core: Add the preliminary logic to parse 802.11 MPDUs

It currently focuses on parsing management frames, and specifically its
authentication and deauthentication frames.

Makefile.am

@@ -48,6 +48,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h linux/kdbus.h \
 					src/dbus.h src/dbus.c \
 					src/manager.h src/manager.c \
 					src/crypto.h src/crypto.c \
+					src/mpdu.h src/mpdu.c \
 					iwd.h
 src_iwd_LDADD = ell/libell-internal.la
 

src/mpdu.c

@@ -0,0 +1,166 @@
+/*
+ *
+ *  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 <ell/ell.h>
+
+#include "mpdu.h"
+
+static inline bool next_byte(const unsigned char *mpdu, int len,
+					int *offset, unsigned char *holder)
+{
+	if (len == *offset)
+		return false;
+
+	*holder = mpdu[*offset];
+	*offset = *offset + 1;
+
+	return true;
+}
+
+static inline bool next_2bytes(const unsigned char *mpdu, int len,
+					int *offset, uint16_t *holder)
+{
+	if (len == *offset || len < *offset + 2)
+		return false;
+
+	*holder = L_LE16_TO_CPU(*((uint16_t *) mpdu+*offset));
+	*offset = *offset + 2;
+
+	return true;
+}
+
+static inline bool next_data(const unsigned char *mpdu, int len,
+				int *offset, unsigned char *holder, int t_len)
+{
+	int i;
+
+	if (len == *offset || len < *offset + t_len)
+		return false;
+
+	for (i = 0; i < t_len; i++)
+		holder[i] = mpdu[*offset+i];
+
+	*offset += t_len;
+
+	return true;
+}
+
+static bool decode_mgmt_header(const unsigned char *mpdu, int len,
+						int *offset, struct mpdu *out)
+{
+	if (!next_2bytes(mpdu, len, offset, &out->mgmt_hdr.duration))
+		return false;
+
+	if (!next_data(mpdu, len, offset, out->mgmt_hdr.address_1, 6))
+		return false;
+
+	if (!next_data(mpdu, len, offset, out->mgmt_hdr.address_2, 6))
+		return false;
+
+	if (!next_data(mpdu, len, offset, out->mgmt_hdr.address_3, 6))
+		return false;
+
+	if (!next_2bytes(mpdu, len, offset, &out->mgmt_hdr.sequence_control))
+		return false;
+
+	if (out->fc.order)
+		*offset += sizeof(uint32_t); /* Skipping ht_control for now */
+
+	return true;
+}
+
+static bool decode_authentication_mgmt_mpdu(const unsigned char *mpdu,
+					int len, int *offset, struct mpdu *out)
+{
+	if (!next_2bytes(mpdu, len, offset, &out->auth.algorithm))
+		return false;
+
+	if (!next_2bytes(mpdu, len, offset, &out->auth.transaction_sequence))
+		return false;
+
+	if (!next_2bytes(mpdu, len, offset, &out->auth.status))
+		return false;
+
+	if (out->auth.algorithm == MPDU_AUTH_ALGO_SK) {
+		if (out->auth.transaction_sequence < 2 &&
+					out->auth.transaction_sequence > 3)
+			return true;
+
+		if (!next_byte(mpdu, len, offset,
+					&out->auth.challenge_text_len))
+			return false;
+
+		if (!next_data(mpdu, len, offset, out->auth.challenge_text,
+						out->auth.challenge_text_len))
+			return false;
+	}
+
+	return true;
+}
+
+static bool decode_deauthentication_mgmt_mpdu(const unsigned char *mpdu,
+					int len, int *offset, struct mpdu *out)
+{
+	return next_2bytes(mpdu, len, offset, &out->deauth.reason_code);
+}
+
+static bool decode_mgmt_mpdu(const unsigned char *mpdu, int len,
+						int *offset, struct mpdu *out)
+{
+	if (!decode_mgmt_header(mpdu, len, offset, out))
+		return false;
+
+	switch (out->fc.subtype) {
+	case MPDU_MGMT_TYPE_AUTHENTICATION:
+		return decode_authentication_mgmt_mpdu(mpdu, len, offset, out);
+	case MPDU_MGMT_TYPE_DEAUTHENTICATION:
+		return decode_deauthentication_mgmt_mpdu(mpdu, len, offset, out);
+	default:
+		return false;
+	}
+
+	return true;
+}
+
+bool mpdu_decode(const unsigned char *mpdu, int len, struct mpdu *out)
+{
+	int offset = 0;
+
+	if (!mpdu || !out)
+		return false;
+
+	if (!next_2bytes(mpdu, len, &offset, &out->fc.content))
+		return false;
+
+	switch (out->fc.type) {
+	case MPDU_TYPE_MANAGEMENT:
+		return decode_mgmt_mpdu(mpdu, len, &offset, out);
+	default:
+		return false;
+	}
+
+	return true;
+}

src/mpdu.h

@@ -0,0 +1,97 @@
+/*
+ *
+ *  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
+ *
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+
+enum mpdu_type {
+	MPDU_TYPE_MANAGEMENT = 0,
+};
+
+enum mpdu_mgmt_type {
+	MPDU_MGMT_TYPE_AUTHENTICATION   = 0xB,
+	MPDU_MGMT_TYPE_DEAUTHENTICATION = 0xC,
+};
+
+enum mpdu_authentication_algorithm_number {
+	MPDU_AUTH_ALGO_OPEN = 0,
+	MPDU_AUTH_ALGO_SK,
+};
+
+struct mpdu_fc {
+	union {
+		struct {
+			uint16_t protocol_version:2;
+			uint16_t type:2;
+			uint16_t subtype:4;
+			uint16_t to_ds:1;
+			uint16_t from_ds:1;
+			uint16_t more_fragments:1;
+			uint16_t retry:1;
+			uint16_t power_mgmt:1;
+			uint16_t more_data:1;
+			uint16_t protected_frame:1;
+			uint16_t order:1;
+		};
+		uint16_t content;
+	};
+};
+
+struct mpdu_mgmt_header {
+	uint16_t duration;
+	unsigned char address_1[6];
+	unsigned char address_2[6];
+	unsigned char address_3[6];
+	union {
+		struct {
+			uint16_t fragment_number:4;
+			uint16_t sequence_number:12;
+		};
+		uint16_t sequence_control;
+	};
+	uint32_t ht_control; /* ToDo? */
+};
+
+struct mpdu_authentication {
+	uint16_t algorithm;
+	uint16_t transaction_sequence;
+	uint16_t status;
+	uint8_t challenge_text_len;
+	unsigned char challenge_text[253];
+	/* ToDo: FT and SAE parts? */
+};
+
+struct mpdu_deauthentication {
+	uint16_t reason_code;
+	/* ToDo: Vendor specific IE? MME? */
+};
+
+struct mpdu {
+	struct mpdu_fc fc;
+	struct mpdu_mgmt_header mgmt_hdr;
+	union {
+		struct mpdu_authentication auth;
+		struct mpdu_deauthentication deauth;
+	};
+};
+
+bool mpdu_decode(const unsigned char *mpdu, int len, struct mpdu *out);