Fixed the code that verifies if a PPI packet encapsulates 802.11 frames.

The bug was causing side effects even when the linktype was not PPI.

diff --git a/gencode.c b/gencode.c
index 1fdd31ea8f50ae7604ef825806fdec23c201120a..51385af2b5bfd059c34ab4db4d040c2f367b1de5 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -21,7 +21,7 @@
  */
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.221.2.50 2007-06-14 18:42:43 gianluca Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.221.2.51 2007-06-14 20:54:12 gianluca Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -243,6 +243,7 @@ static struct slist *xfer_to_a(struct arth *);
 static struct block *gen_mac_multicast(int);
 static struct block *gen_len(int, int);
 
+static struct block *gen_ppi_dlt_check();
 static struct block *gen_msg_abbrev(int type);
 
 static void *
@@ -478,11 +479,20 @@ merge(b0, b1)
        *p = b1;
 }
 
+
 void
 finish_parse(p)
        struct block *p;
 {
-       insert_load_llprefixlen(p);
+       struct block *ppi_dlt_check;
+       
+       ppi_dlt_check = gen_ppi_dlt_check();
+
+       if (ppi_dlt_check != NULL)
+       {
+               gen_and(ppi_dlt_check, p);
+       }
+
        backpatch(p, gen_retblk(snaplen));
        p->sense = !p->sense;
        backpatch(p, gen_retblk(0));
@@ -503,6 +513,8 @@ finish_parse(p)
         * require the length of that header, doing more for that
         * header length isn't really worth the effort.
         */
+
+       insert_load_llprefixlen(root);
 }
 
 void
@@ -1908,9 +1920,6 @@ insert_ppi_load_llprefixlen(b)
        struct block *b;
 {
        struct slist *s1, *s2;
-       struct slist *s_load_dlt;
-       struct block *new_b;
-       struct block temp;
        
        /*
         * Prepend to the statements in this block code to load the
@@ -1968,20 +1977,33 @@ insert_ppi_load_llprefixlen(b)
                sappend(s1, b->stmts);
                b->stmts = s1;
 
-               temp = *b;
+       }
+}
        
+static struct block *
+gen_ppi_dlt_check()
+{
+       struct slist *s_load_dlt;
+       struct block *b;
+
+       if (linktype == DLT_PPI)
+       {
                /* Create the statements that check for the DLT
                 */
                s_load_dlt = new_stmt(BPF_LD|BPF_W|BPF_ABS);
                s_load_dlt->s.k = 4;
 
-               new_b = new_block(JMP(BPF_JEQ));
-
-               new_b->stmts = s_load_dlt;
-               new_b->s.k = SWAPLONG(DLT_IEEE802_11);
+               b = new_block(JMP(BPF_JEQ));
 
-               gen_and(new_b,b);
+               b->stmts = s_load_dlt;
+               b->s.k = SWAPLONG(DLT_IEEE802_11);
        }
+       else
+       {
+               b = NULL;
+       }
+
+       return b;
 }
 
 static void