]> The Tcpdump Group git mirrors - tcpdump/blobdiff - tcpdump.c
CMake: Fix the comment about versions. [skip ci]
[tcpdump] / tcpdump.c
index 3bf78a94ab85bcb643221ae4ec9d3c5cb8ed8dbb..9bab8d87850044e0bb1051346bd77642c556901b 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
  * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
  */
 
-#ifdef HAVE_CONFIG_H
 #include <config.h>
-#endif
 
 /*
- * Some older versions of Mac OS X may ship pcap.h from libpcap 0.6 with a
+ * Some older versions of Mac OS X ship pcap.h from libpcap 0.6 with a
  * libpcap based on 0.8.  That means it has pcap_findalldevs() but the
  * header doesn't define pcap_if_t, meaning that we can't actually *use*
  * pcap_findalldevs().
@@ -63,9 +61,7 @@ The Regents of the University of California.  All rights reserved.\n";
 
 #include <sys/stat.h>
 
-#ifdef HAVE_FCNTL_H
 #include <fcntl.h>
-#endif
 
 #ifdef HAVE_LIBCRYPTO
 #include <openssl/crypto.h>
@@ -433,15 +429,15 @@ show_tstamp_types_and_exit(pcap_t *pc, const char *device)
                    device);
                exit_tcpdump(S_SUCCESS);
        }
-       fprintf(stderr, "Time stamp types for %s (use option -j to set):\n",
+       fprintf(stdout, "Time stamp types for %s (use option -j to set):\n",
            device);
        for (i = 0; i < n_tstamp_types; i++) {
                tstamp_type_name = pcap_tstamp_type_val_to_name(tstamp_types[i]);
                if (tstamp_type_name != NULL) {
-                       (void) fprintf(stderr, "  %s (%s)\n", tstamp_type_name,
+                       (void) fprintf(stdout, "  %s (%s)\n", tstamp_type_name,
                            pcap_tstamp_type_val_to_description(tstamp_types[i]));
                } else {
-                       (void) fprintf(stderr, "  %d\n", tstamp_types[i]);
+                       (void) fprintf(stdout, "  %d\n", tstamp_types[i]);
                }
        }
        pcap_free_tstamp_types(tstamp_types);
@@ -470,28 +466,30 @@ show_dlts_and_exit(pcap_t *pc, const char *device)
         * monitor mode might be different from the ones available when
         * not in monitor mode).
         */
+       (void) fprintf(stdout, "Data link types for ");
        if (supports_monitor_mode)
-               (void) fprintf(stderr, "Data link types for %s %s (use option -y to set):\n",
+               (void) fprintf(stdout, "%s %s",
                    device,
                    Iflag ? "when in monitor mode" : "when not in monitor mode");
        else
-               (void) fprintf(stderr, "Data link types for %s (use option -y to set):\n",
+               (void) fprintf(stdout, "%s",
                    device);
+       (void) fprintf(stdout, " (use option -y to set):\n");
 
        for (i = 0; i < n_dlts; i++) {
                dlt_name = pcap_datalink_val_to_name(dlts[i]);
                if (dlt_name != NULL) {
-                       (void) fprintf(stderr, "  %s (%s)", dlt_name,
+                       (void) fprintf(stdout, "  %s (%s)", dlt_name,
                            pcap_datalink_val_to_description(dlts[i]));
 
                        /*
                         * OK, does tcpdump handle that type?
                         */
                        if (!has_printer(dlts[i]))
-                               (void) fprintf(stderr, " (printing not supported)");
-                       fprintf(stderr, "\n");
+                               (void) fprintf(stdout, " (printing not supported)");
+                       fprintf(stdout, "\n");
                } else {
-                       (void) fprintf(stderr, "  DLT %d (printing not supported)\n",
+                       (void) fprintf(stdout, "  DLT %d (printing not supported)\n",
                            dlts[i]);
                }
        }
@@ -703,6 +701,7 @@ show_remote_devices_and_exit(void)
 #define OPTION_TSTAMP_NANO             134
 #define OPTION_FP_TYPE                 135
 #define OPTION_COUNT                   136
+#define OPTION_TIME_T_SIZE             139
 
