301 lines
11 KiB
C
301 lines
11 KiB
C
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/* Creation of DNS query packets.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/*
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* Copyright (c) 1985, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Portions Copyright (c) 1993 by Digital Equipment Corporation.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies, and that
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* the name of Digital Equipment Corporation not be used in advertising or
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* publicity pertaining to distribution of the document or software without
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* specific, written prior permission.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
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* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
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* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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/*
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* Portions Copyright (c) 1996-1999 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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#include <stdint.h>
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#include <sys/types.h>
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#include <sys/param.h>
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#include <netdb.h>
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#include <resolv/resolv-internal.h>
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#include <resolv/resolv_context.h>
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#include <string.h>
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#include <sys/time.h>
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#include <shlib-compat.h>
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#include <random-bits.h>
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int
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__res_context_mkquery (struct resolv_context *ctx, int op, const char *dname,
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int class, int type, const unsigned char *data,
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unsigned char *buf, int buflen)
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{
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HEADER *hp;
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unsigned char *cp;
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int n;
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unsigned char *dnptrs[20], **dpp, **lastdnptr;
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if (class < 0 || class > 65535 || type < 0 || type > 65535)
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return -1;
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/* Initialize header fields. */
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if ((buf == NULL) || (buflen < HFIXEDSZ))
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return -1;
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memset (buf, 0, HFIXEDSZ);
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hp = (HEADER *) buf;
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/* We randomize the IDs every time. The old code just incremented
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by one after the initial randomization which still predictable if
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the application does multiple requests. */
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hp->id = random_bits ();
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hp->opcode = op;
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if (ctx->resp->options & RES_TRUSTAD)
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hp->ad = 1;
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hp->rd = (ctx->resp->options & RES_RECURSE) != 0;
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hp->rcode = NOERROR;
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cp = buf + HFIXEDSZ;
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buflen -= HFIXEDSZ;
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dpp = dnptrs;
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*dpp++ = buf;
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*dpp++ = NULL;
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lastdnptr = dnptrs + sizeof dnptrs / sizeof dnptrs[0];
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/* Perform opcode specific processing. */
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switch (op)
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{
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case NS_NOTIFY_OP:
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if ((buflen -= QFIXEDSZ + (data == NULL ? 0 : RRFIXEDSZ)) < 0)
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return -1;
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goto compose;
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case QUERY:
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if ((buflen -= QFIXEDSZ) < 0)
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return -1;
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compose:
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n = __ns_name_compress (dname, cp, buflen,
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(const unsigned char **) dnptrs,
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(const unsigned char **) lastdnptr);
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if (n < 0)
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return -1;
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cp += n;
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buflen -= n;
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NS_PUT16 (type, cp);
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NS_PUT16 (class, cp);
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hp->qdcount = htons (1);
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if (op == QUERY || data == NULL)
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break;
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/* Make an additional record for completion domain. */
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n = __ns_name_compress ((char *)data, cp, buflen,
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(const unsigned char **) dnptrs,
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(const unsigned char **) lastdnptr);
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if (__glibc_unlikely (n < 0))
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return -1;
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cp += n;
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buflen -= n;
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NS_PUT16 (T_NULL, cp);
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NS_PUT16 (class, cp);
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NS_PUT32 (0, cp);
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NS_PUT16 (0, cp);
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hp->arcount = htons (1);
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break;
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default:
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return -1;
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}
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return cp - buf;
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}
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libc_hidden_def (__res_context_mkquery)
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/* Common part of res_nmkquery and res_mkquery. */
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static int
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context_mkquery_common (struct resolv_context *ctx,
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int op, const char *dname, int class, int type,
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const unsigned char *data,
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unsigned char *buf, int buflen)
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{
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if (ctx == NULL)
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return -1;
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int result = __res_context_mkquery
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(ctx, op, dname, class, type, data, buf, buflen);
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if (result >= 2)
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memcpy (&ctx->resp->id, buf, 2);
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__resolv_context_put (ctx);
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return result;
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}
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/* Form all types of queries. Returns the size of the result or -1 on
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error.
