Update ND_BYTES_BETWEEN() macro for better accuracy

Update the macro that computes how many bytes are present, starting
at the first argument and running up to (but not including) the second
argument, and returns that as a u_int (cutting it to 32 bits on LP64
and LLP64 platforms).

This reverses, for reasons of readability, the order of the arguments
which was based on old SMB's PTR_DIFF().

With this change the number of bytes "between" given by the macro is 0
when the first argument is greater than or equal to the second argument.

Update ND_BYTES_AVAILABLE_AFTER() accordingly.

This is a follow-up to f9c2c905b118b69a0b102549c1b25cca871947b5.

(cherry picked from commit fb59931bfca6eed43f8aa0bbec37565fc3c084cb)

diff --git a/netdissect.h b/netdissect.h
index b1074ef72bc921fdd7dbcf4d6d59445e11561de9..e9fe9dffda045d21c20d0c9cca8a745d70b3abfe 100644 (file)
--- a/netdissect.h
+++ b/netdissect.h
@@ -386,13 +386,13 @@ nd_trunc_longjmp(netdissect_options *ndo)
 /*
  * Number of bytes between two pointers.
  */
-#define ND_BYTES_BETWEEN(p1, p2) ((u_int)(((const uint8_t *)(p1)) - (const uint8_t *)(p2)))
+#define ND_BYTES_BETWEEN(p1, p2) ((const u_char *)(p1) >= (const u_char *)(p2) ? 0 : ((u_int)(((const u_char *)(p2)) - (const u_char *)(p1))))
 
 /*
  * Number of bytes remaining in the captured data, starting at the
  * byte pointed to by the argument.
  */
-#define ND_BYTES_AVAILABLE_AFTER(p) ND_BYTES_BETWEEN(ndo->ndo_snapend, (p))
+#define ND_BYTES_AVAILABLE_AFTER(p) ND_BYTES_BETWEEN((p), ndo->ndo_snapend)
 
 /* Check length < minimum for invalid packet with a custom message, format %u */
 #define ND_LCHECKMSG_U(length, minimum, what) \

diff --git a/print-bgp.c b/print-bgp.c
index 1acdd5baf32bda82e3e02b700f93a3e8dfba0a6d..50bdddb13e2995de42c1042a5926f620974b361b 100644 (file)
--- a/print-bgp.c
+++ b/print-bgp.c
@@ -2231,8 +2231,10 @@ bgp_attr_print(netdissect_options *ndo,
             ND_PRINT(", no SNPA");
         }
 
-        add_path4 = check_add_path(ndo, tptr, (len-ND_BYTES_BETWEEN(tptr, pptr)), 32);
-        add_path6 = check_add_path(ndo, tptr, (len-ND_BYTES_BETWEEN(tptr, pptr)), 128);
+        add_path4 = check_add_path(ndo, tptr,
+                                   (len-ND_BYTES_BETWEEN(pptr, tptr)), 32);
+        add_path6 = check_add_path(ndo, tptr,
+                                   (len-ND_BYTES_BETWEEN(pptr, tptr)), 128);
 
         while (tptr < pptr + len) {
             advance = bgp_nlri_print(ndo, af, safi, tptr, len, buf, sizeof(buf),
@@ -2258,8 +2260,10 @@ bgp_attr_print(netdissect_options *ndo,
 
         tptr += 3;
 
-        add_path4 = check_add_path(ndo, tptr, (len-ND_BYTES_BETWEEN(tptr, pptr)), 32);
-        add_path6 = check_add_path(ndo, tptr, (len-ND_BYTES_BETWEEN(tptr, pptr)), 128);
+        add_path4 = check_add_path(ndo, tptr,
+                                   (len-ND_BYTES_BETWEEN(pptr, tptr)), 32);
+        add_path6 = check_add_path(ndo, tptr,
+                                   (len-ND_BYTES_BETWEEN(pptr, tptr)), 128);
 
         while (tptr < pptr + len) {
             advance = bgp_nlri_print(ndo, af, safi, tptr, len, buf, sizeof(buf),

diff --git a/print-isoclns.c b/print-isoclns.c
index 648ae3e0974a33cf4ca0d8f61617738202630ee7..df11797209dd4f1565e5e2182fb0194d28bf6b91 100644 (file)
--- a/print-isoclns.c
+++ b/print-isoclns.c
@@ -1125,9 +1125,10 @@ clnp_print(netdissect_options *ndo,
 
