Add tvb_get and proto_tree_add for string-encoded byte arrays

This commit adds tvb_get_string_bytes and proto_tree_add_bytes_item routines for
getting GByteArrays fields from the tvb when they are encoded in ASCII hex string form.

The proto_tree_add_bytes_item routine is also usable for normal
binary encoded byte arrays, and has the advantage of retrieving
the array values even if there's no proto tree.

It also exposes the routines to Lua, both so that a Lua script can take
advantage of this, but also so I can write a testsuite to test the functions.

Change-Id: I112a038653df6482a5d0ebe7c95708f207319e20
Reviewed-on: https://code.wireshark.org/review/1158
Reviewed-by: Hadriel Kaplan <hadrielk@yahoo.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/epan/proto.h b/epan/proto.h
index d17242990e..eac413478a 100644
--- a/epan/proto.h
+++ b/epan/proto.h
@@ -347,6 +347,22 @@ WS_DLL_PUBLIC WS_MSVC_NORETURN void proto_report_dissector_bug(const char *messa
 /* mask out ENC_STR_* and related bits - should this replace ENC_CHARENCODING_MASK? */
 #define ENC_STR_MASK            0x0000FFFE
 
+/* for cases where the number is allowed to have a leading '+'/'-' */
+/* this can't collide with ENC_SEP_* because they can be used simultaneously */
+#define ENC_NUM_PREF    0x00200000
+
+/* For cases where a string encoding contains hex, bit-or one or more
+ * of these for the allowed separator(s), as well as with ENC_STR_HEX.
+ * See hex_str_to_bytes_encoding() in epan/strutil.h for details.
+ */
+#define ENC_SEP_NONE    0x00010000
+#define ENC_SEP_COLON   0x00020000
+#define ENC_SEP_DASH    0x00040000
+#define ENC_SEP_DOT   0x00080000
+#define ENC_SEP_SPACE   0x00100000
+/* a convenience macro for the above */
+#define ENC_SEP_MASK    0x001F0000
+
 /* For cases where a string encoding contains a timestamp, use one
  * of these (but only one). These values can collide with above, because
  * you can't do both at the same time.
@@ -905,6 +921,44 @@ WS_DLL_PUBLIC proto_item *
 proto_tree_add_bytes(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
 	gint length, const guint8* start_ptr);
 
+/** Get and add a byte-array-based FT_* to a proto_tree.
+
+ Supported: FT_BYTES, FT_UINT_BYTES, FT_OID, FT_REL_OID, and FT_SYSTEM_ID.
+
+ The item is extracted from the tvbuff handed to it, based on the ENC_* passed
+ in for the encoding, and the retrieved byte array is also set to *retval so the
+ caller gets it back for other uses.
+
+ This function retrieves the value even if the passed-in tree param is NULL,
+ so that it can be used by dissectors at all times to both get the value
+ and set the tree item to it.
+
+ Like other proto_tree_add functions, if there is a tree and the value cannot
+ be decoded from the tvbuff, then an expert info error is reported. For string
+ encoding, this means that a failure to decode the hex value from the string
+ results in an expert info error being added to the tree.
+
+ If encoding is string-based, it will convert using tvb_get_string_bytes(); see
+ that function's comments for details.
+
+ @note The GByteArray retval must be pre-constructed using g_byte_array_new().
+
+ @param tree the tree to append this item to
+ @param hfindex field index
+ @param tvb the tv buffer of the current data
+ @param start start of data in tvb
+ @param length length of data in tvb
+ @param encoding data encoding (e.g, ENC_LITTLE_ENDIAN, or ENC_UTF_8|ENC_STR_HEX)
+ @param[in,out] retval points to a GByteArray which will be set to the bytes from the Tvb.
+ @param[in,out] endoff if not NULL, gets set to the character after those consumed.
+ @param[in,out] err if not NULL, gets set to 0 if no failure, else the errno code (e.g., EDOM, ERANGE).
+ @return the newly created item, and retval is set to the decoded value
+ */
+WS_DLL_PUBLIC proto_item *
+proto_tree_add_bytes_item(proto_tree *tree, int hfindex, tvbuff_t *tvb,
+    const gint start, gint length, const guint encoding,
+    GByteArray *retval, gint *endoff, gint *err);
+
 /** Add a formatted FT_BYTES to a proto_tree, with the format generating
     the string for the value and with the field name being included
     automatically.