lwres: Modernize packet parsing style.

Enable ND_LONGJMP_FROM_TCHECK. Do not return on truncation. Let the
standard macro guard the snapshot end. Add integers instead of
subtracting pointers where possible. Make functions that now never return
a negative value unsigned and lose respective checks at the calling end.
Return -1 to tell an invalid packet. In lwres_printname() just use
nd_printn(). In lwres_print() add and use a standard invalid section.

diff --git a/print-lwres.c b/print-lwres.c
index 474633c775985134d95aa51d9c259e812bc1d81f..2518823bc3e1a3164e237c8e7734b3ecb17b4783 100644 (file)
--- a/print-lwres.c
+++ b/print-lwres.c
@@ -38,6 +38,7 @@
 #include <stdio.h>
 #include <string.h>
 
 #include <stdio.h>
 #include <string.h>
 

+#define ND_LONGJMP_FROM_TCHECK

 #include "netdissect.h"
 #include "addrtoname.h"
 #include "extract.h"
 #include "netdissect.h"
 #include "addrtoname.h"
 #include "extract.h"


@@ -191,51 +192,31 @@ static const struct tok opcode[] = {
 extern const struct tok ns_type2str[];
 extern const struct tok ns_class2str[];
 
 extern const struct tok ns_type2str[];
 extern const struct tok ns_class2str[];
 

-static int
+static unsigned

 lwres_printname(netdissect_options *ndo,
                 size_t l, const u_char *p0)
 {
 lwres_printname(netdissect_options *ndo,
                 size_t l, const u_char *p0)
 {

-       const u_char *p;
-       size_t i;
-
-       p = p0;
-       /* + 1 for terminating \0 */
-       if (p + l + 1 > ndo->ndo_snapend)
-               goto trunc;
-

        ND_PRINT(" ");
        ND_PRINT(" ");

-       for (i = 0; i < l; i++) {
-               fn_print_char(ndo, GET_U_1(p));
-               p++;
-       }
-       p++;    /* skip terminating \0 */
-
-       return ND_BYTES_BETWEEN(p, p0);
-
-  trunc:
-       return -1;
+       (void)nd_printn(ndo, p0, l, NULL);
+       p0 += l;
+       if (GET_U_1(p0))
+               ND_PRINT(" (not NUL-terminated!)");
+       return l + 1;

 }
 
 }
 

-static int
+static unsigned

 lwres_printnamelen(netdissect_options *ndo,
                    const u_char *p)
 {
        uint16_t l;
        int advance;
 
 lwres_printnamelen(netdissect_options *ndo,
                    const u_char *p)
 {
        uint16_t l;
        int advance;
 

-       if (p + 2 > ndo->ndo_snapend)
-               goto trunc;

        l = GET_BE_U_2(p);
        advance = lwres_printname(ndo, l, p + 2);
        l = GET_BE_U_2(p);
        advance = lwres_printname(ndo, l, p + 2);

-       if (advance < 0)
-               goto trunc;

        return 2 + advance;
        return 2 + advance;

-
-  trunc:
-       return -1;

 }
 
 }
 

-static int
+static unsigned

 lwres_printbinlen(netdissect_options *ndo,
                   const u_char *p0)
 {
 lwres_printbinlen(netdissect_options *ndo,
                   const u_char *p0)
 {


@@ -244,20 +225,13 @@ lwres_printbinlen(netdissect_options *ndo,
        int i;
 
        p = p0;
        int i;
 
        p = p0;

-       if (p + 2 > ndo->ndo_snapend)
-               goto trunc;

        l = GET_BE_U_2(p);
        l = GET_BE_U_2(p);

-       if (p + 2 + l > ndo->ndo_snapend)
-               goto trunc;

        p += 2;
        for (i = 0; i < l; i++) {
                ND_PRINT("%02x", GET_U_1(p));
                p++;
        }
        p += 2;
        for (i = 0; i < l; i++) {
                ND_PRINT("%02x", GET_U_1(p));
                p++;
        }

-       return ND_BYTES_BETWEEN(p, p0);
-
-  trunc:
-       return -1;
+       return 2 + l;

 }
 
 static int
 }
 
 static int


@@ -297,9 +271,6 @@ lwres_printaddr(netdissect_options *ndo,
        }
 
        return ND_BYTES_BETWEEN(p, p0);
        }
 
        return ND_BYTES_BETWEEN(p, p0);

-
-  trunc:
-       return -1;

 }
 
 void
 }
 
 void


@@ -399,8 +370,6 @@ lwres_print(netdissect_options *ndo,
                        s = p + LWRES_GABNREQUEST_LEN;
                        l = GET_BE_U_2(gabn->namelen);
                        advance = lwres_printname(ndo, l, s);
                        s = p + LWRES_GABNREQUEST_LEN;
                        l = GET_BE_U_2(gabn->namelen);
                        advance = lwres_printname(ndo, l, s);

-                       if (advance < 0)
-                               goto trunc;

                        s += advance;
                        break;
                case LWRES_OPCODE_GETNAMEBYADDR:
                        s += advance;
                        break;
                case LWRES_OPCODE_GETNAMEBYADDR:


@@ -416,7 +385,7 @@ lwres_print(netdissect_options *ndo,
                        s = p + LWRES_GNBAREQUEST_LEN;
                        advance = lwres_printaddr(ndo, s);
                        if (advance < 0)
                        s = p + LWRES_GNBAREQUEST_LEN;
                        advance = lwres_printaddr(ndo, s);
                        if (advance < 0)

