X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/4ee1cac427633e2c04df22c430c01667679451e2..f662dad02b51b595592df9fa6b0884e438cef9a3:/tcpdump.c

diff --git a/tcpdump.c b/tcpdump.c
index 7eb3d592..88295d84 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -1244,14 +1244,40 @@ main(int argc, char **argv)
 	(void)setsignal(SIGPIPE, cleanup);
 	(void)setsignal(SIGTERM, cleanup);
 	(void)setsignal(SIGINT, cleanup);
-	(void)setsignal(SIGCHLD, child_cleanup);
 #endif /* WIN32 */
+#if defined(HAVE_FORK) || defined(HAVE_VFORK)
+	(void)setsignal(SIGCHLD, child_cleanup);
+#endif
 	/* Cooperate with nohup(1) */
 #ifndef WIN32	
 	if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
 		(void)setsignal(SIGHUP, oldhandler);
 #endif /* WIN32 */
 
+#ifndef WIN32
+	/*
+	 * If a user name was specified with "-Z", attempt to switch to
+	 * that user's UID.  This would probably be used with sudo,
+	 * to allow tcpdump to be run in a special restricted
+	 * account (if you just want to allow users to open capture
+	 * devices, and can't just give users that permission,
+	 * you'd make tcpdump set-UID or set-GID).
+	 *
+	 * Tcpdump doesn't necessarily write only to one savefile;
+	 * the general only way to allow a -Z instance to write to
+	 * savefiles as the user under whose UID it's run, rather
+	 * than as the user specified with -Z, would thus be to switch
+	 * to the original user ID before opening a capture file and
+	 * then switch back to the -Z user ID after opening the savefile.
+	 * Switching to the -Z user ID only after opening the first
+	 * savefile doesn't handle the general case.
+	 */
+	if (getuid() == 0 || geteuid() == 0) {
+		if (username || chroot_dir)
+			droproot(username, chroot_dir);
+	}
+#endif /* WIN32 */
+
 	if (pcap_setfilter(pd, &fcode) < 0)
 		error("%s", pcap_geterr(pd));
 	if (WFileName) {
@@ -1305,16 +1331,7 @@ main(int argc, char **argv)
 		callback = print_packet;
 		pcap_userdata = (u_char *)&printinfo;
 	}
-#ifndef WIN32
-	/*
-	 * We cannot do this earlier, because we want to be able to open
-	 * the file (if done) for writing before giving up permissions.
-	 */
-	if (getuid() == 0 || geteuid() == 0) {
-		if (username || chroot_dir)
-			droproot(username, chroot_dir);
-	}
-#endif /* WIN32 */
+
 #ifdef SIGINFO
 	/*
 	 * We can't get statistics when reading from a file rather
@@ -1443,13 +1460,13 @@ cleanup(int signo _U_)
   On windows, we do not use a fork, so we do not care less about
   waiting a child processes to die
  */
-#ifndef WIN32
+#if defined(HAVE_FORK) || defined(HAVE_VFORK)
 static RETSIGTYPE
 child_cleanup(int signo _U_)
 {
   wait(NULL);
 }
-#endif /* WIN32 */
+#endif /* HAVE_FORK && HAVE_VFORK */
 
 static void
 info(register int verbose)
@@ -1470,34 +1487,41 @@ info(register int verbose)
 	if (!verbose)
 		fprintf(stderr, "%s: ", program_name);
 
-	(void)fprintf(stderr, "%u packets captured", packets_captured);
+	(void)fprintf(stderr, "%u packet%s captured", packets_captured,
+	    PLURAL_SUFFIX(packets_captured));
 	if (!verbose)
 		fputs(", ", stderr);
 	else
 		putc('\n', stderr);
-	(void)fprintf(stderr, "%u packets received by filter", stat.ps_recv);
+	(void)fprintf(stderr, "%u packet%s received by filter", stat.ps_recv,
+	    PLURAL_SUFFIX(stat.ps_recv));
 	if (!verbose)
 		fputs(", ", stderr);
 	else
 		putc('\n', stderr);
-	(void)fprintf(stderr, "%u packets dropped by kernel", stat.ps_drop);
+	(void)fprintf(stderr, "%u packet%s dropped by kernel", stat.ps_drop,
+	    PLURAL_SUFFIX(stat.ps_drop));
 	if (stat.ps_ifdrop != 0) {
 		if (!verbose)
 			fputs(", ", stderr);
 		else
 			putc('\n', stderr);
-		(void)fprintf(stderr, "%u packets dropped by interface\n",
-		    stat.ps_ifdrop);
+		(void)fprintf(stderr, "%u packet%s dropped by interface\n",
+		    stat.ps_ifdrop, PLURAL_SUFFIX(stat.ps_ifdrop));
 	} else
 		putc('\n', stderr);
 	infoprint = 0;
 }
 
-#ifndef WIN32
+#if defined(HAVE_FORK) || defined(HAVE_VFORK)
 static void
 compress_savefile(const char *filename)
 {
+# ifdef HAVE_FORK
 	if (fork())
+# else
+	if (vfork())
+# endif
 		return;
 	/*
 	 * Set to lowest priority so that this doesn't disturb the capture
@@ -1513,15 +1537,20 @@ compress_savefile(const char *filename)
 			zflag,
 			filename,
 			strerror(errno));
+# ifdef HAVE_FORK
+	exit(1);
+# else
+	_exit(1);
+# endif
 }
-#else  /* WIN32 */
+#else  /* HAVE_FORK && HAVE_VFORK */
 static void
 compress_savefile(const char *filename)
 {
 	fprintf(stderr,
-		"compress_savefile failed. Functionality not implemented under windows\n");
+		"compress_savefile failed. Functionality not implemented under your system\n");
 }
-#endif /* WIN32 */
+#endif /* HAVE_FORK && HAVE_VFORK */
 
 static void
 dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
@@ -1691,6 +1720,11 @@ print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
                 hdrlen = (*print_info->p.printer)(h, sp);
         }
                 
+	/*
+	 * Restore the original snapend, as a printer might have
+	 * changed it.
+	 */
+	snapend = sp + h->caplen;
 	if (Xflag) {
 		/*
 		 * Print the raw packet data in hex and ASCII.