wiretap: remove unused code, drop number_of_interfaces

While investigating an ASAN issue (fixed in
commit dcdd076ab0965c346efe90051678ba790eaf7a02), I got greatly confused
by three different types having the same "interface_data" field name:

 * pcapng_t *pn stores an array of interface_data_t objects.
 * wtap *wth stores an array of wtapng_if_descr_t objects.
 * pcapng_dump_t should store an array of interface_data_t objects.

pcapng_dump_t and friends are unused since
commit c7f1a431d23e17a15777652b1252e139f182b0e6, so drop it.

To fix the confusion, rename the interface_data_t type to
interface_info_t type and use the local variable "iface_info"
everywhere. Rename interface_data of pcapng_t to "interfaces" and
add a comment what this exactly means (interfaces listed in the capture
file).

Drop the number_of_interfaces field for interfaces as the array
length is already available from GArray. Now interface_data is always
initialized for wth (which also gets copied to idb).

s/int/guint/g and replace cast at some places.

There are no regressions for the in-tree test suite.

Change-Id: I2d5985c9f1e43f8230dbb4a73bd1e243c4858170
Reviewed-on: https://code.wireshark.org/review/1656
Reviewed-by: Evan Huus <eapache@gmail.com>
Tested-by: Evan Huus <eapache@gmail.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>

12 files changed, 70 insertions, 183 deletions

diff --git a/cfile.c b/cfile.c
index a689b2e11c..08d73bed90 100644
--- a/cfile.c
+++ b/cfile.c
@@ -38,7 +38,7 @@ cap_file_get_interface_name(void *data, guint32 interface_id)
 
   idb_info = wtap_file_get_idb_info(cf->wth);
 
-  if (interface_id < idb_info->number_of_interfaces)
+  if (interface_id < idb_info->interface_data->len)
     wtapng_if_descr = &g_array_index(idb_info->interface_data, wtapng_if_descr_t, interface_id);
 
   g_free(idb_info);
diff --git a/file.c b/file.c
index 6f743961f3..e75a78d4f9 100644
--- a/file.c
+++ b/file.c
@@ -1382,9 +1382,9 @@ cf_merge_files(char **out_filenamep, int in_file_count,
 
     /* create fake IDB info */
     idb_inf = g_new(wtapng_iface_descriptions_t,1);
-    idb_inf->number_of_interfaces = in_file_count; /* TODO make this the number of DIFFERENT encapsulation types
-                                                    * check that snaplength is the same too?
-                                                    */
+    /* TODO make this the number of DIFFERENT encapsulation types
+     * check that snaplength is the same too?
+     */
     idb_inf->interface_data = g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
 
     for (i = 0; i < in_file_count; i++) {
diff --git a/summary.c b/summary.c
index dee1808f5b..ec9999896e 100644
--- a/summary.c
+++ b/summary.c
@@ -172,7 +172,7 @@ summary_fill_in(capture_file *cf, summary_tally *st)
 
   st->ifaces  = g_array_new(FALSE, FALSE, sizeof(iface_options));
   idb_info = wtap_file_get_idb_info(cf->wth);
-  for (i = 0; i < idb_info->number_of_interfaces; i++) {
+  for (i = 0; i < idb_info->interface_data->len; i++) {
     wtapng_if_descr = g_array_index(idb_info->interface_data, wtapng_if_descr_t, i);
     iface.cfilter = g_strdup(wtapng_if_descr.if_filter_str);
     iface.name = g_strdup(wtapng_if_descr.if_name);
diff --git a/tshark.c b/tshark.c
index c5b3d8b61a..f52b00502f 100644
--- a/tshark.c
+++ b/tshark.c
@@ -3080,7 +3080,7 @@ load_cap_file(capture_file *cf, char *save_file, int out_file_type,
   shb_hdr = wtap_file_get_shb_info(cf->wth);
   idb_inf = wtap_file_get_idb_info(cf->wth);
 #ifdef PCAP_NG_DEFAULT
-  if (idb_inf->number_of_interfaces > 1) {
+  if (idb_inf->interface_data->len > 1) {
     linktype = WTAP_ENCAP_PER_PACKET;
   } else {
     linktype = wtap_file_encap(cf->wth);
diff --git a/ui/gtk/file_import_dlg.c b/ui/gtk/file_import_dlg.c
index cd12985257..8a246d6133 100644
--- a/ui/gtk/file_import_dlg.c
+++ b/ui/gtk/file_import_dlg.c
@@ -493,7 +493,6 @@ file_import_open(text_import_info_t *info)
 
