]> The Tcpdump Group git mirrors - tcpdump/blobdiff - tcpdump.c
Replace some command name 'Tcpdump' with 'tcpdump'
[tcpdump] / tcpdump.c
index 939df0b46fe964ba514b6b706a85fda981a9c67b..7159d1c76fd8677ea395f6e4321c58768f27721e 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -38,7 +38,7 @@
 #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().
@@ -78,7 +78,9 @@ The Regents of the University of California.  All rights reserved.\n";
 #endif
 /* Capsicum-specific code requires macros from <net/bpf.h>, which will fail
  * to compile if <pcap.h> has already been included; including the headers
- * in the opposite order works fine.
+ * in the opposite order works fine. For the most part anyway, because in
+ * FreeBSD <pcap/pcap.h> declares bpf_dump() instead of <net/bpf.h>. Thus
+ * interface.h takes care of it later to avoid a compiler warning.
  */
 #ifdef HAVE_CAPSICUM
 #include <sys/capsicum.h>
@@ -151,6 +153,7 @@ The Regents of the University of California.  All rights reserved.\n";
 #include <sys/sysctl.h>
 #endif /* __FreeBSD__ */
 
+#include "netdissect-stdinc.h"
 #include "netdissect.h"
 #include "interface.h"
 #include "addrtoname.h"
@@ -160,6 +163,8 @@ The Regents of the University of California.  All rights reserved.\n";
 
 #include "print.h"
 
+#include "diag-control.h"
+
 #include "fptype.h"
 
 #ifndef PATH_MAX
@@ -237,34 +242,16 @@ static int infoprint;
 
 char *program_name;
 
-#ifdef HAVE_CASPER
-cap_channel_t *capdns;
-#endif
-
 /* Forwards */
-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 void (*setsignal (int sig, void (*func)(int)))(int);
 static void cleanup(int);
 static void child_cleanup(int);
-static void print_version(void);
-static void print_usage(void);
-#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
-static NORETURN void show_tstamp_types_and_exit(pcap_t *, const char *device);
-#endif
-static NORETURN void show_dlts_and_exit(pcap_t *, const char *device);
-#ifdef HAVE_PCAP_FINDALLDEVS
-static NORETURN void show_devices_and_exit(void);
-#endif
-#ifdef HAVE_PCAP_FINDALLDEVS_EX
-static NORETURN void show_remote_devices_and_exit(void);
-#endif
+static void print_version(FILE *);
+static void print_usage(FILE *);
 
 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 *);
 static void dump_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
-static void droproot(const char *, const char *);
 
 #ifdef SIGNAL_REQ_INFO
 static void requestinfo(int);
@@ -371,9 +358,16 @@ extern
 void pcap_set_optimizer_debug(int);
 #endif
 
+static void NORETURN
+exit_tcpdump(const int status)
+{
+       nd_cleanup();
+       exit(status);
+}
+
 /* VARARGS */
-static void
-error(const char *fmt, ...)
+static void NORETURN PRINTFLIKE(1, 2)
+error(FORMAT_STRING(const char *fmt), ...)
 {
        va_list ap;
 
@@ -391,8 +385,8 @@ error(const char *fmt, ...)
 }
 
 /* VARARGS */
-static void
-warning(const char *fmt, ...)
+static void PRINTFLIKE(1, 2)
+warning(FORMAT_STRING(const char *fmt), ...)
 {
        va_list ap;
 
@@ -407,15 +401,8 @@ warning(const char *fmt, ...)
        }
 }
 
-static void
-exit_tcpdump(int status)
-{
-       nd_cleanup();
-       exit(status);
-}
-
 #ifdef HAVE_PCAP_SET_TSTAMP_TYPE
-static void
+static void NORETURN
 show_tstamp_types_and_exit(pcap_t *pc, const char *device)
 {
        int n_tstamp_types;
@@ -432,15 +419,15 @@ 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);
@@ -448,7 +435,7 @@ show_tstamp_types_and_exit(pcap_t *pc, const char *device)
 }
 #endif
 
