585 lines
12 KiB
C
585 lines
12 KiB
C
/* $NetBSD: hesiod.c,v 1.9 1999/02/11 06:16:38 simonb Exp $ */
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/* Copyright (c) 1996 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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/* Copyright 1996 by the Massachusetts Institute of Technology.
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*
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* Permission to use, copy, modify, and distribute this
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* software and its documentation for any purpose and without
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* fee is hereby granted, provided that the above copyright
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* notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting
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* documentation, and that the name of M.I.T. not be used in
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* advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission.
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* M.I.T. makes no representations about the suitability of
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* this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*/
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/* This file is part of the hesiod library. It implements the core
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* portion of the hesiod resolver.
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*
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* This file is loosely based on an interim version of hesiod.c from
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* the BIND IRS library, which was in turn based on an earlier version
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* of this file. Extensive changes have been made on each step of the
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* path.
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*
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* This implementation is not truly thread-safe at the moment because
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* it uses res_send() and accesses _res.
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*/
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#include <sys/cdefs.h>
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#if 0
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static char *orig_rcsid = "$NetBSD: hesiod.c,v 1.9 1999/02/11 06:16:38 simonb Exp $";
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#endif
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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 <ctype.h>
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#include <errno.h>
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#include <hesiod.h>
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#include <resolv.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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struct hesiod_p {
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char *lhs; /* normally ".ns" */
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char *rhs; /* AKA the default hesiod domain */
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int classes[2]; /* The class search order. */
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};
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#define MAX_HESRESP 1024
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static int read_config_file(struct hesiod_p *, const char *);
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static char **get_txt_records(int, const char *);
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static int init_context(void);
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static void translate_errors(void);
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/*
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* hesiod_init --
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* initialize a hesiod_p.
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*/
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int
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hesiod_init(context)
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void **context;
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{
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struct hesiod_p *ctx;
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const char *p, *configname;
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ctx = malloc(sizeof(struct hesiod_p));
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if (ctx) {
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*context = ctx;
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if (!issetugid())
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configname = getenv("HESIOD_CONFIG");
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else
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configname = NULL;
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if (!configname)
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configname = _PATH_HESIOD_CONF;
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if (read_config_file(ctx, configname) >= 0) {
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/*
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* The default rhs can be overridden by an
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* environment variable.
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*/
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if (!issetugid())
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p = getenv("HES_DOMAIN");
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else
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p = NULL;
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if (p) {
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if (ctx->rhs)
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free(ctx->rhs);
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ctx->rhs = malloc(strlen(p) + 2);
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if (ctx->rhs) {
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*ctx->rhs = '.';
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strcpy(ctx->rhs + 1,
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(*p == '.') ? p + 1 : p);
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return 0;
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} else
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errno = ENOMEM;
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} else
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return 0;
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}
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} else
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errno = ENOMEM;
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if (ctx->lhs)
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free(ctx->lhs);
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if (ctx->rhs)
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free(ctx->rhs);
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if (ctx)
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free(ctx);
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return -1;
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}
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/*
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* hesiod_end --
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* Deallocates the hesiod_p.
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*/
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void
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hesiod_end(context)
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void *context;
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{
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struct hesiod_p *ctx = (struct hesiod_p *) context;
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free(ctx->rhs);
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if (ctx->lhs)
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free(ctx->lhs);
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free(ctx);
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}
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/*
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* hesiod_to_bind --
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* takes a hesiod (name, type) and returns a DNS
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* name which is to be resolved.
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*/
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char *
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hesiod_to_bind(void *context, const char *name, const char *type)
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{
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struct hesiod_p *ctx = (struct hesiod_p *) context;
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char bindname[MAXDNAME], *p, *ret, **rhs_list = NULL;
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const char *rhs;
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int len;
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if (strlcpy(bindname, name, sizeof(bindname)) >= sizeof(bindname)) {
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errno = EMSGSIZE;
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return NULL;
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}
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/*
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* Find the right right hand side to use, possibly
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* truncating bindname.
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*/
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p = strchr(bindname, '@');
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if (p) {
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*p++ = 0;
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if (strchr(p, '.'))
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rhs = name + (p - bindname);
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else {
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rhs_list = hesiod_resolve(context, p, "rhs-extension");
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if (rhs_list)
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rhs = *rhs_list;
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else {
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errno = ENOENT;
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return NULL;
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}
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}
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} else
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rhs = ctx->rhs;
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/* See if we have enough room. */
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len = strlen(bindname) + 1 + strlen(type);
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if (ctx->lhs)
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len += strlen(ctx->lhs) + ((ctx->lhs[0] != '.') ? 1 : 0);
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len += strlen(rhs) + ((rhs[0] != '.') ? 1 : 0);
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if (len > sizeof(bindname) - 1) {
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if (rhs_list)
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hesiod_free_list(context, rhs_list);
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errno = EMSGSIZE;
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return NULL;
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}
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/* Put together the rest of the domain. */
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strcat(bindname, ".");
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strcat(bindname, type);
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/* Only append lhs if it isn't empty. */
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if (ctx->lhs && ctx->lhs[0] != '\0' ) {
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if (ctx->lhs[0] != '.')