     /* Create fake IDB info */
     idb_inf = g_new(wtapng_iface_descriptions_t,1);
-    idb_inf->number_of_interfaces = 1;
     idb_inf->interface_data = g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
 
     /* create the fake interface data */
diff --git a/ui/tap_export_pdu.c b/ui/tap_export_pdu.c
index ec8c78130f..4d0e9e21f6 100644
--- a/ui/tap_export_pdu.c
+++ b/ui/tap_export_pdu.c
@@ -120,7 +120,6 @@ exp_pdu_file_open(exp_pdu_t *exp_pdu_tap_data)
 
     /* Create fake IDB info */
     idb_inf = g_new(wtapng_iface_descriptions_t,1);
-    idb_inf->number_of_interfaces = 1;
     idb_inf->interface_data = g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
 
     /* create the fake interface data */
diff --git a/wiretap/erf.c b/wiretap/erf.c
index 9edef0ecbb..67b7ccab1d 100644
--- a/wiretap/erf.c
+++ b/wiretap/erf.c
@@ -726,10 +726,6 @@ int erf_populate_interfaces(wtap *wth)
   if (!wth)
     return -1;
 
-  if (!wth->interface_data) {
-    wth->interface_data = g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
-  }
-
   memset(&int_data, 0, sizeof(int_data)); /* Zero all fields */
 
   int_data.wtap_encap = WTAP_ENCAP_ERF;
@@ -762,7 +758,6 @@ int erf_populate_interfaces(wtap *wth)
     int_data.if_description = g_strdup_printf("ERF Interface Id %d (Port %c)", i, 'A'+i);
 
     g_array_append_val(wth->interface_data, int_data);
-    wth->number_of_interfaces++;
   }
 
   return 0;
diff --git a/wiretap/file_access.c b/wiretap/file_access.c
index 9a9a34d7c4..1255a94f8c 100644
--- a/wiretap/file_access.c
+++ b/wiretap/file_access.c
@@ -798,6 +798,11 @@ wtap* wtap_open_offline(const char *filename, unsigned int type, int *err, char
 	wth->priv = NULL;
 	wth->wslua_data = NULL;
 
+	/* Initialize the array containing a list of interfaces. pcapng_open and
+	 * erf_open needs this (and libpcap_open for ERF encapsulation types).
+	 * Always initing it here saves checking for a NULL ptr later. */
+	wth->interface_data = g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
+
 	if (wth->random_fh) {
 		wth->fast_seek = g_ptr_array_new();
 
@@ -1021,8 +1026,6 @@ success:
 		descr.if_fcslen = -1;
 		descr.num_stat_entries = 0;          /* Number of ISB:s */
 		descr.interface_statistics = NULL;
-		wth->number_of_interfaces= 1;
-		wth->interface_data= g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
 		g_array_append_val(wth->interface_data, descr);
 
 	}
@@ -1984,8 +1987,7 @@ wtap_dump_init_dumper(int file_type_subtype, int encap, int snaplen, gboolean co
 	/* Set Section Header Block data */
 	wdh->shb_hdr = shb_hdr;
 	/* Set Interface Description Block data */
-	if ((idb_inf != NULL) && (idb_inf->number_of_interfaces > 0)) {
-		wdh->number_of_interfaces = idb_inf->number_of_interfaces;
+	if ((idb_inf != NULL) && (idb_inf->interface_data->len > 0)) {
 		wdh->interface_data = idb_inf->interface_data;
 	} else {
 		wtapng_if_descr_t descr;
@@ -2006,8 +2008,6 @@ wtap_dump_init_dumper(int file_type_subtype, int encap, int snaplen, gboolean co
 		descr.if_fcslen = -1;
 		descr.num_stat_entries = 0;          /* Number of ISB:s */
 		descr.interface_statistics = NULL;
-		wdh->number_of_interfaces= 1;
-		wdh->interface_data= g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
 		g_array_append_val(wdh->interface_data, descr);
 	}
 	return wdh;
diff --git a/wiretap/pcapng.c b/wiretap/pcapng.c
index 39f5aa0f79..a0be4a9eaa 100644
--- a/wiretap/pcapng.c
+++ b/wiretap/pcapng.c
@@ -358,19 +358,18 @@ typedef struct wtapng_block_s {
 } wtapng_block_t;
 
