Adding upstream version 3.2.3+dfsg.upstream/3.2.3+dfsg

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1520 insertions, 0 deletions

diff --git a/src/main/connection.c b/src/main/connection.c
new file mode 100644
index 0000000..7ae4a2a
--- /dev/null
+++ b/src/main/connection.c
@@ -0,0 +1,1520 @@
+/*
+ *   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.
+ *
+ *   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.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/**
+ * @file connection.c
+ * @brief Handle pools of connections (threads, sockets, etc.)
+ * @note This API must be used by all modules in the public distribution that
+ * maintain pools of connections.
+ *
+ * @copyright 2012  The FreeRADIUS server project
+ * @copyright 2012  Alan DeKok <aland@deployingradius.com>
+ */
+RCSID("$Id$")
+
+#include <freeradius-devel/radiusd.h>
+#include <freeradius-devel/heap.h>
+#include <freeradius-devel/modpriv.h>
+#include <freeradius-devel/rad_assert.h>
+
+typedef struct fr_connection fr_connection_t;
+
+static int fr_connection_pool_check(fr_connection_pool_t *pool);
+
+#ifndef NDEBUG
+#ifdef HAVE_PTHREAD_H
+/* #define PTHREAD_DEBUG (1) */
+#endif
+#endif
+
+/*
+ *	We don't need to pollute the logs with "open / close"
+ *	connection information.  Instead, only print these messages
+ *	when debugging.
+ */
+#undef INFO
+#define INFO(fmt, ...) if (rad_debug_lvl) radlog(L_INFO,  fmt, ## __VA_ARGS__)
+
+/** An individual connection within the connection pool
+ *
+ * Defines connection counters, timestamps, and holds a pointer to the
+ * connection handle itself.
+ *
+ * @see fr_connection_pool_t
+ */
+struct fr_connection {
+	fr_connection_t	*prev;			//!< Previous connection in list.
+	fr_connection_t	*next;			//!< Next connection in list.
+
+	time_t		created;		//!< Time connection was created.
+	struct timeval 	last_reserved;		//!< Last time the connection was reserved.
+
+	struct timeval	last_released;  	//!< Time the connection was released.
+
+	uint32_t	num_uses;		//!< Number of times the connection has been reserved.
+	uint64_t	number;			//!< Unique ID assigned when the connection is created,
+						//!< these will monotonically increase over the
+						//!< lifetime of the connection pool.
+	void		*connection;		//!< Pointer to whatever the module uses for a connection
+						//!< handle.
+	bool		in_use;			//!< Whether the connection is currently reserved.
+
+	int		heap;			//!< For the next connection heap.
+
+#ifdef PTHREAD_DEBUG
+	pthread_t	pthread_id;		//!< When 'in_use == true'.
+#endif
+};
+
+/** A connection pool
+ *
+ * Defines the configuration of the connection pool, all the counters and
+ * timestamps related to the connection pool, the mutex that stops multiple
+ * threads leaving the pool in an inconsistent state, and the callbacks
+ * required to open, close and check the status of connections within the pool.
+ *
+ * @see fr_connection
+ */
+struct fr_connection_pool_t {
+	int		ref;			//!< Reference counter to prevent connection
+						//!< pool being freed multiple times.
+	uint32_t       	start;			//!< Number of initial connections.
+	uint32_t       	min;			//!< Minimum number of concurrent connections to keep open.
+	uint32_t       	max;			//!< Maximum number of concurrent connections to allow.
+	uint32_t       	spare;			//!< Number of spare connections to try.
+	uint32_t	pending;		//!< Number of pending open connections.
+	uint32_t       	retry_delay;		//!< seconds to delay re-open after a failed open.
+	uint32_t	max_retries;		//!< Maximum number of retries to attempt for any given
+						//!< operation (e.g. query or bind)
+	uint32_t       	cleanup_interval; 	//!< Initial timer for how often we sweep the pool
+						//!< for free connections. (0 is infinite).
+	int		delay_interval;		//!< When we next do a cleanup.  Initialized to
+						//!< cleanup_interval, and increase from there based
+						//!< on the delay.
+	int		next_delay;    	 	//!< The next delay time.  cleanup.  Initialized to
+						//!< cleanup_interval, and decays from there.
+	uint64_t	max_uses;		//!< Maximum number of times a connection can be used
+						//!< before being closed.
+	uint32_t	lifetime;		//!< How long a connection can be open before being
+						//!< closed (irrespective of whether it's idle or not).
+	uint32_t       	idle_timeout;		//!< How long a connection can be idle before
+						//!< being closed.
+
+	uint32_t	max_pending;		//!< Max number of connections to open.
+
+	bool		spread;			//!< If true we spread requests over the connections,
+						//!< using the connection released longest ago, first.
+
+	fr_connection_pool_stats_t stats;		//!< various statistics
+
+	fr_heap_t	*heap;			//!< For the next connection heap
+
+	fr_connection_t	*head;			//!< Start of the connection list.
+	fr_connection_t *tail;			//!< End of the connection list.
+
+#ifdef HAVE_PTHREAD_H
+	pthread_mutex_t	mutex;			//!< Mutex used to keep consistent state when making
+						//!< modifications in threaded mode.
+#endif
+
+	CONF_SECTION	*cs;			//!< Configuration section holding the section of parsed
+						//!< config file that relates to this pool.
+	void		*opaque;		//!< Pointer to context data that will be passed to callbacks.
+
+	char const	*log_prefix;		//!< Log prefix to prepend to all log messages created
+						//!< by the connection pool code.
+
+	char const	*trigger_prefix;	//!< Prefix to prepend to names of all triggers
+						//!< fired by the connection pool code.
+
+	fr_connection_create_t	create;		//!< Function used to create new connections.
+	fr_connection_alive_t	alive;		//!< Function used to check status of connections.
