Try opening interfaces by name first, then by name-as-index.

Some UN*Xes apparently can have purely numeric interface names, so we
can't unconditionally treat purely numeric interface names as interface
indices.  Do so only for "names" that don't correspond to interfaces.

Fixes GitHub issue #522.

diff --git a/tcpdump.c b/tcpdump.c
index 657158e4e678c153f75f982656ccccbce44bd882..97e2aa55ca9f453a23725ba5bceb1a11d848ef9e 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -129,6 +129,7 @@ The Regents of the University of California.  All rights reserved.\n";
 #define SIGNAL_REQ_INFO SIGUSR1
 #endif
 
 #define SIGNAL_REQ_INFO SIGUSR1
 #endif
 

+static int Bflag;                      /* buffer size */

 static int Cflag;                      /* rotate dump files after this many bytes */
 static int Cflag_count;                        /* Keep track of which file number we're writing */
 static int Dflag;                      /* list available devices and exit */
 static int Cflag;                      /* rotate dump files after this many bytes */
 static int Cflag_count;                        /* Keep track of which file number we're writing */
 static int Dflag;                      /* list available devices and exit */


@@ -153,6 +154,8 @@ static int Iflag;                   /* rfmon (monitor) mode */
 #ifdef HAVE_PCAP_SET_TSTAMP_TYPE
 static int Jflag;                      /* list available time stamp types */
 #endif
 #ifdef HAVE_PCAP_SET_TSTAMP_TYPE
 static int Jflag;                      /* list available time stamp types */
 #endif

+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 */
 #endif
 #ifdef HAVE_PCAP_SETDIRECTION
 int Qflag = -1;                                /* restrict captured packet by send/receive direction */
 #endif


@@ -160,6 +163,7 @@ static int Uflag;                   /* "unbuffered" output of dump files */
 static int Wflag;                      /* recycle output files after this number of files */
 static int WflagChars;
 static char *zflag = NULL;             /* compress each savefile using a specified command (like gzip or bzip2) */
 static int Wflag;                      /* recycle output files after this number of files */
 static int WflagChars;
 static char *zflag = NULL;             /* compress each savefile using a specified command (like gzip or bzip2) */

+static int immediate_mode;

 
 static int infodelay;
 static int infoprint;
 
 static int infodelay;
 static int infoprint;


@@ -206,6 +210,7 @@ RETSIGTYPE requestinfo(int);
 static void info(int);
 static u_int packets_captured;
 
 static void info(int);
 static u_int packets_captured;
 

+#ifdef HAVE_PCAP_FINDALLDEVS

 static const struct tok status_flags[] = {
 #ifdef PCAP_IF_UP
        { PCAP_IF_UP,       "Up"       },
 static const struct tok status_flags[] = {
 #ifdef PCAP_IF_UP
        { PCAP_IF_UP,       "Up"       },


@@ -216,6 +221,7 @@ static const struct tok status_flags[] = {
        { PCAP_IF_LOOPBACK, "Loopback" },
        { 0, NULL }
 };
        { PCAP_IF_LOOPBACK, "Loopback" },
        { 0, NULL }
 };

+#endif

 
 static pcap_t *pd;
 
 
 static pcap_t *pd;
 


