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Diffstat (limited to '')
| -rw-r--r-- | lib/lwres/lwresutil.c | 571 |
1 files changed, 571 insertions, 0 deletions
diff --git a/lib/lwres/lwresutil.c b/lib/lwres/lwresutil.c new file mode 100644 index 0000000..3ddc8d5 --- /dev/null +++ b/lib/lwres/lwresutil.c @@ -0,0 +1,571 @@ +/* + * 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: lwresutil.c,v 1.34 2007/06/19 23:47:22 tbox Exp $ */ + +/*! \file */ + +/** + * lwres_string_parse() retrieves a DNS-encoded string starting the + * current pointer of lightweight resolver buffer b: i.e. b->current. + * When the function returns, the address of the first byte of the + * encoded string is returned via *c and the length of that string is + * given by *len. The buffer's current pointer is advanced to point at + * the character following the string length, the encoded string, and + * the trailing NULL character. + * + * lwres_addr_parse() extracts an address from the buffer b. The + * buffer's current pointer b->current is presumed to point at an + * encoded address: the address preceded by a 32-bit protocol family + * identifier and a 16-bit length field. The encoded address is copied + * to addr->address and addr->length indicates the size in bytes of + * the address that was copied. b->current is advanced to point at the + * next byte of available data in the buffer following the encoded + * address. + * + * lwres_getaddrsbyname() and lwres_getnamebyaddr() use the + * lwres_gnbaresponse_t structure defined below: + * + * \code + * typedef struct { + * uint32_t flags; + * uint16_t naliases; + * uint16_t naddrs; + * char *realname; + * char **aliases; + * uint16_t realnamelen; + * uint16_t *aliaslen; + * lwres_addrlist_t addrs; + * void *base; + * size_t baselen; + * } lwres_gabnresponse_t; + * \endcode + * + * The contents of this structure are not manipulated directly but + * they are controlled through the \link lwres_gabn.c lwres_gabn*\endlink functions. + * + * The lightweight resolver uses lwres_getaddrsbyname() to perform + * foward lookups. Hostname name is looked up using the resolver + * context ctx for memory allocation. addrtypes is a bitmask + * indicating which type of addresses are to be looked up. Current + * values for this bitmask are #LWRES_ADDRTYPE_V4 for IPv4 addresses + * and #LWRES_ADDRTYPE_V6 for IPv6 addresses. Results of the lookup are + * returned in *structp. + * + * lwres_getnamebyaddr() performs reverse lookups. Resolver context + * ctx is used for memory allocation. The address type is indicated by + * addrtype: #LWRES_ADDRTYPE_V4 or #LWRES_ADDRTYPE_V6. The address to be + * looked up is given by addr and its length is addrlen bytes. The + * result of the function call is made available through *structp. + * + * \section lwresutil_return Return Values + * + * Successful calls to lwres_string_parse() and lwres_addr_parse() + * return #LWRES_R_SUCCESS. Both functions return #LWRES_R_FAILURE if + * the buffer is corrupt or #LWRES_R_UNEXPECTEDEND if the buffer has + * less space than expected for the components of the encoded string + * or address. + * + * lwres_getaddrsbyname() returns #LWRES_R_SUCCESS on success and it + * returns #LWRES_R_NOTFOUND if the hostname name could not be found. + * + * #LWRES_R_SUCCESS is returned by a successful call to + * lwres_getnamebyaddr(). + * + * Both lwres_getaddrsbyname() and lwres_getnamebyaddr() return + * #LWRES_R_NOMEMORY when memory allocation requests fail and + * #LWRES_R_UNEXPECTEDEND if the buffers used for sending queries and + * receiving replies are too small. + * + * \section lwresutil_see See Also + * + * lwbuffer.c, lwres_gabn.c + */ + +#include <config.h> + +#include <assert.h> +#include <inttypes.