+};
+
+#ifndef HAVE_PTHREAD_H
+#  define pthread_mutex_lock(_x)
+#  define pthread_mutex_unlock(_x)
+#endif
+
+static const CONF_PARSER connection_config[] = {
+	{ "start", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, start), "5" },
+	{ "min", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, min), "5" },
+	{ "max", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, max), "10" },
+	{ "spare", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, spare), "3" },
+	{ "uses", FR_CONF_OFFSET(PW_TYPE_INTEGER64, fr_connection_pool_t, max_uses), "0" },
+	{ "lifetime", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, lifetime), "0" },
+	{ "cleanup_delay", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, cleanup_interval), NULL},
+	{ "cleanup_interval", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, cleanup_interval), "30" },
+	{ "idle_timeout", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, idle_timeout), "60" },
+	{ "retry_delay", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, retry_delay), "1" },
+	{ "max_retries", FR_CONF_OFFSET(PW_TYPE_INTEGER, fr_connection_pool_t, max_retries), "5" },
+	{ "spread", FR_CONF_OFFSET(PW_TYPE_BOOLEAN, fr_connection_pool_t, spread), "no" },
+	CONF_PARSER_TERMINATOR
+};
+
+/** Order connections by reserved most recently
+ */
+static int last_reserved_cmp(void const *one, void const *two)
+{
+	fr_connection_t const *a = one;
+	fr_connection_t const *b = two;
+
+	if (a->last_reserved.tv_sec < b->last_reserved.tv_sec) return -1;
+	if (a->last_reserved.tv_sec > b->last_reserved.tv_sec) return +1;
+
+	if (a->last_reserved.tv_usec < b->last_reserved.tv_usec) return -1;
+	if (a->last_reserved.tv_usec > b->last_reserved.tv_usec) return +1;
+
+	return 0;
+}
+
+/** Order connections by released longest ago
+ */
+static int last_released_cmp(void const *one, void const *two)
+{
+	fr_connection_t const *a = one;
+	fr_connection_t const *b = two;
+
+	if (b->last_released.tv_sec < a->last_released.tv_sec) return -1;
+	if (b->last_released.tv_sec > a->last_released.tv_sec) return +1;
+
+	if (b->last_released.tv_usec < a->last_released.tv_usec) return -1;
+	if (b->last_released.tv_usec > a->last_released.tv_usec) return +1;
+
+	return 0;
+}
+
+/** Removes a connection from the connection list
+ *
+ * @note Must be called with the mutex held.
+ *
+ * @param[in,out] pool to modify.
+ * @param[in] this Connection to delete.
+ */
+static void fr_connection_unlink(fr_connection_pool_t *pool, fr_connection_t *this)
+{
+	if (this->prev) {
+		rad_assert(pool->head != this);
+		this->prev->next = this->next;
+	} else {
+		rad_assert(pool->head == this);
+		pool->head = this->next;
+	}
+	if (this->next) {
+		rad_assert(pool->tail != this);
+		this->next->prev = this->prev;
+	} else {
+		rad_assert(pool->tail == this);
+		pool->tail = this->prev;
+	}
+
+	this->prev = this->next = NULL;
+}
+
+/** Adds a connection to the head of the connection list
+ *
+ * @note Must be called with the mutex held.
+ *
+ * @param[in,out] pool to modify.
+ * @param[in] this Connection to add.
+ */
+static void fr_connection_link_head(fr_connection_pool_t *pool, fr_connection_t *this)
+{
+	rad_assert(pool != NULL);
+	rad_assert(this != NULL);
+	rad_assert(pool->head != this);
+	rad_assert(pool->tail != this);
+
+	if (pool->head) {
+		pool->head->prev = this;
+	}
+
+	this->next = pool->head;
+	this->prev = NULL;
+	pool->head = this;
+	if (!pool->tail) {
+		rad_assert(this->next == NULL);
+		pool->tail = this;
+	} else {
+		rad_assert(this->next != NULL);
+	}
+}
+
+/** Send a connection pool trigger.
+ *
+ * @param[in] pool to send trigger for.
+ * @param[in] name_suffix trigger name suffix.
+ */
+static void fr_connection_exec_trigger(fr_connection_pool_t *pool, char const *name_suffix)
+{
+	char name[64];
+	rad_assert(pool != NULL);
+	rad_assert(name_suffix != NULL);
+	snprintf(name, sizeof(name), "%s%s", pool->trigger_prefix, name_suffix);
+	exec_trigger(NULL, pool->cs, name, true);
+}
+
+/** Find a connection handle in the connection list
+ *
+ * Walks over the list of connections searching for a specified connection
+ * handle and returns the first connection that contains that pointer.
+ *
+ * @note Will lock mutex and only release mutex if connection handle
+ * is not found, so will usually return will mutex held.
+ * @note Must be called with the mutex free.
+ *
+ * @param[in] pool to search in.
+ * @param[in] conn handle to search for.
+ * @return
+ *	- Connection containing the specified handle.
+ *	- NULL if non if connection was found.
+ */
+static fr_connection_t *fr_connection_find(fr_connection_pool_t *pool, void *conn)
+{
+	fr_connection_t *this;
+
+	if (!pool || !conn) return NULL;
+
+	pthread_mutex_lock(&pool->mutex);
+
+	/*
+	 *	FIXME: This loop could be avoided if we passed a 'void
+	 *	**connection' instead.  We could use "offsetof" in
+	 *	order to find top of the parent structure.
+	 */
+	for (this = pool->head; this != NULL; this = this->next) {
+		if (this->connection == conn) {
+#ifdef PTHREAD_DEBUG
+			pthread_t pthread_id;
+
+			pthread_id = pthread_self();
+			rad_assert(pthread_equal(this->pthread_id, pthread_id) != 0);
+#endif
+
+			rad_assert(this->in_use == true);
+			return this;
+		}
+	}
+
+	pthread_mutex_unlock(&pool->mutex);
+	return NULL;
+}
+
+/** Spawns a new connection
+ *
+ * Spawns a new connection using the create callback, and returns it for
+ * adding to the connection list.
+ *
+ * @note Will call the 'open' trigger.
+ * @note Must be called with the mutex free.
+ *
+ * @param[in] pool to modify.
+ * @param[in] now Current time.
+ * @param[in] in_use whether the new connection should be "in_use" or not
+ * @return
+ *	- New connection struct.
+ *	- NULL on error.
+ */
+static fr_connection_t *fr_connection_spawn(fr_connection_pool_t *pool, time_t now, bool in_use)
+{
+	uint64_t	number;
+	uint32_t	max_pending;
+	TALLOC_CTX	*ctx;
+
+	fr_connection_t	*this;
+	void		*conn;
+
+	rad_assert(pool != NULL);
+
+	/*
+	 *	If we have NO connections, and we've previously failed
+	 *	opening connections, don't open multiple connections until
+	 *	we successfully open at least one.