-static void
+static void NORETURN
 show_dlts_and_exit(pcap_t *pc, const char *device)
 {
        int n_dlts, i;
@@ -469,28 +456,30 @@ 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]);
                }
        }
@@ -501,7 +490,7 @@ show_dlts_and_exit(pcap_t *pc, const char *device)
 }
 
 #ifdef HAVE_PCAP_FINDALLDEVS
-static void
+static void NORETURN
 show_devices_and_exit(void)
 {
        pcap_if_t *dev, *devlist;
@@ -566,7 +555,7 @@ show_devices_and_exit(void)
 #endif /* HAVE_PCAP_FINDALLDEVS */
 
 #ifdef HAVE_PCAP_FINDALLDEVS_EX
-static void
+static void NORETURN
 show_remote_devices_and_exit(void)
 {
        pcap_if_t *dev, *devlist;
@@ -574,8 +563,21 @@ show_remote_devices_and_exit(void)
        int i;
 
        if (pcap_findalldevs_ex(remote_interfaces_source, NULL, &devlist,
-           ebuf) < 0)
+           ebuf) < 0) {
+               if (strcmp(ebuf, "not supported") == 0) {
+                       /*
+                        * macOS 14's pcap_findalldevs_ex(), which is a
+                        * stub that always returns -1 with an error
+                        * message of "not supported".
+                        *
+                        * In this case, as we passed it an rpcap://
+                        * URL, treat that as meaning "remote capture
+                        * not supported".
+                        */
+                       error("Remote capture not supported");
+               }
                error("%s", ebuf);
+       }
        for (i = 0, dev = devlist; dev != NULL; i++, dev = dev->next) {
                printf("%d.%s", i+1, dev->name);
                if (dev->description != NULL)
@@ -702,6 +704,7 @@ show_remote_devices_and_exit(void)
 #define OPTION_TSTAMP_NANO             134
 #define OPTION_FP_TYPE                 135
 #define OPTION_COUNT                   136
+#define OPTION_PRINT_SAMPLING          137
 
 static const struct option longopts[] = {
 #if defined(HAVE_PCAP_CREATE) || defined(_WIN32)
@@ -749,6 +752,7 @@ static const struct option longopts[] = {
        { "fp-type", no_argument, NULL, OPTION_FP_TYPE },
        { "number", no_argument, NULL, '#' },
        { "print", no_argument, NULL, OPTION_PRINT },
+       { "print-sampling", required_argument, NULL, OPTION_PRINT_SAMPLING },
        { "version", no_argument, NULL, OPTION_VERSION },
        { NULL, 0, NULL, 0 }
 };
@@ -805,8 +809,8 @@ 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. */
-DIAG_OFF_CLANG(assign-enum)
+       /* We don't need CAP_SETUID, CAP_SETGID and CAP_SYS_CHROOT anymore. */
+DIAG_OFF_ASSIGN_ENUM
        capng_updatev(
                CAPNG_DROP,
                CAPNG_EFFECTIVE | CAPNG_PERMITTED,
@@ -814,7 +818,7 @@ DIAG_OFF_CLANG(assign-enum)
                CAP_SETGID,
                CAP_SYS_CHROOT,
                -1);
-DIAG_ON_CLANG(assign-enum)
+DIAG_ON_ASSIGN_ENUM
        capng_apply(CAPNG_SELECT_BOTH);
 #endif /* HAVE_LIBCAP_NG */
 
@@ -841,7 +845,9 @@ MakeFilename(char *buffer, char *orig_name, int cnt, int max_chars)
 {
         char *filename = malloc(PATH_MAX + 1);
         if (filename == NULL)
-            error("Makefilename: malloc");
+            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) {
@@ -849,13 +855,29 @@ MakeFilename(char *buffer, char *orig_name, int cnt, int max_chars)
 
           /* Convert Gflag_time to a usable format */
           if ((local_tm = localtime(&Gflag_time)) == NULL) {
-                  error("MakeTimedFilename: localtime");
+                  error("%s: localtime", __func__);
           }
 