 static const struct option longopts[] = {
 #if defined(HAVE_PCAP_CREATE) || defined(_WIN32)
@@ -750,6 +749,7 @@ static const struct option longopts[] = {
        { "fp-type", no_argument, NULL, OPTION_FP_TYPE },
        { "number", no_argument, NULL, '#' },
        { "print", no_argument, NULL, OPTION_PRINT },
+       { "time-t-size", no_argument, NULL, OPTION_TIME_T_SIZE },
        { "version", no_argument, NULL, OPTION_VERSION },
        { NULL, 0, NULL, 0 }
 };
@@ -806,7 +806,7 @@ droproot(const char *username, const char *chroot_dir)
        } else
                error("Couldn't find user '%.32s'", username);
 #ifdef HAVE_LIBCAP_NG
-       /* We don't need CAP_SETUID, CAP_SETGID and CAP_SYS_CHROOT any more. */
+       /* We don't need CAP_SETUID, CAP_SETGID and CAP_SYS_CHROOT anymore. */
 DIAG_OFF_ASSIGN_ENUM
        capng_updatev(
                CAPNG_DROP,
@@ -843,6 +843,8 @@ MakeFilename(char *buffer, char *orig_name, int cnt, int max_chars)
         char *filename = malloc(PATH_MAX + 1);
         if (filename == NULL)
             error("%s: malloc", __func__);
+        if (strlen(orig_name) == 0)
+            error("an empty string is not a valid file name");
 
         /* Process with strftime if Gflag is set. */
         if (Gflag != 0) {
@@ -854,9 +856,25 @@ MakeFilename(char *buffer, char *orig_name, int cnt, int max_chars)
           }
 
           /* There's no good way to detect an error in strftime since a return
-           * value of 0 isn't necessarily failure.
+           * value of 0 isn't necessarily failure; if orig_name is an empty
+           * string, the formatted string will be empty.
+           *
+           * However, the C90 standard says that, if there *is* a
+           * buffer overflow, the content of the buffer is undefined,
+           * so we must check for a buffer overflow.
+           *
+           * So we check above for an empty orig_name, and only call
+           * strftime() if it's non-empty, in which case the return
+           * value will only be 0 if the formatted date doesn't fit
+           * in the buffer.
+           *
+           * (We check above because, even if we don't use -G, we
+           * want a better error message than "tcpdump: : No such
+           * file or directory" for this case.)
            */
-          strftime(filename, PATH_MAX, orig_name, local_tm);
+          if (strftime(filename, PATH_MAX, orig_name, local_tm) == 0) {
+            error("%s: strftime", __func__);
+          }
         } else {
           strncpy(filename, orig_name, PATH_MAX);
         }
@@ -959,7 +977,7 @@ tstamp_precision_to_string(int precision)
  * along the lines of ioctl(), the fact that ioctl() operations are
  * largely specific to particular character devices but fcntl() operations
  * are either generic to all descriptors or generic to all descriptors for
- * regular files nonwithstanding.
+ * regular files notwithstanding.
  *
  * The Capsicum people decided that fine-grained control of descriptor
  * operations was required, so that you need to grant permission for
@@ -1146,7 +1164,7 @@ parse_interface_number(const char *device)
                        /*
                         * No, it's not an ordinal.
                         */
-                       error("Invalid adapter index");
+                       error("Invalid adapter index %s", device);
                }
                return (devnum);
        } else {
@@ -1221,8 +1239,11 @@ _U_
        for (i = 0, dev = devlist; i < devnum-1 && dev != NULL;
            i++, dev = dev->next)
                ;
-       if (dev == NULL)
-               error("Invalid adapter index");
+       if (dev == NULL) {
+               pcap_freealldevs(devlist);
+               error("Invalid adapter index %ld: only %ld interfaces found",
+                   devnum, i);
+       }
        device = strdup(dev->name);
        pcap_freealldevs(devlist);
        return (device);
@@ -1500,6 +1521,157 @@ main(int argc, char **argv)
        netdissect_options Ndo;
        netdissect_options *ndo = &Ndo;
 