 /* Interface data in private struct */
-typedef struct interface_data_s {
+typedef struct interface_info_s {
         int wtap_encap;
         guint32 snap_len;
         guint64 time_units_per_second;
-} interface_data_t;
+} interface_info_t;
 
 typedef struct {
         gboolean shb_read;                                              /**< Set when first SHB read, second read will fail */
         gboolean byte_swapped;
         guint16 version_major;
         guint16 version_minor;
-        GArray *interface_data;
-        guint number_of_interfaces;
+        GArray *interfaces; /**< Interfaces found in the capture file. */
         gint8 if_fcslen;
         wtap_new_ipv4_callback_t add_new_ipv4;
         wtap_new_ipv6_callback_t add_new_ipv6;
@@ -944,7 +943,7 @@ pcapng_read_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *pn, wta
         wtapng_packet_t packet;
         guint32 block_total_length;
         guint32 padding;
-        interface_data_t int_data;
+        interface_info_t iface_info;
         guint64 ts;
         pcapng_option_header_t oh;
         int pseudo_header_len;
@@ -1101,28 +1100,28 @@ pcapng_read_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *pn, wta
                       packet.cap_len,
                       packet.interface_id);
 
-        if (packet.interface_id >= pn->number_of_interfaces) {
+        if (packet.interface_id >= pn->interfaces->len) {
                 *err = WTAP_ERR_BAD_FILE;
                 *err_info = g_strdup_printf("pcapng: interface index %u is not less than interface count %u",
-                    packet.interface_id, pn->number_of_interfaces);
+                    packet.interface_id, pn->interfaces->len);
                 return 0;
         }
-        int_data = g_array_index(pn->interface_data, interface_data_t,
+        iface_info = g_array_index(pn->interfaces, interface_info_t,
             packet.interface_id);
 
         wblock->packet_header->presence_flags = WTAP_HAS_TS|WTAP_HAS_CAP_LEN|WTAP_HAS_INTERFACE_ID;
 
         pcapng_debug3("pcapng_read_packet_block: encapsulation = %d (%s), pseudo header size = %d.",
-                       int_data.wtap_encap,
-                       wtap_encap_string(int_data.wtap_encap),
-                       pcap_get_phdr_size(int_data.wtap_encap, &wblock->packet_header->pseudo_header));
+                       iface_info.wtap_encap,
+                       wtap_encap_string(iface_info.wtap_encap),
+                       pcap_get_phdr_size(iface_info.wtap_encap, &wblock->packet_header->pseudo_header));
         wblock->packet_header->interface_id = packet.interface_id;
-        wblock->packet_header->pkt_encap = int_data.wtap_encap;
+        wblock->packet_header->pkt_encap = iface_info.wtap_encap;
 
         memset((void *)&wblock->packet_header->pseudo_header, 0, sizeof(union wtap_pseudo_header));
         pseudo_header_len = pcap_process_pseudo_header(fh,
                                                        WTAP_FILE_TYPE_SUBTYPE_PCAPNG,
-                                                       int_data.wtap_encap,
+                                                       iface_info.wtap_encap,
                                                        packet.cap_len,
                                                        TRUE,
                                                        wblock->packet_header,
@@ -1132,7 +1131,7 @@ pcapng_read_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *pn, wta
                 return 0;
         }
         block_read += pseudo_header_len;
-        if (pseudo_header_len != pcap_get_phdr_size(int_data.wtap_encap, &wblock->packet_header->pseudo_header)) {
+        if (pseudo_header_len != pcap_get_phdr_size(iface_info.wtap_encap, &wblock->packet_header->pseudo_header)) {
                 pcapng_debug1("pcapng_read_packet_block: Could only read %d bytes for pseudo header.",
                               pseudo_header_len);
         }
@@ -1141,8 +1140,8 @@ pcapng_read_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *pn, wta
 
         /* Combine the two 32-bit pieces of the timestamp into one 64-bit value */
         ts = (((guint64)packet.ts_high) << 32) | ((guint64)packet.ts_low);
-        wblock->packet_header->ts.secs = (time_t)(ts / int_data.time_units_per_second);
-        wblock->packet_header->ts.nsecs = (int)(((ts % int_data.time_units_per_second) * 1000000000) / int_data.time_units_per_second);
+        wblock->packet_header->ts.secs = (time_t)(ts / iface_info.time_units_per_second);
+        wblock->packet_header->ts.nsecs = (int)(((ts % iface_info.time_units_per_second) * 1000000000) / iface_info.time_units_per_second);
 