-                               goto trunc;
+                               goto invalid;

                        s += advance;
                        break;
                case LWRES_OPCODE_GETRDATABYNAME:
                        s += advance;
                        break;
                case LWRES_OPCODE_GETRDATABYNAME:


@@ -440,8 +409,6 @@ lwres_print(netdissect_options *ndo,
                        s = p + LWRES_GRBNREQUEST_LEN;
                        l = GET_BE_U_2(grbn->namelen);
                        advance = lwres_printname(ndo, l, s);
                        s = p + LWRES_GRBNREQUEST_LEN;
                        l = GET_BE_U_2(grbn->namelen);
                        advance = lwres_printname(ndo, l, s);

-                       if (advance < 0)
-                               goto trunc;

                        s += advance;
                        break;
                default:
                        s += advance;
                        break;
                default:


@@ -484,16 +451,12 @@ lwres_print(netdissect_options *ndo,
                        s = p + LWRES_GABNRESPONSE_LEN;
                        l = GET_BE_U_2(gabn->realnamelen);
                        advance = lwres_printname(ndo, l, s);
                        s = p + LWRES_GABNRESPONSE_LEN;
                        l = GET_BE_U_2(gabn->realnamelen);
                        advance = lwres_printname(ndo, l, s);

-                       if (advance < 0)
-                               goto trunc;

                        s += advance;
 
                        /* aliases */
                        na = GET_BE_U_2(gabn->naliases);
                        for (i = 0; i < na; i++) {
                                advance = lwres_printnamelen(ndo, s);
                        s += advance;
 
                        /* aliases */
                        na = GET_BE_U_2(gabn->naliases);
                        for (i = 0; i < na; i++) {
                                advance = lwres_printnamelen(ndo, s);

-                               if (advance < 0)
-                                       goto trunc;

                                s += advance;
                        }
 
                                s += advance;
                        }
 


@@ -502,7 +465,7 @@ lwres_print(netdissect_options *ndo,
                        for (i = 0; i < na; i++) {
                                advance = lwres_printaddr(ndo, s);
                                if (advance < 0)
                        for (i = 0; i < na; i++) {
                                advance = lwres_printaddr(ndo, s);
                                if (advance < 0)

-                                       goto trunc;
+                                       goto invalid;

                                s += advance;
                        }
                        break;
                                s += advance;
                        }
                        break;


@@ -521,16 +484,12 @@ lwres_print(netdissect_options *ndo,
                        s = p + LWRES_GNBARESPONSE_LEN;
                        l = GET_BE_U_2(gnba->realnamelen);
                        advance = lwres_printname(ndo, l, s);
                        s = p + LWRES_GNBARESPONSE_LEN;
                        l = GET_BE_U_2(gnba->realnamelen);
                        advance = lwres_printname(ndo, l, s);

-                       if (advance < 0)
-                               goto trunc;

                        s += advance;
 
                        /* aliases */
                        na = GET_BE_U_2(gnba->naliases);
                        for (i = 0; i < na; i++) {
                                advance = lwres_printnamelen(ndo, s);
                        s += advance;
 
                        /* aliases */
                        na = GET_BE_U_2(gnba->naliases);
                        for (i = 0; i < na; i++) {
                                advance = lwres_printnamelen(ndo, s);

-                               if (advance < 0)
-                                       goto trunc;

                                s += advance;
                        }
                        break;
                                s += advance;
                        }
                        break;


@@ -559,8 +518,6 @@ lwres_print(netdissect_options *ndo,
 
                        s = p + LWRES_GRBNRESPONSE_LEN;
                        advance = lwres_printnamelen(ndo, s);
 
                        s = p + LWRES_GRBNRESPONSE_LEN;
                        advance = lwres_printnamelen(ndo, s);

-                       if (advance < 0)
-                               goto trunc;

                        s += advance;
 
                        /* rdatas */
                        s += advance;
 
                        /* rdatas */


@@ -568,8 +525,6 @@ lwres_print(netdissect_options *ndo,
                        for (i = 0; i < na; i++) {
                                /* XXX should decode resource data */
                                advance = lwres_printbinlen(ndo, s);
                        for (i = 0; i < na; i++) {
                                /* XXX should decode resource data */
                                advance = lwres_printbinlen(ndo, s);

-                               if (advance < 0)
-                                       goto trunc;

                                s += advance;
                        }
 
                                s += advance;
                        }
 


@@ -578,8 +533,6 @@ lwres_print(netdissect_options *ndo,
                        for (i = 0; i < na; i++) {
                                /* XXX how should we print it? */
                                advance = lwres_printbinlen(ndo, s);
                        for (i = 0; i < na; i++) {
                                /* XXX how should we print it? */
                                advance = lwres_printbinlen(ndo, s);

-                               if (advance < 0)
-                                       goto trunc;

                                s += advance;
                        }
                        break;
                                s += advance;
                        }
                        break;


@@ -600,6 +553,6 @@ lwres_print(netdissect_options *ndo,
                ND_PRINT("[extra]");
        return;
 
                ND_PRINT("[extra]");
        return;
 

-  trunc:
-       nd_print_trunc(ndo);
+  invalid:
+       nd_print_invalid(ndo);

 }
 }