+#ifdef _WIN32
+       /*
+        * We need to look for wpcap.dll in \Windows\System32\Npcap first,
+        * as either:
+        *
+        *  1) WinPcap isn't installed and Npcap isn't installed in "WinPcap
+        *     API-compatible Mode", so there's no wpcap.dll in
+        *     \Windows\System32, only in \Windows\System32\Npcap;
+        *
+        *  2) WinPcap is installed and Npcap isn't installed in "WinPcap
+        *     API-compatible Mode", so the wpcap.dll in \Windows\System32
+        *     is a WinPcap DLL, but we'd prefer an Npcap DLL (we should
+        *     work with either one if we're configured against WinPcap,
+        *     and we'll probably require Npcap if we're configured againt
+        *     it), and that's in \Windows\System32\Npcap;
+        *
+        *  3) Npcap is installed in "WinPcap API-compatible Mode", so both
+        *     \Windows\System32 and \Windows\System32\Npcap have an Npcap
+        *     wpcap.dll.
+        *
+        * Unfortunately, Windows has no notion of an rpath, so we can't
+        * set the rpath to include \Windows\System32\Npcap at link time;
+        * what we need to do is to link wpcap as a delay-load DLL and
+        * add \Windows\System32\Npcap to the DLL search path early in
+        * main() with a call to SetDllDirectory().
+        *
+        * The same applies to packet.dll.
+        *
+        * We add \Windows\System32\Npcap here.
+        *
+        * See https://npcap.com/guide/npcap-devguide.html#npcap-feature-native-dll-implicitly
+        */
+       WCHAR *dll_directory = NULL;
+       size_t dll_directory_buf_len = 0;       /* units of bytes */
+       UINT system_directory_buf_len = 0;      /* units of WCHARs */
+       UINT system_directory_len;              /* units of WCHARs */
+       static const WCHAR npcap[] = L"\\Npcap";
+
+       /*
+        * Get the system directory path, in UTF-16, into a buffer that's
+        * large enough for that directory path plus "\Npcap".
+        *
+        * String manipulation in C, plus fetching a variable-length
+        * string into a buffer whose size is fixed at the time of
+        * the call, with an oddball return value (see below), is just
+        * a huge bag of fun.
+        *
+        * And it's even more fun when dealing with UTF-16, so that the
+        * buffer sizes used in GetSystemDirectoryW() are in different
+        * units from the buffer sizes used in realloc()!   We maintain
+        * all sizes/length in units of bytes, not WCHARs, so that our
+        * heads don't explode.
+        */
+       for (;;) {
+               /*
+                * Try to fetch the system directory.
+                *
+                * GetSystemDirectoryW() expects a buffer size in units
+                * of WCHARs, not bytes, and returns a directory path
+                * length in units of WCHARs, not bytes.
+                *
+                * For extra fun, if GetSystemDirectoryW() succeeds,
+                * the return value is the length of the directory
+                * path in units of WCHARs, *not* including the
+                * terminating '\0', but if it fails because the
+                * path string wouldn't fit, the return value is
+                * the length of the directory path in units of WCHARs,
+                * *including* the terminating '\0'.
+                */
+               system_directory_len = GetSystemDirectoryW(dll_directory,
+                   system_directory_buf_len);
+               if (system_directory_len == 0)
+                       error("GetSystemDirectoryW() failed");
+
+               /*
+                * Did the directory path fit in the buffer?
+                *
+                * As per the above, this means that the return value
+                * *plus 1*, so that the terminating '\0' is counted,
+                * is <= the buffer size.
+                *
+                * (If the directory path, complete with the terminating
+                * '\0', fits *exactly*, the return value would be the
+                * size of the buffer minus 1, as it doesn't count the
+                * terminating '\0', so the test below would succeed.
+                *
+                * If everything *but* the terminating '\0' fits,
+                * the return value would be the size of the buffer + 1,
+                * i.e., the size that the string in question would
+                * have required.
+                *
+                * The astute reader will note that returning the
+                * size of the buffer is not one of the two cases
+                * above, and should never happen.)
+                */
+               if ((system_directory_len + 1) <= system_directory_buf_len) {
+                       /*
+                        * No.  We have a buffer that's large enough
+                        * for our purposes.
+                        */
+                       break;
+               }
+
+               /*
+                * Yes.  Grow the buffer.
+                *
+                * The space we'll need in the buffer for the system
+                * directory, in units of WCHARs, is system_directory_len,
+                * as that's the length of the system directory path
+                * including the terminating '\0'.
+                */
+               system_directory_buf_len = system_directory_len;
+
+               /*
+                * The size of the DLL directory buffer, in *bytes*, must
+                * be the number of WCHARs taken by the system directory,
+                * *minus* the terminating '\0' (as we'll overwrite that
+                * with the "\" of the "\Npcap" string), multiplied by
+                * sizeof(WCHAR) to convert it to the number of bytes,
+                * plus the size of the "\Npcap" string, in bytes (which
+                * will include the terminating '\0', as that will become
+                * the DLL path's terminating '\0').
+                */
+               dll_directory_buf_len =
+                   ((system_directory_len - 1)*sizeof(WCHAR)) + sizeof npcap;
+               dll_directory = realloc(dll_directory, dll_directory_buf_len);
+               if (dll_directory == NULL)
+                       error("Can't allocate string for Npcap directory");
+       }
+
+       /*
+        * OK, that worked.
+        *
+        * Now append \Npcap.  We add the length of the system directory path,
+        * in WCHARs, *not* including the terminating '\0' (which, since
+        * GetSystemDirectoryW() succeeded, is the return value of
+        * GetSystemDirectoryW(), as per the above), to the pointer to the
+        * beginning of the path, to go past the end of the system directory
+        * to point to the terminating '\0'.
+        */
+       memcpy(dll_directory + system_directory_len, npcap, sizeof npcap);
+
+       /*
+        * Now add that as a system DLL directory.
+        */
+       if (!SetDllDirectoryW(dll_directory))
+               error("SetDllDirectory failed");
+
+       free(dll_directory);
+#endif
+
        /*
         * Initialize the netdissect code.
         */
@@ -1540,6 +1712,13 @@ main(int argc, char **argv)
        if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
                error("%s", ebuf);
 