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include <lwres/lwbuffer.h> +#include <lwres/lwres.h> +#include <lwres/result.h> + +#include "assert_p.h" +#include "context_p.h" + +/*% Parse data. */ +/*! + * Requires: + * + * The "current" pointer in "b" points to encoded raw data. + * + * Ensures: + * + * The address of the first byte of the data is returned via "p", + * and the length is returned via "len". If NULL, they are not + * set. + * + * On return, the current pointer of "b" will point to the character + * following the data length and the data. + * + */ +lwres_result_t +lwres_data_parse(lwres_buffer_t *b, unsigned char **p, uint16_t *len) +{ + uint16_t datalen; + unsigned char *data; + + REQUIRE(b != NULL); + + /* + * Pull off the length (2 bytes) + */ + if (!SPACE_REMAINING(b, 2)) + return (LWRES_R_UNEXPECTEDEND); + datalen = lwres_buffer_getuint16(b); + + /* + * Set the pointer to this string to the right place, then + * advance the buffer pointer. + */ + if (!SPACE_REMAINING(b, datalen)) + return (LWRES_R_UNEXPECTEDEND); + data = b->base + b->current; + lwres_buffer_forward(b, datalen); + + if (len != NULL) + *len = datalen; + if (p != NULL) + *p = data; + + return (LWRES_R_SUCCESS); +} + +/*% Retrieves a DNS-encoded string. */ +/*! + * Requires: + * + * The "current" pointer in "b" point to an encoded string. + * + * Ensures: + * + * The address of the first byte of the string is returned via "c", + * and the length is returned via "len". If NULL, they are not + * set. + * + * On return, the current pointer of "b" will point to the character + * following the string length, the string, and the trailing NULL. + * + */ +lwres_result_t +lwres_string_parse(lwres_buffer_t *b, char **c, uint16_t *len) +{ + uint16_t datalen; + char *string; + + REQUIRE(b != NULL); + + /* + * Pull off the length (2 bytes) + */ + if (!SPACE_REMAINING(b, 2)) + return (LWRES_R_UNEXPECTEDEND); + datalen = lwres_buffer_getuint16(b); + + /* + * Set the pointer to this string to the right place, then + * advance the buffer pointer. + */ + if (!SPACE_REMAINING(b, datalen)) + return (LWRES_R_UNEXPECTEDEND); + string = (char *)b->base + b->current; + lwres_buffer_forward(b, datalen); + + /* + * Skip the "must be zero" byte. + */ + if (!SPACE_REMAINING(b, 1)) + return (LWRES_R_UNEXPECTEDEND); + if (0 != lwres_buffer_getuint8(b)) + return (LWRES_R_FAILURE); + + if (len != NULL) + *len = datalen; + if (c != NULL) + *c = string; + + return (LWRES_R_SUCCESS); +} + +/*% Extracts an address from the buffer b. */ +lwres_result_t +lwres_addr_parse(lwres_buffer_t *b, lwres_addr_t *addr) +{ + REQUIRE(addr != NULL); + + if (!SPACE_REMAINING(b, 6)) + return (LWRES_R_UNEXPECTEDEND); + + addr->family = lwres_buffer_getuint32(b); + addr->length = lwres_buffer_getuint16(b); + + if (!SPACE_REMAINING(b, addr->length)) + return (LWRES_R_UNEXPECTEDEND); + if (addr->length > LWRES_ADDR_MAXLEN) + return (LWRES_R_FAILURE); + + lwres_buffer_getmem(b, addr->address, addr->length); + + return (LWRES_R_SUCCESS); +} + +/*% Used to perform forward lookups. */ +lwres_result_t +lwres_getaddrsbyname(lwres_context_t *ctx, const char *name, + uint32_t addrtypes, lwres_gabnresponse_t **structp) +{ + lwres_gabnrequest_t request; + lwres_gabnresponse_t *response; + int ret; + int recvlen; + lwres_buffer_t b_in, b_out; + lwres_lwpacket_t pkt; + uint32_t