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-rw-r--r--lib/lwres/context.c511
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diff --git a/lib/lwres/context.c b/lib/lwres/context.c
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+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/* $Id: context.c,v 1.55 2009/09/02 23:48:03 tbox Exp $ */
+
+/*! \file context.c
+ lwres_context_create() creates a #lwres_context_t structure for use in
+ lightweight resolver operations. It holds a socket and other data
+ needed for communicating with a resolver daemon. The new
+ lwres_context_t is returned through contextp, a pointer to a
+ lwres_context_t pointer. This lwres_context_t pointer must initially
+ be NULL, and is modified to point to the newly created
+ lwres_context_t.
+
+ When the lightweight resolver needs to perform dynamic memory
+ allocation, it will call malloc_function to allocate memory and
+ free_function to free it. If malloc_function and free_function are
+ NULL, memory is allocated using malloc and free. It is not
+ permitted to have a NULL malloc_function and a non-NULL free_function
+ or vice versa. arg is passed as the first parameter to the memory
+ allocation functions. If malloc_function and free_function are NULL,
+ arg is unused and should be passed as NULL.
+
+ Once memory for the structure has been allocated, it is initialized
+ using lwres_conf_init() and returned via *contextp.
+
+ lwres_context_destroy() destroys a #lwres_context_t, closing its
+ socket. contextp is a pointer to a pointer to the context that is to
+ be destroyed. The pointer will be set to NULL when the context has
+ been destroyed.
+
+ The context holds a serial number that is used to identify resolver
+ request packets and associate responses with the corresponding
+ requests. This serial number is controlled using
+ lwres_context_initserial() and lwres_context_nextserial().
+ lwres_context_initserial() sets the serial number for context *ctx to
+ serial. lwres_context_nextserial() increments the serial number and
+ returns the previous value.
+
+ Memory for a lightweight resolver context is allocated and freed using
+ lwres_context_allocmem() and lwres_context_freemem(). These use
+ whatever allocations were defined when the context was created with
+ lwres_context_create(). lwres_context_allocmem() allocates len bytes
+ of memory and if successful returns a pointer to the allocated
+ storage. lwres_context_freemem() frees len bytes of space starting at
+ location mem.
+
+ lwres_context_sendrecv() performs I/O for the context ctx. Data are
+ read and written from the context's socket. It writes data from
+ sendbase -- typically a lightweight resolver query packet -- and waits
+ for a reply which is copied to the receive buffer at recvbase. The
+ number of bytes that were written to this receive buffer is returned
+ in *recvd_len.
+
+\section context_return Return Values
+
+ lwres_context_create() returns #LWRES_R_NOMEMORY if memory for the
+ struct lwres_context could not be allocated, #LWRES_R_SUCCESS
+ otherwise.
+
+ Successful calls to the memory allocator lwres_context_allocmem()
+ return a pointer to the start of the allocated space. It returns NULL
+ if memory could not be allocated.
+
+ #LWRES_R_SUCCESS is returned when lwres_context_sendrecv() completes
+ successfully. #LWRES_R_IOERROR is returned if an I/O error occurs and
+ #LWRES_R_TIMEOUT is returned if lwres_context_sendrecv() times out
+ waiting for a response.
+
+\section context_see See Also
+
+ lwres_conf_init(), malloc, free.
+ */
+#include <config.h>
+
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <lwres/lwres.h>
+#include <lwres/net.h>
+#include <lwres/platform.h>
+
+#ifdef LWRES_PLATFORM_NEEDSYSSELECTH
+#include <sys/select.h>
+#endif
+
+#include "context_p.h"
+#include "assert_p.h"
+
+/*!
+ * 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
+
+/*!
+ * Make a socket nonblocking.