         default:
             /* dump the PDU specific data */
-            if (length > ND_BYTES_BETWEEN(pptr, optr)) {
+            if (length > ND_BYTES_BETWEEN(optr, pptr)) {
                 ND_PRINT("\n\t  undecoded non-header data, length %u", length-li);
-                print_unknown_data(ndo, pptr, "\n\t  ", length - ND_BYTES_BETWEEN(pptr, optr));
+                print_unknown_data(ndo, pptr, "\n\t  ",
+                                   length - ND_BYTES_BETWEEN(optr, pptr));
             }
         }
 

diff --git a/print-lwres.c b/print-lwres.c
index 97f176cb30054515a1da88ec6f5e07610833646c..bec6318acd21b27b52918ceda14acbcbcedffe97 100644 (file)
--- a/print-lwres.c
+++ b/print-lwres.c
@@ -267,7 +267,7 @@ lwres_printaddr(netdissect_options *ndo,
                }
        }
 
-       return ND_BYTES_BETWEEN(p, p0);
+       return ND_BYTES_BETWEEN(p0, p);
 }
 
 void
@@ -546,7 +546,7 @@ lwres_print(netdissect_options *ndo,
                ND_PRINT(" [len: %u != %u]", GET_BE_U_4(np->length),
                          length);
        }
-       if (!unsupported && ND_BYTES_BETWEEN(s, bp) < GET_BE_U_4(np->length))
+       if (!unsupported && ND_BYTES_BETWEEN(bp, s) < GET_BE_U_4(np->length))
                ND_PRINT("[extra]");
        return;
 

diff --git a/print-resp.c b/print-resp.c
index 37a386e3122c96f501266ef688a21beb75d1e180..7388a73fbd573dcb5c4779c9f720d871482a19d4 100644 (file)
--- a/print-resp.c
+++ b/print-resp.c
@@ -306,7 +306,7 @@ resp_print_string_error_integer(netdissect_options *ndo, const u_char *bp, int l
      * preceding the \r\n.  That includes the opcode, so don't print
      * that.
      */
-    len = ND_BYTES_BETWEEN(bp_ptr, bp);
+    len = ND_BYTES_BETWEEN(bp, bp_ptr);
     RESP_PRINT_SEGMENT(ndo, bp, len);
     ret_len = 1 /*<opcode>*/ + len /*<string>*/ + 2 /*<CRLF>*/;
 
@@ -431,7 +431,7 @@ resp_print_inline(netdissect_options *ndo, const u_char *bp, int length) {
      * Found it; bp_ptr points to the \r or \n, so bp_ptr - bp is the
      * Length of the line text that precedes it.  Print it.
      */
-    len = ND_BYTES_BETWEEN(bp_ptr, bp);
+    len = ND_BYTES_BETWEEN(bp, bp_ptr);
     RESP_PRINT_SEGMENT(ndo, bp, len);
 
     /*

diff --git a/print-smb.c b/print-smb.c
index bcd7363dec955c22a7cb42db4ee8bdd2d26f7fb0..fa7a2c024782d64ab23f34d2c075cfd494988d0a 100644 (file)
--- a/print-smb.c
+++ b/print-smb.c
@@ -414,7 +414,8 @@ print_negprot(netdissect_options *ndo,
        smb_fdata(ndo, words + 1, f1, ND_MIN(words + 1 + wct * 2, maxbuf),
            unicodestr);
     else
-       smb_data_print(ndo, words + 1, ND_MIN(wct * 2, ND_BYTES_BETWEEN(maxbuf, words + 1)));
+       smb_data_print(ndo, words + 1,
+                       ND_MIN(wct * 2, ND_BYTES_BETWEEN(words + 1, maxbuf)));
 
     bcc = GET_LE_U_2(data);
     ND_PRINT("smb_bcc=%u\n", bcc);
@@ -424,7 +425,7 @@ print_negprot(netdissect_options *ndo,
                                              maxbuf), unicodestr);
        else
            smb_data_print(ndo, data + 2,
-                           ND_MIN(GET_LE_U_2(data), ND_BYTES_BETWEEN(maxbuf, data + 2)));
+                           ND_MIN(GET_LE_U_2(data), ND_BYTES_BETWEEN(data + 2, maxbuf)));
     }
 }
 