         /* "(Enhanced) Packet Block" read capture data */
         errno = WTAP_ERR_CANT_READ;
@@ -1263,7 +1262,7 @@ pcapng_read_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *pn, wta
 
         g_free(option_content);
 
-        pcap_read_post_process(WTAP_FILE_TYPE_SUBTYPE_PCAPNG, int_data.wtap_encap,
+        pcap_read_post_process(WTAP_FILE_TYPE_SUBTYPE_PCAPNG, iface_info.wtap_encap,
             wblock->packet_header, buffer_start_ptr(wblock->frame_buffer),
             pn->byte_swapped, fcslen);
         return block_read;
@@ -1276,7 +1275,7 @@ pcapng_read_simple_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *
         int bytes_read;
         guint block_read;
         guint64 file_offset64;
-        interface_data_t int_data;
+        interface_info_t iface_info;
         pcapng_simple_packet_block_t spb;
         wtapng_simple_packet_t simple_packet;
         guint32 block_total_length;
@@ -1321,12 +1320,12 @@ pcapng_read_simple_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *
         }
         block_read = bytes_read;
 
-        if (0 >= pn->number_of_interfaces) {
+        if (0 >= pn->interfaces->len) {
                 *err = WTAP_ERR_BAD_FILE;
                 *err_info = g_strdup_printf("pcapng: SPB appeared before any IDBs");
                 return 0;
         }
-        int_data = g_array_index(pn->interface_data, interface_data_t, 0);
+        iface_info = g_array_index(pn->interfaces, interface_info_t, 0);
 
         if (pn->byte_swapped) {
                 simple_packet.packet_len   = GUINT32_SWAP_LE_BE(spb.packet_len);
@@ -1340,8 +1339,8 @@ pcapng_read_simple_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *
 	 * IDB and the packet length, as per the pcap-ng spec.
          */
         simple_packet.cap_len = simple_packet.packet_len;
-        if (simple_packet.cap_len > int_data.snap_len)
-                simple_packet.cap_len = int_data.snap_len;
+        if (simple_packet.cap_len > iface_info.snap_len)
+                simple_packet.cap_len = iface_info.snap_len;
 
         /*
          * How much padding is there at the end of the packet data?
@@ -1386,12 +1385,12 @@ pcapng_read_simple_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *
                        simple_packet.packet_len);
 
         pcapng_debug1("pcapng_read_simple_packet_block: Need to read pseudo header of size %d",
-                      pcap_get_phdr_size(int_data.wtap_encap, &wblock->packet_header->pseudo_header));
+                      pcap_get_phdr_size(iface_info.wtap_encap, &wblock->packet_header->pseudo_header));
 
         /* No time stamp in a simple packet block; no options, either */
         wblock->packet_header->presence_flags = WTAP_HAS_CAP_LEN|WTAP_HAS_INTERFACE_ID;
         wblock->packet_header->interface_id = 0;
-        wblock->packet_header->pkt_encap = int_data.wtap_encap;
+        wblock->packet_header->pkt_encap = iface_info.wtap_encap;
         wblock->packet_header->ts.secs = 0;
         wblock->packet_header->ts.nsecs = 0;
         wblock->packet_header->interface_id = 0;
@@ -1402,7 +1401,7 @@ pcapng_read_simple_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *
         memset((void *)&wblock->packet_header->pseudo_header, 0, sizeof(union wtap_pseudo_header));
         pseudo_header_len = pcap_process_pseudo_header(fh,
                                                        WTAP_FILE_TYPE_SUBTYPE_PCAPNG,
-                                                       int_data.wtap_encap,
+                                                       iface_info.wtap_encap,
                                                        simple_packet.cap_len,
                                                        TRUE,
                                                        wblock->packet_header,
@@ -1414,7 +1413,7 @@ pcapng_read_simple_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *
         wblock->packet_header->caplen = simple_packet.cap_len - pseudo_header_len;
         wblock->packet_header->len = simple_packet.packet_len - pseudo_header_len;
         block_read += pseudo_header_len;
-        if (pseudo_header_len != pcap_get_phdr_size(int_data.wtap_encap, &wblock->packet_header->pseudo_header)) {
+        if (pseudo_header_len != pcap_get_phdr_size(iface_info.wtap_encap, &wblock->packet_header->pseudo_header)) {
                 pcapng_debug1("pcapng_read_simple_packet_block: Could only read %d bytes for pseudo header.",
                               pseudo_header_len);
         }
@@ -1439,7 +1438,7 @@ pcapng_read_simple_packet_block(FILE_T fh, pcapng_block_header_t *bh, pcapng_t *
                 block_read += 4 - (simple_packet.cap_len % 4);
         }
 