+ */
+#ifndef MAKE_NONBLOCKING
+#define MAKE_NONBLOCKING(sd, retval) \
+do { \
+ retval = fcntl(sd, F_GETFL, 0); \
+ if (retval != -1) { \
+ retval |= O_NONBLOCK; \
+ retval = fcntl(sd, F_SETFL, retval); \
+ } \
+} while (0)
+#endif
+
+LIBLWRES_EXTERNAL_DATA uint16_t lwres_udp_port = LWRES_UDP_PORT;
+LIBLWRES_EXTERNAL_DATA const char *lwres_resolv_conf = LWRES_RESOLV_CONF;
+
+static void *
+lwres_malloc(void *, size_t);
+
+static void
+lwres_free(void *, void *, size_t);
+
+/*!
+ * lwres_result_t
+ */
+static lwres_result_t
+context_connect(lwres_context_t *);
+
+/*%
+ * Creates a #lwres_context_t structure for use in
+ * lightweight resolver operations.
+ */
+lwres_result_t
+lwres_context_create(lwres_context_t **contextp, void *arg,
+ lwres_malloc_t malloc_function,
+ lwres_free_t free_function,
+ unsigned int flags)
+{
+ 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));
+ if (ctx == NULL)
+ return (LWRES_R_NOMEMORY);
+
+ /*
+ * Set up the context.
+ */
+ ctx->malloc = malloc_function;
+ ctx->free = free_function;
+ ctx->arg = arg;
+ ctx->sock = -1;
+
+ ctx->timeout = LWRES_DEFAULT_TIMEOUT;
+#ifndef WIN32
+ ctx->serial = time(NULL); /* XXXMLG or BEW */
+#else
+ ctx->serial = _time32(NULL);
+#endif
+
+ ctx->use_ipv4 = 1;
+ ctx->use_ipv6 = 1;
+ if ((flags & (LWRES_CONTEXT_USEIPV4 | LWRES_CONTEXT_USEIPV6)) ==
+ LWRES_CONTEXT_USEIPV6) {
+ ctx->use_ipv4 = 0;
+ }
+ if ((flags & (LWRES_CONTEXT_USEIPV4 | LWRES_CONTEXT_USEIPV6)) ==
+ LWRES_CONTEXT_USEIPV4) {
+ ctx->use_ipv6 = 0;
+ }
+
+ /*
+ * Init resolv.conf bits.
+ */
+ lwres_conf_init(ctx);
+
+ *contextp = ctx;
+ return (LWRES_R_SUCCESS);
+}
+
+/*%
+Destroys a #lwres_context_t, closing its socket.
+contextp is a pointer to a pointer to the context that is
+to be destroyed. The pointer will be set to NULL
+when the context has been destroyed.
+ */
+void
+lwres_context_destroy(lwres_context_t **contextp) {
+ lwres_context_t *ctx;
+
+ REQUIRE(contextp != NULL && *contextp != NULL);
+
+ ctx = *contextp;
+ *contextp = NULL;
+
+ if (ctx->sock != -1) {
+#ifdef WIN32
+ DestroySockets();
+#endif
+ (void)close(ctx->sock);
+ ctx->sock = -1;
+ }
+
+ CTXFREE(ctx, sizeof(lwres_context_t));
+}
+/*% Increments the serial number and returns the previous value. */
+uint32_t
+lwres_context_nextserial(lwres_context_t *ctx) {
+ REQUIRE(ctx != NULL);
+
+ return (ctx->serial++);
+}
+
+/*% Sets the serial number for context *ctx to serial. */
+void
+lwres_context_initserial(lwres_context_t *ctx, uint32_t serial) {
+ REQUIRE(ctx != NULL);
+
+ ctx->serial = serial;
+}
+
+/*% Frees len bytes of space starting at location mem. */
+void
+lwres_context_freemem(lwres_context_t *ctx, void *mem, size_t len) {
+ REQUIRE(mem != NULL);
+ REQUIRE(len != 0U);
+
+ CTXFREE(mem, len);
+}
+
+/*% Allocates len bytes of memory and if successful returns a pointer to the allocated storage. */
+void *
+lwres_context_allocmem(lwres_context_t *ctx, size_t len) {
+ REQUIRE(len != 0U);
+
+ return (CTXMALLOC(len));
+}
+
+static void *
+lwres_malloc(void *arg, size_t len) {
+ void *mem;
+
+ UNUSED(arg);
+
+ mem = malloc(len);
+ if (mem == NULL)