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STATP points to an initialized resolver state. OP is the opcode of
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the query. DNAME is the domain. CLASS and TYPE are the DNS query
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class and type. DATA can be NULL; otherwise, it is a pointer to a
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domain name which is included in the generated packet (if op ==
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NS_NOTIFY_OP). BUF must point to the out buffer of BUFLEN bytes.
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DATALEN and NEWRR_IN are currently ignored. */
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int
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___res_nmkquery (res_state statp, int op, const char *dname,
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int class, int type,
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const unsigned char *data, int datalen,
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const unsigned char *newrr_in,
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unsigned char *buf, int buflen)
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{
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return context_mkquery_common
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(__resolv_context_get_override (statp),
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op, dname, class, type, data, buf, buflen);
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}
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versioned_symbol (libc, ___res_nmkquery, res_nmkquery, GLIBC_2_34);
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
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compat_symbol (libresolv, ___res_nmkquery, __res_nmkquery, GLIBC_2_2);
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#endif
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int
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___res_mkquery (int op, const char *dname, int class, int type,
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const unsigned char *data, int datalen,
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const unsigned char *newrr_in,
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unsigned char *buf, int buflen)
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{
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return context_mkquery_common
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(__resolv_context_get_preinit (),
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op, dname, class, type, data, buf, buflen);
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}
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versioned_symbol (libc, ___res_mkquery, res_mkquery, GLIBC_2_34);
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2)
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compat_symbol (libresolv, ___res_mkquery, res_mkquery, GLIBC_2_0);
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#endif
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
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compat_symbol (libresolv, ___res_mkquery, __res_mkquery, GLIBC_2_2);
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#endif
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/* Create an OPT resource record. Return the length of the final
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packet, or -1 on error.
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STATP must be an initialized resolver state. N0 is the current
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number of bytes of the packet (already written to BUF by the
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aller). BUF is the packet being constructed. The array it
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pointers to must be BUFLEN bytes long. ANSLEN is the advertised
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EDNS buffer size (to be included in the OPT resource record). */
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int
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__res_nopt (struct resolv_context *ctx,
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int n0, unsigned char *buf, int buflen, int anslen)
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{
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uint16_t flags = 0;
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HEADER *hp = (HEADER *) buf;
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unsigned char *cp = buf + n0;
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unsigned char *ep = buf + buflen;
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if ((ep - cp) < 1 + RRFIXEDSZ)
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return -1;
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/* Add the root label. */
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*cp++ = 0;
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NS_PUT16 (T_OPT, cp); /* Record type. */
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/* Lowering the advertised buffer size based on the actual
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answer buffer size is desirable because the server will
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minimize the reply to fit into the UDP packet (and A
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non-minimal response might not fit the buffer).
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The RESOLV_EDNS_BUFFER_SIZE limit could still result in TCP
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fallback and a non-minimal response which has to be
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hard-truncated in the stub resolver, but this is price to
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pay for avoiding fragmentation. (This issue does not
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affect the nss_dns functions because they use the stub
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resolver in such a way that it allocates a properly sized
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response buffer.) */
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{
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uint16_t buffer_size;
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if (anslen < 512)
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buffer_size = 512;
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else if (anslen > RESOLV_EDNS_BUFFER_SIZE)
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buffer_size = RESOLV_EDNS_BUFFER_SIZE;
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else
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buffer_size = anslen;
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NS_PUT16 (buffer_size, cp);
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}
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*cp++ = NOERROR; /* Extended RCODE. */
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*cp++ = 0; /* EDNS version. */
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if (ctx->resp->options & RES_USE_DNSSEC)
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flags |= NS_OPT_DNSSEC_OK;
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NS_PUT16 (flags, cp);
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NS_PUT16 (0, cp); /* RDATA length (no options are preent). */
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hp->arcount = htons (ntohs (hp->arcount) + 1);
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return cp - buf;
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}
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libc_hidden_def (__res_nopt)
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