+       /*
+        * An explicit tzset() call is usually not needed as it happens
+        * implicitly the first time we call localtime() or mktime(),
+        * but in some cases (sandboxing, chroot) this may be too late.
+        */
+       tzset();
+
        while (
            (op = getopt_long(argc, argv, SHORTOPTS, longopts, NULL)) != -1)
                switch (op) {
@@ -1708,7 +1887,7 @@ main(int argc, char **argv)
                                if (nd_load_smi_module(optarg, ebuf, sizeof(ebuf)) == -1)
                                        error("%s", ebuf);
                        } else {
-                               (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
+                               (void)fprintf(stderr, "%s: ignoring option '-m %s' ",
                                              program_name, optarg);
                                (void)fprintf(stderr, "(no libsmi support)\n");
                        }
@@ -1752,7 +1931,7 @@ main(int argc, char **argv)
                        else if (ascii_strcasecmp(optarg, "inout") == 0)
                                Qflag = PCAP_D_INOUT;
                        else
-                               error("unknown capture direction `%s'", optarg);
+                               error("unknown capture direction '%s'", optarg);
                        break;
 #endif /* HAVE_PCAP_SETDIRECTION */
 
@@ -1818,7 +1997,7 @@ main(int argc, char **argv)
                        else if (ascii_strcasecmp(optarg, "domain") == 0)
                                ndo->ndo_packettype = PT_DOMAIN;
                        else
-                               error("unknown packet type `%s'", optarg);
+                               error("unknown packet type '%s'", optarg);
                        break;
 
                case 'u':
@@ -1888,6 +2067,10 @@ main(int argc, char **argv)
                        ndo->ndo_packet_number = 1;
                        break;
 
+               case OPTION_TIME_T_SIZE:
+                       printf("%zu\n", sizeof(time_t) * 8);
+                       return 0;
+
                case OPTION_VERSION:
                        print_version(stdout);
                        exit_tcpdump(S_SUCCESS);
@@ -1942,6 +2125,13 @@ main(int argc, char **argv)
                        /* NOTREACHED */
                }
 
+       if (ndo->ndo_Aflag && ndo->ndo_xflag)
+               warning("-A and -x[x] are mutually exclusive. -A ignored.");
+       if (ndo->ndo_Aflag && ndo->ndo_Xflag)
+               warning("-A and -X[X] are mutually exclusive. -A ignored.");
+       if (ndo->ndo_xflag && ndo->ndo_Xflag)
+               warning("-x[x] and -X[X] are mutually exclusive. -x[x] ignored.");
+
 #ifdef HAVE_PCAP_FINDALLDEVS
        if (Dflag)
                show_devices_and_exit();
@@ -1951,14 +2141,6 @@ main(int argc, char **argv)
                show_remote_devices_and_exit();
 #endif
 
-#if defined(DLT_LINUX_SLL2) && defined(HAVE_PCAP_SET_DATALINK)
-/* Set default linktype DLT_LINUX_SLL2 when capturing on the "any" device */
-               if (device != NULL &&
-                   strncmp (device, "any", strlen("any")) == 0
-                   && yflag_dlt == -1)
-                       yflag_dlt = DLT_LINUX_SLL2;
-#endif
-
        switch (ndo->ndo_tflag) {
 
        case 0: /* Default */
@@ -2008,6 +2190,8 @@ main(int argc, char **argv)
                /* Run with '-Z root' to restore old behaviour */
                if (!username)
                        username = WITH_USER;
+               else if (strcmp(username, "root") == 0)
+                       username = NULL;
        }
 #endif
 
