1 files changed, 351 insertions, 0 deletions
diff --git a/src/libstrongswan/networking/host_resolver.c b/src/libstrongswan/networking/host_resolver.c
new file mode 100644
index 000000000..5e244f114
--- /dev/null
+++ b/src/libstrongswan/networking/host_resolver.c
@@ -0,0 +1,351 @@
+/*
+ * Copyright (C) 2012 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+
+#include "host_resolver.h"
+
+#include <library.h>
+#include <utils/debug.h>
+#include <threading/condvar.h>
+#include <threading/mutex.h>
+#include <threading/thread.h>
+#include <collections/hashtable.h>
+#include <collections/linked_list.h>
+
+/**
+ * Default minimum and maximum number of threads
+ */
+#define MIN_THREADS_DEFAULT 0
+#define MAX_THREADS_DEFAULT 3
+
+/**
+ * Timeout in seconds to wait for new queries until a thread may be stopped
+ */
+#define NEW_QUERY_WAIT_TIMEOUT 30
+
+typedef struct private_host_resolver_t private_host_resolver_t;
+
+/**
+ * Private data of host_resolver_t
+ */
+struct private_host_resolver_t {
+
+	/**
+	 * Public interface
+	 */
+	host_resolver_t public;
+
+	/**
+	 * Hashtable to check for queued queries, query_t*
+	 */
+	hashtable_t *queries;
+
+	/**
+	 * Queue for queries, query_t*
+	 */
+	linked_list_t *queue;
+
+	/**
+	 * Mutex to safely access private data
+	 */
+	mutex_t *mutex;
+
+	/**
+	 * Condvar to signal arrival of new queries
+	 */
+	condvar_t *new_query;
+
+	/**
+	 * Minimum number of resolver threads
+	 */
+	u_int min_threads;
+
+	/**
+	 * Maximum number of resolver threads
+	 */
+	u_int max_threads;
+
+	/**
+	 * Current number of threads
+	 */
+	u_int threads;
+
+	/**
+	 * Current number of busy threads
+	 */
+	u_int busy_threads;
+
+	/**
+	 * Pool of threads, thread_t*
+	 */
+	linked_list_t *pool;
+
+	/**
+	 * TRUE if no new queries are accepted
+	 */
+	bool disabled;
+
+};
+
+typedef struct {
+	/** DNS name we are looking for */
+	char *name;
+	/** address family we request */
+	int family;
+	/** Condvar to signal completion of a query */
+	condvar_t *done;
+	/** refcount */
+	refcount_t refcount;
+	/** the result if successful */
+	host_t *result;
+} query_t;
+
+/**
+ * Destroy the given query_t object if refcount is zero
+ */
+static void query_destroy(query_t *this)
+{
+	if (ref_put(&this->refcount))
+	{
+		DESTROY_IF(this->result);
+		this->done->destroy(this->done);
+		free(this->name);
+		free(this);
+	}
+}
+
+/**
+ * Signals all waiting threads and destroys the query
+ */
+static void query_signal_and_destroy(query_t *this)
+{
+	this->done->broadcast(this->done);
+	query_destroy(this);
+}
+
+/**
+ * Hash a queued query
+ */
+static u_int query_hash(query_t *this)
+{
+	return chunk_hash_inc(chunk_create(this->name, strlen(this->name)),
+						  chunk_hash(chunk_from_thing(this->family)));
+}
+
+/**
+ * Compare two queued queries
+ */
+static bool query_equals(query_t *this, query_t *other)
+{
+	return this->family == other->family && streq(this->name, other->name);
+}
+
+/**
+ * Main function of resolver threads
+ */
+static void *resolve_hosts(private_host_resolver_t *this)
+{
+	struct addrinfo hints, *result;
+	query_t *query;
+	int error;
+	bool old, timed_out;
+
+	while (TRUE)
+	{
+		this->mutex->lock(this->mutex);
+		thread_cleanup_push((thread_cleanup_t)this->mutex->unlock, this->mutex);
+		while (this->queue->remove_first(this->queue,
+										(void**)&query) != SUCCESS)
+		{
+			old = thread_cancelability(TRUE);
+			timed_out = this->new_query->timed_wait(this->new_query,
+									this->mutex, NEW_QUERY_WAIT_TIMEOUT * 1000);
+			thread_cancelability(old);
+			if (this->disabled)
+			{
+				thread_cleanup_pop(TRUE);
+				return NULL;
+			}
+			else if (timed_out && (this->threads > this->min_threads))
+			{	/* terminate this thread by detaching it */
+				thread_t *thread = thread_current();
+
+				this->threads--;
+				this->pool->remove(this->pool, thread, NULL);
+				thread_cleanup_pop(TRUE);
+				thread->detach(thread);
+				return NULL;
+			}
+		}
+		this->busy_threads++;
+		thread_cleanup_pop(TRUE);
+
+		memset(&hints, 0, sizeof(hints));
+		hints.ai_family = query->family;
+		hints.ai_socktype = SOCK_DGRAM;
+