+	 */
+	if ((pool->stats.num == 0) && pool->pending && pool->stats.last_failed) return NULL;
+
+	pthread_mutex_lock(&pool->mutex);
+	rad_assert(pool->stats.num <= pool->max);
+
+	/*
+	 *	Don't spawn too many connections at the same time.
+	 */
+	if ((pool->stats.num + pool->pending) >= pool->max) {
+		pthread_mutex_unlock(&pool->mutex);
+
+		ERROR("%s: Cannot open new connection, already at max", pool->log_prefix);
+		return NULL;
+	}
+
+	/*
+	 *	If the last attempt failed, wait a bit before
+	 *	retrying.
+	 */
+	if (pool->stats.last_failed && ((pool->stats.last_failed + pool->retry_delay) > now)) {
+		bool complain = false;
+
+		if (pool->stats.last_throttled != now) {
+			complain = true;
+
+			pool->stats.last_throttled = now;
+		}
+
+		pthread_mutex_unlock(&pool->mutex);
+
+		if (!RATE_LIMIT_ENABLED || complain) {
+			ERROR("%s: Last connection attempt failed, waiting %d seconds before retrying",
+			      pool->log_prefix, pool->retry_delay);
+		}
+
+		return NULL;
+	}
+
+	/*
+	 *	We limit the rate of new connections after a failed attempt.
+	 */
+	if (pool->pending > pool->max_pending) {
+		pthread_mutex_unlock(&pool->mutex);
+		RATE_LIMIT(WARN("%s: Cannot open a new connection due to rate limit after failure",
+				pool->log_prefix));
+		return NULL;
+	}
+
+	pool->pending++;
+	number = pool->stats.opened++;
+
+	/*
+	 *	Unlock the mutex while we try to open a new
+	 *	connection.  If there are issues with the back-end,
+	 *	opening a new connection may take a LONG time.  In
+	 *	that case, we want the other connections to continue
+	 *	to be used.
+	 */
+	pthread_mutex_unlock(&pool->mutex);
+
+	/*
+	 *	The true value for max_pending is the smaller of
+	 *	free connection slots, or pool->max_pending.
+	 */
+	max_pending = (pool->max - pool->stats.num);
+	if (pool->max_pending < max_pending) max_pending = pool->max_pending;
+	INFO("%s: Opening additional connection (%" PRIu64 "), %u of %u pending slots used",
+	     pool->log_prefix, number, pool->pending, max_pending);
+
+	/*
+	 *	Allocate a new top level ctx for the create callback
+	 *	to hang its memory off of.
+	 */
+	ctx = talloc_init("fr_connection_ctx");
+	if (!ctx) return NULL;
+
+	/*
+	 *	This may take a long time, which prevents other
+	 *	threads from releasing connections.  We don't care
+	 *	about other threads opening new connections, as we
+	 *	already have no free connections.
+	 */
+	conn = pool->create(ctx, pool->opaque);
+	if (!conn) {
+		ERROR("%s: Opening connection failed (%" PRIu64 ")", pool->log_prefix, number);
+
+		pool->stats.last_failed = now;
+		pthread_mutex_lock(&pool->mutex);
+		pool->max_pending = 1;
+		pool->pending--;
+		pool->stats.failed++;
+		pthread_mutex_unlock(&pool->mutex);
+
+		talloc_free(ctx);
+
+		return NULL;
+	}
+
+	/*
+	 *	And lock the mutex again while we link the new
+	 *	connection back into the pool.
+	 */
+	pthread_mutex_lock(&pool->mutex);
+
+	this = talloc_zero(pool, fr_connection_t);
+	if (!this) {
+		pthread_mutex_unlock(&pool->mutex);
+		talloc_free(ctx);
+
+		return NULL;
+	}
+	fr_link_talloc_ctx_free(this, ctx);
+
+	this->created = now;
+	this->connection = conn;
+	this->in_use = in_use;
+
+	this->number = number;
+	gettimeofday(&this->last_reserved, NULL);
+	this->last_released = this->last_reserved;
+
+	/*
+	 *	The connection pool is starting up.  Insert the
+	 *	connection into the heap.
+	 */
+	if (!in_use) fr_heap_insert(pool->heap, this);
+
+	fr_connection_link_head(pool, this);
+
+	/*
+	 *	Do NOT insert the connection into the heap.  That's
+	 *	done when the connection is released.
+	 */
+
+	pool->stats.num++;
+
+	rad_assert(pool->pending > 0);
+	pool->pending--;
+
+	/*
+	 *	We've successfully opened one more connection.  Allow
+	 *	more connections to open in parallel.
+	 */
+	if (pool->max_pending < pool->max) pool->max_pending++;
+
+	pool->stats.last_opened = time(NULL);
+	pool->delay_interval = pool->cleanup_interval;
+	pool->next_delay = pool->cleanup_interval;
+	pool->stats.last_failed = 0;
+
+	pthread_mutex_unlock(&pool->mutex);
+
+	fr_connection_exec_trigger(pool, "open");
+
+	return this;
+}
+
+/** Close an existing connection.
+ *
+ * Removes the connection from the list, calls the delete callback to close
+ * the connection, then frees memory allocated to the connection.
+ *
+ * @note Will call the 'close' trigger.
+ * @note Must be called with the mutex held.
+ *
+ * @param[in,out] pool to modify.
+ * @param[in] this Connection to delete.
+ * @param[in] reason to close the connection
+ * @param[in] msg optional message
+ */
+static void fr_connection_close_internal(fr_connection_pool_t *pool, fr_connection_t *this,
+					 char const *reason, char const *msg)
+{
+	if (!msg) {
+		INFO("%s: %s (%" PRIu64 ")", pool->log_prefix, reason, this->number);
+	} else {
+		INFO("%s: %s (%" PRIu64 ") - %s", pool->log_prefix, reason, this->number, msg);
+	}
+
+
+	/*
+	 *	If it's in use, release it.
+	 */
+	if (this->in_use) {
+#ifdef PTHREAD_DEBUG
+		pthread_t pthread_id = pthread_self();
+		rad_assert(pthread_equal(this->pthread_id, pthread_id) != 0);
+#endif
+
+		this->in_use = false;
+
+		rad_assert(pool->stats.active != 0);
+		pool->stats.active--;
+
+	} else {
+		/*
+		 *	Connection isn't used, remove it from the heap.