@@ -454,7 +455,8 @@ print_sesssetup(netdissect_options *ndo,
        smb_fdata(ndo, words + 1, f1, ND_MIN(words + 1 + wct * 2, maxbuf),
            unicodestr);
     else
-       smb_data_print(ndo, words + 1, ND_MIN(wct * 2, ND_BYTES_BETWEEN(maxbuf, words + 1)));
+       smb_data_print(ndo, words + 1,
+                       ND_MIN(wct * 2, ND_BYTES_BETWEEN(words + 1, maxbuf)));
 
     bcc = GET_LE_U_2(data);
     ND_PRINT("smb_bcc=%u\n", bcc);
@@ -464,7 +466,7 @@ print_sesssetup(netdissect_options *ndo,
                                              maxbuf), unicodestr);
        else
            smb_data_print(ndo, data + 2,
-                           ND_MIN(GET_LE_U_2(data), ND_BYTES_BETWEEN(maxbuf, data + 2)));
+                           ND_MIN(GET_LE_U_2(data), ND_BYTES_BETWEEN(data + 2, maxbuf)));
     }
 }
 
@@ -499,7 +501,7 @@ print_lockingandx(netdissect_options *ndo,
                                              maxbuf), unicodestr);
        else
            smb_data_print(ndo, data + 2,
-                           ND_MIN(GET_LE_U_2(data), ND_BYTES_BETWEEN(maxbuf, data + 2)));
+                           ND_MIN(GET_LE_U_2(data), ND_BYTES_BETWEEN(data + 2, maxbuf)));
     }
 }
 
@@ -871,7 +873,8 @@ print_smb(netdissect_options *ndo,
            } else {
                if (bcc > 0) {
                    ND_PRINT("smb_buf[]=\n");
-                   smb_data_print(ndo, data + 2, ND_MIN(bcc, ND_BYTES_BETWEEN(maxbuf, data + 2)));
+                   smb_data_print(ndo, data + 2,
+                                   ND_MIN(bcc, ND_BYTES_BETWEEN(data + 2, maxbuf)));
                }
            }
        }
@@ -1194,7 +1197,8 @@ nbt_udp137_print(netdissect_options *ndo,
                } else {
                    if (p >= maxbuf)
                        goto out;
-                   smb_data_print(ndo, p, ND_MIN(rdlen, length - ND_BYTES_BETWEEN(p, data)));
+                   smb_data_print(ndo, p,
+                                   ND_MIN(rdlen, length - ND_BYTES_BETWEEN(data, p)));
                    p += rdlen;
                }
            }

diff --git a/smbutil.c b/smbutil.c
index 97217a8d9fc6a8a4def9fbd160b9217e37cd2d92..e512e324d6a056a11853ba362d6e25b3faa3a5b4 100644 (file)
--- a/smbutil.c
+++ b/smbutil.c
@@ -251,7 +251,7 @@ name_len(netdissect_options *ndo,
        s += GET_U_1(s) + 1;
        ND_TCHECK_1(s);
     }
-    return(ND_BYTES_BETWEEN(s, s0) + 1);
+    return(ND_BYTES_BETWEEN(s0, s) + 1);
 
 trunc:
     return(-1);        /* name goes past the end of the buffer */
@@ -334,7 +334,7 @@ write_bits(netdissect_options *ndo,
     u_int i = 0;
 
     while ((p = strchr(fmt, '|'))) {
-       u_int l = ND_BYTES_BETWEEN(p, fmt);
+       u_int l = ND_BYTES_BETWEEN(fmt, p);
        if (l && (val & (1 << i)))
            ND_PRINT("%.*s ", (int)l, fmt);
        fmt = p + 1;
@@ -493,7 +493,7 @@ smb_fdata1(netdissect_options *ndo,
            u_int l;
 
            p = strchr(++fmt, '}');
-           l = ND_BYTES_BETWEEN(p, fmt);
+           l = ND_BYTES_BETWEEN(fmt, p);
 
            if (l > sizeof(bitfmt) - 1)
                l = sizeof(bitfmt)-1;
@@ -742,8 +742,9 @@ smb_fdata1(netdissect_options *ndo,
 
            switch (t) {
            case 1:
-               name_type = name_extract(ndo, startbuf, ND_BYTES_BETWEEN(buf, startbuf),
-                   maxbuf, nbuf);
+               name_type = name_extract(ndo, startbuf,
+                                         ND_BYTES_BETWEEN(startbuf, buf),
+                                         maxbuf, nbuf);
                if (name_type < 0)
                    goto trunc;
                len = name_len(ndo, buf, maxbuf);
@@ -933,7 +934,7 @@ smb_fdata(netdissect_options *ndo,
        }
     }
     if (!depth && buf < maxbuf) {
-       u_int len = ND_BYTES_BETWEEN(maxbuf, buf);
+       u_int len = ND_BYTES_BETWEEN(buf, maxbuf);
        ND_PRINT("Data: (%u bytes)\n", len);
        smb_data_print(ndo, buf, len);
        return(buf + len);