-        pcap_read_post_process(WTAP_FILE_TYPE_SUBTYPE_PCAPNG, int_data.wtap_encap,
+        pcap_read_post_process(WTAP_FILE_TYPE_SUBTYPE_PCAPNG, iface_info.wtap_encap,
             wblock->packet_header, buffer_start_ptr(wblock->frame_buffer),
             pn->byte_swapped, pn->if_fcslen);
         return block_read;
@@ -2099,7 +2098,7 @@ static void
 pcapng_process_idb(wtap *wth, pcapng_t *pcapng, wtapng_block_t *wblock)
 {
         wtapng_if_descr_t int_data;
-        interface_data_t interface_data;
+        interface_info_t iface_info;
 
         int_data.wtap_encap = wblock->data.if_descr.wtap_encap;
         int_data.time_units_per_second = wblock->data.if_descr.time_units_per_second;
@@ -2127,14 +2126,12 @@ pcapng_process_idb(wtap *wth, pcapng_t *pcapng, wtapng_block_t *wblock)
         int_data.interface_statistics = NULL;
 
         g_array_append_val(wth->interface_data, int_data);
-        wth->number_of_interfaces++;
 
-        interface_data.wtap_encap = wblock->data.if_descr.wtap_encap;
-        interface_data.snap_len = wblock->data.if_descr.snap_len;
-        interface_data.time_units_per_second = wblock->data.if_descr.time_units_per_second;
+        iface_info.wtap_encap = wblock->data.if_descr.wtap_encap;
+        iface_info.snap_len = wblock->data.if_descr.snap_len;
+        iface_info.time_units_per_second = wblock->data.if_descr.time_units_per_second;
 
-        g_array_append_val(pcapng->interface_data, interface_data);
-        pcapng->number_of_interfaces++;
+        g_array_append_val(pcapng->interfaces, iface_info);
 }
 
 /* classic wtap: open capture file */
@@ -2154,8 +2151,7 @@ pcapng_open(wtap *wth, int *err, gchar **err_info)
         pn.if_fcslen = -1;
         pn.version_major = -1;
         pn.version_minor = -1;
-        pn.interface_data = g_array_new(FALSE, FALSE, sizeof(interface_data_t));
-        pn.number_of_interfaces = 0;
+        pn.interfaces = g_array_new(FALSE, FALSE, sizeof(interface_info_t));
 
 
         /* we don't expect any packet blocks yet */
@@ -2209,10 +2205,6 @@ pcapng_open(wtap *wth, int *err, gchar **err_info)
         wth->subtype_close = pcapng_close;
         wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_PCAPNG;
 
-        /* Read IDBs */
-        wth->interface_data = g_array_new(FALSE, FALSE, sizeof(wtapng_if_descr_t));
-        wth->number_of_interfaces = 0;
-
         /* Loop over all IDB:s that appear before any packets */
         while (1) {
                 /* peek at next block */
@@ -2257,7 +2249,8 @@ pcapng_open(wtap *wth, int *err, gchar **err_info)
                         return -1;
                 }
                 pcapng_process_idb(wth, pcapng, &wblock);
-                pcapng_debug2("pcapng_open: Read IDB number_of_interfaces %u, wtap_encap %i", wth->number_of_interfaces, *wblock.file_encap);
+                pcapng_debug2("pcapng_open: Read IDB number_of_interfaces %u, wtap_encap %i",
+                        wth->interface_data->len, *wblock.file_encap);
         }
         return 1;
 }
@@ -2325,7 +2318,7 @@ pcapng_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
                         pcapng_debug0("pcapng_read: block type BLOCK_TYPE_ISB");
                         *data_offset += bytes_read;
                         pcapng_debug1("pcapng_read: *data_offset is updated to %" G_GINT64_MODIFIER "d", *data_offset);
-                        if (wth->number_of_interfaces < wblock.data.if_stats.interface_id) {
+                        if (wth->interface_data->len < wblock.data.if_stats.interface_id) {
                                 pcapng_debug1("pcapng_read: BLOCK_TYPE_ISB wblock.if_stats.interface_id %u > number_of_interfaces", wblock.data.if_stats.interface_id);
                         } else {
                                 /* Get the interface description */
@@ -2422,18 +2415,10 @@ pcapng_close(wtap *wth)
         pcapng_t *pcapng = (pcapng_t *)wth->priv;
 
