Error if driver reports 0 timestamp modes supported

Additionally, simplify logic by using num_ts_modes directly, since VS
Code Analysis thought there was a read/write overrun otherwise.

(cherry picked from commit 9ddc784af1190350397f4d7c67f29ae86243e49a)

diff --git a/pcap-npf.c b/pcap-npf.c
index 1a30e1d794e5411af2b9a11d17ef2e0d87df3c57..2fcd6df92f7ac3f3d726d372b13f8452e2b28916 100644 (file)
--- a/pcap-npf.c
+++ b/pcap-npf.c
@@ -1616,6 +1616,18 @@ pcap_create_interface(const char *device _U_, char *ebuf)
                        return (NULL);
                }
 
+               /* If the driver reports no modes supported *and*
+                * ERROR_MORE_DATA, something is seriously wrong.
+                * We *could* ignore the error and continue without supporting
+                * settable timestamp modes, but that would hide a bug.
+                */
+               if (num_ts_modes == 0) {
+                               snprintf(ebuf, PCAP_ERRBUF_SIZE,
+                                   "PacketGetTimestampModes() reports 0 modes supported.");
+                               pcap_close(p);
+                               return (NULL);
+               }
+
                /*
                 * Yes, so we now know how many types to fetch.
                 *
@@ -1647,70 +1659,67 @@ pcap_create_interface(const char *device _U_, char *ebuf)
                        pcap_close(p);
                        return (NULL);
                }
-               if (num_ts_modes != 0) {
-                       u_int num_ts_types;
 
-                       /*
-                        * Allocate a buffer big enough for
-                        * PCAP_TSTAMP_HOST (default) plus
-                        * the explicitly specified modes.
-                        */
-                       p->tstamp_type_list = malloc((1 + modes[0]) * sizeof(u_int));
-                       if (p->tstamp_type_list == NULL) {
-                               pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "malloc");
-                               free(modes);
-                               pcap_close(p);
-                               return (NULL);
-                       }
-                       num_ts_types = 0;
-                       p->tstamp_type_list[num_ts_types] =
-                           PCAP_TSTAMP_HOST;
-                       num_ts_types++;
-                       for (ULONG i = 0; i < modes[0]; i++) {
-                               switch (modes[i + 1]) {
-
-                               case TIMESTAMPMODE_SINGLE_SYNCHRONIZATION:
-                                       /*
-                                        * Better than low-res,
-                                        * but *not* synchronized
-                                        * with the OS clock.
-                                        */
-                                       p->tstamp_type_list[num_ts_types] =
-                                           PCAP_TSTAMP_HOST_HIPREC_UNSYNCED;
-                                       num_ts_types++;
-                                       break;
-
-                               case TIMESTAMPMODE_QUERYSYSTEMTIME:
-                                       /*
-                                        * Low-res, but synchronized
-                                        * with the OS clock.
-                                        */
-                                       p->tstamp_type_list[num_ts_types] =
-                                           PCAP_TSTAMP_HOST_LOWPREC;
-                                       num_ts_types++;
-                                       break;
-
-                               case TIMESTAMPMODE_QUERYSYSTEMTIME_PRECISE:
-                                       /*
-                                        * High-res, and synchronized
-                                        * with the OS clock.
-                                        */
-                                       p->tstamp_type_list[num_ts_types] =
-                                           PCAP_TSTAMP_HOST_HIPREC;
-                                       num_ts_types++;
-                                       break;
-
-                               default:
-                                       /*
-                                        * Unknown, so we can't
-                                        * report it.
-                                        */
-                                       break;
-                               }
-                       }
-                       p->tstamp_type_count = num_ts_types;
+               /*
+                * Allocate a buffer big enough for
+                * PCAP_TSTAMP_HOST (default) plus
+                * the explicitly specified modes.
+                */
+               p->tstamp_type_list = malloc((1 + num_ts_modes) * sizeof(u_int));
+               if (p->tstamp_type_list == NULL) {
+                       pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "malloc");
                        free(modes);
+                       pcap_close(p);
+                       return (NULL);
+               }
+               u_int num_ts_types = 0;
+               p->tstamp_type_list[num_ts_types] =
+                   PCAP_TSTAMP_HOST;
+               num_ts_types++;
+               for (ULONG i = 0; i < num_ts_modes; i++) {
+                       switch (modes[i + 1]) {
+
+                       case TIMESTAMPMODE_SINGLE_SYNCHRONIZATION:
+                               /*
+                                * Better than low-res,
+                                * but *not* synchronized
+                                * with the OS clock.
+                                */
+                               p->tstamp_type_list[num_ts_types] =
+                                   PCAP_TSTAMP_HOST_HIPREC_UNSYNCED;
+                               num_ts_types++;
+                               break;
+
+                       case TIMESTAMPMODE_QUERYSYSTEMTIME:
+                               /*
+                                * Low-res, but synchronized
+                                * with the OS clock.
+                                */
+                               p->tstamp_type_list[num_ts_types] =
+                                   PCAP_TSTAMP_HOST_LOWPREC;
+                               num_ts_types++;
+                               break;
+
+                       case TIMESTAMPMODE_QUERYSYSTEMTIME_PRECISE:
+                               /*
+                                * High-res, and synchronized
+                                * with the OS clock.
+                                */
+                               p->tstamp_type_list[num_ts_types] =
+                                   PCAP_TSTAMP_HOST_HIPREC;
+                               num_ts_types++;
+                               break;
+
+                       default:
+                               /*
+                                * Unknown, so we can't
+                                * report it.
+                                */
+                               break;
+                       }
                }
+               p->tstamp_type_count = num_ts_types;
+               free(modes);
        }
        PacketCloseAdapter(adapter);
 #endif /* HAVE_PACKET_GET_TIMESTAMP_MODES */