radius_client.c

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/*
 * Host AP (software wireless LAN access point) user space daemon for
 * Host AP kernel driver / RADIUS client
 * Copyright (c) 2002-2005, Jouni Malinen <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <errno.h>

#include "hostapd.h"
#include "radius.h"
#include "radius_client.h"
#include "eloop.h"

/* Defaults for RADIUS retransmit values (exponential backoff) */
#define RADIUS_CLIENT_FIRST_WAIT 3 /* seconds */
#define RADIUS_CLIENT_MAX_WAIT 120 /* seconds */
#define RADIUS_CLIENT_MAX_RETRIES 10 /* maximum number of retransmit attempts
				      * before entry is removed from retransmit
				      * list */
#define RADIUS_CLIENT_MAX_ENTRIES 30 /* maximum number of entries in retransmit
				      * list (oldest will be removed, if this
				      * limit is exceeded) */
#define RADIUS_CLIENT_NUM_FAILOVER 4 /* try to change RADIUS server after this
				      * many failed retry attempts */


struct radius_rx_handler {
	RadiusRxResult (*handler)(struct radius_msg *msg,
				  struct radius_msg *req,
				  u8 *shared_secret, size_t shared_secret_len,
				  void *data);
	void *data;
};


/* RADIUS message retransmit list */
struct radius_msg_list {
	u8 addr[ETH_ALEN]; /* STA/client address; used to find RADIUS messages
			    * for the same STA. */
	struct radius_msg *msg;
	RadiusType msg_type;
	time_t first_try;
	time_t next_try;
	int attempts;
	int next_wait;
	struct timeval last_attempt;

	u8 *shared_secret;
	size_t shared_secret_len;

	/* TODO: server config with failover to backup server(s) */

	struct radius_msg_list *next;
};


struct radius_client_data {
	void *ctx;
	struct hostapd_radius_servers *conf;

	int auth_serv_sock; /* socket for authentication RADIUS messages */
	int acct_serv_sock; /* socket for accounting RADIUS messages */
	int auth_serv_sock6;
	int acct_serv_sock6;
	int auth_sock; /* currently used socket */
	int acct_sock; /* currently used socket */

	struct radius_rx_handler *auth_handlers;
	size_t num_auth_handlers;
	struct radius_rx_handler *acct_handlers;
	size_t num_acct_handlers;

	struct radius_msg_list *msgs;
	size_t num_msgs;

	u8 next_radius_identifier;
};


static int
radius_change_server(struct radius_client_data *radius,
		     struct hostapd_radius_server *nserv,
		     struct hostapd_radius_server *oserv,
		     int sock, int sock6, int auth);
static int radius_client_init_acct(struct radius_client_data *radius);
static int radius_client_init_auth(struct radius_client_data *radius);


static void radius_client_msg_free(struct radius_msg_list *req)
{
	radius_msg_free(req->msg);
	free(req->msg);
	free(req);
}


int radius_client_register(struct radius_client_data *radius,
			   RadiusType msg_type,
			   RadiusRxResult (*handler)(struct radius_msg *msg,
						     struct radius_msg *req,
						     u8 *shared_secret,
						     size_t shared_secret_len,
						     void *data),
			   void *data)
{
	struct radius_rx_handler **handlers, *newh;
	size_t *num;

	if (msg_type == RADIUS_ACCT) {
		handlers = &radius->acct_handlers;
		num = &radius->num_acct_handlers;
	} else {
		handlers = &radius->auth_handlers;
		num = &radius->num_auth_handlers;
	}

	newh = (struct radius_rx_handler *)
		realloc(*handlers,
			(*num + 1) * sizeof(struct radius_rx_handler));
	if (newh == NULL)
		return -1;

	newh[*num].handler = handler;
	newh[*num].data = data;
	(*num)++;
	*handlers = newh;

	return 0;
}


static void radius_client_handle_send_error(struct radius_client_data *radius,
					    int s, RadiusType msg_type)
{
	int _errno = errno;
	perror("send[RADIUS]");
	if (_errno == ENOTCONN || _errno == EDESTADDRREQ || _errno == EINVAL) {
		hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
			       HOSTAPD_LEVEL_INFO,
			       "Send failed - maybe interface status changed -"
			       " try to connect again");
		eloop_unregister_read_sock(s);
		close(s);
		if (msg_type == RADIUS_ACCT || msg_type == RADIUS_ACCT_INTERIM)
			radius_client_init_acct(radius);
		else
			radius_client_init_auth(radius);
	}
}