         pcapng_debug0("pcapng_close: closing file");
-        if (pcapng->interface_data != NULL) {
-                g_array_free(pcapng->interface_data, TRUE);
-        }
+        g_array_free(pcapng->interfaces, TRUE);
 }
 
 
-
-typedef struct {
-        GArray *interface_data;
-        guint number_of_interfaces;
-} pcapng_dump_t;
-
 static gboolean
 pcapng_write_section_header_block(wtap_dumper *wdh, int *err)
 {
@@ -3297,7 +3282,7 @@ pcapng_write_enhanced_packet_block(wtap_dumper *wdh,
          * Split the 64-bit timestamp into two 32-bit pieces, using
          * the time stamp resolution for the interface.
          */
-        if (epb.interface_id >= wdh->number_of_interfaces) {
+        if (epb.interface_id >= wdh->interface_data->len) {
                 /*
                  * Our caller is doing something bad.
                  */
@@ -3557,32 +3542,11 @@ pcapng_write_name_resolution_block(wtap_dumper *wdh, int *err)
     return TRUE;
 }
 
-#if 0
-static guint32
-pcapng_lookup_interface_id_by_encap(int wtap_encap, wtap_dumper *wdh)
-{
-        gint i;
-        interface_data_t int_data;
-        pcapng_dump_t *pcapng = (pcapng_dump_t *)wdh->priv;
-
-        for(i = 0; i < (gint)pcapng->number_of_interfaces; i++) {
-                int_data = g_array_index(pcapng->interface_data, interface_data_t, i);
-                if (wtap_encap == int_data.wtap_encap) {
-                        return (guint32)i;
-                }
-        }
-        return G_MAXUINT32;
-}
-#endif
-
 static gboolean pcapng_dump(wtap_dumper *wdh,
         const struct wtap_pkthdr *phdr,
         const guint8 *pd, int *err)
 {
         const union wtap_pseudo_header *pseudo_header = &phdr->pseudo_header;
-        /*interface_data_t int_data;*/
-        /* pcapng_dump_t *pcapng = (pcapng_dump_t *)wdh->priv; */
-        /*int pcap_encap;*/
 
         pcapng_debug2("pcapng_dump: encap = %d (%s)",
                       phdr->pkt_encap,
@@ -3603,31 +3567,26 @@ static gboolean pcapng_dump(wtap_dumper *wdh,
    Returns TRUE on success, FALSE on failure. */
 static gboolean pcapng_dump_close(wtap_dumper *wdh, int *err _U_)
 {
-        int i, j;
-        pcapng_dump_t *pcapng = (pcapng_dump_t *)wdh->priv;
+        guint i, j;
 
-        if ((wdh->number_of_interfaces > 0) && (wdh->interface_data != NULL)) {
-                for (i = 0; i < (int)wdh->number_of_interfaces; i++) {
+        for (i = 0; i < wdh->interface_data->len; i++) {
 
-                        /* Get the interface description */
-                        wtapng_if_descr_t int_data;
+                /* Get the interface description */
+                wtapng_if_descr_t int_data;
 
-                        int_data = g_array_index(wdh->interface_data, wtapng_if_descr_t, i);
-                        for (j = 0; j < (int)int_data.num_stat_entries; j++) {
-                                wtapng_if_stats_t if_stats;
+                int_data = g_array_index(wdh->interface_data, wtapng_if_descr_t, i);
+                for (j = 0; j < int_data.num_stat_entries; j++) {
+                        wtapng_if_stats_t if_stats;
 
