X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/c1bb8784abd3ca978e376b0d10e324db0491237b..febd0bc5aa33b3de9b5864e8c5565fe7b63f519f:/tcpdump.c

diff --git a/tcpdump.c b/tcpdump.c
index b69de64e..270f79b4 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -114,6 +114,10 @@ The Regents of the University of California.  All rights reserved.\n";
 #endif /* HAVE_CAP_NG_H */
 #endif /* HAVE_LIBCAP_NG */
 
+#ifdef __FreeBSD__
+#include <sys/sysctl.h>
+#endif /* __FreeBSD__ */
+
 #include "netdissect.h"
 #include "interface.h"
 #include "addrtoname.h"
@@ -181,26 +185,17 @@ cap_channel_t *capdns;
 #endif
 
 /* Forwards */
-static void error(const char *, ...)
-     __attribute__((noreturn))
-#ifdef __ATTRIBUTE___FORMAT_OK
-     __attribute__((format (printf, 1, 2)))
-#endif /* __ATTRIBUTE___FORMAT_OK */
-     ;
-static void warning(const char *, ...)
-#ifdef __ATTRIBUTE___FORMAT_OK
-     __attribute__((format (printf, 1, 2)))
-#endif /* __ATTRIBUTE___FORMAT_OK */
-     ;
-static void exit_tcpdump(int) __attribute__((noreturn));
+static NORETURN void error(FORMAT_STRING(const char *), ...) PRINTFLIKE(1, 2);
+static void warning(FORMAT_STRING(const char *), ...) PRINTFLIKE(1, 2);
+static NORETURN void exit_tcpdump(int);
 static RETSIGTYPE cleanup(int);
 static RETSIGTYPE child_cleanup(int);
 static void print_version(void);
 static void print_usage(void);
-static void show_tstamp_types_and_exit(pcap_t *, const char *device) __attribute__((noreturn));
-static void show_dlts_and_exit(pcap_t *, const char *device) __attribute__((noreturn));
+static NORETURN void show_tstamp_types_and_exit(pcap_t *, const char *device);
+static NORETURN void show_dlts_and_exit(pcap_t *, const char *device);
 #ifdef HAVE_PCAP_FINDALLDEVS
-static void show_devices_and_exit (void) __attribute__((noreturn));
+static NORETURN void show_devices_and_exit(void);
 #endif
 
 static void print_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
@@ -1041,10 +1036,16 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
 		supports_monitor_mode = 1;
 	else
 		supports_monitor_mode = 0;
-	status = pcap_set_snaplen(pc, ndo->ndo_snaplen);
-	if (status != 0)
-		error("%s: Can't set snapshot length: %s",
-		    device, pcap_statustostr(status));
+	if (ndo->ndo_snaplen != 0) {
+		/*
+		 * A snapshot length was explicitly specified;
+		 * use it.
+		 */
+		status = pcap_set_snaplen(pc, ndo->ndo_snaplen);
+		if (status != 0)
+			error("%s: Can't set snapshot length: %s",
+			    device, pcap_statustostr(status));
+	}
 	status = pcap_set_promisc(pc, !pflag);
 	if (status != 0)
 		error("%s: Can't set promiscuous mode: %s",
@@ -1104,6 +1105,10 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
 			sysctlbyname(sysctl, parent, &s, NULL, 0);
 			strlcpy(newdev, device, sizeof(newdev));
 			/* Suggest a new wlan device. */
+			/* FIXME: incrementing the index this way is not going to work well
+			 * when the index is 9 or greater but the only consequence in this
+			 * specific case would be an error message that looks a bit odd.
+			 */
 			newdev[strlen(newdev)-1]++;
 			error("%s is not a monitor mode VAP\n"
 			    "To create a new monitor mode VAP use:\n"
@@ -1141,6 +1146,12 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
 #endif /* HAVE_PCAP_SETDIRECTION */
 #else /* HAVE_PCAP_CREATE */
 	*ebuf = '\0';
+	/*
+	 * If no snapshot length was specified, or a length of 0 was
+	 * specified, default to 256KB.
+	 */
+	if (ndo->ndo_snaplen == 0)
+		ndo->ndo_snaplen = 262144;
 	pc = pcap_open_live(device, ndo->ndo_snaplen, !pflag, 1000, ebuf);
 	if (pc == NULL) {
 		/*
@@ -1207,7 +1218,6 @@ main(int argc, char **argv)
 
 	memset(ndo, 0, sizeof(*ndo));
 	ndo_set_function_pointers(ndo);
-	ndo->ndo_snaplen = DEFAULT_SNAPLEN;
 
 	cnt = -1;
 	device = NULL;
@@ -1437,8 +1447,6 @@ main(int argc, char **argv)
 			if (optarg == end || *end != '\0'
 			    || ndo->ndo_snaplen < 0 || ndo->ndo_snaplen > MAXIMUM_SNAPLEN)
 				error("invalid snaplen %s", optarg);
-			else if (ndo->ndo_snaplen == 0)
-				ndo->ndo_snaplen = MAXIMUM_SNAPLEN;
 			break;
 
 		case 'S':
@@ -1776,7 +1784,8 @@ main(int argc, char **argv)
 		}
 
 		/*
-		 * Let user own process after socket has been opened.
+		 * Let user own process after capture device has
+		 * been opened.
 		 */
 #ifndef _WIN32
 		if (setgid(getgid()) != 0 || setuid(getuid()) != 0)
@@ -1811,7 +1820,11 @@ main(int argc, char **argv)
 		}
 		i = pcap_snapshot(pd);
 		if (ndo->ndo_snaplen < i) {
-			warning("snaplen raised from %d to %d", ndo->ndo_snaplen, i);
+			if (ndo->ndo_snaplen != 0)
+				warning("snaplen raised from %d to %d", ndo->ndo_snaplen, i);
+			ndo->ndo_snaplen = i;
+		} else if (ndo->ndo_snaplen > i) {
+			warning("snaplen lowered from %d to %d", ndo->ndo_snaplen, i);
 			ndo->ndo_snaplen = i;
 		}
                 if(ndo->ndo_fflag != 0) {