static int radius_client_retransmit(struct radius_client_data *radius,
				    struct radius_msg_list *entry, time_t now)
{
	struct hostapd_radius_servers *conf = radius->conf;
	int s;

	if (entry->msg_type == RADIUS_ACCT ||
	    entry->msg_type == RADIUS_ACCT_INTERIM) {
		s = radius->acct_sock;
		if (entry->attempts == 0)
			conf->acct_server->requests++;
		else {
			conf->acct_server->timeouts++;
			conf->acct_server->retransmissions++;
		}
	} else {
		s = radius->auth_sock;
		if (entry->attempts == 0)
			conf->auth_server->requests++;
		else {
			conf->auth_server->timeouts++;
			conf->auth_server->retransmissions++;
		}
	}

	/* retransmit; remove entry if too many attempts */
	entry->attempts++;
	hostapd_logger(radius->ctx, entry->addr, HOSTAPD_MODULE_RADIUS,
		       HOSTAPD_LEVEL_DEBUG, "Resending RADIUS message (id=%d)",
		       entry->msg->hdr->identifier);

	gettimeofday(&entry->last_attempt, NULL);
	if (send(s, entry->msg->buf, entry->msg->buf_used, 0) < 0)
		radius_client_handle_send_error(radius, s, entry->msg_type);

	entry->next_try = now + entry->next_wait;
	entry->next_wait *= 2;
	if (entry->next_wait > RADIUS_CLIENT_MAX_WAIT)
		entry->next_wait = RADIUS_CLIENT_MAX_WAIT;
	if (entry->attempts >= RADIUS_CLIENT_MAX_RETRIES) {
		printf("Removing un-ACKed RADIUS message due to too many "
		       "failed retransmit attempts\n");
		return 1;
	}

	return 0;
}


static void radius_client_timer(void *eloop_ctx, void *timeout_ctx)
{
	struct radius_client_data *radius = eloop_ctx;
	struct hostapd_radius_servers *conf = radius->conf;
	time_t now, first;
	struct radius_msg_list *entry, *prev, *tmp;
	int auth_failover = 0, acct_failover = 0;
	char abuf[50];

	entry = radius->msgs;
	if (!entry)
		return;

	time(&now);
	first = 0;

	prev = NULL;
	while (entry) {
		if (now >= entry->next_try &&
		    radius_client_retransmit(radius, entry, now)) {
			if (prev)
				prev->next = entry->next;
			else
				radius->msgs = entry->next;

			tmp = entry;
			entry = entry->next;
			radius_client_msg_free(tmp);
			radius->num_msgs--;
			continue;
		}

		if (entry->attempts > RADIUS_CLIENT_NUM_FAILOVER) {
			if (entry->msg_type == RADIUS_ACCT ||
			    entry->msg_type == RADIUS_ACCT_INTERIM)
				acct_failover++;
			else
				auth_failover++;
		}

		if (first == 0 || entry->next_try < first)
			first = entry->next_try;

		prev = entry;
		entry = entry->next;
	}

	if (radius->msgs) {
		if (first < now)
			first = now;
		eloop_register_timeout(first - now, 0,
				       radius_client_timer, radius, NULL);
		hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
			       HOSTAPD_LEVEL_DEBUG, "Next RADIUS client "
			       "retransmit in %ld seconds",
			       (long int) (first - now));
	}

	if (auth_failover && conf->num_auth_servers > 1) {
		struct hostapd_radius_server *next, *old;
		old = conf->auth_server;
		hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
			       HOSTAPD_LEVEL_NOTICE,
			       "No response from Authentication server "
			       "%s:%d - failover",
			       hostapd_ip_txt(&old->addr, abuf, sizeof(abuf)),
			       old->port);

		for (entry = radius->msgs; entry; entry = entry->next) {
			if (entry->msg_type == RADIUS_AUTH)
				old->timeouts++;
		}

