496 lines
14 KiB
C
496 lines
14 KiB
C
/* Hosts file parser in nss_files module.
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Copyright (C) 1996-2022 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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#include <assert.h>
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#include <netinet/in.h>
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#include <arpa/inet.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 <scratch_buffer.h>
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#include <alloc_buffer.h>
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#include <nss.h>
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/* Get implementation for some internal functions. */
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#include "../resolv/res_hconf.h"
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#define ENTNAME hostent
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#define DATABASE "hosts"
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#define NEED_H_ERRNO
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#define EXTRA_ARGS , af
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#define EXTRA_ARGS_DECL , int af
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#define ENTDATA hostent_data
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struct hostent_data
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{
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unsigned char host_addr[16]; /* IPv4 or IPv6 address. */
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char *h_addr_ptrs[2]; /* Points to that and null terminator. */
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};
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#define TRAILING_LIST_MEMBER h_aliases
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#define TRAILING_LIST_SEPARATOR_P isspace
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#include "files-parse.c"
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LINE_PARSER
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("#",
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{
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char *addr;
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STRING_FIELD (addr, isspace, 1);
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/* Parse address. */
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if (__inet_pton (af == AF_UNSPEC ? AF_INET : af, addr, entdata->host_addr)
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> 0)
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af = af == AF_UNSPEC ? AF_INET : af;
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else
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{
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if (af == AF_INET
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&& __inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
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{
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if (IN6_IS_ADDR_V4MAPPED (entdata->host_addr))
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memcpy (entdata->host_addr, entdata->host_addr + 12, INADDRSZ);
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else if (IN6_IS_ADDR_LOOPBACK (entdata->host_addr))
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{
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in_addr_t localhost = htonl (INADDR_LOOPBACK);
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memcpy (entdata->host_addr, &localhost, sizeof (localhost));
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}
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else
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/* Illegal address: ignore line. */
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return 0;
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}
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else if (af == AF_UNSPEC
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&& __inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
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af = AF_INET6;
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else
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/* Illegal address: ignore line. */
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return 0;
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}
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/* We always return entries of the requested form. */
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result->h_addrtype = af;
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result->h_length = af == AF_INET ? INADDRSZ : IN6ADDRSZ;
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/* Store a pointer to the address in the expected form. */
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entdata->h_addr_ptrs[0] = (char *) entdata->host_addr;
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entdata->h_addr_ptrs[1] = NULL;
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result->h_addr_list = entdata->h_addr_ptrs;
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STRING_FIELD (result->h_name, isspace, 1);
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})
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#define EXTRA_ARGS_VALUE , AF_INET
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#include "files-XXX.c"
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#undef EXTRA_ARGS_VALUE
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/* We only need to consider IPv4 mapped addresses if the input to the
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gethostbyaddr() function is an IPv6 address. */
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#define EXTRA_ARGS_VALUE , af
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DB_LOOKUP (hostbyaddr, ,,,
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{
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if (result->h_length == (int) len
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&& ! memcmp (addr, result->h_addr_list[0], len))
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break;
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}, const void *addr, socklen_t len, int af)
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#undef EXTRA_ARGS_VALUE
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/* Type of the address and alias arrays. */
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#define DYNARRAY_STRUCT array
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#define DYNARRAY_ELEMENT char *
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#define DYNARRAY_PREFIX array_
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#include <malloc/dynarray-skeleton.c>
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static enum nss_status
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gethostbyname3_multi (FILE * stream, const char *name, int af,
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struct hostent *result, char *buffer, size_t buflen,
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int *errnop, int *herrnop)
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{
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assert (af == AF_INET || af == AF_INET6);
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/* We have to get all host entries from the file. */
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struct scratch_buffer tmp_buffer;
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scratch_buffer_init (&tmp_buffer);
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struct hostent tmp_result_buf;
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struct array addresses;
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array_init (&addresses);
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struct array aliases;
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array_init (&aliases);
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enum nss_status status;
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/* Preserve the addresses and aliases encountered so far. */
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for (size_t i = 0; result->h_addr_list[i] != NULL; ++i)
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array_add (&addresses, result->h_addr_list[i]);
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for (size_t i = 0; result->h_aliases[i] != NULL; ++i)
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array_add (&aliases, result->h_aliases[i]);
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/* The output buffer re-uses now-unused space at the end of the
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buffer, starting with the aliases array. It comes last in the
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data produced by internal_getent. (The alias names themselves
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are still located in the line read in internal_getent, which is