-                                if_stats = g_array_index(int_data.interface_statistics, wtapng_if_stats_t, j);
-                                pcapng_debug1("pcapng_dump_close: write ISB for interface %u",if_stats.interface_id);
-                                if (!pcapng_write_interface_statistics_block(wdh, &if_stats, err)) {
-                                        return FALSE;
-                                }
+                        if_stats = g_array_index(int_data.interface_statistics, wtapng_if_stats_t, j);
+                        pcapng_debug1("pcapng_dump_close: write ISB for interface %u",if_stats.interface_id);
+                        if (!pcapng_write_interface_statistics_block(wdh, &if_stats, err)) {
+                                return FALSE;
                         }
                 }
         }
 
         pcapng_debug0("pcapng_dump_close");
-        g_array_free(pcapng->interface_data, TRUE);
-        pcapng->number_of_interfaces = 0;
         return TRUE;
 }
 
@@ -3637,19 +3596,14 @@ static gboolean pcapng_dump_close(wtap_dumper *wdh, int *err _U_)
 gboolean
 pcapng_dump_open(wtap_dumper *wdh, int *err)
 {
-        pcapng_dump_t *pcapng;
-        int i;
-        interface_data_t interface_data;
+        guint i;
 
         pcapng_debug0("pcapng_dump_open");
         /* This is a pcapng file */
         wdh->subtype_write = pcapng_dump;
         wdh->subtype_close = pcapng_dump_close;
-        pcapng = (pcapng_dump_t *)g_malloc0(sizeof(pcapng_dump_t));
-        wdh->priv = (void *)pcapng;
-        pcapng->interface_data = g_array_new(FALSE, FALSE, sizeof(interface_data_t));
 
-        if ((wdh->number_of_interfaces == 0) || (wdh->interface_data == NULL)) {
+        if (wdh->interface_data->len == 0) {
                 pcapng_debug0("There are no interfaces. Can't handle that...");
                 *err = WTAP_ERR_INTERNAL;
                 return FALSE;
@@ -3662,76 +3616,21 @@ pcapng_dump_open(wtap_dumper *wdh, int *err)
         pcapng_debug0("pcapng_dump_open: wrote section header block.");
 
         /* Write the Interface description blocks */
-        pcapng_debug1("pcapng_dump_open: Number of IDB:s to write (number of interfaces) %u", wdh->number_of_interfaces);
+        pcapng_debug1("pcapng_dump_open: Number of IDB:s to write (number of interfaces) %u",
+                wdh->interface_data->len);
 
-        for (i = 0; i < (int)wdh->number_of_interfaces; i++) {
+        for (i = 0; i < wdh->interface_data->len; i++) {
 
                 /* Get the interface description */
                 wtapng_if_descr_t int_data;
 
                 int_data = g_array_index(wdh->interface_data, wtapng_if_descr_t, i);
 
-                interface_data.wtap_encap = int_data.wtap_encap;
-                interface_data.time_units_per_second = int_data.time_units_per_second;
-
-                g_array_append_val(pcapng->interface_data, interface_data);
-                pcapng->number_of_interfaces++;
-
                 if (!pcapng_write_if_descr_block(wdh, &int_data, err)) {
                         return FALSE;
                 }
 
         }
-#if 0
-        interface_id = pcapng_lookup_interface_id_by_encap(phdr->pkt_encap, wdh);
-        if (interface_id == G_MAXUINT32) {
-                /*
-                 * We haven't yet written out an interface description
-                 * block for an interface with this encapsulation.
-                 *
-                 * Is this encapsulation even supported in pcap-ng?
-                 */
-                pcap_encap = wtap_wtap_encap_to_pcap_encap(phdr->pkt_encap);
-                if (pcap_encap == -1) {
-                        /*
-                         * No.  Fail.
-                         */
-                        *err = WTAP_ERR_UNSUPPORTED_ENCAP;
-                        return FALSE;
-                }
-
-                /* write the interface description block */
-                wblock.frame_buffer            = NULL;
-                wblock.pseudo_header           = NULL;
-                wblock.packet_header           = NULL;
-                wblock.file_encap              = NULL;
-                wblock.type                    = BLOCK_TYPE_IDB;
-                wblock.data.if_descr.link_type = pcap_encap;
-                wblock.data.if_descr.snap_len = (wdh->snaplen != 0) ? wdh->snaplen :
-                                                                      WTAP_MAX_PACKET_SIZE; /* XXX */
-
-                /* XXX - options unused */
-                wblock.data.if_descr.if_speed   = -1;
-                /*wblock.data.if_descr.if_tsresol = 6;*/    /* default: usec */
-                wblock.data.if_descr.if_os      = NULL;
-                wblock.data.if_descr.if_fcslen  = -1;
-
-                if (!pcapng_write_if_descr_block(wdh, &wblock, err)) {
-                        return FALSE;
-                }
-
-                interface_id = pcapng->number_of_interfaces;
-                int_data.wtap_encap = phdr->pkt_encap;
-                int_data.time_units_per_second = 0;
-                g_array_append_val(pcapng->interface_data, int_data);
-                pcapng->number_of_interfaces++;
-
-                pcapng_debug3("pcapng_dump: added interface description block with index %u for encap = %d (%s).",
-                              interface_id,
-                              phdr->pkt_encap,
-                              wtap_encap_string(phdr->pkt_encap));
-        }
-#endif
 