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strcat(bindname, ".");
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strcat(bindname, ctx->lhs);
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}
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if (rhs[0] != '.')
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strcat(bindname, ".");
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strcat(bindname, rhs);
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/* rhs_list is no longer needed, since we're done with rhs. */
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if (rhs_list)
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hesiod_free_list(context, rhs_list);
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/* Make a copy of the result and return it to the caller. */
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ret = strdup(bindname);
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if (!ret)
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errno = ENOMEM;
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return ret;
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}
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/*
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* hesiod_resolve --
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* Given a hesiod name and type, return an array of strings returned
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* by the resolver.
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*/
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char **
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hesiod_resolve(context, name, type)
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void *context;
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const char *name;
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const char *type;
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{
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struct hesiod_p *ctx = (struct hesiod_p *) context;
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char *bindname, **retvec;
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bindname = hesiod_to_bind(context, name, type);
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if (!bindname)
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return NULL;
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retvec = get_txt_records(ctx->classes[0], bindname);
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if (retvec == NULL && errno == ENOENT && ctx->classes[1])
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retvec = get_txt_records(ctx->classes[1], bindname);
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free(bindname);
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return retvec;
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}
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/*ARGSUSED*/
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void
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hesiod_free_list(context, list)
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void *context;
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char **list;
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{
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char **p;
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if (list == NULL)
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return;
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for (p = list; *p; p++)
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free(*p);
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free(list);
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}
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/* read_config_file --
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* Parse the /etc/hesiod.conf file. Returns 0 on success,
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* -1 on failure. On failure, it might leave values in ctx->lhs
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* or ctx->rhs which need to be freed by the caller.
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*/
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static int
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read_config_file(ctx, filename)
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struct hesiod_p *ctx;
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const char *filename;
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{
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char *key, *data, *p, **which;
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char buf[MAXDNAME + 7];
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int n;
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FILE *fp;
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/* Set default query classes. */
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ctx->classes[0] = C_IN;
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ctx->classes[1] = C_HS;
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/* Try to open the configuration file. */
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fp = fopen(filename, "re");
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if (!fp) {
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/* Use compiled in default domain names. */
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ctx->lhs = strdup(DEF_LHS);
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ctx->rhs = strdup(DEF_RHS);
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if (ctx->lhs && ctx->rhs)
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return 0;
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else {
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errno = ENOMEM;
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return -1;
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}
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}
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ctx->lhs = NULL;
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ctx->rhs = NULL;
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while (fgets(buf, sizeof(buf), fp) != NULL) {
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p = buf;
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if (*p == '#' || *p == '\n' || *p == '\r')
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continue;
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while (*p == ' ' || *p == '\t')
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p++;
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key = p;
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while (*p != ' ' && *p != '\t' && *p != '=')
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p++;
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*p++ = 0;
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while (isspace(*p) || *p == '=')
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p++;
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data = p;
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while (!isspace(*p))
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p++;
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*p = 0;
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if (strcasecmp(key, "lhs") == 0 ||
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strcasecmp(key, "rhs") == 0) {
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which = (strcasecmp(key, "lhs") == 0)
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? &ctx->lhs : &ctx->rhs;
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*which = strdup(data);
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if (!*which) {
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fclose(fp);
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errno = ENOMEM;
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return -1;
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}
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} else {
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if (strcasecmp(key, "classes") == 0) {
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n = 0;
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while (*data && n < 2) {
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p = data;
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while (*p && *p != ',')
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p++;
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if (*p)
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*p++ = 0;
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if (strcasecmp(data, "IN") == 0)
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ctx->classes[n++] = C_IN;
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else
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if (strcasecmp(data, "HS") == 0)
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ctx->classes[n++] =
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C_HS;
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data = p;
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}
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while (n < 2)
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ctx->classes[n++] = 0;
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}
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}
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}
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fclose(fp);
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if (!ctx->rhs || ctx->classes[0] == 0 ||
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ctx->classes[0] == ctx->classes[1]) {
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errno = ENOEXEC;
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return -1;
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}
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return 0;
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}
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/*
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* get_txt_records --
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* Given a DNS class and a DNS name, do a lookup for TXT records, and
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* return a list of them.
