This adds a new function that allows using the bpf compiler without

	having a pcap open.  One could argue that this and the existing
	compiler should be factored in common routines, but I was trying to
	make it clear that this wouldn't break the existing code.
	from Greg Troxel <[email protected]>

diff --git a/gencode.c b/gencode.c
index 83f16b0cb44ddd640ae5f780f1b7bdc35cb6e55c..6c7d7cbfa4b604fe3714ed142949c8cd23325194 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -21,7 +21,7 @@
  */
 #ifndef lint
 static const char rcsid[] =
-    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.99 1999-11-01 15:56:40 itojun Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.100 1999-12-08 19:54:03 mcr Exp $ (LBL)";
 #endif
 
 #include <sys/types.h>
@@ -316,6 +316,54 @@ pcap_compile(pcap_t *p, struct bpf_program *program,
        return (0);
 }
 
+/*
+ * entry point for using the compiler with no pcap open
+ * pass in all the stuff that is needed explicitly instead.
+ */
+int
+pcap_compile_nopcap(int snaplen_arg, int linktype_arg,
+                   struct bpf_program *program,
+            char *buf, int optimize, bpf_u_int32 mask)
+{
+       extern int n_errors;
+       int len;
+
+       n_errors = 0;
+       root = NULL;
+       bpf_pcap = NULL;
+       if (setjmp(top_ctx)) {
+               freechunks();
+               return (-1);
+       }
+
+       netmask = mask;
+
+       /* XXX needed? I don't grok the use of globals here. */
+       snaplen = snaplen_arg;
+
+       lex_init(buf ? buf : "");
+       init_linktype(linktype_arg);
+       (void)pcap_parse();
+
+       if (n_errors)
+               syntax();
+
+       if (root == NULL)
+               root = gen_retblk(snaplen_arg);
+
+       if (optimize) {
+               bpf_optimize(&root);
+               if (root == NULL ||
+                   (root->s.code == (BPF_RET|BPF_K) && root->s.k == 0))
+                       bpf_error("expression rejects all packets");
+       }
+       program->bf_insns = icode_to_fcode(root, &len);
+       program->bf_len = len;
+
+       freechunks();
+       return (0);
+}
+
 /*
  * Backpatch the blocks in 'list' to 'target'.  The 'sense' field indicates
  * which of the jt and jf fields has been resolved and which is a pointer

diff --git a/pcap.3 b/pcap.3
index 23e5b52b3b1ca815efb2e22a820ecee26e7a861d..c358c631372cd8d907afb2389225025fa03cdce5 100644 (file)
--- a/pcap.3
+++ b/pcap.3
@@ -225,6 +225,15 @@ controls whether optimization on the resulting code is performed.
 .I netmask
 specifies the netmask of the local net.
 .PP
+.B pcap_compile_nopcap()
+is similar to
+.B pcap_compile()
+except that instead of passing a pcap structure, one passes the
+snaplen and linktype explicitly.  It is intended to be used for
+compiling filters for direct bpf usage, without necessarily having
+called
+.BR pcap_open() .
+.PP
 .B pcap_setfilter()
 is used to specify a filter program.
 .I fp

diff --git a/pcap.h b/pcap.h
index cffbad8e1febf68df97c29cee2379ce5c01001fe..42a99ff206663586e4b56e68819a5282180c52ba 100644 (file)
--- a/pcap.h
+++ b/pcap.h
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * @(#) $Header: /tcpdump/master/libpcap/pcap.h,v 1.21 1999-10-07 23:46:40 mcr Exp $ (LBL)
+ * @(#) $Header: /tcpdump/master/libpcap/pcap.h,v 1.22 1999-12-08 19:54:03 mcr Exp $ (LBL)
  */
 
 #ifndef lib_pcap_h
@@ -115,6 +115,8 @@ char        *pcap_strerror(int);
 char   *pcap_geterr(pcap_t *);
 int    pcap_compile(pcap_t *, struct bpf_program *, char *, int,
            bpf_u_int32);
+int    pcap_compile_nopcap(int, int, struct bpf_program *,
+           char *, int, bpf_u_int32);
 /* XXX */
 int    pcap_freecode(pcap_t *, struct bpf_program *);
 int    pcap_datalink(pcap_t *);