+	pasv_addr = ctrl_addr;
+	for (pasv_port = pasv_start_port; pasv_port <= pasv_end_port; pasv_port++) {
+		pasv_addr.sin_port = htons(pasv_port);
+		if (bind(pdata, (struct sockaddr *)&pasv_addr, sizeof(pasv_addr)) == 0)
+			break;
+		if (errno != EADDRINUSE || pasv_port == pasv_end_port) {
+			(void) seteuid((uid_t)pw->pw_uid);
+			goto pasv_error;
+		}
 	}
 	(void) seteuid((uid_t)pw->pw_uid);
 	len = sizeof(pasv_addr);

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