+		 */
+		fr_heap_extract(pool->heap, this);
+	}
+
+	fr_connection_exec_trigger(pool, "close");
+
+	fr_connection_unlink(pool, this);
+
+	rad_assert(pool->stats.num > 0);
+	pool->stats.num--;
+	pool->stats.closed++;
+	pool->stats.last_closed = time(NULL);
+	talloc_free(this);
+}
+
+/** Check whether a connection needs to be removed from the pool
+ *
+ * Will verify that the connection is within idle_timeout, max_uses, and
+ * lifetime values. If it is not, the connection will be closed.
+ *
+ * @note Will only close connections not in use.
+ * @note Must be called with the mutex held.
+ *
+ * @param[in,out] pool to modify.
+ * @param[in,out] this Connection to manage.
+ * @param[in] now Current time.
+ * @param[in] get whether we want to get a connection
+ * @return
+ *	- 0 if connection was closed.
+ *	- 1 if connection handle was left open.
+ */
+static int fr_connection_manage(fr_connection_pool_t *pool,
+				fr_connection_t *this,
+				time_t now, bool get)
+{
+	rad_assert(pool != NULL);
+	rad_assert(this != NULL);
+	char const *reason = "Closing expired connection";
+	char const *msg = NULL;
+
+	/*
+	 *	Don't terminate in-use connections
+	 */
+	if (this->in_use) return 1;
+
+	if ((pool->max_uses > 0) &&
+	    (this->num_uses >= pool->max_uses)) {
+		msg = "Hit max_uses limit";
+
+	do_delete:
+		if (pool->stats.num <= pool->min) {
+			DEBUG("%s: You probably need to lower \"min\"", pool->log_prefix);
+		}
+		fr_connection_close_internal(pool, this, reason, msg);
+		return 0;
+	}
+
+	if ((pool->lifetime > 0) &&
+	    ((this->created + pool->lifetime) < now)) {
+		msg = "Hit lifetime limit";
+		goto do_delete;
+	}
+
+	/*
+	 *	The connection WAS idle, but the caller is interested
+	 *	in getting a new one.  Instead of closing the old one
+	 *	and opening a new one, we just return the old one.
+	 */
+	if (get) return 1;
+
+	if ((pool->idle_timeout > 0) &&
+	    ((this->last_released.tv_sec + pool->idle_timeout) < now)) {
+		msg = "Hit idle_timeout limit";
+		goto do_delete;
+	}
+
+	return 1;
+}
+
+
+/** Check whether any connections need to be removed from the pool
+ *
+ * Maintains the number of connections in the pool as per the configuration
+ * parameters for the connection pool.
+ *
+ * @note Will only run checks the first time it's called in a given second,
+ * to throttle connection spawning/closing.
+ * @note Will only close connections not in use.
+ * @note Must be called with the mutex held, will release mutex before
+ * returning.
+ *
+ * @param[in,out] pool to manage.
+ * @return 1
+ */
+static int fr_connection_pool_check(fr_connection_pool_t *pool)
+{
+	uint32_t num, spare;
+	time_t now = time(NULL);
+	fr_connection_t *this, *next;
+
+	if (pool->stats.last_checked == now) {
+		pthread_mutex_unlock(&pool->mutex);
+		return 1;
+	}
+
+	/*
+	 *	Get "real" number of connections, and count pending
+	 *	connections as spare.
+	 */
+	num = pool->stats.num + pool->pending;
+	spare = pool->pending + (pool->stats.num - pool->stats.active);
+
+	/*
+	 *	The other end can close connections.  If so, we'll
+	 *	have fewer than "min".  When that happens, open more
+	 *	connections to enforce "min".
+	 *
+	 *	The code for spawning connections enforces that
+	 *	num + pending <= max.
+	 */
+	if (num < pool->min) {
+		INFO("Need %u more connections to reach min connections (%i)", pool->min - num, pool->min);
+		goto add_connection;
+	}
+
+	/*
+	 *	On the odd chance that we've opened too many
+	 *	connections, take care of that.
+	 */
+	if (num > pool->max) {
+		/*
+		 *	Pending connections don't get closed as "spare".
+		 */
+		if (pool->pending > 0) goto manage_connections;
+
+		/*
+		 *	Otherwise close one of the connections to
+		 *	bring us down to "max".
+		 */
+		goto close_connection;
+	}
+
+	/*
+	 *	Now that we've enforced min/max connections, try to
+	 *	keep the "spare" connections at the correct number.
+	 */
+
+	/*
+	 *	Nothing to do?  Go check all of the connections for
+	 *	timeouts, etc.
+	 */
+	if (spare == pool->spare) goto manage_connections;
+
+	/*
+	 *	Too many spare connections, delete some.
+	 */
+	if (spare > pool->spare) {
+		fr_connection_t *found;
+
+		/*
+		 *	Pending connections don't get closed as "spare".
+		 */
+		if (pool->pending > 0) goto manage_connections;
+
+		/*
+		 *	Don't close too many connections, even they
+		 *	are spare.
+		 */
+		if (num <= pool->min) goto manage_connections;
+
+		/*
+		 *	Too many spares, go close one.
+		 */
+
+	close_connection:
+		/*
+		 *	Don't close connections too often, in order to
+		 *	prevent flapping.
+		 */
+		if (now < (pool->stats.last_opened + pool->delay_interval)) goto manage_connections;
+
+		/*
+		 *	Find a connection to close.
+		 */
+		found = NULL;
+		for (this = pool->tail; this != NULL; this = this->prev) {
+			if (this->in_use) continue;
+
+			if (!found ||
+			    timercmp(&this->last_reserved, &found->last_reserved, <)) {
+				found = this;
+			}
+		}
+
+		rad_assert(found != NULL);
+
+		fr_connection_close_internal(pool, found, "Closing connection", "Too many unused connections.");
+
+		/*
+		 *	Decrease the delay for the next time we clean
+		 *	up.
+		 */
+		pool->next_delay >>= 1;
+		if (pool->next_delay == 0) pool->next_delay = 1;
+		pool->delay_interval += pool->next_delay;
+
+		goto manage_connections;
+	}
+
+	/*
+	 *	Too few connections, open some more.