@@ -2211,6 +2395,24 @@ main(int argc, char **argv)
                                      pcap_datalink_val_to_name(yflag_dlt));
                        (void)fflush(stderr);
                }
+#if defined(DLT_LINUX_SLL2) && defined(HAVE_PCAP_SET_DATALINK)
+               else {
+                       /*
+                        * Attempt to set default linktype to
+                        * DLT_LINUX_SLL2 when capturing on the
+                        * "any" device.
+                        *
+                        * If the attempt fails, just quietly drive
+                        * on; this may be a non-Linux "any" device
+                        * that doesn't support DLT_LINUX_SLL2.
+                        */
+                       if (strcmp(device, "any") == 0) {
+DIAG_OFF_WARN_UNUSED_RESULT
+                               (void) pcap_set_datalink(pd, DLT_LINUX_SLL2);
+DIAG_ON_WARN_UNUSED_RESULT
+                       }
+               }
+#endif
                i = pcap_snapshot(pd);
                if (ndo->ndo_snaplen < i) {
                        if (ndo->ndo_snaplen != 0)
@@ -2262,7 +2464,21 @@ main(int argc, char **argv)
 #endif
        /* Cooperate with nohup(1) */
 #ifndef _WIN32
+       /*
+        * In illumos /usr/include/sys/iso/signal_iso.h causes Clang to
+        * generate a -Wstrict-prototypes warning here, see [1].  The
+        * __illumos__ macro is available since at least GCC 11 and Clang 13,
+        * see [2].
+        * 1: https://www.illumos.org/issues/16344
+        * 2: https://www.illumos.org/issues/13726
+        */
+#ifdef __illumos__
+       DIAG_OFF_STRICT_PROTOTYPES
+#endif /* __illumos__ */
        if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
+#ifdef __illumos__
+       DIAG_ON_STRICT_PROTOTYPES
+#endif /* __illumos__ */
                (void)setsignal(SIGHUP, oldhandler);
 #endif /* _WIN32 */
 
@@ -2543,6 +2759,9 @@ DIAG_ON_ASSIGN_ENUM
 #else
        cansandbox = (cansandbox && ndo->ndo_nflag);
 #endif /* HAVE_CASPER */
+       cansandbox = (cansandbox && (pcap_fileno(pd) != -1 ||
+           RFileName != NULL));
+
        if (cansandbox && cap_enter() < 0 && errno != ENOSYS)
                error("unable to enter the capability mode");
 #endif /* HAVE_CAPSICUM */
@@ -2634,6 +2853,8 @@ DIAG_ON_ASSIGN_ENUM
                                         */
                                        dlt = new_dlt;
                                        ndo->ndo_if_printer = get_if_printer(dlt);
+                                       /* Free the old filter */
+                                       pcap_freecode(&fcode);
                                        if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
                                                error("%s", pcap_geterr(pd));
                                }
@@ -2668,7 +2889,7 @@ DIAG_ON_ASSIGN_ENUM
 
        free(cmdbuf);
        pcap_freecode(&fcode);
-       exit_tcpdump(status == -1 ? 1 : 0);
+       exit_tcpdump(status == -1 ? S_ERR_HOST_PROGRAM : S_SUCCESS);
 }
 
 /*
@@ -2684,10 +2905,24 @@ static void
 
        memset(&new, 0, sizeof(new));
        new.sa_handler = func;
-       if (sig == SIGCHLD)
+       if ((sig == SIGCHLD)
+# ifdef SIGNAL_REQ_INFO
+               || (sig == SIGNAL_REQ_INFO)
+# endif
+# ifdef SIGNAL_FLUSH_PCAP
+               || (sig == SIGNAL_FLUSH_PCAP)
+# endif
+               )
                new.sa_flags = SA_RESTART;
        if (sigaction(sig, &new, &old) < 0)
+               /* The same workaround as for SIG_DFL above. */
+#ifdef __illumos__
+               DIAG_OFF_STRICT_PROTOTYPES
+#endif /* __illumos__ */
                return (SIG_ERR);
+#ifdef __illumos__
+               DIAG_ON_STRICT_PROTOTYPES
+#endif /* __illumos__ */
        return (old.sa_handler);
 #endif
 }
@@ -2749,7 +2984,7 @@ cleanup(int signo _U_)
 static void
 child_cleanup(int signo _U_)
 {
-  wait(NULL);
+  while (waitpid(-1, NULL, WNOHANG) >= 0);
 }
 #endif /* HAVE_FORK && HAVE_VFORK */
 
@@ -3191,6 +3426,8 @@ print_version(FILE *f)
        (void)fprintf (f, "Compiled with MemorySanitizer/Clang.\n");
 #  endif
 #endif /* __SANITIZE_ADDRESS__ or __has_feature */
+       (void)fprintf (f, "%zu-bit build, %zu-bit time_t\n",
+                      sizeof(void *) * 8, sizeof(time_t) * 8);
 }
 DIAG_ON_DEPRECATION