         return TRUE;
 }
diff --git a/wiretap/wtap-int.h b/wiretap/wtap-int.h
index 1d47f25423..dfa3441835 100644
--- a/wiretap/wtap-int.h
+++ b/wiretap/wtap-int.h
@@ -109,7 +109,6 @@ struct wtap_dumper {
                                              */
     addrinfo_lists_t        *addrinfo_lists;        /**< Struct containing lists of resolved addresses */
     struct wtapng_section_s *shb_hdr;
-    guint                   number_of_interfaces;   /**< The number of interfaces a capture was made on, number of IDB:s in a pcapng file or equivalent(?)*/
     GArray                  *interface_data;        /**< An array holding the interface data from pcapng IDB:s or equivalent(?) NULL if not present.*/
 };
 
diff --git a/wiretap/wtap.c b/wiretap/wtap.c
index 403734706c..c32524be80 100644
--- a/wiretap/wtap.c
+++ b/wiretap/wtap.c
@@ -201,7 +201,6 @@ wtap_file_get_idb_info(wtap *wth)
 
 	idb_info = g_new(wtapng_iface_descriptions_t,1);
 
-	idb_info->number_of_interfaces	= wth->number_of_interfaces;
 	idb_info->interface_data	= wth->interface_data;
 
 	return idb_info;
@@ -907,7 +906,7 @@ wtap_fdclose(wtap *wth)
 void
 wtap_close(wtap *wth)
 {
-	gint i, j;
+	guint i, j;
 	wtapng_if_descr_t *wtapng_if_descr;
 	wtapng_if_stats_t *if_stats;
 
@@ -926,7 +925,7 @@ wtap_close(wtap *wth)
 		g_ptr_array_foreach(wth->fast_seek, g_fast_seek_item_free, NULL);
 		g_ptr_array_free(wth->fast_seek, TRUE);
 	}
-	for(i = 0; i < (gint)wth->number_of_interfaces; i++) {
+	for(i = 0; i < wth->interface_data->len; i++) {
 		wtapng_if_descr = &g_array_index(wth->interface_data, wtapng_if_descr_t, i);
 		if(wtapng_if_descr->opt_comment != NULL){
 			g_free(wtapng_if_descr->opt_comment);
@@ -946,19 +945,17 @@ wtap_close(wtap *wth)
 		if(wtapng_if_descr->if_os != NULL){
 			g_free(wtapng_if_descr->if_os);
 		}
-		for(j = 0; j < (gint)wtapng_if_descr->num_stat_entries; j++) {
+		for(j = 0; j < wtapng_if_descr->num_stat_entries; j++) {
 			if_stats = &g_array_index(wtapng_if_descr->interface_statistics, wtapng_if_stats_t, j);
 			if(if_stats->opt_comment != NULL){
 				g_free(if_stats->opt_comment);
 			}
 		}
 		if(wtapng_if_descr->num_stat_entries != 0){
-			 g_array_free(wtapng_if_descr->interface_statistics, TRUE);
+			g_array_free(wtapng_if_descr->interface_statistics, TRUE);
 		}
 	}
-	if(wth->number_of_interfaces != 0){
-		 g_array_free(wth->interface_data, TRUE);
-	}
+	g_array_free(wth->interface_data, TRUE);
 	g_free(wth);
 }
 
diff --git a/wiretap/wtap.h b/wiretap/wtap.h
index 6c99f73323..005d748304 100644
--- a/wiretap/wtap.h
+++ b/wiretap/wtap.h
@@ -990,7 +990,6 @@ typedef struct wtapng_section_s {
  *  one per interface.
  */
 typedef struct wtapng_iface_descriptions_s {
-    guint number_of_interfaces;
     GArray *interface_data;
 } wtapng_iface_descriptions_t;