+	 */
+	if (spare < pool->spare) {
+		/*
+		 *	Don't open too many pending connections.
+		 */
+		if (pool->pending >= pool->max_pending) goto manage_connections;
+
+		/*
+		 *	Don't open too many connections, even if we
+		 *	need more spares.
+		 */
+		if (num >= pool->max) goto manage_connections;
+
+		/*
+		 *	Too few spares, go add one.
+		 */
+
+	add_connection:
+		INFO("Need more connections to reach %i spares", pool->spare);
+
+		/*
+		 *	Only try to open spares if we're not already attempting to open
+		 *	a connection. Avoids spurious log messages.
+		 */
+		pthread_mutex_unlock(&pool->mutex);
+		fr_connection_spawn(pool, now, false); /* ignore return code */
+		pthread_mutex_lock(&pool->mutex);
+		goto manage_connections;
+	}
+
+	/*
+	 *	Pass over all of the connections in the pool, limiting
+	 *	lifetime, idle time, max requests, etc.
+	 */
+manage_connections:
+	for (this = pool->head; this != NULL; this = next) {
+		next = this->next;
+		fr_connection_manage(pool, this, now, false);
+	}
+
+	pool->stats.last_checked = now;
+	pthread_mutex_unlock(&pool->mutex);
+
+	return 1;
+}
+
+/** Get a connection from the connection pool
+ *
+ * @note Must be called with the mutex free.
+ *
+ * @param[in,out] pool to reserve the connection from.
+ * @param[in] spawn whether to spawn a new connection
+ * @return
+ *	- A pointer to the connection handle.
+ *	- NULL on error.
+ */
+static void *fr_connection_get_internal(fr_connection_pool_t *pool, bool spawn)
+{
+	time_t now;
+	fr_connection_t *this;
+
+	if (!pool) return NULL;
+
+	/*
+	 *	Allow CTRL-C to kill the server in debugging mode.
+	 */
+	if (main_config.exiting) return NULL;
+
+#ifdef HAVE_PTHREAD_H
+	if (spawn) pthread_mutex_lock(&pool->mutex);
+#endif
+
+	now = time(NULL);
+
+	/*
+	 *	Grab the link with the lowest latency, and check it
+	 *	for limits.  If "connection manage" says the link is
+	 *	no longer usable, go grab another one.
+	 */
+	do {
+		this = fr_heap_peek(pool->heap);
+		if (!this) break;
+
+		fr_assert(!this->in_use);
+	} while (!fr_connection_manage(pool, this, now, true));
+
+	/*
+	 *	We have a working connection.  Extract it from the
+	 *	heap and use it.
+	 */
+	if (this) {
+		fr_heap_extract(pool->heap, this);
+		goto do_return;
+	}
+
+	/*
+	 *	We were asked to avoid spawning a new connection, by
+	 *	fr_connection_reconnect_internal().  So we just return
+	 *	here.
+	 */
+	if (!spawn) return NULL;
+
+	if (pool->stats.num == pool->max) {
+		bool complain = false;
+
+		/*
+		 *	Rate-limit complaints.
+		 */
+		if (pool->stats.last_at_max != now) {
+			complain = true;
+			pool->stats.last_at_max = now;
+		}
+
+		pthread_mutex_unlock(&pool->mutex);
+
+		if (!RATE_LIMIT_ENABLED || complain) {
+			ERROR("%s: No connections available and at max connection limit", pool->log_prefix);
+		}
+
+		return NULL;
+	}
+
+	pthread_mutex_unlock(&pool->mutex);
+
+	DEBUG("%s: %i of %u connections in use.  You  may need to increase \"spare\"", pool->log_prefix,
+	      pool->stats.active, pool->stats.num);
+	this = fr_connection_spawn(pool, now, true); /* MY connection! */
+	if (!this) return NULL;
+
+	pthread_mutex_lock(&pool->mutex);
+
+do_return:
+	pool->stats.active++;
+	this->num_uses++;
+	gettimeofday(&this->last_reserved, NULL);
+	this->in_use = true;
+
+#ifdef PTHREAD_DEBUG
+	this->pthread_id = pthread_self();
+#endif
+
+#ifdef HAVE_PTHREAD_H
+	if (spawn) pthread_mutex_unlock(&pool->mutex);
+#endif
+
+	DEBUG("%s: Reserved connection (%" PRIu64 ")", pool->log_prefix, this->number);
+
+	return this->connection;
+}
+
+/** Reconnect a suspected inviable connection
+ *
+ * @note Must be called with the mutex held, will not release mutex.
+ *
+ * @see fr_connection_get
+ * @param[in,out] pool to reconnect the connection in.
+ * @param[in,out] conn to reconnect.
+ * @return new connection handle if successful else NULL.
+ */
+static fr_connection_t *fr_connection_reconnect_internal(fr_connection_pool_t *pool, fr_connection_t *conn)
+{
+	void		*new_conn;
+	uint64_t	conn_number;
+	TALLOC_CTX	*ctx;
+
+	conn_number = conn->number;
+
+	/*
+	 *	Destroy any handles associated with the fr_connection_t
+	 */
+	talloc_free_children(conn);
+
+	DEBUG("%s: Reconnecting (%" PRIu64 ")", pool->log_prefix, conn_number);
+
+	/*
+	 *	Allocate a new top level ctx for the create callback
+	 *	to hang its memory off of.
+	 */
+	ctx = talloc_init("fr_connection_ctx");
+	if (!ctx) return NULL;
+	fr_link_talloc_ctx_free(conn, ctx);
+
+	new_conn = pool->create(ctx, pool->opaque);
+	if (!new_conn) {
+		/*
+		 *	We can't create a new connection, so close the current one.
+		 */
+		fr_connection_close_internal(pool, conn, "Closing connection", "Failed to reconnect");
+
+		/*
+		 *	Maybe there's a connection which is unused and
+		 *	available.  If so, return it.
+		 */
+		new_conn = fr_connection_get_internal(pool, false);
+		if (new_conn) return new_conn;
+
+		RATE_LIMIT(ERROR("%s: Failed to reconnect (%" PRIu64 "), no free connections are available",
+				 pool->log_prefix, conn_number));
+
+		return NULL;
+	}
+
+	fr_connection_exec_trigger(pool, "close");
+	conn->connection = new_conn;
+
+	return new_conn;
+}
+
+/** Create a new connection pool
+ *
+ * Allocates structures used by the connection pool, initialises the various
+ * configuration options and counters, and sets the callback functions.