+ return (NULL);
+
+ memset(mem, 0xe5, len);
+
+ return (mem);
+}
+
+static void
+lwres_free(void *arg, void *mem, size_t len) {
+ UNUSED(arg);
+
+ memset(mem, 0xa9, len);
+ free(mem);
+}
+
+static lwres_result_t
+context_connect(lwres_context_t *ctx) {
+#ifndef WIN32
+ int s;
+#else
+ SOCKET s;
+#endif
+ int ret;
+ struct sockaddr_in sin;
+ struct sockaddr_in6 sin6;
+ struct sockaddr *sa;
+ LWRES_SOCKADDR_LEN_T salen;
+ int domain;
+
+ if (ctx->confdata.lwnext != 0) {
+ memmove(&ctx->address, &ctx->confdata.lwservers[0],
+ sizeof(lwres_addr_t));
+ LWRES_LINK_INIT(&ctx->address, link);
+ } else {
+ /* The default is the IPv4 loopback address 127.0.0.1. */
+ memset(&ctx->address, 0, sizeof(ctx->address));
+ ctx->address.family = LWRES_ADDRTYPE_V4;
+ ctx->address.length = 4;
+ ctx->address.address[0] = 127;
+ ctx->address.address[1] = 0;
+ ctx->address.address[2] = 0;
+ ctx->address.address[3] = 1;
+ }
+
+ if (ctx->address.family == LWRES_ADDRTYPE_V4) {
+ memmove(&sin.sin_addr, ctx->address.address,
+ sizeof(sin.sin_addr));
+ sin.sin_port = htons(lwres_udp_port);
+ sin.sin_family = AF_INET;
+ sa = (struct sockaddr *)&sin;
+ salen = sizeof(sin);
+ domain = PF_INET;
+ } else if (ctx->address.family == LWRES_ADDRTYPE_V6) {
+ memmove(&sin6.sin6_addr, ctx->address.address,
+ sizeof(sin6.sin6_addr));
+ sin6.sin6_port = htons(lwres_udp_port);
+ sin6.sin6_family = AF_INET6;
+ sa = (struct sockaddr *)&sin6;
+ salen = sizeof(sin6);
+ domain = PF_INET6;
+ } else
+ return (LWRES_R_IOERROR);
+
+#ifdef WIN32
+ InitSockets();
+#endif
+ s = socket(domain, SOCK_DGRAM, IPPROTO_UDP);
+#ifndef WIN32
+ if (s < 0) {
+ return (LWRES_R_IOERROR);
+ }
+#else
+ if (s == INVALID_SOCKET) {
+ DestroySockets();
+ return (LWRES_R_IOERROR);
+ }
+#endif
+
+ ret = connect(s, sa, salen);
+ if (ret != 0) {
+#ifdef WIN32
+ DestroySockets();
+#endif
+ (void)close(s);
+ return (LWRES_R_IOERROR);
+ }
+
+ MAKE_NONBLOCKING(s, ret);
+ if (ret < 0) {
+#ifdef WIN32
+ DestroySockets();
+#endif
+ (void)close(s);
+ return (LWRES_R_IOERROR);
+ }
+
+ ctx->sock = (int)s;
+
+ return (LWRES_R_SUCCESS);
+}
+
+int
+lwres_context_getsocket(lwres_context_t *ctx) {
+ return (ctx->sock);
+}
+
+lwres_result_t
+lwres_context_send(lwres_context_t *ctx,
+ void *sendbase, int sendlen) {
+ int ret;
+ lwres_result_t lwresult;
+
+ if (ctx->sock == -1) {
+ lwresult = context_connect(ctx);
+ if (lwresult != LWRES_R_SUCCESS)
+ return (lwresult);
+ INSIST(ctx->sock >= 0);
+ }
+
+ ret = sendto(ctx->sock, sendbase, sendlen, 0, NULL, 0);
+ if (ret < 0)
+ return (LWRES_R_IOERROR);
+ if (ret != sendlen)
+ return (LWRES_R_IOERROR);
+
+ return (LWRES_R_SUCCESS);
+}
+
+lwres_result_t
+lwres_context_recv(lwres_context_t *ctx,
+ void *recvbase, int recvlen,
+ int *recvd_len)
+{
+ LWRES_SOCKADDR_LEN_T fromlen;
+ struct sockaddr_in sin;
+ struct sockaddr_in6 sin6;
+ struct sockaddr *sa;
+ int ret;
+
+ if (ctx->address.family == LWRES_ADDRTYPE_V4) {
+ sa = (struct sockaddr *)&sin;
+ fromlen = sizeof(sin);
+ } else {
+ sa = (struct sockaddr *)&sin6;
+ fromlen = sizeof(sin6);
+ }
+
+ /*
+ * 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.