serial; + char *buffer; + char target_name[1024]; + unsigned int target_length; + + REQUIRE(ctx != NULL); + REQUIRE(name != NULL); + REQUIRE(addrtypes != 0); + REQUIRE(structp != NULL && *structp == NULL); + + b_in.base = NULL; + b_out.base = NULL; + response = NULL; + buffer = NULL; + serial = lwres_context_nextserial(ctx); + + buffer = CTXMALLOC(LWRES_RECVLENGTH); + if (buffer == NULL) { + ret = LWRES_R_NOMEMORY; + goto out; + } + + target_length = strlen(name); + if (target_length >= sizeof(target_name)) + return (LWRES_R_FAILURE); + strcpy(target_name, name); /* strcpy is safe */ + + /* + * Set up our request and render it to a buffer. + */ + request.flags = 0; + request.addrtypes = addrtypes; + request.name = target_name; + request.namelen = target_length; + pkt.pktflags = 0; + pkt.serial = serial; + pkt.result = 0; + pkt.recvlength = LWRES_RECVLENGTH; + + again: + ret = lwres_gabnrequest_render(ctx, &request, &pkt, &b_out); + if (ret != LWRES_R_SUCCESS) + goto out; + + ret = lwres_context_sendrecv(ctx, b_out.base, b_out.length, buffer, + LWRES_RECVLENGTH, &recvlen); + if (ret != LWRES_R_SUCCESS) + goto out; + + lwres_buffer_init(&b_in, buffer, recvlen); + b_in.used = recvlen; + + /* + * Parse the packet header. + */ + ret = lwres_lwpacket_parseheader(&b_in, &pkt); + if (ret != LWRES_R_SUCCESS) + goto out; + + /* + * Sanity check. + */ + if (pkt.serial != serial) + goto again; + if (pkt.opcode != LWRES_OPCODE_GETADDRSBYNAME) + goto again; + + /* + * Free what we've transmitted + */ + CTXFREE(b_out.base, b_out.length); + b_out.base = NULL; + b_out.length = 0; + + if (pkt.result != LWRES_R_SUCCESS) { + ret = pkt.result; + goto out; + } + + /* + * Parse the response. + */ + ret = lwres_gabnresponse_parse(ctx, &b_in, &pkt, &response); + if (ret != LWRES_R_SUCCESS) + goto out; + response->base = buffer; + response->baselen = LWRES_RECVLENGTH; + buffer = NULL; /* don't free this below */ + + *structp = response; + return (LWRES_R_SUCCESS); + + out: + if (b_out.base != NULL) + CTXFREE(b_out.base, b_out.length); + if (buffer != NULL) + CTXFREE(buffer, LWRES_RECVLENGTH); + if (response != NULL) + lwres_gabnresponse_free(ctx, &response); + + return (ret); +} + + +/*% Used to perform reverse lookups. */ +lwres_result_t +lwres_getnamebyaddr(lwres_context_t *ctx, uint32_t addrtype, + uint16_t addrlen, const unsigned char *addr, + lwres_gnbaresponse_t **structp) +{ + lwres_gnbarequest_t request; + lwres_gnbaresponse_t *response; + int ret; + int recvlen; + lwres_buffer_t b_in, b_out; + lwres_lwpacket_t pkt; + uint32_t serial; + char *buffer; + + REQUIRE(ctx != NULL); + REQUIRE(addrtype != 0); + REQUIRE(addrlen != 0); + REQUIRE(addr != NULL); + REQUIRE(structp != NULL && *structp == NULL); + + b_in.base = NULL; + b_out.base = NULL; + response = NULL; + buffer = NULL; + serial = lwres_context_nextserial(ctx); + + buffer = CTXMALLOC(LWRES_RECVLENGTH); + if (buffer == NULL) { + ret = LWRES_R_NOMEMORY; + goto out; + } + + /* + * Set up our request and render it to a buffer. + */ + request.flags = 0; + request.addr.family = addrtype; + request.addr.length = addrlen; + memmove(request.addr.address, addr, addrlen); + pkt.pktflags = 0; + pkt.serial = serial; + pkt.result = 0; + pkt.recvlength = LWRES_RECVLENGTH; + + again: + ret = lwres_gnbarequest_render(ctx, &request, &pkt, &b_out); + if (ret != LWRES_R_SUCCESS) + goto out; + + ret = lwres_context_sendrecv(ctx, b_out.base, b_out.length, buffer, + LWRES_RECVLENGTH, &recvlen); + if (ret != LWRES_R_SUCCESS) + goto out; + + lwres_buffer_init(&b_in, buffer, recvlen); + b_in.used = recvlen; + + /* + * Parse the packet header. + */ + ret = lwres_lwpacket_parseheader(&b_in, &pkt); + if (ret != LWRES_R_SUCCESS) + goto out; + + /* + * Sanity check. + */ + if (pkt.serial != serial) + goto again; + if (pkt.opcode != LWRES_OPCODE_GETNAMEBYADDR) + goto again; + + /* + * Free what we've transmitted + */ + CTXFREE(b_out.base, b_out.length); + b_out.base = NULL; + b_out.length = 0; + + if (pkt.result != LWRES_R_SUCCESS) { + ret = pkt.result; + goto out; + } + + /* + * Parse the response. + */ + ret = lwres_gnbaresponse_parse(ctx, &b_in, &pkt, &response); + if (ret != LWRES_R_SUCCESS) + goto out; + response->base = buffer; + response->baselen = LWRES_RECVLENGTH; + buffer = NULL; /* don't free this below */ + + *structp = response; + return (LWRES_R_SUCCESS); + + out: + if (b_out.base != NULL) + CTXFREE(b_out.base, b_out.length); + if (buffer != NULL) + CTXFREE(buffer, LWRES_RECVLENGTH); + if (response != NULL) + lwres_gnbaresponse_free(ctx, &response); + + return (ret); +} + +/*% Get rdata by name. */ +lwres_result_t +lwres_getrdatabyname(lwres_context_t *ctx, const char *name, + uint16_t rdclass, uint16_t rdtype, + uint32_t flags, lwres_grbnresponse_t **structp) +{ + int ret; + int recvlen; + lwres_buffer_t b_in, b_out; + lwres_lwpacket_t pkt; + uint32_t serial; + char *buffer; + lwres_grbnrequest_t request; + lwres_grbnresponse_t *response; + char target_name[1024]; + unsigned int target_length; + + REQUIRE(ctx != NULL); + REQUIRE(name != NULL); + REQUIRE(structp != NULL && *structp == NULL); + + b_in.base = NULL; + b_out.base = NULL; + response = NULL; + buffer = NULL; + serial = lwres_context_nextserial(ctx); + + buffer = CTXMALLOC(LWRES_RECVLENGTH); + if (buffer == NULL) { + ret = LWRES_R_NOMEMORY; + goto out; + } + + target_length = strlen(name); + if (target_length >= sizeof(target_name)) + return (LWRES_R_FAILURE); + strcpy(target_name, name); /* strcpy is safe */ + + /* + * Set up our request and render it to a buffer. + */ + request.rdclass = rdclass; + request.rdtype = rdtype; + request.flags = flags; + request.name = target_name; + request.namelen = target_length; + pkt.pktflags = 0; + pkt.serial = serial; + pkt.result = 0; + pkt.recvlength = LWRES_RECVLENGTH; + + again: + ret = lwres_grbnrequest_render(ctx, &request, &pkt, &b_out); + if (ret != LWRES_R_SUCCESS) + goto out; + + ret = lwres_context_sendrecv(ctx, b_out.base, b_out.length, buffer, + LWRES_RECVLENGTH, &recvlen); + if (ret != LWRES_R_SUCCESS) + goto out; + + lwres_buffer_init(&b_in, buffer, recvlen); + b_in.used = recvlen; + + /* + * Parse the packet header. + */ + ret = lwres_lwpacket_parseheader(&b_in, &pkt); + if (ret != LWRES_R_SUCCESS) + goto out; + + /* + * Sanity check. + */ + if (pkt.serial != serial) + goto again; + if (pkt.opcode != LWRES_OPCODE_GETRDATABYNAME) + goto again; + + /* + * Free what we've transmitted + */ + CTXFREE(b_out.base, b_out.length); + b_out.base = NULL; + b_out.length = 0; + + if (pkt.result != LWRES_R_SUCCESS) { + ret = pkt.result; + goto out; + } + + /* + * Parse the response. + */ + ret = lwres_grbnresponse_parse(ctx, &b_in, &pkt, &response); + if (ret != LWRES_R_SUCCESS) + goto out; + response->base = buffer; + response->baselen = LWRES_RECVLENGTH; + buffer = NULL; /* don't free this below */ + + *structp = response; + return (LWRES_R_SUCCESS); + + out: + if (b_out.base != NULL) + CTXFREE(b_out.base, b_out.length); + if (buffer != NULL) + CTXFREE(buffer, LWRES_RECVLENGTH); + if (response != NULL) + lwres_grbnresponse_free(ctx, &response); + + return (ret); +} |