+ *
+ * Will also spawn the number of connections specified by the 'start'
+ * configuration options.
+ *
+ * @note Will call the 'start' trigger.
+ *
+ * @param[in] ctx Context to link pool's destruction to.
+ * @param[in] cs pool section.
+ * @param[in] opaque data pointer to pass to callbacks.
+ * @param[in] c Callback to create new connections.
+ * @param[in] a Callback to check the status of connections.
+ * @param[in] log_prefix prefix to prepend to all log messages.
+ * @param[in] trigger_prefix prefix to prepend to all trigger names.
+ * @return
+ *	- New connection pool.
+ *	- NULL on error.
+ */
+static fr_connection_pool_t *fr_connection_pool_init(TALLOC_CTX *ctx,
+						     CONF_SECTION *cs,
+						     void *opaque,
+						     fr_connection_create_t c,
+						     fr_connection_alive_t a,
+						     char const *log_prefix,
+						     char const *trigger_prefix)
+{
+	uint32_t i;
+	fr_connection_pool_t *pool;
+	fr_connection_t *this;
+	time_t now;
+
+	if (!cs || !opaque || !c) return NULL;
+
+	now = time(NULL);
+
+	/*
+	 *	Pool is allocated in the NULL context as
+	 *	threads are likely to allocate memory
+	 *	beneath the pool.
+	 */
+	pool = talloc_zero(NULL, fr_connection_pool_t);
+	if (!pool) return NULL;
+
+	/*
+	 *	Ensure the pool is freed at the same time
+	 *	as its parent.
+	 */
+	if (fr_link_talloc_ctx_free(ctx, pool) < 0) {
+		talloc_free(pool);
+
+		return NULL;
+	}
+
+	pool->cs = cs;
+	pool->opaque = opaque;
+	pool->create = c;
+	pool->alive = a;
+
+	pool->head = pool->tail = NULL;
+
+	/*
+	 *	We keep a heap of connections, sorted by the last time
+	 *	we STARTED using them.  Newly opened connections
+	 *	aren't in the heap.  They're only inserted in the list
+	 *	once they're released.
+	 *
+	 *	We do "most recently started" instead of "most
+	 *	recently used", because MRU is done as most recently
+	 *	*released*.  We want to order connections by
+	 *	responsiveness, and MRU prioritizes high latency
+	 *	connections.
+	 *
+	 *	We want most recently *started*, which gives
+	 *	preference to low latency links, and pushes high
+	 *	latency links down in the priority heap.
+	 *
+	 *	https://code.facebook.com/posts/1499322996995183/solving-the-mystery-of-link-imbalance-a-metastable-failure-state-at-scale/
+	 */
+	if (!pool->spread) {
+		pool->heap = fr_heap_create(last_reserved_cmp, offsetof(fr_connection_t, heap));
+	/*
+	 *	For some types of connections we need to used a different
+	 *	algorithm, because load balancing benefits are secondary
+	 *	to maintaining a cache of open connections.
+	 *
+	 *	With libcurl's multihandle, connections can only be reused
+	 *	if all handles that make up the multhandle are done processing
+	 *	their requests.
+	 *
+	 *	We can't tell when that's happened using libcurl, and even
+	 *	if we could, blocking until all servers had responded
+	 *	would have huge cost.
+	 *
+	 *	The solution is to order the heap so that the connection that
+	 *	was released longest ago is at the top.
+	 *
+	 *	That way we maximise time between connection use.
+	 */
+	} else {
+		pool->heap = fr_heap_create(last_released_cmp, offsetof(fr_connection_t, heap));
+	}
+	if (!pool->heap) {
+		talloc_free(pool);
+		return NULL;
+	}
+
+	pool->log_prefix = log_prefix ? talloc_typed_strdup(pool, log_prefix) : "core";
+	pool->trigger_prefix = trigger_prefix ? talloc_typed_strdup(pool, trigger_prefix) : "";
+
+#ifdef HAVE_PTHREAD_H
+	pthread_mutex_init(&pool->mutex, NULL);
+#endif
+
+	DEBUG("%s: Initialising connection pool", pool->log_prefix);
+
+	if (cf_section_parse(cs, pool, connection_config) < 0) goto error;
+
+	/*
+	 *	Some simple limits
+	 */
+	if (pool->max == 0) {
+		cf_log_err_cs(cs, "Cannot set 'max' to zero");
+		goto error;
+	}
+	pool->max_pending = pool->max; /* can open all connections now */
+
+	if (pool->min > pool->max) {
+		cf_log_err_cs(cs, "Cannot set 'min' to more than 'max'");
+		goto error;
+	}
+
+	FR_INTEGER_BOUND_CHECK("max", pool->max, <=, 1024);
+	FR_INTEGER_BOUND_CHECK("start", pool->start, <=, pool->max);
+	FR_INTEGER_BOUND_CHECK("spare", pool->spare, <=, (pool->max - pool->min));
+
+	if (pool->lifetime > 0) {
+		FR_INTEGER_COND_CHECK("idle_timeout", pool->idle_timeout, (pool->idle_timeout <= pool->lifetime), 0);
+	}
+
+	if (pool->idle_timeout > 0) {
+		FR_INTEGER_BOUND_CHECK("cleanup_interval", pool->cleanup_interval, <=, pool->idle_timeout);
+	}
+
+	/*
+	 *	Don't open any connections.  Instead, force the limits
+	 *	to only 1 connection.
+	 *
+	 */
+	if (check_config) {
+		pool->start = pool->min = pool->max = 1;
+		return pool;
+	}
+
+	/*
+	 *	Create all of the connections, unless the admin says
+	 *	not to.
+	 */
+	for (i = 0; i < pool->start; i++) {
+		this = fr_connection_spawn(pool, now, false);
+		if (!this) {
+		error:
+			fr_connection_pool_free(pool);
+			return NULL;
+		}
+	}
+
+	fr_connection_exec_trigger(pool, "start");
+
+	return pool;
+}
+
+/** Initialise a module specific connection pool
+ *
+ * @see fr_connection_pool_init
+ *
+ * @param[in] module section.
