context.c - This C code defines a DNS resolver context, whi…

/contrib/bind9/lib/irs/context.c

https://bitbucket.org/freebsd/freebsd-head/ · C · 396 lines · 291 code · 79 blank · 26 comment · 72 complexity · 9d261fe3413f853bcd57983d3c561391 MD5 · raw file


/*
 * Copyright (C) 2009  Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id: context.c,v 1.3 2009/09/02 23:48:02 tbox Exp $ */

#include <config.h>

#include <isc/app.h>
#include <isc/lib.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/once.h>
#include <isc/socket.h>
#include <isc/task.h>
#include <isc/thread.h>
#include <isc/timer.h>
#include <isc/util.h>

#include <dns/client.h>
#include <dns/lib.h>

#include <irs/context.h>
#include <irs/dnsconf.h>
#include <irs/resconf.h>

#define IRS_CONTEXT_MAGIC		ISC_MAGIC('I', 'R', 'S', 'c')
#define IRS_CONTEXT_VALID(c)		ISC_MAGIC_VALID(c, IRS_CONTEXT_MAGIC)

#ifndef RESOLV_CONF
/*% location of resolve.conf */
#define RESOLV_CONF "/etc/resolv.conf"
#endif

#ifndef DNS_CONF
/*% location of dns.conf */
#define DNS_CONF "/etc/dns.conf"
#endif

#ifndef ISC_PLATFORM_USETHREADS
irs_context_t *irs_g_context = NULL;
#else
static isc_boolean_t thread_key_initialized = ISC_FALSE;
static isc_mutex_t thread_key_mutex;
static isc_thread_key_t irs_context_key;
static isc_once_t once = ISC_ONCE_INIT;
#endif


struct irs_context {
	/*
	 * An IRS context is a thread-specific object, and does not need to
	 * be locked.
	 */
	unsigned int			magic;
	isc_mem_t			*mctx;
	isc_appctx_t			*actx;
	isc_taskmgr_t			*taskmgr;
	isc_task_t			*task;
	isc_socketmgr_t			*socketmgr;
	isc_timermgr_t			*timermgr;
	dns_client_t			*dnsclient;
	irs_resconf_t			*resconf;
	irs_dnsconf_t			*dnsconf;
};

static void
ctxs_destroy(isc_mem_t **mctxp, isc_appctx_t **actxp,
	     isc_taskmgr_t **taskmgrp, isc_socketmgr_t **socketmgrp,
	     isc_timermgr_t **timermgrp)
{
	if (taskmgrp != NULL)
		isc_taskmgr_destroy(taskmgrp);

	if (timermgrp != NULL)
		isc_timermgr_destroy(timermgrp);

	if (socketmgrp != NULL)
		isc_socketmgr_destroy(socketmgrp);

	if (actxp != NULL)
		isc_appctx_destroy(actxp);

	if (mctxp != NULL)
		isc_mem_destroy(mctxp);
}

static isc_result_t
ctxs_init(isc_mem_t **mctxp, isc_appctx_t **actxp,
	  isc_taskmgr_t **taskmgrp, isc_socketmgr_t **socketmgrp,
	  isc_timermgr_t **timermgrp)
{
	isc_result_t result;

	result = isc_mem_create(0, 0, mctxp);
	if (result != ISC_R_SUCCESS)
		goto fail;

	result = isc_appctx_create(*mctxp, actxp);
	if (result != ISC_R_SUCCESS)
		goto fail;

	result = isc_taskmgr_createinctx(*mctxp, *actxp, 1, 0, taskmgrp);
	if (result != ISC_R_SUCCESS)
		goto fail;

	result = isc_socketmgr_createinctx(*mctxp, *actxp, socketmgrp);
	if (result != ISC_R_SUCCESS)
		goto fail;

	result = isc_timermgr_createinctx(*mctxp, *actxp, timermgrp);
	if (result != ISC_R_SUCCESS)
		goto fail;

	return (ISC_R_SUCCESS);