           /* 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);
         }
@@ -907,6 +929,7 @@ capdns_setup(void)
        if (cap_dns_type_limit(capdnsloc, types, 1) < 0)
                error("unable to limit access to system.dns service");
        families[0] = AF_INET;
+       /* Casper is a feature of FreeBSD, which defines AF_INET6. */
        families[1] = AF_INET6;
        if (cap_dns_family_limit(capdnsloc, families, 2) < 0)
                error("unable to limit access to system.dns service");
@@ -958,7 +981,7 @@ 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
@@ -974,7 +997,7 @@ tstamp_precision_to_string(int precision)
  * that requires that it be able to do an F_GETFL fcntl() to read
  * the O_ flags.
  *
- * Tcpdump uses ftell() to determine how much data has been written
+ * tcpdump uses ftell() to determine how much data has been written
  * to a file in order to, when used with -C, determine when it's time
  * to rotate capture files.  ftell() therefore needs to do an lseek()
  * to find out the file offset and must, thanks to the aforementioned
@@ -1035,7 +1058,7 @@ copy_argv(char **argv)
 
        buf = (char *)malloc(len);
        if (buf == NULL)
-               error("copy_argv: malloc");
+               error("%s: malloc", __func__);
 
        p = argv;
        dst = buf;
@@ -1065,15 +1088,22 @@ read_infile(char *fname)
        int i, fd;
        ssize_t cc;
        char *cp;
-       struct stat buf;
+       our_statb buf;
 
        fd = open(fname, O_RDONLY|O_BINARY);
        if (fd < 0)
                error("can't open %s: %s", fname, pcap_strerror(errno));
 
-       if (fstat(fd, &buf) < 0)
+       if (our_fstat(fd, &buf) < 0)
                error("can't stat %s: %s", fname, pcap_strerror(errno));
 
+       /*
+        * Reject files whose size doesn't fit into an int; a filter
+        * *that* large will probably be too big.
+        */
+       if (buf.st_size > INT_MAX)
+               error("%s is too large", fname);
+
        cp = malloc((u_int)buf.st_size + 1);
        if (cp == NULL)
                error("malloc(%d) for %s: %s", (u_int)buf.st_size + 1,
@@ -1082,7 +1112,8 @@ read_infile(char *fname)
        if (cc < 0)
                error("read %s: %s", fname, pcap_strerror(errno));
        if (cc != buf.st_size)
-               error("short read %s (%zd != %d)", fname, cc, (int)buf.st_size);
+               error("short read %s (%d != %d)", fname, (int) cc,
+                   (int)buf.st_size);
 
        close(fd);
        /* replace "# comment" with spaces */
@@ -1251,6 +1282,18 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
                    pflag ? 0 : PCAP_OPENFLAG_PROMISCUOUS, timeout, NULL,
                    ebuf);
                if (pc == NULL) {
+                       /*
+                        * macOS 14's pcap_pcap_open(), which is a
+                        * stub that always returns NULL with an error
+                        * message of "not supported".
+                        *
+                        * In this case, as we passed it an rpcap://
+                        * URL, treat that as meaning "remote capture
+                        * not supported".
+                        */
+                       if (strcmp(ebuf, "not supported") == 0)
+                               error("Remote capture not supported");
+
                        /*
                         * If this failed with "No such device" or "The system
                         * cannot find the device specified", that means
@@ -1420,7 +1463,7 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
                if (status != 0)
                        error("%s: pcap_setdirection() failed: %s",
                              device,  pcap_geterr(pc));
-               }
+       }
 #endif /* HAVE_PCAP_SETDIRECTION */
 #else /* HAVE_PCAP_CREATE */
        *ebuf = '\0';
@@ -1487,6 +1530,7 @@ main(int argc, char **argv)
        int yflag_dlt = -1;
        const char *yflag_dlt_name = NULL;
        int print = 0;
+       long Cflagmult;
 