+ * @param[in] opaque data pointer to pass to callbacks.
+ * @param[in] c Callback to create new connections.
+ * @param[in] a Callback to check the status of connections.
+ * @param[in] log_prefix override, if NULL will be set automatically from the module CONF_SECTION.
+ * @return
+ *	- New connection pool.
+ *	- NULL on error.
+ */
+fr_connection_pool_t *fr_connection_pool_module_init(CONF_SECTION *module,
+						     void *opaque,
+						     fr_connection_create_t c,
+						     fr_connection_alive_t a,
+						     char const *log_prefix)
+{
+	CONF_SECTION *cs, *mycs;
+	char buff[128];
+	char trigger_prefix[64];
+
+	fr_connection_pool_t *pool;
+	char const *cs_name1, *cs_name2;
+
+	int ret;
+
+#define CONNECTION_POOL_CF_KEY "connection_pool"
+#define parent_name(_x) cf_section_name(cf_item_parent(cf_section_to_item(_x)))
+
+	cs_name1 = cf_section_name1(module);
+	cs_name2 = cf_section_name2(module);
+	if (!cs_name2) cs_name2 = cs_name1;
+
+	snprintf(trigger_prefix, sizeof(trigger_prefix), "modules.%s.", cs_name1);
+
+	if (!log_prefix) {
+		snprintf(buff, sizeof(buff), "rlm_%s (%s)", cs_name1, cs_name2);
+		log_prefix = buff;
+	}
+
+	/*
+	 *	Get sibling's pool config section
+	 */
+	ret = find_module_sibling_section(&cs, module, "pool");
+	switch (ret) {
+	case -1:
+		return NULL;
+
+	case 1:
+		DEBUG4("%s: Using pool section from \"%s\"", log_prefix, parent_name(cs));
+		break;
+
+	case 0:
+		DEBUG4("%s: Using local pool section", log_prefix);
+		break;
+	}
+
+	/*
+	 *	Get our pool config section
+	 */
+	mycs = cf_section_sub_find(module, "pool");
+	if (!mycs) {
+		DEBUG4("%s: Adding pool section to config item \"%s\" to store pool references", log_prefix,
+		       cf_section_name(module));
+
+		mycs = cf_section_alloc(module, "pool", NULL);
+		cf_section_add(module, mycs);
+	}
+
+	/*
+	 *	Sibling didn't have a pool config section
+	 *	Use our own local pool.
+	 */
+	if (!cs) {
+		DEBUG4("%s: \"%s.pool\" section not found, using \"%s.pool\"", log_prefix,
+		       parent_name(cs), parent_name(mycs));
+		cs = mycs;
+	}
+
+	/*
+	 *	If fr_connection_pool_init has already been called
+	 *	for this config section, reuse the previous instance.
+	 *
+	 *	This allows modules to pass in the config sections
+	 *	they would like to use the connection pool from.
+	 */
+	pool = cf_data_find(cs, CONNECTION_POOL_CF_KEY);
+	if (!pool) {
+		DEBUG4("%s: No pool reference found for config item \"%s.pool\"", log_prefix, parent_name(cs));
+		pool = fr_connection_pool_init(cs, cs, opaque, c, a, log_prefix, trigger_prefix);
+		if (!pool) return NULL;
+
+		DEBUG4("%s: Adding pool reference %p to config item \"%s.pool\"", log_prefix, pool, parent_name(cs));
+		cf_data_add(cs, CONNECTION_POOL_CF_KEY, pool, NULL);
+		return pool;
+	}
+	pool->ref++;
+
+	DEBUG4("%s: Found pool reference %p in config item \"%s.pool\"", log_prefix, pool, parent_name(cs));
+
+	/*
+	 *	We're reusing pool data add it to our local config
+	 *	section. This allows other modules to transitively
+	 *	re-use a pool through this module.
+	 */
+	if (mycs != cs) {
+		DEBUG4("%s: Copying pool reference %p from config item \"%s.pool\" to config item \"%s.pool\"",
+		       log_prefix, pool, parent_name(cs), parent_name(mycs));
+		cf_data_add(mycs, CONNECTION_POOL_CF_KEY, pool, NULL);
+	}
+
+	return pool;
+}
+
+/** Get the number of connections currently in the pool
+ *
+ * @param pool to count connections for.
+ * @return the number of connections in the pool
+ */
+int fr_connection_pool_get_num(fr_connection_pool_t *pool)
+{
+	return pool->stats.num;
+}
+
+/** Get the number of times an operation should be retried
+ *
+ * The lower of either the number of available connections or
+ * the configured max_retries.
+ *
+ * @param pool to get the retry count for.
+ * @return the number of times an operation can be retried.
+ */
+int fr_connection_pool_get_retries(fr_connection_pool_t *pool)
+{
+	return (pool->max_retries < pool->stats.num) ? pool->max_retries : pool->stats.num;
+}
+
+/** Get the number of connections currently in the pool
+ *
+ * @param module the module configuration which should contain the pool
+ * @return the stats, or NULL on "not found"
+ */
+fr_connection_pool_stats_t const *fr_connection_pool_stats(CONF_SECTION *module)
+{
+	fr_connection_pool_t *pool = NULL;
+	CONF_SECTION *cs;
+
+	cs = cf_section_sub_find(module, "pool");
+	if (!cs) {
+		CONF_PAIR *cp;
+		module_instance_t *mi;
+		char const *value;
+
+		/*
+		 *	This is the name of the module, not a
+		 *	reference.  <sigh>.
+		 */
+		cp = cf_pair_find(module, "pool");
+		if (!cp) return NULL;
+
+		value = cf_pair_value(cp);
+		if (!value) return NULL;
+
+		mi = module_find(cf_item_parent(cf_section_to_item(module)), value);
+		if (!mi) return NULL;
+
+		cs = cf_section_sub_find(mi->cs, "pool");
+		if (!cs) return NULL;
+	}
+
+	pool = cf_data_find(cs, CONNECTION_POOL_CF_KEY);
+	if (!pool) return NULL;
+
+	return &pool->stats;
+}
+
+
+/** Delete a connection pool
+ *
+ * Closes, unlinks and frees all connections in the connection pool, then frees
+ * all memory used by the connection pool.