		next = old + 1;
		if (next > &(conf->auth_servers[conf->num_auth_servers - 1]))
			next = conf->auth_servers;
		conf->auth_server = next;
		radius_change_server(radius, next, old,
				     radius->auth_serv_sock,
				     radius->auth_serv_sock6, 1);
	}

	if (acct_failover && conf->num_acct_servers > 1) {
		struct hostapd_radius_server *next, *old;
		old = conf->acct_server;
		hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
			       HOSTAPD_LEVEL_NOTICE,
			       "No response from Accounting server "
			       "%s:%d - failover",
			       hostapd_ip_txt(&old->addr, abuf, sizeof(abuf)),
			       old->port);

		for (entry = radius->msgs; entry; entry = entry->next) {
			if (entry->msg_type == RADIUS_ACCT ||
			    entry->msg_type == RADIUS_ACCT_INTERIM)
				old->timeouts++;
		}

		next = old + 1;
		if (next > &conf->acct_servers[conf->num_acct_servers - 1])
			next = conf->acct_servers;
		conf->acct_server = next;
		radius_change_server(radius, next, old,
				     radius->acct_serv_sock,
				     radius->acct_serv_sock6, 0);
	}
}


static void radius_client_update_timeout(struct radius_client_data *radius)
{
	time_t now, first;
	struct radius_msg_list *entry;

	eloop_cancel_timeout(radius_client_timer, radius, NULL);

	if (radius->msgs == NULL) {
		return;
	}

	first = 0;
	for (entry = radius->msgs; entry; entry = entry->next) {
		if (first == 0 || entry->next_try < first)
			first = entry->next_try;
	}

	time(&now);
	if (first < now)
		first = now;
	eloop_register_timeout(first - now, 0, radius_client_timer, radius,
			       NULL);
	hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
		       HOSTAPD_LEVEL_DEBUG, "Next RADIUS client retransmit in"
		       " %ld seconds\n", (long int) (first - now));
}


static void radius_client_list_add(struct radius_client_data *radius,
				   struct radius_msg *msg,
				   RadiusType msg_type, u8 *shared_secret,
				   size_t shared_secret_len, u8 *addr)
{
	struct radius_msg_list *entry, *prev;

	if (eloop_terminated()) {
		/* No point in adding entries to retransmit queue since event
		 * loop has already been terminated. */
		radius_msg_free(msg);
		free(msg);
		return;
	}

	entry = malloc(sizeof(*entry));
	if (entry == NULL) {
		printf("Failed to add RADIUS packet into retransmit list\n");
		radius_msg_free(msg);
		free(msg);
		return;
	}

	memset(entry, 0, sizeof(*entry));
	if (addr)
		memcpy(entry->addr, addr, ETH_ALEN);
	entry->msg = msg;
	entry->msg_type = msg_type;
	entry->shared_secret = shared_secret;
	entry->shared_secret_len = shared_secret_len;
	time(&entry->first_try);
	entry->next_try = entry->first_try + RADIUS_CLIENT_FIRST_WAIT;
	entry->attempts = 1;
	gettimeofday(&entry->last_attempt, NULL);
	entry->next_wait = RADIUS_CLIENT_FIRST_WAIT * 2;
	entry->next = radius->msgs;
	radius->msgs = entry;
	radius_client_update_timeout(radius);

	if (radius->num_msgs >= RADIUS_CLIENT_MAX_ENTRIES) {
		printf("Removing the oldest un-ACKed RADIUS packet due to "
		       "retransmit list limits.\n");
		prev = NULL;
		while (entry->next) {
			prev = entry;
			entry = entry->next;
		}
		if (prev) {
			prev->next = NULL;
			radius_client_msg_free(entry);
		}
	} else
		radius->num_msgs++;
}


static void radius_client_list_del(struct radius_client_data *radius,
				   RadiusType msg_type, u8 *addr)
{
	struct radius_msg_list *entry, *prev, *tmp;

	if (addr == NULL)
		return;

	entry = radius->msgs;
	prev = NULL;
	while (entry) {
		if (entry->msg_type == msg_type &&
		    memcmp(entry->addr, addr, ETH_ALEN) == 0) {
			if (prev)
				prev->next = entry->next;
			else
				radius->msgs = entry->next;
			tmp = entry;
			entry = entry->next;
			hostapd_logger(radius->ctx, addr,
				       HOSTAPD_MODULE_RADIUS,
				       HOSTAPD_LEVEL_DEBUG,
				       "Removing matching RADIUS message");
			radius_client_msg_free(tmp);
			radius->num_msgs--;
			continue;
		}
		prev = entry;
		entry = entry->next;
	}
}


