text2pcap: encap types option (instead of link type)

Add an option to text2pcap to specify the encapsulation type
via wiretap encapsulation type short names instead of pcap
link layer types, similar to editcap.

Update the documentation to reflect this.

1 files changed, 80 insertions, 19 deletions

diff --git a/text2pcap.c b/text2pcap.c
index 627cbef61a..0d6718d638 100644
--- a/text2pcap.c
+++ b/text2pcap.c
@@ -86,6 +86,7 @@
 #include <glib.h>
 
 #include <wsutil/str_util.h>
+#include <wsutil/strnatcmp.h>
 #include <wsutil/wslog.h>
 #include <wsutil/ws_getopt.h>
 
@@ -162,9 +163,6 @@ static char *output_filename;
 
 static wtap_dumper* wdh;
 
-/* Encapsulation type; see wiretap/wtap.h for details */
-static guint32 wtap_encap_type = 1;   /* Default is WTAP_ENCAP_ETHERNET */
-
 /*----------------------------------------------------------------------
  * Print usage string and exit
  */
@@ -214,11 +212,13 @@ print_usage (FILE *output)
             "Output:\n"
             "  -F <capture type>      set the output file type; default is pcap.\n"
             "                         an empty \"-F\" option will list the file types.\n"
-            "  -l <typenum>           link-layer type number; default is 1 (Ethernet).  See\n"
+            "  -E <encap type>        set the output file encapsulation type; default is\n"
+            "                         ether (Ethernet). An empty \"-E\" option will list\n"
+            "                         the encapsulation types.\n"
+            "  -l <typenum>           set the output file encapsulation type via link-layer\n"
+            "                         type number; default is 1 (Ethernet). See\n"
             "                         https://www.tcpdump.org/linktypes.html for a list of\n"
-            "                         numbers.  Use this option if your dump is a complete\n"
-            "                         hex dump of an encapsulated packet and you wish to\n"
-            "                         specify the exact type of encapsulation.\n"
+            "                         numbers.\n"
             "                         Example: -l 7 for ARCNet packets.\n"
             "  -m <max-packet>        max packet length in output; default is %d\n"
             "  -n                     use pcapng instead of pcap as output format.\n"
@@ -289,16 +289,62 @@ set_hdr_ip_proto(guint8 ip_proto)
 
 static void
 list_capture_types(void) {
-  GArray *writable_type_subtypes;
+    GArray *writable_type_subtypes;
 
-  cmdarg_err("The available capture file types for the \"-F\" flag are:\n");
-  writable_type_subtypes = wtap_get_writable_file_types_subtypes(FT_SORT_BY_NAME);
-  for (guint i = 0; i < writable_type_subtypes->len; i++) {
-    int ft = g_array_index(writable_type_subtypes, int, i);
-    fprintf(stderr, "    %s - %s\n", wtap_file_type_subtype_name(ft),
+    cmdarg_err("The available capture file types for the \"-F\" flag are:\n");
+    writable_type_subtypes = wtap_get_writable_file_types_subtypes(FT_SORT_BY_NAME);
+    for (guint i = 0; i < writable_type_subtypes->len; i++) {
+        int ft = g_array_index(writable_type_subtypes, int, i);
+        fprintf(stderr, "    %s - %s\n", wtap_file_type_subtype_name(ft),
             wtap_file_type_subtype_description(ft));
-  }
-  g_array_free(writable_type_subtypes, TRUE);
+    }
+    g_array_free(writable_type_subtypes, TRUE);
+}
+
+struct string_elem {
+    const char *sstr;   /* The short string */
+    const char *lstr;   /* The long string */
+};
+
+static gint
+string_nat_compare(gconstpointer a, gconstpointer b)
+{
+    return ws_ascii_strnatcmp(((const struct string_elem *)a)->sstr,
+        ((const struct string_elem *)b)->sstr);
+}
+
+static void
+string_elem_print(gpointer data, gpointer stream_ptr)
+{
+    fprintf((FILE *) stream_ptr, "    %s - %s\n",
+        ((struct string_elem *)data)->sstr,
+        ((struct string_elem *)data)->lstr);
+}
+
+static void
+list_encap_types(void) {
+    int i;
+    struct string_elem *encaps;
+    GSList *list = NULL;
+
+    encaps = g_new(struct string_elem, wtap_get_num_encap_types());
+    cmdarg_err("The available encapsulation types for the \"-E\" flag are:\n");
+    for (i = 0; i < wtap_get_num_encap_types(); i++) {
+        /* Exclude wtap encapsulations that require a pseudo header,
+         * because we won't setup one from the text we import and
+         * wiretap doesn't allow us to write 'raw' frames
+         */
+        if (!wtap_encap_requires_phdr(i)) {
+            encaps[i].sstr = wtap_encap_name(i);
+            if (encaps[i].sstr != NULL) {
+                encaps[i].lstr = wtap_encap_description(i);
+                list = g_slist_insert_sorted(list, &encaps[i], string_nat_compare);
+            }
+        }
+    }
+    g_slist_foreach(list, string_elem_print, stderr);
+    g_slist_free(list);
+    g_free(encaps);
 }
 