        netdissect_options Ndo;
        netdissect_options *ndo = &Ndo;
@@ -1531,6 +1575,13 @@ 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) {
@@ -1568,19 +1619,77 @@ main(int argc, char **argv)
 #else
                        Cflag = strtol(optarg, &endp, 10);
 #endif
-                       if (endp == optarg || *endp != '\0' || errno != 0
-                           || Cflag <= 0)
+                       if (endp == optarg || errno != 0 || Cflag <= 0)
                                error("invalid file size %s", optarg);
+
+                       if (*endp == '\0') {
+                               /*
+                                * There's nothing after the file size,
+                                * so the size is in units of 1 MB
+                                * (1,000,000 bytes).
+                                */
+                               Cflagmult = 1000000;
+                       } else {
+                               /*
+                                * There's something after the file
+                                * size.
+                                *
+                                * If it's a single letter, then:
+                                *
+                                *   if the letter is k or K, the size
+                                *   is in units of 1 KiB (1024 bytes);
+                                *
+                                *   if the letter is m or M, the size
+                                *   is in units of 1 MiB (1,048,576 bytes);
+                                *
+                                *   if the letter is g or G, the size
+                                *   is in units of 1 GiB (1,073,741,824 bytes).
+                                *
+                                * Otherwise, it's an error.
+                                */
+                               switch (*endp) {
+
+                               case 'k':
+                               case 'K':
+                                       Cflagmult = 1024;
+                                       break;
+
+                               case 'm':
+                               case 'M':
+                                       Cflagmult = 1024*1024;
+                                       break;
+
+                               case 'g':
+                               case 'G':
+                                       Cflagmult = 1024*1024*1024;
+                                       break;
+
+                               default:
+                                       error("invalid file size %s", optarg);
+                               }
+
+                               /*
+                                * OK, there was a letter that we treat
+                                * as a units indication; was there
+                                * anything after it?
+                                */
+                               endp++;
+                               if (*endp != '\0') {
+                                       /* Yes - error */
+                                       error("invalid file size %s", optarg);
+                               }
+                       }
+
                        /*
-                        * Will multiplying it by 1000000 overflow?
+                        * Will multiplying it by multiplier overflow?
                         */
 #ifdef HAVE_PCAP_DUMP_FTELL64
-                       if (Cflag > INT64_T_CONSTANT(0x7fffffffffffffff) / 1000000)
+                       if (Cflag > INT64_T_CONSTANT(0x7fffffffffffffff) / Cflagmult)
 #else
-                       if (Cflag > LONG_MAX / 1000000)
+                       if (Cflag > LONG_MAX / Cflagmult)
 #endif
                                error("file size %s is too large", optarg);
-                       Cflag *= 1000000;
+                       Cflag *= Cflagmult;
                        break;
 
                case 'd':
@@ -1632,13 +1741,13 @@ main(int argc, char **argv)
 
                        /* Grab the current time for rotation use. */
                        if ((Gflag_time = time(NULL)) == (time_t)-1) {
-                               error("main: can't get current time: %s",
-                                   pcap_strerror(errno));
+                               error("%s: can't get current time: %s",
+                                   __func__, pcap_strerror(errno));
                        }
                        break;
 
                case 'h':
-                       print_usage();
+                       print_usage(stdout);
                        exit_tcpdump(S_SUCCESS);
                        break;
 
@@ -1699,7 +1808,7 @@ 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");
                        }
@@ -1743,7 +1852,7 @@ 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 */
 
@@ -1808,8 +1917,10 @@ main(int argc, char **argv)
                                ndo->ndo_packettype = PT_SOMEIP;
                        else if (ascii_strcasecmp(optarg, "domain") == 0)
                                ndo->ndo_packettype = PT_DOMAIN;
+                       else if (ascii_strcasecmp(optarg, "quic") == 0)
+                               ndo->ndo_packettype = PT_QUIC;
                        else
-                               error("unknown packet type `%s'", optarg);
+                               error("unknown packet type '%s'", optarg);
                        break;
 
                case 'u':
@@ -1880,7 +1991,7 @@ main(int argc, char **argv)
                        break;
 
                case OPTION_VERSION:
-                       print_version();
+                       print_version(stdout);
                        exit_tcpdump(S_SUCCESS);
                        break;
 
@@ -1902,6 +2013,14 @@ main(int argc, char **argv)
                        print = 1;
                        break;
 