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stored at the beginning of the buffer.) */
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struct alloc_buffer outbuf;
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{
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char *bufferend = (char *) result->h_aliases;
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outbuf = alloc_buffer_create (bufferend, buffer + buflen - bufferend);
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}
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while (true)
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{
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status = internal_getent (stream, &tmp_result_buf, tmp_buffer.data,
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tmp_buffer.length, errnop, herrnop, af);
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/* Enlarge the buffer if necessary. */
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if (status == NSS_STATUS_TRYAGAIN && *herrnop == NETDB_INTERNAL
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&& *errnop == ERANGE)
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{
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if (!scratch_buffer_grow (&tmp_buffer))
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{
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*errnop = ENOMEM;
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/* *herrnop and status already have the right value. */
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break;
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}
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/* Loop around and retry with a larger buffer. */
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}
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else if (status == NSS_STATUS_SUCCESS)
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{
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/* A line was read. Check that it matches the search
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criteria. */
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int matches = 1;
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struct hostent *old_result = result;
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result = &tmp_result_buf;
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/* The following piece is a bit clumsy but we want to use
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the `LOOKUP_NAME_CASE' value. The optimizer should do
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its job. */
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do
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{
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LOOKUP_NAME_CASE (h_name, h_aliases)
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result = old_result;
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}
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while ((matches = 0));
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/* If the line matches, we need to copy the addresses and
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aliases, so that we can reuse tmp_buffer for the next
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line. */
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if (matches)
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{
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/* Record the addresses. */
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for (size_t i = 0; tmp_result_buf.h_addr_list[i] != NULL; ++i)
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{
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/* Allocate the target space in the output buffer,
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depending on the address family. */
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void *target;
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if (af == AF_INET)
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{
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assert (tmp_result_buf.h_length == 4);
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target = alloc_buffer_alloc (&outbuf, struct in_addr);
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}
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else if (af == AF_INET6)
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{
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assert (tmp_result_buf.h_length == 16);
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target = alloc_buffer_alloc (&outbuf, struct in6_addr);
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}
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else
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__builtin_unreachable ();
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if (target == NULL)
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{
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/* Request a larger output buffer. */
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*errnop = ERANGE;
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*herrnop = NETDB_INTERNAL;
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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memcpy (target, tmp_result_buf.h_addr_list[i],
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tmp_result_buf.h_length);
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array_add (&addresses, target);
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}
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/* Record the aliases. */
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for (size_t i = 0; tmp_result_buf.h_aliases[i] != NULL; ++i)
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{
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char *alias = tmp_result_buf.h_aliases[i];
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array_add (&aliases,
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alloc_buffer_copy_string (&outbuf, alias));
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}
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/* If the real name is different add, it also to the
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aliases. This means that there is a duplication in
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the alias list but this is really the user's
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problem. */
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{
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char *new_name = tmp_result_buf.h_name;
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if (strcmp (old_result->h_name, new_name) != 0)
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array_add (&aliases,
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alloc_buffer_copy_string (&outbuf, new_name));
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}
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/* Report memory allocation failures during the
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expansion of the temporary arrays. */
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if (array_has_failed (&addresses) || array_has_failed (&aliases))
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{
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*errnop = ENOMEM;
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*herrnop = NETDB_INTERNAL;
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status = NSS_STATUS_UNAVAIL;
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break;
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}
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/* Request a larger output buffer if we ran out of room. */
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if (alloc_buffer_has_failed (&outbuf))
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{
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*errnop = ERANGE;
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*herrnop = NETDB_INTERNAL;
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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result = old_result;
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} /* If match was found. */
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/* If no match is found, loop around and fetch another
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line. */
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} /* status == NSS_STATUS_SUCCESS. */
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else
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/* internal_getent returned an error. */
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break;
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} /* while (true) */
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/* Propagate the NSS_STATUS_TRYAGAIN error to the caller. It means
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that we may not have loaded the complete result.