int radius_client_send(struct radius_client_data *radius,
		       struct radius_msg *msg, RadiusType msg_type, u8 *addr)
{
	struct hostapd_radius_servers *conf = radius->conf;
	u8 *shared_secret;
	size_t shared_secret_len;
	char *name;
	int s, res;

	if (msg_type == RADIUS_ACCT_INTERIM) {
		/* Remove any pending interim acct update for the same STA. */
		radius_client_list_del(radius, msg_type, addr);
	}

	if (msg_type == RADIUS_ACCT || msg_type == RADIUS_ACCT_INTERIM) {
		shared_secret = conf->acct_server->shared_secret;
		shared_secret_len = conf->acct_server->shared_secret_len;
		radius_msg_finish_acct(msg, shared_secret, shared_secret_len);
		name = "accounting";
		s = radius->acct_sock;
		conf->acct_server->requests++;
	} else {
		shared_secret = conf->auth_server->shared_secret;
		shared_secret_len = conf->auth_server->shared_secret_len;
		radius_msg_finish(msg, shared_secret, shared_secret_len);
		name = "authentication";
		s = radius->auth_sock;
		conf->auth_server->requests++;
	}

	hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
		       HOSTAPD_LEVEL_DEBUG, "Sending RADIUS message to %s "
		       "server", name);
	if (conf->msg_dumps)
		radius_msg_dump(msg);

	res = send(s, msg->buf, msg->buf_used, 0);
	if (res < 0)
		radius_client_handle_send_error(radius, s, msg_type);

	radius_client_list_add(radius, msg, msg_type, shared_secret,
			       shared_secret_len, addr);

	return res;
}


static void radius_client_receive(int sock, void *eloop_ctx, void *sock_ctx)
{
	struct radius_client_data *radius = eloop_ctx;
	struct hostapd_radius_servers *conf = radius->conf;
	RadiusType msg_type = (RadiusType) sock_ctx;
	int len, i, roundtrip;
	unsigned char buf[3000];
	struct radius_msg *msg;
	struct radius_rx_handler *handlers;
	size_t num_handlers;
	struct radius_msg_list *req, *prev_req;
	struct timeval tv;
	struct hostapd_radius_server *rconf;
	int invalid_authenticator = 0;

	if (msg_type == RADIUS_ACCT) {
		handlers = radius->acct_handlers;
		num_handlers = radius->num_acct_handlers;
		rconf = conf->acct_server;
	} else {
		handlers = radius->auth_handlers;
		num_handlers = radius->num_auth_handlers;
		rconf = conf->auth_server;
	}

	len = recv(sock, buf, sizeof(buf), MSG_DONTWAIT);
	if (len < 0) {
		perror("recv[RADIUS]");
		return;
	}
	hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
		       HOSTAPD_LEVEL_DEBUG, "Received %d bytes from RADIUS "
		       "server", len);
	if (len == sizeof(buf)) {
		printf("Possibly too long UDP frame for our buffer - "
		       "dropping it\n");
		return;
	}

	msg = radius_msg_parse(buf, len);
	if (msg == NULL) {
		printf("Parsing incoming RADIUS frame failed\n");
		rconf->malformed_responses++;
		return;
	}

	hostapd_logger(radius->ctx, NULL, HOSTAPD_MODULE_RADIUS,
		       HOSTAPD_LEVEL_DEBUG, "Received RADIUS message");
	if (conf->msg_dumps)
		radius_msg_dump(msg);

	switch (msg->hdr->code) {
	case RADIUS_CODE_ACCESS_ACCEPT:
		rconf->access_accepts++;
		break;
	case RADIUS_CODE_ACCESS_REJECT:
		rconf->access_rejects++;
		break;
	case RADIUS_CODE_ACCESS_CHALLENGE:
		rconf->access_challenges++;
		break;
	case RADIUS_CODE_ACCOUNTING_RESPONSE:
		rconf->responses++;
		break;