@@ -889,6 +895,190 @@ read_infile(char *fname)
        return (cp);
 }
 
        return (cp);
 }
 

+#ifdef HAVE_PCAP_FINDALLDEVS
+static long
+parse_interface_number(const char *device)
+{
+       long devnum;
+       char *end;
+
+       devnum = strtol(device, &end, 10);
+       if (device != end && *end == '\0') {
+               /*
+                * It's all-numeric, but is it a valid number?
+                */
+               if (devnum <= 0) {
+                       /*
+                        * No, it's not an ordinal.
+                        */
+                       error("Invalid adapter index");
+               }
+               return (devnum);
+       } else {
+               /*
+                * It's not all-numeric; return -1, so our caller
+                * knows that.
+                */
+               return (-1);
+       }
+}
+
+static char *
+find_interface_by_number(long devnum)
+{
+       pcap_if_t *dev, *devlist;
+       long i;
+       char ebuf[PCAP_ERRBUF_SIZE];
+       char *device;
+
+       if (pcap_findalldevs(&devlist, ebuf) < 0)
+               error("%s", ebuf);
+       /*
+        * Look for the devnum-th entry in the list of devices (1-based).
+        */
+       for (i = 0, dev = devlist; i < devnum-1 && dev != NULL;
+           i++, dev = dev->next)
+               ;
+       if (dev == NULL)
+               error("Invalid adapter index");
+       device = strdup(dev->name);
+       pcap_freealldevs(devlist);
+       return (device);
+}
+#endif
+
+static pcap_t *
+open_interface(const char *device, netdissect_options *ndo, char *ebuf)
+{
+       pcap_t *pc;
+#ifdef HAVE_PCAP_CREATE
+       int status;
+       char *cp;
+#endif
+
+#ifdef HAVE_PCAP_CREATE
+       pc = pcap_create(device, ebuf);
+       if (pc == NULL)
+               error("%s", ebuf);
+#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
+       if (Jflag)
+               show_tstamp_types_and_exit(device);
+#endif
+#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
+       status = pcap_set_tstamp_precision(pc, ndo->ndo_tstamp_precision);
+       if (status != 0)
+               error("%s: Can't set %ssecond time stamp precision: %s",
+                       device,
+                       tstamp_precision_to_string(ndo->ndo_tstamp_precision),
+                       pcap_statustostr(status));
+#endif
+
+#ifdef HAVE_PCAP_SET_IMMEDIATE_MODE
+       if (immediate_mode) {
+               status = pcap_set_immediate_mode(pc, 1);
+               if (status != 0)
+                       error("%s: Can't set immediate mode: %s",
+                       device,
+                       pcap_statustostr(status));
+       }
+#endif
+       /*
+        * Is this an interface that supports monitor mode?
+        */
+       if (pcap_can_set_rfmon(pc) == 1)
+               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));
+       status = pcap_set_promisc(pc, !pflag);
+       if (status != 0)
+               error("%s: Can't set promiscuous mode: %s",
+                   device, pcap_statustostr(status));
+       if (Iflag) {
+               status = pcap_set_rfmon(pc, 1);
+               if (status != 0)
+                       error("%s: Can't set monitor mode: %s",
+                           device, pcap_statustostr(status));
+       }
+       status = pcap_set_timeout(pc, 1000);
+       if (status != 0)
+               error("%s: pcap_set_timeout failed: %s",
+                   device, pcap_statustostr(status));
+       if (Bflag != 0) {
+               status = pcap_set_buffer_size(pc, Bflag);
+               if (status != 0)
+                       error("%s: Can't set buffer size: %s",
+                           device, pcap_statustostr(status));
+       }
+#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
+       if (jflag != -1) {
+               status = pcap_set_tstamp_type(pc, jflag);
+               if (status < 0)
+                       error("%s: Can't set time stamp type: %s",
+                             device, pcap_statustostr(status));
+       }
+#endif
+       status = pcap_activate(pc);
+       if (status < 0) {
+               /*
+                * pcap_activate() failed.
+                */
+               cp = pcap_geterr(pc);
+               if (status == PCAP_ERROR)
+                       error("%s", cp);
+               else if (status == PCAP_ERROR_NO_SUCH_DEVICE) {
+                       /*
+                        * Return an error for our caller to handle.
+                        */
+                       pcap_close(pc);
+                       snprintf(ebuf, PCAP_ERRBUF_SIZE, "%s: %s\n(%s)",
+                           device, pcap_statustostr(status), cp);
+                       return (NULL);
+               } else if (status == PCAP_ERROR_PERM_DENIED && *cp != '\0')
+                       error("%s: %s\n(%s)", device,
+                           pcap_statustostr(status), cp);
+               else
+                       error("%s: %s", device,
+                           pcap_statustostr(status));
+       } else if (status > 0) {
+               /*
+                * pcap_activate() succeeded, but it's warning us
+                * of a problem it had.
+                */
+               cp = pcap_geterr(pc);
+               if (status == PCAP_WARNING)
+                       warning("%s", cp);
+               else if (status == PCAP_WARNING_PROMISC_NOTSUP &&
+                        *cp != '\0')
+                       warning("%s: %s\n(%s)", device,
+                           pcap_statustostr(status), cp);
+               else
+                       warning("%s: %s", device,
+                           pcap_statustostr(status));
+       }
+#ifdef HAVE_PCAP_SETDIRECTION
+       if (Qflag != -1) {
+               status = pcap_setdirection(pc, Qflag);
+               if (status != 0)
+                       error("%s: pcap_setdirection() failed: %s",
+                             device,  pcap_geterr(pc));
+               }
+#endif /* HAVE_PCAP_SETDIRECTION */
+#else /* HAVE_PCAP_CREATE */
+       *ebuf = '\0';
+       pc = pcap_open_live(device, ndo->ndo_snaplen, !pflag, 1000, ebuf);
+       if (pc == NULL)
+               error("%s", ebuf);
+       else if (*ebuf)
+               warning("%s", ebuf);
+#endif /* HAVE_PCAP_CREATE */
+
+       return (pc);
+}
+