+               case OPTION_PRINT_SAMPLING:
+                       print = 1;
+                       ++ndo->ndo_Sflag;
+                       ndo->ndo_print_sampling = atoi(optarg);
+                       if (ndo->ndo_print_sampling <= 0)
+                               error("invalid print sampling %s", optarg);
+                       break;
+
 #ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
                case OPTION_TSTAMP_MICRO:
                        ndo->ndo_tstamp_precision = PCAP_TSTAMP_PRECISION_MICRO;
@@ -1928,7 +2047,7 @@ main(int argc, char **argv)
                        break;
 
                default:
-                       print_usage();
+                       print_usage(stderr);
                        exit_tcpdump(S_ERR_HOST_PROGRAM);
                        /* NOTREACHED */
                }
@@ -1942,14 +2061,6 @@ 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 */
@@ -1999,6 +2110,8 @@ 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
 
@@ -2202,6 +2315,24 @@ 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)
@@ -2266,7 +2397,7 @@ main(int argc, char **argv)
         * 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;
+        * 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
@@ -2281,33 +2412,33 @@ main(int argc, char **argv)
                /* Initialize capng */
                capng_clear(CAPNG_SELECT_BOTH);
                if (username) {
-DIAG_OFF_CLANG(assign-enum)
+DIAG_OFF_ASSIGN_ENUM
                        capng_updatev(
                                CAPNG_ADD,
                                CAPNG_PERMITTED | CAPNG_EFFECTIVE,
                                CAP_SETUID,
                                CAP_SETGID,
                                -1);
-DIAG_ON_CLANG(assign-enum)
+DIAG_ON_ASSIGN_ENUM
                }
                if (chroot_dir) {
-DIAG_OFF_CLANG(assign-enum)
+DIAG_OFF_ASSIGN_ENUM
                        capng_update(
                                CAPNG_ADD,
                                CAPNG_PERMITTED | CAPNG_EFFECTIVE,
                                CAP_SYS_CHROOT
                                );
-DIAG_ON_CLANG(assign-enum)
+DIAG_ON_ASSIGN_ENUM
                }
 
                if (WFileName) {
-DIAG_OFF_CLANG(assign-enum)
+DIAG_OFF_ASSIGN_ENUM
                        capng_update(
                                CAPNG_ADD,
                                CAPNG_PERMITTED | CAPNG_EFFECTIVE,
                                CAP_DAC_OVERRIDE
                                );
-DIAG_ON_CLANG(assign-enum)
+DIAG_ON_ASSIGN_ENUM
                }
                capng_apply(CAPNG_SELECT_BOTH);
 #endif /* HAVE_LIBCAP_NG */
@@ -2373,17 +2504,44 @@ DIAG_ON_CLANG(assign-enum)
 #endif
                if (Cflag != 0 || Gflag != 0) {
 #ifdef HAVE_CAPSICUM
-                       dumpinfo.WFileName = strdup(basename(WFileName));
+                       /*
+                        * basename() and dirname() may modify their input buffer
+                        * and they do since FreeBSD 12.0, but they didn't before.
+                        * Hence use the return value only, but always assume the
+                        * input buffer has been modified and would need to be
+                        * reset before the next use.
+                        */
+                       char *WFileName_copy;
+
+                       if ((WFileName_copy = strdup(WFileName)) == NULL) {
+                               error("Unable to allocate memory for file %s",
+                                   WFileName);
+                       }
+                       DIAG_OFF_C11_EXTENSIONS
+                       dumpinfo.WFileName = strdup(basename(WFileName_copy));
+                       DIAG_ON_C11_EXTENSIONS
                        if (dumpinfo.WFileName == NULL) {
                                error("Unable to allocate memory for file %s",
                                    WFileName);
                        }
-                       dumpinfo.dirfd = open(dirname(WFileName),
+                       free(WFileName_copy);
+
+                       if ((WFileName_copy = strdup(WFileName)) == NULL) {
+                               error("Unable to allocate memory for file %s",
+                                   WFileName);
+                       }
+                       DIAG_OFF_C11_EXTENSIONS
+                       char *WFileName_dirname = dirname(WFileName_copy);
+                       DIAG_ON_C11_EXTENSIONS
+                       dumpinfo.dirfd = open(WFileName_dirname,
                            O_DIRECTORY | O_RDONLY);
                        if (dumpinfo.dirfd < 0) {
                                error("unable to open directory %s",
-                                   dirname(WFileName));
+                                   WFileName_dirname);
                        }
+                       free(WFileName_dirname);
+                       free(WFileName_copy);
+
                        cap_rights_init(&rights, CAP_CREATE, CAP_FCNTL,
                            CAP_FTRUNCATE, CAP_LOOKUP, CAP_SEEK, CAP_WRITE);
                        if (cap_rights_limit(dumpinfo.dirfd, &rights) < 0 &&
@@ -2438,11 +2596,14 @@ DIAG_ON_CLANG(assign-enum)
        (void)setsignal(SIGNAL_FLUSH_PCAP, flushpcap);
 #endif
 