 fail:
	ctxs_destroy(mctxp, actxp, taskmgrp, socketmgrp, timermgrp);

	return (result);
}

#ifdef ISC_PLATFORM_USETHREADS
static void
free_specific_context(void *arg) {
	irs_context_t *context = arg;

	irs_context_destroy(&context);

	isc_thread_key_setspecific(irs_context_key, NULL);
}

static void
thread_key_mutex_init(void) {
	RUNTIME_CHECK(isc_mutex_init(&thread_key_mutex) == ISC_R_SUCCESS);
}

static isc_result_t
thread_key_init() {
	isc_result_t result;

	result = isc_once_do(&once, thread_key_mutex_init);
	if (result != ISC_R_SUCCESS)
		return (result);

	if (!thread_key_initialized) {
		LOCK(&thread_key_mutex);

		if (!thread_key_initialized &&
		    isc_thread_key_create(&irs_context_key,
					  free_specific_context) != 0) {
			result = ISC_R_FAILURE;
		} else
			thread_key_initialized = ISC_TRUE;

		UNLOCK(&thread_key_mutex);
	}

	return (result);
}
#endif /* ISC_PLATFORM_USETHREADS */

isc_result_t
irs_context_get(irs_context_t **contextp) {
	irs_context_t *context;
	isc_result_t result;

	REQUIRE(contextp != NULL && *contextp == NULL);

#ifndef ISC_PLATFORM_USETHREADS
	if (irs_g_context == NULL) {
		result = irs_context_create(&irs_g_context);
		if (result != ISC_R_SUCCESS)
			return (result);
	}

	context = irs_g_context;
#else
	result = thread_key_init();
	if (result != ISC_R_SUCCESS)
		return (result);

	context = isc_thread_key_getspecific(irs_context_key);
	if (context == NULL) {
		result = irs_context_create(&context);
		if (result != ISC_R_SUCCESS)
			return (result);
		result = isc_thread_key_setspecific(irs_context_key, context);
		if (result != ISC_R_SUCCESS) {
			irs_context_destroy(&context);
			return (result);
		}
	}
#endif /* ISC_PLATFORM_USETHREADS */

	*contextp = context;

	return (ISC_R_SUCCESS);
}

isc_result_t
irs_context_create(irs_context_t **contextp) {
	isc_result_t result;
	irs_context_t *context;
	isc_appctx_t *actx = NULL;
	isc_mem_t *mctx = NULL;
	isc_taskmgr_t *taskmgr = NULL;
	isc_socketmgr_t *socketmgr = NULL;
	isc_timermgr_t *timermgr = NULL;
	dns_client_t *client = NULL;
	isc_sockaddrlist_t *nameservers;
	irs_dnsconf_dnskeylist_t *trustedkeys;
	irs_dnsconf_dnskey_t *trustedkey;

	isc_lib_register();
	result = dns_lib_init();
	if (result != ISC_R_SUCCESS)
		return (result);

	result = ctxs_init(&mctx, &actx, &taskmgr, &socketmgr, &timermgr);
	if (result != ISC_R_SUCCESS)
		return (result);

	result = isc_app_ctxstart(actx);
	if (result != ISC_R_SUCCESS) {
		ctxs_destroy(&mctx, &actx, &taskmgr, &socketmgr, &timermgr);
		return (result);
	}

	context = isc_mem_get(mctx, sizeof(*context));
	if (context == NULL) {
		ctxs_destroy(&mctx, &actx, &taskmgr, &socketmgr, &timermgr);
		return (ISC_R_NOMEMORY);
	}

	context->mctx = mctx;
	context->actx = actx;
	context->taskmgr = taskmgr;
	context->socketmgr = socketmgr;
	context->timermgr = timermgr;
	context->resconf = NULL;
	context->dnsconf = NULL;
	context->task = NULL;
	result = isc_task_create(taskmgr, 0, &context->task);
	if (result != ISC_R_SUCCESS)
		goto fail;

