Cleanroom libnl_2 library

By overriding the netlink cache pointer, able to pass nl80211 family id.
Scan and connecting open access point work
Added legal stuff to headers

Change-Id: I1c60452f35fdd1f80edebc03fef33067722d0543
diff --git a/libnl_2/attr.c b/libnl_2/attr.c
new file mode 100644
index 0000000..11e8ae5
--- /dev/null
+++ b/libnl_2/attr.c
@@ -0,0 +1,226 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* NOTICE: This is a clean room re-implementation of libnl */
+
+#include <errno.h>
+#include "netlink/netlink.h"
+#include "netlink/msg.h"
+#include "netlink/attr.h"
+#include "netlink-types.h"
+
+/* Return payload of string attribute. */
+char *nla_get_string(struct nlattr *nla)
+{
+	return (char *) nla_data(nla);
+}
+
+/* Return payload of 16 bit integer attribute. */
+uint16_t nla_get_u16(struct nlattr *nla)
+{
+	return *((uint16_t *) nla_data(nla));
+}
+
+/* Return payload of 32 bit integer attribute. */
+uint32_t nla_get_u32(struct nlattr *nla)
+{
+	return *((uint32_t *) nla_data(nla));
+}
+
+/* Return value of 8 bit integer attribute. */
+uint8_t nla_get_u8(struct nlattr *nla)
+{
+	return *((uint8_t *) nla_data(nla));
+}
+
+/* Return payload of uint64_t attribute. */
+uint64_t nla_get_u64(struct nlattr *nla)
+{
+	uint64_t tmp;
+	nla_memcpy(&tmp, nla, sizeof(tmp));
+	return tmp;
+}
+
+/* Head of payload */
+void *nla_data(const struct nlattr *nla)
+{
+	return (void *) ((char *) nla + NLA_HDRLEN);
+}
+
+/* Return length of the payload . */
+int nla_len(const struct nlattr *nla)
+{
+	return nla->nla_len - NLA_HDRLEN;
+}
+
+/* Start a new level of nested attributes. */
+struct nlattr *nla_nest_start(struct nl_msg *msg, int attrtype)
+{
+	if (!nla_put(msg, attrtype, 0, NULL)) {
+		/* Get ref to last (nested start) attr	*/
+		int padding;
+		struct nlattr *nla;
+
+		padding = nlmsg_padlen(nlmsg_datalen(nlmsg_hdr(msg)));
+		nla = (struct nlattr *) \
+			((char *) nlmsg_tail(msg->nm_nlh) - padding);
+		return nla;
+
+	} else
+		return NULL;
+
+}
+
+/* Finalize nesting of attributes. */
+int nla_nest_end(struct nl_msg *msg, struct nlattr *start)
+{
+	start->nla_len = (unsigned char *) \
+		nlmsg_tail(nlmsg_hdr(msg)) - (unsigned char *)start;
+	return 0;
+}
+
+/* Return next attribute in a stream of attributes. */
+struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
+{
+	struct nlattr *next_nla = NULL;
+	if (nla->nla_len >= sizeof(struct nlattr) &&
+	   nla->nla_len <= *remaining){
+		next_nla = (struct nlattr *) \
+			((char *) nla + NLA_ALIGN(nla->nla_len));
+		*remaining = *remaining - NLA_ALIGN(nla->nla_len);
+	}
+
+	return next_nla;
+
+}
+
+/* Check if the attribute header and payload can be accessed safely. */
+int nla_ok(const struct nlattr *nla, int remaining)
+{
+	return remaining > 0 &&
+		nla->nla_len >= sizeof(struct nlattr) &&
+		sizeof(struct nlattr) <= (unsigned int) remaining &&
+		nla->nla_len <= remaining;
+}
+
+/* Create attribute index based on a stream of attributes. */
+/* NOTE: Policy not used ! */
+int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
+	int len, struct nla_policy *policy)
+{
+	struct nlattr *pos;
+	int rem;
+
+	/* First clear table */
+	memset(tb, 0, (maxtype+1) * sizeof(struct nlattr *));
+
+	nla_for_each_attr(pos, head, len, rem) {
+		const int type = nla_type(pos);
+
+		if (type <= maxtype)
+			tb[type] = pos;
+
+	}
+
+	return 0;
+}
+
+
+/* Create attribute index based on nested attribute. */
+int nla_parse_nested(struct nlattr *tb[], int maxtype,
+		struct nlattr *nla, struct nla_policy *policy)
+{
+	return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy);
+}
+
+
+/* Add a unspecific attribute to netlink message. */
+int nla_put(struct nl_msg *msg, int attrtype, int datalen, const void *data)
+{
+	struct nlattr *nla;
+
+	/* Reserve space and init nla header */
+	nla = nla_reserve(msg, attrtype, datalen);
+	if (nla)
+		memcpy(nla_data(nla), data, datalen);
+
+	return -errno;
+
+}
+
+
+/* Add nested attributes to netlink message. */
+/* Takes the attributes found in the nested message and appends them
+ * to the message msg nested in a container of the type attrtype. The
+ * nested message may not have a family specific header */
+int nla_put_nested(struct nl_msg *msg, int attrtype, struct nl_msg *nested)
+{
+	int rc = -1;
+	const int NO_HEADER = 0;
+
+	rc = nla_put(
+		msg,
+		attrtype,
+		nlmsg_attrlen(nlmsg_hdr(nested), NO_HEADER),
+		(const void *) nlmsg_attrdata(nlmsg_hdr(nested), NO_HEADER)
+		);
+	return rc;
+
+}
+
+/* Return type of the attribute. */
+int nla_type(const struct nlattr *nla)
+{
+	return (int) nla->nla_type;
+}
+
+/* Reserves room for an attribute in specified netlink message and fills
+ * in the attribute header (type,length). Return NULL if insufficient space */
+struct nlattr *nla_reserve(struct nl_msg * msg, int attrtype, int data_len)
+{
+
+	struct nlattr *nla;
+	const unsigned int NEW_SIZE = \
+		msg->nm_nlh->nlmsg_len + NLA_ALIGN(NLA_HDRLEN + data_len);
+
+	/* Check enough space for attribute */
+	if (NEW_SIZE <= msg->nm_size) {
+		const int fam_hdrlen = msg->nm_nlh->nlmsg_len - NLMSG_HDRLEN;
+		msg->nm_nlh->nlmsg_len = NEW_SIZE;
+		nla = nlmsg_attrdata(msg->nm_nlh, fam_hdrlen);
+		nla->nla_type = attrtype;
+		nla->nla_len = NLA_HDRLEN + data_len;
+	} else
+		goto fail;
+
+	return nla;
+fail:
+	return NULL;
+
+}
+
+/* Copy attribute payload to another memory area. */
+int nla_memcpy(void *dest, struct nlattr *src, int count)
+{
+	int rc;
+	void *ret_dest = memcpy(dest, nla_data(src), count);
+	if (!ret_dest)
+		return count;
+	else
+		return 0;
+}
+
+