-       if (ndo->ndo_vflag > 0 && WFileName && !print) {
+       if (ndo->ndo_vflag > 0 && WFileName && RFileName == NULL && !print) {
                /*
                 * When capturing to a file, if "--print" wasn't specified,
                 *"-v" means tcpdump should, once per second,
                 * "v"erbosely report the number of packets captured.
+                * Except when reading from a file, because -r, -w and -v
+                * together used to make a corner case, in which pcap_loop()
+                * errored due to EINTR (see GH #155 for details).
                 */
 #ifdef _WIN32
                /*
@@ -2504,6 +2665,9 @@ DIAG_ON_CLANG(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 */
@@ -2595,6 +2759,8 @@ DIAG_ON_CLANG(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));
                                }
@@ -2624,12 +2790,12 @@ DIAG_ON_CLANG(assign-enum)
        while (ret != NULL);
 
        if (count_mode && RFileName != NULL)
-               fprintf(stderr, "%u packet%s\n", packets_captured,
+               fprintf(stdout, "%u packet%s\n", packets_captured,
                        PLURAL_SUFFIX(packets_captured));
 
        free(cmdbuf);
        pcap_freecode(&fcode);
-       exit_tcpdump(status == -1 ? 1 : 0);
+       exit_tcpdump(status == -1 ? S_ERR_HOST_PROGRAM : S_SUCCESS);
 }
 
 /*
@@ -2645,7 +2811,14 @@ 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)
                return (SIG_ERR);
@@ -2710,7 +2883,7 @@ cleanup(int signo _U_)
 static void
 child_cleanup(int signo _U_)
 {
-  wait(NULL);
+  while (waitpid(-1, NULL, WNOHANG) >= 0);
 }
 #endif /* HAVE_FORK && HAVE_VFORK */
 
@@ -2837,8 +3010,8 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
 
                /* Get the current time */
                if ((t = time(NULL)) == (time_t)-1) {
-                       error("dump_and_trunc_packet: can't get current_time: %s",
-                           pcap_strerror(errno));
+                       error("%s: can't get current_time: %s",
+                           __func__, pcap_strerror(errno));
                }
 
 
@@ -2979,7 +3152,7 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
                                free(dump_info->CurrentFileName);
                        dump_info->CurrentFileName = (char *)malloc(PATH_MAX + 1);
                        if (dump_info->CurrentFileName == NULL)
-                               error("dump_packet_and_trunc: malloc");
+                               error("%s: malloc", __func__);
                        MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, Cflag_count, WflagChars);
 #ifdef HAVE_LIBCAP_NG
                        capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
@@ -3115,9 +3288,9 @@ static void verbose_stats_dump(int sig _U_)
 }
 #endif /* _WIN32 */
 
-USES_APPLE_DEPRECATED_API
+DIAG_OFF_DEPRECATION
 static void
-print_version(void)
+print_version(FILE *f)
 {
 #ifndef HAVE_PCAP_LIB_VERSION
   #ifdef HAVE_PCAP_VERSION
@@ -3128,61 +3301,63 @@ print_version(void)
 #endif /* HAVE_PCAP_LIB_VERSION */
        const char *smi_version_string;
 
