context.c 6.19 KB
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/*
 * Copyright (C) 2000  Internet Software Consortium.
 * 
 * Permission to use, copy, modify, and 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

#include <config.h>

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#include <fcntl.h>
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#include <limits.h>
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#include <stdlib.h>
#include <string.h>
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#include <unistd.h>

#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/socket.h>

#include <netinet/in.h>
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#include <lwres/lwres.h>
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#include "context_p.h"
#include "assert_p.h"

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/*
 * Some systems define the socket length argument as an int, some as size_t,
 * some as socklen_t.  The last is what the current POSIX standard mandates.
 * This definition is here so it can be portable but easily changed if needed.
 */
#ifndef LWRES_SOCKADDR_LEN_T
#define LWRES_SOCKADDR_LEN_T unsigned int
#endif

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lwres_uint16_t lwres_udp_port = LWRES_UDP_PORT;

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static void *
lwres_malloc(void *, size_t);

static void
lwres_free(void *, void *, size_t);

static lwres_result_t
context_connect(lwres_context_t *);
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lwres_result_t
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lwres_context_create(lwres_context_t **contextp, void *arg,
		     lwres_malloc_t malloc_function,
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		     lwres_free_t free_function,
		     unsigned int flags)
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{
	lwres_context_t *ctx;

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

	/*
	 * If we were not given anything special to use, use our own
	 * functions.  These are just wrappers around malloc() and free().
	 */
	if (malloc_function == NULL || free_function == NULL) {
		REQUIRE(malloc_function == NULL);
		REQUIRE(free_function == NULL);
		malloc_function = lwres_malloc;
		free_function = lwres_free;
	}

	ctx = malloc_function(arg, sizeof(lwres_context_t));
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	if (ctx == NULL)
		return (LWRES_R_NOMEMORY);
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	/*
	 * Set up the context.
	 */
	ctx->malloc = malloc_function;
	ctx->free = free_function;
	ctx->arg = arg;
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	ctx->sock = -1;
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	ctx->timeout = LWRES_DEFAULT_TIMEOUT;
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	ctx->serial = (lwres_uint32_t)ctx; /* XXXMLG */
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	if ((flags & LWRES_CONTEXT_SERVERMODE) == 0)
		(void)context_connect(ctx); /* XXXMLG */
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	/*
	 * Init resolv.conf bits.
	 */
	lwres_conf_init(ctx);

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	*contextp = ctx;
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	return (LWRES_R_SUCCESS);
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}

void
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lwres_context_destroy(lwres_context_t **contextp) {
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	lwres_context_t *ctx;

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

	ctx = *contextp;
	*contextp = NULL;

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	if (ctx->sock != -1) {
		close(ctx->sock);
		ctx->sock = -1;
	}

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	CTXFREE(ctx, sizeof(lwres_context_t));
}

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lwres_uint32_t
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lwres_context_nextserial(lwres_context_t *ctx) {
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	REQUIRE(ctx != NULL);

	return (ctx->serial++);
}

void
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lwres_context_initserial(lwres_context_t *ctx, lwres_uint32_t serial) {
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	REQUIRE(ctx != NULL);

	ctx->serial = serial;
}

void
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lwres_context_freemem(lwres_context_t *ctx, void *mem, size_t len) {
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	REQUIRE(mem != NULL);
	REQUIRE(len != 0);

	CTXFREE(mem, len);
}

void *
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lwres_context_allocmem(lwres_context_t *ctx, size_t len) {
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	REQUIRE(len != 0);

	return (CTXMALLOC(len));
}

static void *
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lwres_malloc(void *arg, size_t len) {
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	void *mem;

	(void)arg;

	mem = malloc(len);
	if (mem == NULL)
		return (NULL);

	memset(mem, 0xe5, len);

	return (mem);
}

static void
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lwres_free(void *arg, void *mem, size_t len) {
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	(void)arg;

	memset(mem, 0xa9, len);
	free(mem);
}
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static lwres_result_t
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context_connect(lwres_context_t *ctx) {
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	int s;
	int ret;
	struct sockaddr_in localhost;

	memset(&localhost, 0, sizeof(localhost));
	localhost.sin_family = AF_INET;
	localhost.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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	localhost.sin_port = htons(lwres_udp_port);
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	s = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if (s < 0)
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		return (LWRES_R_IOERROR);
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	ret = connect(s, (struct sockaddr *)&localhost, sizeof(localhost));
	if (ret != 0) {
		close(s);
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		return (LWRES_R_IOERROR);
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	}

	ctx->sock = s;

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	return (LWRES_R_SUCCESS);
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}

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lwres_result_t
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lwres_context_sendrecv(lwres_context_t *ctx,
		       void *sendbase, int sendlen,
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		       void *recvbase, int recvlen,
		       int *recvd_len)
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{
	int ret;
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	int ret2;
	int flags;
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	struct sockaddr_in sin;
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	LWRES_SOCKADDR_LEN_T fromlen;
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	fd_set readfds;
	struct timeval timeout;

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	/*
	 * Type of tv_sec is long, so make sure the unsigned long timeout
	 * does not overflow it.
	 */
	if (ctx->timeout <= LONG_MAX)
		timeout.tv_sec = (long)ctx->timeout;
	else
		timeout.tv_sec = LONG_MAX;

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	timeout.tv_usec = 0;
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	ret = sendto(ctx->sock, sendbase, sendlen, 0, NULL, 0);
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	if (ret < 0)
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		return (LWRES_R_IOERROR);
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	if (ret != sendlen)
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		return (LWRES_R_IOERROR);
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 again:
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	flags = fcntl(ctx->sock, F_GETFL, 0);
	flags |= O_NONBLOCK;
	ret = fcntl(ctx->sock, F_SETFL, flags);
	if (ret < 0)
		return (LWRES_R_IOERROR);

	FD_ZERO(&readfds);
	FD_SET(ctx->sock, &readfds);
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	ret2 = select(ctx->sock + 1, &readfds, NULL, NULL, &timeout);
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	flags = fcntl(ctx->sock, F_GETFL, 0);
	flags &= ~O_NONBLOCK;
	ret = fcntl(ctx->sock, F_SETFL, flags);
	if (ret < 0)
		return (LWRES_R_IOERROR);

	/*
	 * What happened with select?
	 */
	if (ret2 < 0)
		return (LWRES_R_IOERROR);
	if (ret2 == 0)
		return (LWRES_R_TIMEOUT);

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	fromlen = sizeof(sin);
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	/*
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	 * The address of fromlen is cast to void * to shut up compiler
	 * warnings, namely on systems that have the sixth parameter
	 * prototyped as a signed int when LWRES_SOCKADDR_LEN_T is
	 * defined as unsigned.
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	 */
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	ret = recvfrom(ctx->sock, recvbase, recvlen, 0,
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		       (struct sockaddr *)&sin, (void *)&fromlen);
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	if (ret < 0)
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		return (LWRES_R_IOERROR);
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	/*
	 * If we got something other than what we expect, re-issue our
	 * recvfrom() call.  This can happen if an old result comes in,
	 * or if someone is sending us random stuff.
	 */
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	if (sin.sin_addr.s_addr != htonl(INADDR_LOOPBACK)
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	    || sin.sin_port != htons(lwres_udp_port))
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		goto again;
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	if (recvd_len != NULL)
		*recvd_len = ret;

	return (LWRES_R_SUCCESS);
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}