 int
 main(int argc, char **argv)
 {
 int
 main(int argc, char **argv)
 {


@@ -912,8 +1102,8 @@ main(int argc, char **argv)
        char *ret = NULL;
        char *end;
 #ifdef HAVE_PCAP_FINDALLDEVS
        char *ret = NULL;
        char *end;
 #ifdef HAVE_PCAP_FINDALLDEVS

-       pcap_if_t *dev, *devlist;
-       int devnum;
+       pcap_if_t *devlist;
+       long devnum;

 #endif
        int status;
        FILE *VFile;
 #endif
        int status;
        FILE *VFile;


@@ -921,16 +1111,12 @@ main(int argc, char **argv)
        cap_rights_t rights;
        int cansandbox;
 #endif /* HAVE_CAPSICUM */
        cap_rights_t rights;
        int cansandbox;
 #endif /* HAVE_CAPSICUM */

-       int Bflag = 0;                  /* buffer size */
-       int jflag = -1;                 /* packet time stamp source */

        int Oflag = 1;                  /* run filter code optimizer */
        int Oflag = 1;                  /* run filter code optimizer */

-       int pflag = 0;                  /* don't go promiscuous */

        int yflag_dlt = -1;
        const char *yflag_dlt_name = NULL;
 
        netdissect_options Ndo;
        netdissect_options *ndo = &Ndo;
        int yflag_dlt = -1;
        const char *yflag_dlt_name = NULL;
 
        netdissect_options Ndo;
        netdissect_options *ndo = &Ndo;

-       int immediate_mode = 0;

 
        /*
         * Initialize the netdissect code.
 
        /*
         * Initialize the netdissect code.


@@ -1062,42 +1248,6 @@ main(int argc, char **argv)
                        break;
 
                case 'i':
                        break;
 
                case 'i':

-                       if (optarg[0] == '0' && optarg[1] == 0)
-                               error("Invalid adapter index");
-
-#ifdef HAVE_PCAP_FINDALLDEVS
-                       /*
-                        * If the argument is a number, treat it as
-                        * an index into the list of adapters, as
-                        * printed by "tcpdump -D".
-                        *
-                        * This should be OK on UNIX systems, as interfaces
-                        * shouldn't have names that begin with digits.
-                        * It can be useful on Windows, where more than
-                        * one interface can have the same name.
-                        */
-                       devnum = strtol(optarg, &end, 10);
-                       if (optarg != end && *end == '\0') {
-                               if (devnum < 0)
-                                       error("Invalid adapter index");
-
-                               if (pcap_findalldevs(&devlist, ebuf) < 0)
-                                       error("%s", ebuf);
-                               /*
-                                * Look for the devnum-th entry in the
-                                * list of devices (1-based).
-                                */
-                               for (i = 0, dev = devlist;
-                                   i < devnum-1 && dev != NULL;
-                                   i++, dev = dev->next)
-                                       ;
-                               if (dev == NULL)
-                                       error("Invalid adapter index");
-                               device = strdup(dev->name);
-                               pcap_freealldevs(devlist);
-                               break;
-                       }
-#endif /* HAVE_PCAP_FINDALLDEVS */

