editcap, tshark: process IDBs in the middle of input files.

Instead of grabbing the set of IDBs found at open time, have a loop
using wtap_get_next_interface_description() to read all unread IDBs run
after opening the input file, after reading a packet from the input
file, and after getting an EOF on the input file.

Add a routine wtap_uses_interface_ids() to check whether the file type
and subtype for a dump file uses interface IDs and requires IDBs.  If
so, in the aforementioned loop, add the IDBs to the dump stream.

Add a routine wtap_dump_add_idb() to add IDBs to a dump stream.  Have it
call a file-format-specific routine to add the IDBs; the only file type
that supports it is pcapng, and it 1) writes out the IDB and 2) adds it
to the set of IDBs for the stream.

Add a wtap_dump_params_init_no_idbs() routine that prevents the IDBs
from the input file from being used to initialize the output file; use
it in cases where we're using the aforementioned loop to copy over IDBs.

Don't require any IDBs to be present when opening a pcapng file for
writing; 1) the simplest pcapng file has just an SHB in it, 2) that
requirement causes dumps that don't provide IDBs at open time to fail,
and 3) the real issue is that we don't want packets with an interface ID
not corresponding to a known IDB, and we already have a check for that.

(There are some hacks here; eventually, when everything processes the
IDBs in such a loop, we may be able to get rid of the "two favors of
dump parameter initialization" hack.)

Fixes #15844.

Addresses the same issue in #15502, but there are other issues there
that also need to be addressed.

In addition, the merge code also needs to be changed to handle this.

1 files changed, 10 insertions, 6 deletions

diff --git a/wiretap/wtap-int.h b/wiretap/wtap-int.h
index 14ab66d584..7c7efb428d 100644
--- a/wiretap/wtap-int.h
+++ b/wiretap/wtap-int.h
@@ -80,6 +80,9 @@ struct wtap_dumper;
  */
 typedef void *WFILE_T;
 
+typedef gboolean (*subtype_add_idb_func)(struct wtap_dumper*, wtap_block_t,
+                                         int *, gchar **);
+
 typedef gboolean (*subtype_write_func)(struct wtap_dumper*,
                                        const wtap_rec *rec,
                                        const guint8*, int*, gchar**);
@@ -91,18 +94,19 @@ struct wtap_dumper {
     int                     snaplen;
     int                     encap;
     wtap_compression_type   compression_type;
-    gboolean                needs_reload;   /* TRUE if the file requires re-loading after saving with wtap */
+    gboolean                needs_reload;    /* TRUE if the file requires re-loading after saving with wtap */
     gint64                  bytes_dumped;
 
-    void                    *priv;          /* this one holds per-file state and is free'd automatically by wtap_dump_close() */
-    void                    *wslua_data;    /* this one holds wslua state info and is not free'd */
+    void                    *priv;           /* this one holds per-file state and is free'd automatically by wtap_dump_close() */
+    void                    *wslua_data;     /* this one holds wslua state info and is not free'd */
 
-    subtype_write_func      subtype_write;  /* write out a record */
-    subtype_finish_func     subtype_finish; /* write out information to finish writing file */
+    subtype_add_idb_func    subtype_add_idb; /* add an IDB, writing it as necessary */
+    subtype_write_func      subtype_write;   /* write out a record */
+    subtype_finish_func     subtype_finish;  /* write out information to finish writing file */
 
     addrinfo_lists_t        *addrinfo_lists; /**< Struct containing lists of resolved addresses */
     GArray                  *shb_hdrs;
-    GArray                  *nrb_hdrs;        /**< name resolution comment/custom_opt, or NULL */
+    GArray                  *nrb_hdrs;       /**< name resolution comment/custom_opt, or NULL */
     GArray                  *interface_data; /**< An array holding the interface data from pcapng IDB:s or equivalent(?) NULL if not present.*/
     GArray                  *dsbs_initial;   /**< An array of initial DSBs (of type wtap_block_t) */