+ */
+ ret = recvfrom(ctx->sock, recvbase, recvlen, 0, sa, (void *)&fromlen);
+
+ if (ret < 0)
+ return (LWRES_R_IOERROR);
+
+ if (ret == recvlen)
+ return (LWRES_R_TOOLARGE);
+
+ /*
+ * If we got something other than what we expect, have the caller
+ * wait for another packet. This can happen if an old result
+ * comes in, or if someone is sending us random stuff.
+ */
+ if (ctx->address.family == LWRES_ADDRTYPE_V4) {
+ if (fromlen != sizeof(sin)
+ || memcmp(&sin.sin_addr, ctx->address.address,
+ sizeof(sin.sin_addr)) != 0
+ || sin.sin_port != htons(lwres_udp_port))
+ return (LWRES_R_RETRY);
+ } else {
+ if (fromlen != sizeof(sin6)
+ || memcmp(&sin6.sin6_addr, ctx->address.address,
+ sizeof(sin6.sin6_addr)) != 0
+ || sin6.sin6_port != htons(lwres_udp_port))
+ return (LWRES_R_RETRY);
+ }
+
+ if (recvd_len != NULL)
+ *recvd_len = ret;
+
+ return (LWRES_R_SUCCESS);
+}
+
+/*% performs I/O for the context ctx. */
+lwres_result_t
+lwres_context_sendrecv(lwres_context_t *ctx,
+ void *sendbase, int sendlen,
+ void *recvbase, int recvlen,
+ int *recvd_len)
+{
+ lwres_result_t result;
+ int ret2;
+ fd_set readfds;
+ struct timeval timeout;
+
+ /*
+ * Type of tv_sec is 32 bits long.
+ */
+ if (ctx->timeout <= 0x7FFFFFFFU)
+ timeout.tv_sec = (int)ctx->timeout;
+ else
+ timeout.tv_sec = 0x7FFFFFFF;
+
+ timeout.tv_usec = 0;
+
+ result = lwres_context_send(ctx, sendbase, sendlen);
+ if (result != LWRES_R_SUCCESS)
+ return (result);
+
+ /*
+ * If this is not checked, select() can overflow,
+ * causing corruption elsewhere.
+ */
+ if (ctx->sock >= (int)FD_SETSIZE) {
+ close(ctx->sock);
+ ctx->sock = -1;
+ return (LWRES_R_IOERROR);
+ }
+
+ again:
+ FD_ZERO(&readfds);
+ FD_SET(ctx->sock, &readfds);
+ ret2 = select(ctx->sock + 1, &readfds, NULL, NULL, &timeout);
+
+ /*
+ * What happened with select?
+ */
+ if (ret2 < 0)
+ return (LWRES_R_IOERROR);
+ if (ret2 == 0)
+ return (LWRES_R_TIMEOUT);
+
+ result = lwres_context_recv(ctx, recvbase, recvlen, recvd_len);
+ if (result == LWRES_R_RETRY)
+ goto again;
+
+ return (result);
+}
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