diff -ur tcp_wrappers_7.6.orig/fix_options.c tcp_wrappers_7.6/fix_options.c

--- tcp_wrappers_7.6.orig/fix_options.c	Tue Apr  8 04:29:19 1997

+++ tcp_wrappers_7.6/fix_options.c	Mon Oct  2 06:04:58 2000

@@ -11,6 +11,7 @@

 #include <sys/types.h>

 #include <sys/param.h>

+#include <sys/socket.h>

 #include <netinet/in.h>

 #include <netinet/in_systm.h>

 #include <netinet/ip.h>

@@ -29,80 +30,59 @@

 /* fix_options - get rid of IP-level socket options */

+void

 fix_options(request)

 struct request_info *request;

 {

 #ifdef IP_OPTIONS

-    unsigned char optbuf[BUFFER_SIZE / 3], *cp;

-    char    lbuf[BUFFER_SIZE], *lp;

+    struct ip_options optbuf;

+    char    lbuf[BUFFER_SIZE], *lp, *cp;

     int     optsize = sizeof(optbuf), ipproto;

     struct protoent *ip;

     int     fd = request->fd;

-    unsigned int opt;

-    int     optlen;

-    struct in_addr dummy;

+    int     i;

     if ((ip = getprotobyname("ip")) != 0)

 	ipproto = ip->p_proto;

     else

 	ipproto = IPPROTO_IP;

-    if (getsockopt(fd, ipproto, IP_OPTIONS, (char *) optbuf, &optsize) == 0

+    if (getsockopt(fd, ipproto, IP_OPTIONS, (char *) &optbuf, &optsize) == 0

 	&& optsize != 0) {

 	/*

-	 * Horror! 4.[34] BSD getsockopt() prepends the first-hop destination

-	 * address to the result IP options list when source routing options

-	 * are present (see <netinet/ip_var.h>), but produces no output for

-	 * other IP options. Solaris 2.x getsockopt() does produce output for

-	 * non-routing IP options, and uses the same format as BSD even when

-	 * the space for the destination address is unused. The code below

-	 * does the right thing with 4.[34]BSD derivatives and Solaris 2, but

-	 * may occasionally miss source routing options on incompatible

-	 * systems such as Linux. Their choice.

-	 * 

-	 * Look for source routing options. Drop the connection when one is

-	 * found. Just wiping the IP options is insufficient: we would still

-	 * help the attacker by providing a real TCP sequence number, and the

-	 * attacker would still be able to send packets (blind spoofing). I

-	 * discussed this attack with Niels Provos, half a year before the

-	 * attack was described in open mailing lists.

-	 * 

-	 * It would be cleaner to just return a yes/no reply and let the caller

-	 * decide how to deal with it. Resident servers should not terminate.

-	 * However I am not prepared to make changes to internal interfaces

-	 * on short notice.

+	 * Properly deal with source routing entries.  The original code

+	 * here was wrong.

+	 *

+	 * This replacement code is OpenBSD-derived, but ported to Linux

+	 * (struct ipoption vs. struct ip_options).  Most systems will have

+	 * source-routed packets disallowed in the kernel, so this is of

+	 * little importance now.

 	 */

-#define ADDR_LEN sizeof(dummy.s_addr)

-

-	for (cp = optbuf + ADDR_LEN; cp < optbuf + optsize; cp += optlen) {

-	    opt = cp[IPOPT_OPTVAL];

-	    if (opt == IPOPT_LSRR || opt == IPOPT_SSRR) {

-		syslog(LOG_WARNING,

-		   "refused connect from %s with IP source routing options",

-		       eval_client(request));

-		shutdown(fd, 2);

-		return;

-	    }

-	    if (opt == IPOPT_EOL)

-		break;

-	    if (opt == IPOPT_NOP) {

-		optlen = 1;

-	    } else {

-		optlen = cp[IPOPT_OLEN];

-		if (optlen <= 0)		/* Do not loop! */

-		    break;

-	    }

+	for (i = 0; (void *)&optbuf.__data[i] - (void *)&optbuf <

+	    optsize; ) {

+		u_char c = (u_char)optbuf.__data[i];

+		if (c == IPOPT_LSRR || c == IPOPT_SSRR) {

+			syslog(LOG_WARNING,

+			   "refused connect from %s with IP source routing options",

+			       eval_client(request));

+			clean_exit(request);

+		}

+		if (c == IPOPT_EOL)

+			break;

+		i += (c == IPOPT_NOP) ? 1 : (u_char)optbuf.__data[i+1];

 	}

+

 	lp = lbuf;

-	for (cp = optbuf; optsize > 0; cp++, optsize--, lp += 3)

-	    sprintf(lp, " %2.2x", *cp);

+	for (cp = (char *)&optbuf; optsize > 0 && lp < &lbuf[sizeof lbuf-1];

+	    cp++, optsize--, lp += 3)

+		sprintf(lp, " %2.2x", *cp);

 	syslog(LOG_NOTICE,

 	       "connect from %s with IP options (ignored):%s",

 	       eval_client(request), lbuf);

 	if (setsockopt(fd, ipproto, IP_OPTIONS, (char *) 0, optsize) != 0) {

 	    syslog(LOG_ERR, "setsockopt IP_OPTIONS NULL: %m");

-	    shutdown(fd, 2);

+	    clean_exit(request);

 	}

     }

 #endif