                        device = optarg;
                        break;
 
                        device = optarg;
                        break;
 


@@ -1477,13 +1627,24 @@ main(int argc, char **argv)
                 * We're doing a live capture.
                 */
                if (device == NULL) {
                 * We're doing a live capture.
                 */
                if (device == NULL) {

+                       /*
+                        * No interface was specified.  Pick one.
+                        */

 #ifdef HAVE_PCAP_FINDALLDEVS
 #ifdef HAVE_PCAP_FINDALLDEVS

+                       /*
+                        * Find the list of interfaces, and pick
+                        * the first interface.
+                        */

                        if (pcap_findalldevs(&devlist, ebuf) >= 0 &&
                            devlist != NULL) {
                                device = strdup(devlist->name);
                                pcap_freealldevs(devlist);
                        }
 #else /* HAVE_PCAP_FINDALLDEVS */
                        if (pcap_findalldevs(&devlist, ebuf) >= 0 &&
                            devlist != NULL) {
                                device = strdup(devlist->name);
                                pcap_freealldevs(devlist);
                        }
 #else /* HAVE_PCAP_FINDALLDEVS */

+                       /*
+                        * Use whatever interface pcap_lookupdev()
+                        * chooses.
+                        */

                        device = pcap_lookupdev(ebuf);
 #endif
                        if (device == NULL)
                        device = pcap_lookupdev(ebuf);
 #endif
                        if (device == NULL)


@@ -1505,120 +1666,50 @@ main(int argc, char **argv)
 
                fflush(stderr);
 #endif /* _WIN32 */
 
                fflush(stderr);
 #endif /* _WIN32 */

-#ifdef HAVE_PCAP_CREATE
-               pd = pcap_create(device, ebuf);
-               if (pd == NULL)
-                       error("%s", ebuf);
-#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
-               if (Jflag)
-                       show_tstamp_types_and_exit(device);
-#endif
-#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
-               status = pcap_set_tstamp_precision(pd, ndo->ndo_tstamp_precision);
-               if (status != 0)
-                       error("%s: Can't set %ssecond time stamp precision: %s",
-                               device,
-                               tstamp_precision_to_string(ndo->ndo_tstamp_precision),
-                               pcap_statustostr(status));
-#endif

 
 

-#ifdef HAVE_PCAP_SET_IMMEDIATE_MODE
-               if (immediate_mode) {
-                       status = pcap_set_immediate_mode(pd, 1);
-                       if (status != 0)
-                               error("%s: Can't set immediate mode: %s",
-                               device,
-                               pcap_statustostr(status));
-               }
-#endif

                /*
                /*

-                * Is this an interface that supports monitor mode?
+                * Try to open the interface with the specified name.

