remove redundant ND_TCHECK, let GET_ routines handle checks

[tcpdump] / print-loopback.c

diff --git a/print-loopback.c b/print-loopback.c
index 07fbcbdd14b45f1120a0b47485dded4160511777..e9d0b1a298a71748b11d7722baa5926d5b4e6cd0 100644 (file)
--- a/print-loopback.c
+++ b/print-loopback.c
@@ -53,60 +53,60 @@ static const struct tok fcode_str[] = {
 };
 
 static void
-loopback_message_print(netdissect_options *ndo, const u_char *cp, const u_int len)
+loopback_message_print(netdissect_options *ndo,
+                       const u_char *cp, u_int len)
 {
-       const u_char *ep = ndo->ndo_snapend;
        uint16_t function;
 
        if (len < 2)
                goto invalid;
        /* function */
-       ND_TCHECK_2(cp);
        function = GET_LE_U_2(cp);
        cp += 2;
+       len -= 2;
        ND_PRINT(", %s", tok2str(fcode_str, " invalid (%u)", function));
 
        switch (function) {
                case LOOPBACK_REPLY:
-                       if (len < 4)
+                       if (len < 2)
                                goto invalid;
                        /* receipt number */
-                       ND_TCHECK_2(cp);
                        ND_PRINT(", receipt number %u", GET_LE_U_2(cp));
                        cp += 2;
+                       len -= 2;
                        /* data */
-                       ND_PRINT(", data (%u octets)", len - 4);
-                       ND_TCHECK_LEN(cp, len - 4);
+                       ND_PRINT(", data (%u octets)", len);
+                       ND_TCHECK_LEN(cp, len);
                        break;
                case LOOPBACK_FWDDATA:
-                       if (len < 8)
+                       if (len < MAC_ADDR_LEN)
                                goto invalid;
                        /* forwarding address */
-                       ND_TCHECK_LEN(cp, MAC_ADDR_LEN);
                        ND_PRINT(", forwarding address %s", GET_ETHERADDR_STRING(cp));
                        cp += MAC_ADDR_LEN;
+                       len -= MAC_ADDR_LEN;
                        /* data */
-                       ND_PRINT(", data (%u octets)", len - 8);
-                       ND_TCHECK_LEN(cp, len - 8);
+                       ND_PRINT(", data (%u octets)", len);
+                       ND_TCHECK_LEN(cp, len);
                        break;
                default:
-                       ND_TCHECK_LEN(cp, len - 2);
+                       ND_TCHECK_LEN(cp, len);
                        break;
        }
        return;
 
 invalid:
        nd_print_invalid(ndo);
-       ND_TCHECK_LEN(cp, ep - cp);
+       ND_TCHECK_LEN(cp, len);
        return;
 trunc:
-       nd_print_trunc(ndo);
+       nd_trunc(ndo);
 }
 
 void
-loopback_print(netdissect_options *ndo, const u_char *cp, const u_int len)
+loopback_print(netdissect_options *ndo,
+               const u_char *cp, u_int len)
 {
-       const u_char *ep = ndo->ndo_snapend;
        uint16_t skipCount;
 
        ndo->ndo_protocol = "loopback";
@@ -114,22 +114,27 @@ loopback_print(netdissect_options *ndo, const u_char *cp, const u_int len)
        if (len < 2)
                goto invalid;
        /* skipCount */
-       ND_TCHECK_2(cp);
        skipCount = GET_LE_U_2(cp);
        cp += 2;
+       len -= 2;
        ND_PRINT(", skipCount %u", skipCount);
        if (skipCount % 8)
                ND_PRINT(" (bogus)");
-       if (skipCount > len - 2)
+       if (skipCount > len)
                goto invalid;
-       loopback_message_print(ndo, cp + skipCount, len - 2 - skipCount);
+       /* the octets to skip */
+       ND_TCHECK_LEN(cp, skipCount);
+       cp += skipCount;
+       len -= skipCount;
+       /* the first message to decode */
+       loopback_message_print(ndo, cp, len);
        return;
 
 invalid:
        nd_print_invalid(ndo);
-       ND_TCHECK_LEN(cp, ep - cp);
+       ND_TCHECK_LEN(cp, len);
        return;
 trunc:
-       nd_print_trunc(ndo);
+       nd_trunc(ndo);
 }