More bounds checking when fetching addresses and converting to strings.

[tcpdump] / print-loopback.c

diff --git a/print-loopback.c b/print-loopback.c
index c0297b8d6cc6da7a41dfe0602f2d55d03caccaf5..07fbcbdd14b45f1120a0b47485dded4160511777 100644 (file)
--- a/print-loopback.c
+++ b/print-loopback.c
@@ -1,9 +1,4 @@
 /*
- * This module implements decoding of the the Loopback Protocol, originally
- * defined as the Configuration Testing Protocol. It is based on the following
- * specification:
- * http://www.mit.edu/people/jhawk/ctp.pdf
- *
  * Copyright (c) 2014 The TCPDUMP project
  * All rights reserved.
  *
@@ -30,20 +25,23 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#define NETDISSECT_REWORKED
+/* \summary: Loopback Protocol printer */
+
+/*
+ * originally defined as the Ethernet Configuration Testing Protocol.
+ * specification: https://www.mit.edu/people/jhawk/ctp.pdf
+ */
+
 #ifdef HAVE_CONFIG_H
-#include "config.h"
+#include <config.h>
 #endif
 
-#include <tcpdump-stdinc.h>
+#include "netdissect-stdinc.h"
 
-#include "interface.h"
+#include "netdissect.h"
 #include "extract.h"
-#include "ether.h"
 #include "addrtoname.h"
 
-static const char tstr[] = " [|loopback]";
-static const char cstr[] = " (corrupt)";
 
 #define LOOPBACK_REPLY   1
 #define LOOPBACK_FWDDATA 2
@@ -57,80 +55,81 @@ static const struct tok fcode_str[] = {
 static void
 loopback_message_print(netdissect_options *ndo, const u_char *cp, const u_int len)
 {
-       const u_char *ep = cp + len;
+       const u_char *ep = ndo->ndo_snapend;
        uint16_t function;
 
        if (len < 2)
-               goto corrupt;
+               goto invalid;
        /* function */
-       ND_TCHECK2(*cp, 2);
-       function = EXTRACT_LE_16BITS(cp);
+       ND_TCHECK_2(cp);
+       function = GET_LE_U_2(cp);
        cp += 2;
-       ND_PRINT((ndo, ", %s", tok2str(fcode_str, " invalid (%u)", function)));
+       ND_PRINT(", %s", tok2str(fcode_str, " invalid (%u)", function));
 
        switch (function) {
                case LOOPBACK_REPLY:
                        if (len < 4)
-                               goto corrupt;
+                               goto invalid;
                        /* receipt number */
-                       ND_TCHECK2(*cp, 2);
-                       ND_PRINT((ndo, ", receipt number %u", EXTRACT_LE_16BITS(cp)));
+                       ND_TCHECK_2(cp);
+                       ND_PRINT(", receipt number %u", GET_LE_U_2(cp));
                        cp += 2;
                        /* data */
-                       ND_PRINT((ndo, ", data (%u octets)", len - 4));
-                       ND_TCHECK2(*cp, len - 4);
+                       ND_PRINT(", data (%u octets)", len - 4);
+                       ND_TCHECK_LEN(cp, len - 4);
                        break;
                case LOOPBACK_FWDDATA:
                        if (len < 8)
-                               goto corrupt;
+                               goto invalid;
                        /* forwarding address */
-                       ND_TCHECK2(*cp, ETHER_ADDR_LEN);
-                       ND_PRINT((ndo, ", forwarding address %s", etheraddr_string(cp)));
-                       cp += ETHER_ADDR_LEN;
+                       ND_TCHECK_LEN(cp, MAC_ADDR_LEN);
+                       ND_PRINT(", forwarding address %s", GET_ETHERADDR_STRING(cp));
+                       cp += MAC_ADDR_LEN;
                        /* data */
-                       ND_PRINT((ndo, ", data (%u octets)", len - 8));
-                       ND_TCHECK2(*cp, len - 8);
+                       ND_PRINT(", data (%u octets)", len - 8);
+                       ND_TCHECK_LEN(cp, len - 8);
                        break;
                default:
-                       ND_TCHECK2(*cp, len - 2);
+                       ND_TCHECK_LEN(cp, len - 2);
                        break;
        }
        return;
 
-corrupt:
-       ND_PRINT((ndo, "%s", cstr));
-       ND_TCHECK2(*cp, ep - cp);
+invalid:
+       nd_print_invalid(ndo);
+       ND_TCHECK_LEN(cp, ep - cp);
        return;
 trunc:
-       ND_PRINT((ndo, "%s", tstr));
+       nd_print_trunc(ndo);
 }
 
 void
 loopback_print(netdissect_options *ndo, const u_char *cp, const u_int len)
 {
-       const u_char *ep = cp + len;
+       const u_char *ep = ndo->ndo_snapend;
        uint16_t skipCount;
 
-       ND_PRINT((ndo, "Loopback"));
+       ndo->ndo_protocol = "loopback";
+       ND_PRINT("Loopback");
        if (len < 2)
-               goto corrupt;
+               goto invalid;
        /* skipCount */
-       ND_TCHECK2(*cp, 2);
-       skipCount = EXTRACT_LE_16BITS(cp);
+       ND_TCHECK_2(cp);
+       skipCount = GET_LE_U_2(cp);
        cp += 2;
-       ND_PRINT((ndo, ", skipCount %u", skipCount));
+       ND_PRINT(", skipCount %u", skipCount);
        if (skipCount % 8)
-               ND_PRINT((ndo, " (bogus)"));
+               ND_PRINT(" (bogus)");
        if (skipCount > len - 2)
-               goto corrupt;
+               goto invalid;
        loopback_message_print(ndo, cp + skipCount, len - 2 - skipCount);
        return;
 
-corrupt:
-       ND_PRINT((ndo, "%s", cstr));
-       ND_TCHECK2(*cp, ep - cp);
+invalid:
+       nd_print_invalid(ndo);
+       ND_TCHECK_LEN(cp, ep - cp);
        return;
 trunc:
-       ND_PRINT((ndo, "%s", tstr));
+       nd_print_trunc(ndo);
 }