ie: Simple informational element parser

The parsing API goes through the byte stream and parses the
TLV (Type, Length and Value) values and avoids data copying.

Makefile.am

@@ -40,7 +40,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h linux/kdbus.h \
 					src/kdbus.h src/kdbus.c \
 					src/netdev.h src/netdev.c \
 					src/sha1.h src/sha1.c \
-					src/ie.h
+					src/ie.h src/ie.c
 src_iwd_LDADD = ell/libell-internal.la
 
 client_iwctl_SOURCES = client/main.c linux/kdbus.h \

src/ie.c

@@ -0,0 +1,65 @@
+/*
+ *
+ *  Wireless daemon for Linux
+ *
+ *  Copyright (C) 2014  Intel Corporation. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <errno.h>
+#include <ell/ell.h>
+
+#include "ie.h"
+
+void ie_tlv_iter_init(struct ie_tlv_iter *iter, const unsigned char *tlv,
+			unsigned int len)
+{
+	iter->tlv = tlv;
+	iter->max = len;
+	iter->pos = 0;
+}
+
+unsigned int ie_tlv_iter_get_tag(struct ie_tlv_iter *iter)
+{
+	return iter->tag;
+}
+
+bool ie_tlv_iter_next(struct ie_tlv_iter *iter)
+{
+	const unsigned char *tlv = iter->tlv + iter->pos;
+	const unsigned char *end = iter->tlv + iter->max;
+	unsigned int tag;
+	unsigned int len;
+
+	tag = *tlv++;
+	len = *tlv++;
+
+	if (tlv + len > end)
+		return false;
+
+	iter->tag = tag;
+	iter->len = len;
+	iter->data = tlv;
+
+	iter->pos = tlv + len - iter->tlv;
+
+	return true;
+}

src/ie.h

@@ -153,3 +153,17 @@ enum ie_type {
 	IE_TYPE_VENDOR_SPECIFIC                      = 221,
 	/* Reserved 222 - 255 */
 };
+
+struct ie_tlv_iter {
+	unsigned int max;
+	unsigned int pos;
+	const unsigned char *tlv;
+	unsigned int tag;
+	unsigned int len;
+	const unsigned char *data;
+};
+
+void ie_tlv_iter_init(struct ie_tlv_iter *iter, const unsigned char *tlv,
+			unsigned int len);
+unsigned int ie_tlv_iter_get_tag(struct ie_tlv_iter *iter);
+bool ie_tlv_iter_next(struct ie_tlv_iter *iter);