Try marking structures as UNALIGNED.

[tcpdump] / tcpdump.c

diff --git a/tcpdump.c b/tcpdump.c
index 2ac7757f7a06fd6271447318c4780df9661adb87..053dd5401999ffbc9c6364a4636aa2b9d92c410b 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -185,26 +185,17 @@ cap_channel_t *capdns;
 #endif
 
 /* Forwards */
-static void error(const char *, ...)
-     __attribute__((noreturn))
-#ifdef __ATTRIBUTE___FORMAT_OK
-     __attribute__((format (printf, 1, 2)))
-#endif /* __ATTRIBUTE___FORMAT_OK */
-     ;
-static void warning(const char *, ...)
-#ifdef __ATTRIBUTE___FORMAT_OK
-     __attribute__((format (printf, 1, 2)))
-#endif /* __ATTRIBUTE___FORMAT_OK */
-     ;
-static void exit_tcpdump(int) __attribute__((noreturn));
+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 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(pcap_t *, const char *device) __attribute__((noreturn));
-static void show_dlts_and_exit(pcap_t *, const char *device) __attribute__((noreturn));
+static NORETURN void show_tstamp_types_and_exit(pcap_t *, const char *device);
+static NORETURN void show_dlts_and_exit(pcap_t *, const char *device);
 #ifdef HAVE_PCAP_FINDALLDEVS
-static void show_devices_and_exit (void) __attribute__((noreturn));
+static NORETURN void show_devices_and_exit(void);
 #endif
 
 static void print_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
@@ -1045,10 +1036,16 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
                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));
+       if (ndo->ndo_snaplen != 0) {
+               /*
+                * A snapshot length was explicitly specified;
+                * use it.
+                */
+               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",
@@ -1149,6 +1146,12 @@ open_interface(const char *device, netdissect_options *ndo, char *ebuf)
 #endif /* HAVE_PCAP_SETDIRECTION */
 #else /* HAVE_PCAP_CREATE */
        *ebuf = '\0';
+       /*
+        * If no snapshot length was specified, or a length of 0 was
+        * specified, default to 256KB.
+        */
+       if (ndo->ndo_snaplen == 0)
+               ndo->ndo_snaplen = 262144;
        pc = pcap_open_live(device, ndo->ndo_snaplen, !pflag, 1000, ebuf);
        if (pc == NULL) {
                /*
@@ -1215,7 +1218,6 @@ main(int argc, char **argv)
 
        memset(ndo, 0, sizeof(*ndo));
        ndo_set_function_pointers(ndo);
-       ndo->ndo_snaplen = DEFAULT_SNAPLEN;
 
        cnt = -1;
        device = NULL;
@@ -1445,8 +1447,6 @@ main(int argc, char **argv)
                        if (optarg == end || *end != '\0'
                            || ndo->ndo_snaplen < 0 || ndo->ndo_snaplen > MAXIMUM_SNAPLEN)
                                error("invalid snaplen %s", optarg);
-                       else if (ndo->ndo_snaplen == 0)
-                               ndo->ndo_snaplen = MAXIMUM_SNAPLEN;
                        break;
 
                case 'S':
@@ -1724,20 +1724,21 @@ main(int argc, char **argv)
                         * 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);
-                       }
+                       if (pcap_findalldevs(&devlist, ebuf) == -1)
+                               error("%s", ebuf);
+                       if (devlist == NULL)
+                               error("no interfaces available for capture");
+                       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)
                                error("%s", ebuf);
+#endif
                }
 
                /*
@@ -1784,7 +1785,8 @@ main(int argc, char **argv)
                }
 
                /*
-                * Let user own process after socket has been opened.
+                * Let user own process after capture device has
+                * been opened.
                 */
 #ifndef _WIN32
                if (setgid(getgid()) != 0 || setuid(getuid()) != 0)
@@ -1819,7 +1821,11 @@ main(int argc, char **argv)
                }
                i = pcap_snapshot(pd);
                if (ndo->ndo_snaplen < i) {
-                       warning("snaplen raised from %d to %d", ndo->ndo_snaplen, i);
+                       if (ndo->ndo_snaplen != 0)
+                               warning("snaplen raised from %d to %d", ndo->ndo_snaplen, i);
+                       ndo->ndo_snaplen = i;
+               } else if (ndo->ndo_snaplen > i) {
+                       warning("snaplen lowered from %d to %d", ndo->ndo_snaplen, i);
                        ndo->ndo_snaplen = i;
                }
                 if(ndo->ndo_fflag != 0) {