 /*----------------------------------------------------------------------
@@ -319,6 +365,7 @@ parse_options(int argc, char *argv[], text_import_info_t * const info, wtap_dump
     /* Link-layer type; see https://www.tcpdump.org/linktypes.html for details */
     guint32 pcap_link_type = 1;   /* Default is LINKTYPE_ETHERNET */
     int file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_UNKNOWN;
+    int wtap_encap_type = WTAP_ENCAP_ETHERNET;
     int err;
     char* err_info;
     GError* gerror = NULL;
@@ -333,7 +380,7 @@ parse_options(int argc, char *argv[], text_import_info_t * const info, wtap_dump
     ws_init_version_info("Text2pcap (Wireshark)", NULL, NULL, NULL);
 
     /* Scan CLI parameters */
-    while ((c = ws_getopt_long(argc, argv, "hqab:De:F:i:l:m:nN:o:u:P:r:s:S:t:T:v4:6:", long_options, NULL)) != -1) {
+    while ((c = ws_getopt_long(argc, argv, "hqab:De:E:F:i:l:m:nN:o:u:P:r:s:S:t:T:v4:6:", long_options, NULL)) != -1) {
         switch (c) {
         case 'h':
             show_help_header("Generate a capture file from an ASCII hexdump of packets.");
@@ -343,7 +390,10 @@ parse_options(int argc, char *argv[], text_import_info_t * const info, wtap_dump
         case 'q': quiet = TRUE; break;
         case 'a': info->hexdump.identify_ascii = TRUE; break;
         case 'D': info->hexdump.has_direction = TRUE; break;
-        case 'l': pcap_link_type = (guint32)strtol(ws_optarg, NULL, 0); break;
+        case 'l':
+            pcap_link_type = (guint32)strtol(ws_optarg, NULL, 0);
+            wtap_encap_type = wtap_pcap_encap_to_wtap_encap(pcap_link_type);
+            break;
         case 'm': max_offset = (guint32)strtol(ws_optarg, NULL, 0); break;
         case 'n': file_type_subtype = wtap_pcapng_file_type_subtype(); break;
         case 'N': interface_name = ws_optarg; break;
@@ -391,6 +441,15 @@ parse_options(int argc, char *argv[], text_import_info_t * const info, wtap_dump
             }
             break;
 
+        case 'E':
+            wtap_encap_type = wtap_name_to_encap(ws_optarg);
+            if (wtap_encap_type < 0) {
+                cmdarg_err("\"%s\" isn't a valid encapsulation type", ws_optarg);
+                list_encap_types();
+                return INVALID_OPTION;
+            }
+            break;
+
         case 'F':
             file_type_subtype = wtap_name_to_file_type_subtype(ws_optarg);
             if  (file_type_subtype < 0) {
@@ -649,6 +708,10 @@ parse_options(int argc, char *argv[], text_import_info_t * const info, wtap_dump
 
         case '?':
             switch(ws_optopt) {
+            case 'E':
+                list_encap_types();
+                return INVALID_OPTION;
+                break;
             case 'F':
                 list_capture_types();
                 return INVALID_OPTION;
@@ -712,8 +775,6 @@ parse_options(int argc, char *argv[], text_import_info_t * const info, wtap_dump
         hdr_ip = TRUE;
     }
 
-    wtap_encap_type = wtap_pcap_encap_to_wtap_encap(pcap_link_type);
-
     if (hdr_export_pdu && wtap_encap_type != WTAP_ENCAP_WIRESHARK_UPPER_PDU) {
         cmdarg_err("Export PDU (-P) requires WIRESHARK_UPPER_PDU link type (252)");
         return INVALID_OPTION;