[PATCH] pcap_setdirection support

[Thomas Jacob <jacob () internet24 de>]

---
 configure.in |    7 +++++++
 tcpdump.1.in |   10 ++++++++++
 tcpdump.c    |   35 +++++++++++++++++++++++++++++++++--
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/configure.in b/configure.in
index 50ac7ad..79478c5 100644
--- a/configure.in
+++ b/configure.in
@@ -785,6 +785,13 @@ else
                AC_MSG_RESULT(no)
        fi
 fi
+
+AC_CHECK_FUNCS(pcap_setdirection)
+if test $ac_cv_func_pcap_setdirection = "yes" ; then
+dnl Check for capture direction setting support
+       AC_DEFINE(HAVE_PCAP_SETDIRECTION)
+fi
+
 AC_REPLACE_FUNCS(bpf_dump)     dnl moved to libpcap in 0.6
 
 V_GROUP=0
diff --git a/tcpdump.1.in b/tcpdump.1.in
index f0f7ce0..fb27e4a 100644
--- a/tcpdump.1.in
+++ b/tcpdump.1.in
@@ -109,6 +109,11 @@ tcpdump \- dump traffic on a network
 ]
 .ti +8
 [
+.B \-P
+.I in|out|inout
+]
+.ti +8
+[
 .I expression
 ]
 .br
@@ -410,6 +415,11 @@ Note that the interface might be in promiscuous
 mode for some other reason; hence, `-p' cannot be used as an abbreviation for
 `ether host {local-hw-addr} or ether broadcast'.
 .TP
+.B \-P
+Choose send/receive direction \fIdirection\fR for which packets should be
+captured. Possible values are `in', `out' and `inout'. Not available
+on all platforms.
+.TP
 .B \-q
 Quick (quiet?) output.
 Print less protocol information so output
diff --git a/tcpdump.c b/tcpdump.c
index 26d1d80..fdbd880 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -92,6 +92,9 @@ netdissect_options *gndo = &Gndo;
 
 int dflag;                     /* print filter code */
 int Lflag;                     /* list available data link types and exit */
+#ifdef HAVE_PCAP_SETDIRECTION
+int Pflag = PCAP_D_INOUT;      /* Restrict captured packet by sent/receive direction */
+#endif
 char *zflag = NULL;            /* compress each savefile using a specified command (like gzip or bzip2) */
 
 static int infodelay;
@@ -387,6 +390,12 @@ show_dlts_and_exit(pcap_t *pd)
 #define U_FLAG
 #endif
 
+#ifdef HAVE_PCAP_SETDIRECTION
+#define P_FLAG "P:"
+#else
+#define P_FLAG
+#endif
+
 #ifndef WIN32
 /* Drop root privileges and chroot if necessary */
 static void
@@ -541,7 +550,7 @@ main(int argc, char **argv)
 
        opterr = 0;
        while (
-           (op = getopt(argc, argv, "aA" B_FLAG "c:C:d" D_FLAG "eE:fF:G:i:" I_FLAG "KlLm:M:nNOpqr:Rs:StT:u" U_FLAG 
"vw:W:xXy:Yz:Z:")) != -1)
+           (op = getopt(argc, argv, "aA" B_FLAG "c:C:d" D_FLAG "eE:fF:G:i:" I_FLAG "KlLm:M:nNOp" P_FLAG "qr:Rs:StT:u" 
U_FLAG "vw:W:xXy:Yz:Z:")) != -1)
                switch (op) {
 
                case 'a':
@@ -741,7 +750,18 @@ main(int argc, char **argv)
                case 'p':
                        ++pflag;
                        break;
-
+#ifdef HAVE_PCAP_SETDIRECTION
+               case 'P':
+                       if (strcasecmp(optarg, "in") == 0)
+                               Pflag = PCAP_D_IN;
+                       else if (strcasecmp(optarg, "out") == 0)
+                               Pflag = PCAP_D_OUT;
+                       else if (strcasecmp(optarg, "inout") == 0)
+                               Pflag = PCAP_D_INOUT;
+                       else
+                               error("unknown capture direction `%s'", optarg);
+                       break;
+#endif /* HAVE_PCAP_SETDIRECTION */
                case 'q':
                        ++qflag;
                        ++suppress_default_print;
@@ -996,6 +1016,7 @@ main(int argc, char **argv)
                                error("%s: pcap_set_buffer_size failed: %s",
                                    device, pcap_statustostr(status));
                }
+
                status = pcap_activate(pd);
                if (status < 0) {
                        /*
@@ -1028,6 +1049,12 @@ main(int argc, char **argv)
                                warning("%s: %s", device,
                                    pcap_statustostr(status));
                }
+#ifdef HAVE_PCAP_SETDIRECTION
+               status = pcap_setdirection(pd, Pflag);
+               if (status != 0)
+                       error("%s: pcap_set_direction failed: %s",
+                           device,  pcap_geterr(pd));
+#endif
 #else
                *ebuf = '\0';
                pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
@@ -1697,6 +1724,10 @@ usage(void)
 "\t\t[ -s snaplen ] [ -T type ] [ -w file ] [ -W filecount ]\n");
        (void)fprintf(stderr,
 "\t\t[ -y datalinktype ] [ -z command ] [ -Z user ]\n");
+#ifdef HAVE_PCAP_SETDIRECTION
+       (void)fprintf(stderr,
+"\t\t[ -P in|out|inout ]\n");
+#endif
        (void)fprintf(stderr,
 "\t\t[ expression ]\n");
        exit(1);
-- 
1.5.6.5

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