+ *
+ * @note Will call the 'stop' trigger.
+ * @note Must be called with the mutex free.
+ *
+ * @param[in,out] pool to delete.
+ */
+void fr_connection_pool_free(fr_connection_pool_t *pool)
+{
+	fr_connection_t *this;
+
+	if (!pool) return;
+
+	/*
+	 *	More modules hold a reference to this pool, don't free
+	 *	it yet.
+	 */
+	if (pool->ref > 0) {
+		pool->ref--;
+		return;
+	}
+
+	DEBUG("%s: Removing connection pool", pool->log_prefix);
+
+	pthread_mutex_lock(&pool->mutex);
+
+	/*
+	 *	Don't loop over the list.  Just keep removing the head
+	 *	until they're all gone.
+	 */
+	while ((this = pool->head) != NULL) {
+		fr_connection_close_internal(pool, this, "Closing connection", "Shutting down connection pool");
+	}
+
+	fr_heap_delete(pool->heap);
+
+	fr_connection_exec_trigger(pool, "stop");
+
+	rad_assert(pool->head == NULL);
+	rad_assert(pool->tail == NULL);
+	rad_assert(pool->stats.num == 0);
+
+#ifdef HAVE_PTHREAD_H
+	pthread_mutex_destroy(&pool->mutex);
+#endif
+
+	talloc_free(pool);
+}
+
+/** Reserve a connection in the connection pool
+ *
+ * Will attempt to find an unused connection in the connection pool, if one is
+ * found, will mark it as in in use increment the number of active connections
+ * and return the connection handle.
+ *
+ * If no free connections are found will attempt to spawn a new one, conditional
+ * on a connection spawning not already being in progress, and not being at the
+ * 'max' connection limit.
+ *
+ * @note fr_connection_release must be called once the caller has finished
+ * using the connection.
+ *
+ * @see fr_connection_release
+ * @param[in,out] pool to reserve the connection from.
+ * @return
+ *	- A pointer to the connection handle.
+ *	- NULL on error.
+ */
+void *fr_connection_get(fr_connection_pool_t *pool)
+{
+	return fr_connection_get_internal(pool, true);
+}
+
+/** Release a connection
+ *
+ * Will mark a connection as unused and decrement the number of active
+ * connections.
+ *
+ * @see fr_connection_get
+ * @param[in,out] pool to release the connection in.
+ * @param[in,out] conn to release.
+ */
+void fr_connection_release(fr_connection_pool_t *pool, void *conn)
+{
+	fr_connection_t *this;
+
+	this = fr_connection_find(pool, conn);
+	if (!this) return;
+
+	this->in_use = false;
+
+	/*
+	 *	Record when the connection was last released
+	 */
+	gettimeofday(&this->last_released, NULL);
+
+	/*
+	 *	Insert the connection in the heap.
+	 *
+	 *	This will either be based on when we *started* using it
+	 *	(allowing fast links to be re-used, and slow links to be
+	 *	gradually expired), or when we released it (allowing
+	 *	the maximum amount of time between connection use).
+	 */
+	fr_heap_insert(pool->heap, this);
+
+	rad_assert(pool->stats.active != 0);
+	pool->stats.active--;
+
+	DEBUG("%s: Released connection (%" PRIu64 ")", pool->log_prefix, this->number);
+
+	/*
+	 *	We mirror the "spawn on get" functionality by having
+	 *	"delete on release".  If there are too many spare
+	 *	connections, go manage the pool && clean some up.
+	 */
+	fr_connection_pool_check(pool);
+}
+
+/** Reconnect a suspected inviable connection
+ *
+ * This should be called by the module if it suspects that a connection is
+ * not viable (e.g. the server has closed it).
+ *
+ * Will attempt to create a new connection handle using the create callback,
+ * and if this is successful the new handle will be assigned to the existing
+ * pool connection.
+ *
+ * If this is not successful, the connection will be removed from the pool.
+ *
+ * When implementing a module that uses the connection pool API, it is advisable
+ * to pass a pointer to the pointer to the handle (void **conn)
+ * to all functions which may call reconnect. This is so that if a new handle
+ * is created and returned, the handle pointer can be updated up the callstack,
+ * and a function higher up the stack doesn't attempt to use a now invalid
+ * connection handle.
+ *
+ * @note Will free any talloced memory hung off the context of the connection,
+ *	being reconnected.
+ *
+ * @warning After calling reconnect the caller *MUST NOT* attempt to use
+ *	the old handle in any other operations, as its memory will have been
+ *	freed.
+ *
+ * @see fr_connection_get
+ * @param[in,out] pool to reconnect the connection in.
+ * @param[in,out] conn to reconnect.
+ * @return new connection handle if successful else NULL.
+ */
+void *fr_connection_reconnect(fr_connection_pool_t *pool, void *conn)
+{
+	void		*new_conn;
+	fr_connection_t	*this;
+
+	if (!pool || !conn) return NULL;
+
+	/*
+	 *	Don't allow opening of new connections if we're trying
+	 *	to exit.
+	 */
+	if (main_config.exiting) {
+		fr_connection_release(pool, conn);
+		return NULL;
+	}
+
+	/*
+	 *	If fr_connection_find is successful the pool is now locked
+	 */
+	this = fr_connection_find(pool, conn);
+	if (!this) return NULL;
+
+	new_conn = fr_connection_reconnect_internal(pool, this);
+	pthread_mutex_unlock(&pool->mutex);
+
+	return new_conn;
+}
+
+/** Delete a connection from the connection pool.
+ *
+ * Resolves the connection handle to a connection, then (if found)
+ * closes, unlinks and frees that connection.
+ *
+ * @note Must be called with the mutex free.
+ *
+ * @param[in,out] pool Connection pool to modify.
+ * @param[in] conn to delete.
+ * @param[in] msg why the connection was closed.
+ * @return
+ *	- 0 If the connection could not be found.
+ *	- 1 if the connection was deleted.
+ */
+int fr_connection_close(fr_connection_pool_t *pool, void *conn, char const *msg)
+{
+	fr_connection_t *this;
+
+	this = fr_connection_find(pool, conn);
+	if (!this) return 0;
+
+	fr_connection_close_internal(pool, this, "Deleting connection", msg);
+	fr_connection_pool_check(pool);
+	return 1;
+}