-       (void)fprintf(stderr, "%s version " PACKAGE_VERSION "\n", program_name);
+       (void)fprintf(f, "%s version " PACKAGE_VERSION "\n", program_name);
 #ifdef HAVE_PCAP_LIB_VERSION
-       (void)fprintf(stderr, "%s\n", pcap_lib_version());
+       (void)fprintf(f, "%s\n", pcap_lib_version());
 #else /* HAVE_PCAP_LIB_VERSION */
-       (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
+       (void)fprintf(f, "libpcap version %s\n", pcap_version);
 #endif /* HAVE_PCAP_LIB_VERSION */
 
 #if defined(HAVE_LIBCRYPTO) && defined(SSLEAY_VERSION)
-       (void)fprintf (stderr, "%s\n", SSLeay_version(SSLEAY_VERSION));
+       (void)fprintf (f, "%s\n", SSLeay_version(SSLEAY_VERSION));
 #endif
 
        smi_version_string = nd_smi_version_string();
        if (smi_version_string != NULL)
-               (void)fprintf (stderr, "SMI-library: %s\n", smi_version_string);
+               (void)fprintf (f, "SMI-library: %s\n", smi_version_string);
 
 #if defined(__SANITIZE_ADDRESS__)
-       (void)fprintf (stderr, "Compiled with AddressSanitizer/GCC.\n");
+       (void)fprintf (f, "Compiled with AddressSanitizer/GCC.\n");
 #elif defined(__has_feature)
 #  if __has_feature(address_sanitizer)
-       (void)fprintf (stderr, "Compiled with AddressSanitizer/Clang.\n");
+       (void)fprintf (f, "Compiled with AddressSanitizer/Clang.\n");
 #  elif __has_feature(memory_sanitizer)
-       (void)fprintf (stderr, "Compiled with MemorySanitizer/Clang.\n");
+       (void)fprintf (f, "Compiled with MemorySanitizer/Clang.\n");
 #  endif
 #endif /* __SANITIZE_ADDRESS__ or __has_feature */
 }
-USES_APPLE_RST
+DIAG_ON_DEPRECATION
 
 static void
-print_usage(void)
+print_usage(FILE *f)
 {
-       print_version();
-       (void)fprintf(stderr,
+       print_version(f);
+       (void)fprintf(f,
 "Usage: %s [-Abd" D_FLAG "efhH" I_FLAG J_FLAG "KlLnNOpqStu" U_FLAG "vxX#]" B_FLAG_USAGE " [ -c count ] [--count]\n", program_name);
-       (void)fprintf(stderr,
+       (void)fprintf(f,
 "\t\t[ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ]\n");
-       (void)fprintf(stderr,
+       (void)fprintf(f,
 "\t\t[ -i interface ]" IMMEDIATE_MODE_USAGE j_FLAG_USAGE "\n");
 #ifdef HAVE_PCAP_FINDALLDEVS_EX
-       (void)fprintf(stderr,
+       (void)fprintf(f,
 "\t\t" LIST_REMOTE_INTERFACES_USAGE "\n");
 #endif
 #ifdef USE_LIBSMI
-       (void)fprintf(stderr,
+       (void)fprintf(f,
 "\t\t" m_FLAG_USAGE "\n");
 #endif
-       (void)fprintf(stderr,
-"\t\t[ -M secret ] [ --number ] [ --print ]" Q_FLAG_USAGE "\n");
-       (void)fprintf(stderr,
-"\t\t[ -r file ] [ -s snaplen ] [ -T type ] [ --version ]\n");
-       (void)fprintf(stderr,
+       (void)fprintf(f,
+"\t\t[ -M secret ] [ --number ] [ --print ]\n");
+       (void)fprintf(f,
+"\t\t[ --print-sampling nth ]" Q_FLAG_USAGE " [ -r file ]\n");
+       (void)fprintf(f,
+"\t\t[ -s snaplen ] [ -T type ] [ --version ]\n");
+       (void)fprintf(f,
 "\t\t[ -V file ] [ -w file ] [ -W filecount ] [ -y datalinktype ]\n");
 #ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
-       (void)fprintf(stderr,
+       (void)fprintf(f,
 "\t\t[ --time-stamp-precision precision ] [ --micro ] [ --nano ]\n");
 #endif
-       (void)fprintf(stderr,
+       (void)fprintf(f,
 "\t\t[ -z postrotate-command ] [ -Z user ] [ expression ]\n");
 }