+		thread_cleanup_push((thread_cleanup_t)query_signal_and_destroy, query);
+		old = thread_cancelability(TRUE);
+		error = getaddrinfo(query->name, NULL, &hints, &result);
+		thread_cancelability(old);
+		thread_cleanup_pop(FALSE);
+
+		this->mutex->lock(this->mutex);
+		this->busy_threads--;
+		if (error != 0)
+		{
+			DBG1(DBG_LIB, "resolving '%s' failed: %s", query->name,
+				 gai_strerror(error));
+		}
+		else
+		{	/* result is a linked list, but we use only the first address */
+			query->result = host_create_from_sockaddr(result->ai_addr);
+			freeaddrinfo(result);
+		}
+		this->queries->remove(this->queries, query);
+		query->done->broadcast(query->done);
+		this->mutex->unlock(this->mutex);
+		query_destroy(query);
+	}
+	return NULL;
+}
+
+METHOD(host_resolver_t, resolve, host_t*,
+	private_host_resolver_t *this, char *name, int family)
+{
+	query_t *query, lookup = {
+		.name = name,
+		.family = family,
+	};
+	host_t *result;
+
+	if (family == AF_INET && strchr(name, ':'))
+	{	/* do not try to convert v6 addresses for v4 family */
+		return NULL;
+	}
+	this->mutex->lock(this->mutex);
+	if (this->disabled)
+	{
+		this->mutex->unlock(this->mutex);
+		return NULL;
+	}
+	query = this->queries->get(this->queries, &lookup);
+	if (!query)
+	{
+		INIT(query,
+			.name = strdup(name),
+			.family = family,
+			.done = condvar_create(CONDVAR_TYPE_DEFAULT),
+			.refcount = 1,
+		);
+		this->queries->put(this->queries, query, query);
+		this->queue->insert_last(this->queue, query);
+		this->new_query->signal(this->new_query);
+	}
+	ref_get(&query->refcount);
+	if (this->busy_threads == this->threads &&
+		this->threads < this->max_threads)
+	{
+		thread_t *thread;
+
+		thread = thread_create((thread_main_t)resolve_hosts, this);
+		if (thread)
+		{
+			this->threads++;
+			this->pool->insert_last(this->pool, thread);
+		}
+	}
+	query->done->wait(query->done, this->mutex);
+	this->mutex->unlock(this->mutex);
+
+	result = query->result ? query->result->clone(query->result) : NULL;
+	query_destroy(query);
+	return result;
+}
+
+METHOD(host_resolver_t, flush, void,
+	private_host_resolver_t *this)
+{
+	enumerator_t *enumerator;
+	query_t *query;
+
+	this->mutex->lock(this->mutex);
+	enumerator = this->queries->create_enumerator(this->queries);
+	while (enumerator->enumerate(enumerator, &query, NULL))
+	{	/* use the hashtable here as we also want to signal dequeued queries */
+		this->queries->remove_at(this->queries, enumerator);
+		query->done->broadcast(query->done);
+	}
+	enumerator->destroy(enumerator);
+	this->queue->destroy_function(this->queue, (void*)query_destroy);
+	this->queue = linked_list_create();
+	this->disabled = TRUE;
+	/* this will already terminate most idle threads */
+	this->new_query->broadcast(this->new_query);
+	this->mutex->unlock(this->mutex);
+}
+
+METHOD(host_resolver_t, destroy, void,
+	private_host_resolver_t *this)
+{
+	thread_t *thread;
+
+	flush(this);
+	this->pool->invoke_offset(this->pool, offsetof(thread_t, cancel));
+	while (this->pool->remove_first(this->pool, (void**)&thread) == SUCCESS)
+	{
+		thread->join(thread);
+	}
+	this->pool->destroy(this->pool);
+	this->queue->destroy(this->queue);
+	this->queries->destroy(this->queries);
+	this->new_query->destroy(this->new_query);
+	this->mutex->destroy(this->mutex);
+	free(this);
+}
+
+/*
+ * Described in header
+ */
+host_resolver_t *host_resolver_create()
+{
+	private_host_resolver_t *this;
+
+	INIT(this,
+		.public = {
+			.resolve = _resolve,
+			.flush = _flush,
+			.destroy = _destroy,
+		},
+		.queries = hashtable_create((hashtable_hash_t)query_hash,
+									(hashtable_equals_t)query_equals, 8),
+		.queue = linked_list_create(),
+		.pool = linked_list_create(),
+		.mutex = mutex_create(MUTEX_TYPE_DEFAULT),
+		.new_query = condvar_create(CONDVAR_TYPE_DEFAULT),
+	);
+
+	this->min_threads = max(0, lib->settings->get_int(lib->settings,
+									"libstrongswan.host_resolver.min_threads",
+									 MIN_THREADS_DEFAULT));
+	this->max_threads = max(this->min_threads ?: 1,
+							lib->settings->get_int(lib->settings,
+									"libstrongswan.host_resolver.max_threads",
+									 MAX_THREADS_DEFAULT));
+	return &this->public;
+}