Clean up direction setting.

Reject direction arguments other than PCAP_D_IN, PCAP_D_OUT, and
PCAP_D_INOUT.

De-nerdify some errors.

diff --git a/pcap-bpf.c b/pcap-bpf.c
index d9de13b8719b064467ba8d461e5a5628c3f0eb9e..1690baa29c85ec9663d72d631cd8eb60acd2fe48 100644 (file)
--- a/pcap-bpf.c
+++ b/pcap-bpf.c
@@ -3258,17 +3258,48 @@ static int
 pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d)
 {
        u_int direction;
+       const char *direction_name;
 
        /*
         * FreeBSD and NetBSD.
         */
-       direction = (d == PCAP_D_IN) ? BPF_D_IN :
-           ((d == PCAP_D_OUT) ? BPF_D_OUT : BPF_D_INOUT);
+       switch (d) {
+
+       case PCAP_D_IN:
+               /*
+                * Incoming, but not outgoing, so accept only
+                * incoming packets.
+                */
+               direction = BPF_D_IN;
+               direction_name = "\"incoming only\"";
+               break;
+
+       case PCAP_D_OUT:
+               /*
+                * Outgoing, but not incoming, so accept only
+                * outgoing packets.
+                */
+               direction = BPF_D_OUT;
+               direction_name = "\"outgoing only\"";
+               break;
+
+       case PCAP_D_INOUT:
+               /*
+                * Incoming and outgoing, so accept both
+                * incoming and outgoing packets.
+                */
+               direction = BPF_D_INOUT;
+               direction_name = "\"incoming and outgoing\"";
+               break;
+
+       default:
+               snprintf(p->errbuf, sizeof(p->errbuf), "Invalid direction");
+               return (-1);
+       }
+               
        if (ioctl(p->fd, BIOCSDIRECTION, &direction) == -1) {
                pcap_fmt_errmsg_for_errno(p->errbuf, sizeof(p->errbuf),
-                   errno, "Cannot set direction to %s",
-                       (d == PCAP_D_IN) ? "PCAP_D_IN" :
-                       ((d == PCAP_D_OUT) ? "PCAP_D_OUT" : "PCAP_D_INOUT"));
+                   errno, "Cannot set direction to %s", direction_name);
                return (-1);
        }
        return (0);
@@ -3277,7 +3308,8 @@ pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d)
 static int
 pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d)
 {
-       u_int direction;
+       u_int dirfilt;
+       const char *direction_name;
 
        /*
         * OpenBSD; same functionality, different names, different
@@ -3285,13 +3317,42 @@ pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d)
         * that direction", not "*capture only* packets in that
         * direction").
         */
-       direction = (d == PCAP_D_IN) ? BPF_DIRECTION_OUT :
-           ((d == PCAP_D_OUT) ? BPF_DIRECTION_IN : 0);
-       if (ioctl(p->fd, BIOCSDIRFILT, &direction) == -1) {
+       switch (d) {
+
+       case PCAP_D_IN:
+               /*
+                * Incoming, but not outgoing, so filter out
+                * outgoing packets.
+                */
+               dirfilt = BPF_DIRECTION_OUT;
+               direction_name = "\"incoming only\"";
+               break;
+
+       case PCAP_D_OUT:
+               /*
+                * Outgoing, but not incoming, so filter out
+                * incoming packets.
+                */
+               dirfilt = BPF_DIRECTION_IN;
+               direction_name = "\"outgoing only\"";
+               break;
+
+       case PCAP_D_INOUT:
+               /*
+                * Incoming and outgoing, so don't filter out
+                * any packets based on direction.
+                */
+               dirfilt = 0;
+               direction_name = "\"incoming and outgoing\"";
+               break;
+
+       default:
+               snprintf(p->errbuf, sizeof(p->errbuf), "Invalid direction");
+               return (-1);
+       }
+       if (ioctl(p->fd, BIOCSDIRFILT, &dirfilt) == -1) {
                pcap_fmt_errmsg_for_errno(p->errbuf, sizeof(p->errbuf),
-                   errno, "Cannot set direction to %s",
-                       (d == PCAP_D_IN) ? "PCAP_D_IN" :
-                       ((d == PCAP_D_OUT) ? "PCAP_D_OUT" : "PCAP_D_INOUT"));
+                   errno, "Cannot set direction to %s", direction_name);
                return (-1);
        }
        return (0);
@@ -3301,21 +3362,47 @@ static int
 pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d)
 {
        u_int seesent;
+       const char *direction_name;
 
        /*
-        * We don't support PCAP_D_OUT.
+        * OS with just BIOCSSEESENT.
         */
-       if (d == PCAP_D_OUT) {
+       switch (d) {
+
+       case PCAP_D_IN:
+               /*
+                * Incoming, but not outgoing, so we don't want to
+                * see transmitted packets.
+                */
+               seesent = 0;
+               direction_name = "\"incoming only\"";
+               break;
+
+       case PCAP_D_OUT:
+               /*
+                * Outgoing, but not incoming; we can't specify that.
+                */
                snprintf(p->errbuf, sizeof(p->errbuf),
                    "Setting direction to \"outgoing only\" is not supported on this operating system");
-               return -1;
-       }
+               return (-1);
+
+       case PCAP_D_INOUT:
+               /*
+                * Incoming and outgoing, so we want to see transmitted
+                * packets.
+                */
+               seesent = 1;
+               direction_name = "\"incoming and outgoing\"";
+               break;
 
-       seesent = (d == PCAP_D_INOUT);
+       default:
+               snprintf(p->errbuf, sizeof(p->errbuf), "Invalid direction");
+               return (-1);
+       }
+               
        if (ioctl(p->fd, BIOCSSEESENT, &seesent) == -1) {
                pcap_fmt_errmsg_for_errno(p->errbuf, sizeof(p->errbuf),
-                   errno, "Cannot set direction to %s",
-                   (d == PCAP_D_INOUT) ? "PCAP_D_INOUT" : "PCAP_D_IN");
+                   errno, "Cannot set direction to %s", direction_name);
                return (-1);
        }
        return (0);
@@ -3325,7 +3412,7 @@ static int
 pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d _U_)
 {
        (void) snprintf(p->errbuf, sizeof(p->errbuf),
-           "This system doesn't support BIOCSSEESENT, so the direction can't be set");
+           "Setting direction is not supported on this operating system");
        return (-1);
 }
 #endif