do source routing check correctly; this could use a test

diff --git a/lib/libwrap/fix_options.c b/lib/libwrap/fix_options.c
index 619f146..48e9597 100644 (file)
--- a/lib/libwrap/fix_options.c
+++ b/lib/libwrap/fix_options.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: fix_options.c,v 1.1 1997/02/26 03:06:51 downsj Exp $  */
+/*     $OpenBSD: fix_options.c,v 1.2 1997/04/04 09:06:28 deraadt Exp $ */
 
  /*
   * Routine to disable IP-level socket options. This code was taken from 4.4BSD
@@ -11,7 +11,7 @@
 #if 0
 static char sccsid[] = "@(#) fix_options.c 1.4 97/02/12 02:13:22";
 #else
-static char rcsid[] = "$OpenBSD: fix_options.c,v 1.1 1997/02/26 03:06:51 downsj Exp $";
+static char rcsid[] = "$OpenBSD: fix_options.c,v 1.2 1997/04/04 09:06:28 deraadt Exp $";
 #endif
 #endif
 
@@ -20,6 +20,7 @@ static char rcsid[] = "$OpenBSD: fix_options.c,v 1.1 1997/02/26 03:06:51 downsj
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
+#include <netinet/ip_var.h>
 #include <netinet/ip.h>
 #include <netdb.h>
 #include <stdio.h>
@@ -41,85 +42,44 @@ fix_options(request)
 struct request_info *request;
 {
 #ifdef IP_OPTIONS
-    unsigned char optbuf[BUFFER_SIZE / 3], *cp;
-    char    lbuf[BUFFER_SIZE], *lp;
+    struct ipoption optbuf;
+    char    lbuf[BUFFER_SIZE], *lp, *cp;
     int     optsize = sizeof(optbuf), ipproto;
     struct protoent *ip;
     int     fd = request->fd;
     unsigned int opt;
-    int     optlen;
-    unsigned char *first_option = optbuf;
+    int     optlen, 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. However, we must
-        * be prepared to deal with systems that return the options only. 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.
+        * Properly deal with source routing entries.  The original code
+        * here was wrong.
         */
-#define ADDR_LEN sizeof(struct in_addr)
-
-       for (cp = optbuf + ADDR_LEN; cp < optbuf + optsize; cp++) {
-           opt = cp[IPOPT_OPTVAL];
-           if (opt != IPOPT_NOP) {
-               if (opt == IPOPT_RR
-                   || opt == IPOPT_TS
-                   || opt == IPOPT_SECURITY
-                   || opt == IPOPT_LSRR
-                   || opt == IPOPT_SATID
-                   || opt == IPOPT_SSRR)
-                   first_option = cp;
-               break;
-           }
+       for (i = 0; (void *)&optbuf.ipopt_list[i] - (void *)&optbuf <
+           optsize; ) {
+               u_char c = (u_char)optbuf.ipopt_list[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.ipopt_list[i+1];
        }
 
-       /*
-        * 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.
-        */
-       for (cp = first_option; 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));
-               clean_exit(request);
-           }
-           if (opt == IPOPT_EOL)
-               break;
-           if (opt == IPOPT_NOP) {
-               optlen = 1;
-           } else {
-               optlen = cp[IPOPT_OLEN];
-               if (optlen <= 0)                /* Do not loop! */
-                   break;
-           }
-       }
        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);