Avoid using a global variable when it's not needed

[tcpdump] / tcpdump.c

diff --git a/tcpdump.c b/tcpdump.c
index 97e2aa55ca9f453a23725ba5bceb1a11d848ef9e..b76b426d691be1ceaf12862316a26772c9ba67ab 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -157,7 +157,7 @@ static int Jflag;                   /* list available time stamp types */
 static int jflag = -1;                 /* packet time stamp source */
 static int pflag;                      /* don't go promiscuous */
 #ifdef HAVE_PCAP_SETDIRECTION
-int Qflag = -1;                                /* restrict captured packet by send/receive direction */
+static int Qflag = -1;                 /* restrict captured packet by send/receive direction */
 #endif
 static int Uflag;                      /* "unbuffered" output of dump files */
 static int Wflag;                      /* recycle output files after this number of files */
@@ -187,8 +187,11 @@ 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(const char *device) __attribute__((noreturn));
-static void show_dlts_and_exit(const char *device) __attribute__((noreturn));
+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));
+#ifdef HAVE_PCAP_FINDALLDEVS
+static void show_devices_and_exit (void) __attribute__((noreturn));
+#endif
 
 static void print_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
 static void dump_packet_and_trunc(u_char *, const struct pcap_pkthdr *, const u_char *);
@@ -337,16 +340,16 @@ exit_tcpdump(int status)
 
 #ifdef HAVE_PCAP_SET_TSTAMP_TYPE
 static void
-show_tstamp_types_and_exit(const char *device)
+show_tstamp_types_and_exit(pcap_t *pc, const char *device)
 {
        int n_tstamp_types;
        int *tstamp_types = 0;
        const char *tstamp_type_name;
        int i;
 
-       n_tstamp_types = pcap_list_tstamp_types(pd, &tstamp_types);
+       n_tstamp_types = pcap_list_tstamp_types(pc, &tstamp_types);
        if (n_tstamp_types < 0)
-               error("%s", pcap_geterr(pd));
+               error("%s", pcap_geterr(pc));
 
        if (n_tstamp_types == 0) {
                fprintf(stderr, "Time stamp type cannot be set for %s\n",
@@ -370,15 +373,15 @@ show_tstamp_types_and_exit(const char *device)
 #endif
 
 static void
-show_dlts_and_exit(const char *device)
+show_dlts_and_exit(pcap_t *pc, const char *device)
 {
        int n_dlts, i;
        int *dlts = 0;
        const char *dlt_name;
 
-       n_dlts = pcap_list_datalinks(pd, &dlts);
+       n_dlts = pcap_list_datalinks(pc, &dlts);
        if (n_dlts < 0)
-               error("%s", pcap_geterr(pd));
+               error("%s", pcap_geterr(pc));
        else if (n_dlts == 0 || !dlts)
                error("No data link types.");
 
@@ -828,7 +831,7 @@ copy_argv(register char **argv)
        char *src, *dst;
 
        p = argv;
-       if (*p == 0)
+       if (*p == NULL)
                return 0;
 
        while (*p)
@@ -958,11 +961,20 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
 
 #ifdef HAVE_PCAP_CREATE
        pc = pcap_create(device, ebuf);
-       if (pc == NULL)
+       if (pc == NULL) {
+               /*
+                * If this failed with "No such device", that means
+                * the interface doesn't exist; return NULL, so that
+                * the caller can see whether the device name is
+                * actually an interface index.
+                */
+               if (strstr(ebuf, "No such device") != NULL)
+                       return (NULL);
                error("%s", ebuf);
+       }
 #ifdef HAVE_PCAP_SET_TSTAMP_TYPE
        if (Jflag)
-               show_tstamp_types_and_exit(device);
+               show_tstamp_types_and_exit(pc, device);
 #endif
 #ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
        status = pcap_set_tstamp_precision(pc, ndo->ndo_tstamp_precision);
@@ -1070,9 +1082,18 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
 #else /* HAVE_PCAP_CREATE */
        *ebuf = '\0';
        pc = pcap_open_live(device, ndo->ndo_snaplen, !pflag, 1000, ebuf);
-       if (pc == NULL)
+       if (pc == NULL) {
+               /*
+                * If this failed with "No such device", that means
+                * the interface doesn't exist; return NULL, so that
+                * the caller can see whether the device name is
+                * actually an interface index.
+                */
+               if (strstr(ebuf, "No such device") != NULL)
+                       return (NULL);
                error("%s", ebuf);
-       else if (*ebuf)
+       }
+       if (*ebuf)
                warning("%s", ebuf);
 #endif /* HAVE_PCAP_CREATE */
 
@@ -1650,22 +1671,6 @@ main(int argc, char **argv)
                        if (device == NULL)
                                error("%s", ebuf);
                }
-#ifdef _WIN32
-               /*
-                * Print a message to the standard error on Windows.
-                * XXX - why do it here, with a different message?
-                */
-               if(strlen(device) == 1) /* we assume that an ASCII string is always longer than 1 char */
-               {                                               /* a Unicode string has a \0 as second byte (so strlen() is 1) */
-                       fprintf(stderr, "%s: listening on %ws\n", program_name, device);
-               }
-               else
-               {
-                       fprintf(stderr, "%s: listening on %s\n", program_name, device);
-               }
-
-               fflush(stderr);
-#endif /* _WIN32 */
 
                /*
                 * Try to open the interface with the specified name.
@@ -1724,7 +1729,7 @@ main(int argc, char **argv)
                        }
 #endif /* !defined(HAVE_PCAP_CREATE) && defined(_WIN32) */
                if (Lflag)
-                       show_dlts_and_exit(device);
+                       show_dlts_and_exit(pd, device);
                if (yflag_dlt >= 0) {
 #ifdef HAVE_PCAP_SET_DATALINK
                        if (pcap_set_datalink(pd, yflag_dlt) < 0)
@@ -1956,7 +1961,6 @@ main(int argc, char **argv)
 #endif
        }
 
-#ifndef _WIN32
        if (RFileName == NULL) {
                /*
                 * Live capture (if -V was specified, we set RFileName
@@ -1981,7 +1985,6 @@ main(int argc, char **argv)
                }
                (void)fflush(stderr);
        }
-#endif /* _WIN32 */
 
 #ifdef HAVE_CAPSICUM
        cansandbox = (ndo->ndo_nflag && VFileName == NULL && zflag == NULL);