                 */
                 */

-               if (pcap_can_set_rfmon(pd) == 1)
-                       supports_monitor_mode = 1;
-               else
-                       supports_monitor_mode = 0;
-               status = pcap_set_snaplen(pd, ndo->ndo_snaplen);
-               if (status != 0)
-                       error("%s: Can't set snapshot length: %s",
-                           device, pcap_statustostr(status));
-               status = pcap_set_promisc(pd, !pflag);
-               if (status != 0)
-                       error("%s: Can't set promiscuous mode: %s",
-                           device, pcap_statustostr(status));
-               if (Iflag) {
-                       status = pcap_set_rfmon(pd, 1);
-                       if (status != 0)
-                               error("%s: Can't set monitor mode: %s",
-                                   device, pcap_statustostr(status));
-               }
-               status = pcap_set_timeout(pd, 1000);
-               if (status != 0)
-                       error("%s: pcap_set_timeout failed: %s",
-                           device, pcap_statustostr(status));
-               if (Bflag != 0) {
-                       status = pcap_set_buffer_size(pd, Bflag);
-                       if (status != 0)
-                               error("%s: Can't set buffer size: %s",
-                                   device, pcap_statustostr(status));
-               }
-#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
-                if (jflag != -1) {
-                       status = pcap_set_tstamp_type(pd, jflag);
-                       if (status < 0)
-                               error("%s: Can't set time stamp type: %s",
-                                     device, pcap_statustostr(status));
-               }
-#endif
-               status = pcap_activate(pd);
-               if (status < 0) {
+               pd = open_interface(device, ndo, ebuf);
+               if (pd == NULL) {

                        /*
                        /*

-                        * pcap_activate() failed.
+                        * That failed.  If we can get a list of
+                        * interfaces, and the interface name
+                        * is purely numeric, try to use it as
+                        * a 1-based index in the list of
+                        * interfaces.

                         */
                         */

-                       cp = pcap_geterr(pd);
-                       if (status == PCAP_ERROR)
-                               error("%s", cp);
-                       else if ((status == PCAP_ERROR_NO_SUCH_DEVICE ||
-                                 status == PCAP_ERROR_PERM_DENIED) &&
-                                *cp != '\0')
-                               error("%s: %s\n(%s)", device,
-                                   pcap_statustostr(status), cp);
-                       else
-                               error("%s: %s", device,
-                                   pcap_statustostr(status));
-               } else if (status > 0) {
+#ifdef HAVE_PCAP_FINDALLDEVS
+                       devnum = parse_interface_number(device);
+                       if (devnum == -1) {
+                               /*
+                                * It's not a number; just report
+                                * the open error and fail.
+                                */
+                               error("%s", ebuf);
+                       }
+

                        /*
                        /*

-                        * pcap_activate() succeeded, but it's warning us
-                        * of a problem it had.
+                        * OK, it's a number; try to find the
+                        * interface with that index, and try
+                        * to open it.
+                        *
+                        * find_interface_by_number() exits if it
+                        * couldn't be found.
+                        */
+                       device = find_interface_by_number(devnum);
+                       pd = open_interface(device, ndo, ebuf);
+                       if (pd == NULL)
+                               error("%s", ebuf);
+#else /* HAVE_PCAP_FINDALLDEVS */
+                       /*
+                        * We can't get a list of interfaces; just
+                        * fail.

                         */
                         */

-                       cp = pcap_geterr(pd);
-                       if (status == PCAP_WARNING)
-                               warning("%s", cp);
-                       else if (status == PCAP_WARNING_PROMISC_NOTSUP &&
-                                *cp != '\0')
-                               warning("%s: %s\n(%s)", device,
-                                   pcap_statustostr(status), cp);
-                       else
-                               warning("%s: %s", device,
-                                   pcap_statustostr(status));
-               }
-#ifdef HAVE_PCAP_SETDIRECTION
-               if (Qflag != -1) {
-                       status = pcap_setdirection(pd, Qflag);
-                       if (status != 0)
-                               error("%s: pcap_setdirection() failed: %s",
-                                     device,  pcap_geterr(pd));
-               }
-#endif /* HAVE_PCAP_SETDIRECTION */
-#else
-               *ebuf = '\0';
-               pd = pcap_open_live(device, ndo->ndo_snaplen, !pflag, 1000,
-                   ebuf);
-               if (pd == NULL)

                        error("%s", ebuf);
                        error("%s", ebuf);

-               else if (*ebuf)
-                       warning("%s", ebuf);
-#endif /* HAVE_PCAP_CREATE */
+#endif /* HAVE_PCAP_FINDALLDEVS */
+               }
+

                /*
                 * Let user own process after socket has been opened.
                 */
                /*
                 * Let user own process after socket has been opened.
                 */