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*/
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static char **
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get_txt_records(qclass, name)
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int qclass;
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const char *name;
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{
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HEADER *hp;
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unsigned char qbuf[PACKETSZ], abuf[MAX_HESRESP], *p, *eom, *eor;
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char *dst, **list;
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int ancount, qdcount, i, j, n, skip, type, class, len;
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/* Make sure the resolver is initialized. */
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if ((_res.options & RES_INIT) == 0 && res_init() == -1)
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return NULL;
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/* Construct the query. */
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n = res_mkquery(QUERY, name, qclass, T_TXT, NULL, 0,
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NULL, qbuf, PACKETSZ);
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if (n < 0)
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return NULL;
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/* Send the query. */
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n = res_send(qbuf, n, abuf, MAX_HESRESP);
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if (n < 0 || n > MAX_HESRESP) {
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errno = ECONNREFUSED; /* XXX */
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return NULL;
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}
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/* Parse the header of the result. */
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hp = (HEADER *) (void *) abuf;
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ancount = ntohs(hp->ancount);
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qdcount = ntohs(hp->qdcount);
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p = abuf + sizeof(HEADER);
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eom = abuf + n;
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/*
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* Skip questions, trying to get to the answer section
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* which follows.
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*/
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for (i = 0; i < qdcount; i++) {
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skip = dn_skipname(p, eom);
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if (skip < 0 || p + skip + QFIXEDSZ > eom) {
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errno = EMSGSIZE;
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return NULL;
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}
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p += skip + QFIXEDSZ;
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}
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/* Allocate space for the text record answers. */
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list = malloc((ancount + 1) * sizeof(char *));
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if (!list) {
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errno = ENOMEM;
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return NULL;
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}
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/* Parse the answers. */
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j = 0;
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for (i = 0; i < ancount; i++) {
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/* Parse the header of this answer. */
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skip = dn_skipname(p, eom);
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if (skip < 0 || p + skip + 10 > eom)
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break;
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type = p[skip + 0] << 8 | p[skip + 1];
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class = p[skip + 2] << 8 | p[skip + 3];
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len = p[skip + 8] << 8 | p[skip + 9];
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p += skip + 10;
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if (p + len > eom) {
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errno = EMSGSIZE;
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break;
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}
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/* Skip entries of the wrong class and type. */
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if (class != qclass || type != T_TXT) {
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p += len;
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continue;
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}
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/* Allocate space for this answer. */
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list[j] = malloc((size_t)len);
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if (!list[j]) {
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errno = ENOMEM;
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break;
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}
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dst = list[j++];
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/* Copy answer data into the allocated area. */
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eor = p + len;
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while (p < eor) {
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n = (unsigned char) *p++;
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if (p + n > eor) {
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errno = EMSGSIZE;
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break;
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}
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memcpy(dst, p, (size_t)n);
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p += n;
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dst += n;
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}
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if (p < eor) {
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errno = EMSGSIZE;
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break;
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}
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*dst = 0;
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}
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/*
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* If we didn't terminate the loop normally, something
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* went wrong.
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*/
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if (i < ancount) {
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for (i = 0; i < j; i++)
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free(list[i]);
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free(list);
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return NULL;
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}
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if (j == 0) {
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errno = ENOENT;
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free(list);
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return NULL;
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}
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list[j] = NULL;
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return list;
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}
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/*
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* COMPATIBILITY FUNCTIONS
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*/
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static int inited = 0;
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static void *context;
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static int errval = HES_ER_UNINIT;
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int
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hes_init()
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{
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init_context();
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return errval;
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}
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char *
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hes_to_bind(name, type)
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const char *name;
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const char *type;
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{
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static char *bindname;
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if (init_context() < 0)
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return NULL;
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if (bindname)
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free(bindname);
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bindname = hesiod_to_bind(context, name, type);
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if (!bindname)
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translate_errors();
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return bindname;
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}
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char **
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hes_resolve(name, type)
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const char *name;
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const char *type;
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{
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static char **list;
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if (init_context() < 0)
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return NULL;
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/*
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* In the old Hesiod interface, the caller was responsible for
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* freeing the returned strings but not the vector of strings itself.
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*/
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if (list)
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free(list);
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list = hesiod_resolve(context, name, type);
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if (!list)
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translate_errors();
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return list;
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}
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int
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hes_error()
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{
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return errval;
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}
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void
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hes_free(hp)
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char **hp;
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{
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hesiod_free_list(context, hp);
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}
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static int
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init_context()
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{
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if (!inited) {
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inited = 1;
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if (hesiod_init(&context) < 0) {
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errval = HES_ER_CONFIG;
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return -1;
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}
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errval = HES_ER_OK;
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}
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return 0;
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}
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static void
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translate_errors()
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{
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switch (errno) {
|
|
case ENOENT:
|
|
errval = HES_ER_NOTFOUND;
|
|
break;
|
|
case ECONNREFUSED:
|
|
case EMSGSIZE:
|
|
errval = HES_ER_NET;
|
|
break;
|
|
case ENOMEM:
|
|
default:
|
|
/* Not a good match, but the best we can do. */
|
|
errval = HES_ER_CONFIG;
|
|
break;
|
|
}
|
|
}
|