	/* Create a DNS client object */
	result = dns_client_createx(mctx, actx, taskmgr, socketmgr, timermgr,
				    0, &client);
	if (result != ISC_R_SUCCESS)
		goto fail;
	context->dnsclient = client;

	/* Read resolver configuration file */
	result = irs_resconf_load(mctx, RESOLV_CONF, &context->resconf);
	if (result != ISC_R_SUCCESS)
		goto fail;
	/* Set nameservers */
	nameservers = irs_resconf_getnameservers(context->resconf);
	result = dns_client_setservers(client, dns_rdataclass_in, NULL,
				       nameservers);
	if (result != ISC_R_SUCCESS)
		goto fail;

	/* Read advanced DNS configuration (if any) */
	result = irs_dnsconf_load(mctx, DNS_CONF, &context->dnsconf);
	if (result != ISC_R_SUCCESS)
		goto fail;
	trustedkeys = irs_dnsconf_gettrustedkeys(context->dnsconf);
	for (trustedkey = ISC_LIST_HEAD(*trustedkeys);
	     trustedkey != NULL;
	     trustedkey = ISC_LIST_NEXT(trustedkey, link)) {
		result = dns_client_addtrustedkey(client, dns_rdataclass_in,
						  trustedkey->keyname,
						  trustedkey->keydatabuf);
		if (result != ISC_R_SUCCESS)
			goto fail;
	}

	context->magic = IRS_CONTEXT_MAGIC;
	*contextp = context;

	return (ISC_R_SUCCESS);

  fail:
	if (context->task != NULL)
		isc_task_detach(&context->task);
	if (context->resconf != NULL)
		irs_resconf_destroy(&context->resconf);
	if (context->dnsconf != NULL)
		irs_dnsconf_destroy(&context->dnsconf);
	if (client != NULL)
		dns_client_destroy(&client);
	ctxs_destroy(NULL, &actx, &taskmgr, &socketmgr, &timermgr);
	isc_mem_putanddetach(&mctx, context, sizeof(*context));

	return (result);
}

void
irs_context_destroy(irs_context_t **contextp) {
	irs_context_t *context;

	REQUIRE(contextp != NULL);
	context = *contextp;
	REQUIRE(IRS_CONTEXT_VALID(context));

	isc_task_detach(&context->task);
	irs_dnsconf_destroy(&context->dnsconf);
	irs_resconf_destroy(&context->resconf);
	dns_client_destroy(&context->dnsclient);

	ctxs_destroy(NULL, &context->actx, &context->taskmgr,
		     &context->socketmgr, &context->timermgr);

	context->magic = 0;

	isc_mem_putanddetach(&context->mctx, context, sizeof(*context));

	*contextp = NULL;

#ifndef ISC_PLATFORM_USETHREADS
	irs_g_context = NULL;
#else
	(void)isc_thread_key_setspecific(irs_context_key, NULL);
#endif
}

isc_mem_t *
irs_context_getmctx(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->mctx);
}

isc_appctx_t *
irs_context_getappctx(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->actx);
}

isc_taskmgr_t *
irs_context_gettaskmgr(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->taskmgr);
}

isc_timermgr_t *
irs_context_gettimermgr(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->timermgr);
}

isc_task_t *
irs_context_gettask(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->task);
}

dns_client_t *
irs_context_getdnsclient(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->dnsclient);
}

irs_resconf_t *
irs_context_getresconf(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->resconf);
}

irs_dnsconf_t *
irs_context_getdnsconf(irs_context_t *context) {
	REQUIRE(IRS_CONTEXT_VALID(context));

	return (context->dnsconf);
}

Summary ✨

This C code defines a DNS resolver context, which is an object that manages DNS queries and responses. It provides functions to create, destroy, and manipulate this context, including setting up a DNS client, reading configuration files, and handling tasks such as resolving names and adding trusted keys. The context also stores memory management information for efficient use of system resources.

Alerts (1)

Complexity hotspot; line 180 (total complexity: 3)
180