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NSS_STATUS_NOTFOUND, however, means that we reached the end of
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the file successfully. */
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if (status != NSS_STATUS_TRYAGAIN)
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status = NSS_STATUS_SUCCESS;
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if (status == NSS_STATUS_SUCCESS)
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{
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/* Copy the address and alias arrays into the output buffer and
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add NULL terminators. The pointed-to elements were directly
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written into the output buffer above and do not need to be
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copied again. */
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size_t addresses_count = array_size (&addresses);
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size_t aliases_count = array_size (&aliases);
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char **out_addresses = alloc_buffer_alloc_array
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(&outbuf, char *, addresses_count + 1);
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char **out_aliases = alloc_buffer_alloc_array
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(&outbuf, char *, aliases_count + 1);
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if (out_addresses == NULL || out_aliases == NULL)
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{
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/* The output buffer is not large enough. */
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*errnop = ERANGE;
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*herrnop = NETDB_INTERNAL;
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status = NSS_STATUS_TRYAGAIN;
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/* Fall through to function exit. */
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}
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else
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{
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/* Everything is allocated in place. Make the copies and
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adjust the array pointers. */
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memcpy (out_addresses, array_begin (&addresses),
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addresses_count * sizeof (char *));
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out_addresses[addresses_count] = NULL;
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memcpy (out_aliases, array_begin (&aliases),
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aliases_count * sizeof (char *));
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out_aliases[aliases_count] = NULL;
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result->h_addr_list = out_addresses;
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result->h_aliases = out_aliases;
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status = NSS_STATUS_SUCCESS;
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}
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}
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scratch_buffer_free (&tmp_buffer);
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array_free (&addresses);
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array_free (&aliases);
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return status;
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}
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enum nss_status
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_nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
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char *buffer, size_t buflen, int *errnop,
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int *herrnop, int32_t *ttlp, char **canonp)
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{
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FILE *stream = NULL;
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uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct hostent_data);
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buffer += pad;
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buflen = buflen > pad ? buflen - pad : 0;
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/* Open file. */
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enum nss_status status = internal_setent (&stream);
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if (status == NSS_STATUS_SUCCESS)
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{
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while ((status = internal_getent (stream, result, buffer, buflen, errnop,
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herrnop, af))
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== NSS_STATUS_SUCCESS)
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{
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LOOKUP_NAME_CASE (h_name, h_aliases)
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}
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if (status == NSS_STATUS_SUCCESS
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&& _res_hconf.flags & HCONF_FLAG_MULTI)
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status = gethostbyname3_multi
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(stream, name, af, result, buffer, buflen, errnop, herrnop);
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fclose (stream);
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}
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if (canonp && status == NSS_STATUS_SUCCESS)
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*canonp = result->h_name;
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return status;
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}
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libc_hidden_def (_nss_files_gethostbyname3_r)
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enum nss_status
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_nss_files_gethostbyname_r (const char *name, struct hostent *result,
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char *buffer, size_t buflen, int *errnop,
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int *herrnop)
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{
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return _nss_files_gethostbyname3_r (name, AF_INET, result, buffer, buflen,
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errnop, herrnop, NULL, NULL);
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}
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libc_hidden_def (_nss_files_gethostbyname_r)
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enum nss_status
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_nss_files_gethostbyname2_r (const char *name, int af, struct hostent *result,
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char *buffer, size_t buflen, int *errnop,
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int *herrnop)
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{
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return _nss_files_gethostbyname3_r (name, af, result, buffer, buflen,
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errnop, herrnop, NULL, NULL);
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}
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libc_hidden_def (_nss_files_gethostbyname2_r)
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enum nss_status
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_nss_files_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
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char *buffer, size_t buflen, int *errnop,
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int *herrnop, int32_t *ttlp)
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{
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FILE *stream = NULL;
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/* Open file. */
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enum nss_status status = internal_setent (&stream);
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if (status == NSS_STATUS_SUCCESS)
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{
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bool any = false;
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bool got_canon = false;
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while (1)
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{
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/* Align the buffer for the next record. */
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uintptr_t pad = (-(uintptr_t) buffer
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% __alignof__ (struct hostent_data));
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buffer += pad;
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buflen = buflen > pad ? buflen - pad : 0;
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struct hostent result;
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status = internal_getent (stream, &result, buffer, buflen, errnop,
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herrnop, AF_UNSPEC);
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if (status != NSS_STATUS_SUCCESS)
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break;
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int naliases = 0;
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if (__strcasecmp (name, result.h_name) != 0)
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{
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for (; result.h_aliases[naliases] != NULL; ++naliases)
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if (! __strcasecmp (name, result.h_aliases[naliases]))
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break;
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if (result.h_aliases[naliases] == NULL)
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continue;
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/* We know this alias exist. Count it. */
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++naliases;
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}
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/* Determine how much memory has been used so far. */
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// XXX It is not necessary to preserve the aliases array
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while (result.h_aliases[naliases] != NULL)
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++naliases;
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char *bufferend = (char *) &result.h_aliases[naliases + 1];
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assert (buflen >= bufferend - buffer);
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buflen -= bufferend - buffer;
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buffer = bufferend;
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/* We found something. */
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any = true;
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/* Create the record the caller expects. There is only one
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address. */
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assert (result.h_addr_list[1] == NULL);
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if (*pat == NULL)
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{
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uintptr_t pad = (-(uintptr_t) buffer
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% __alignof__ (struct gaih_addrtuple));
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buffer += pad;
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buflen = buflen > pad ? buflen - pad : 0;
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if (__builtin_expect (buflen < sizeof (struct gaih_addrtuple),
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0))
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{
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*errnop = ERANGE;
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*herrnop = NETDB_INTERNAL;
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status = NSS_STATUS_TRYAGAIN;
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break;
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}
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*pat = (struct gaih_addrtuple *) buffer;
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buffer += sizeof (struct gaih_addrtuple);
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buflen -= sizeof (struct gaih_addrtuple);
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}
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(*pat)->next = NULL;
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(*pat)->name = got_canon ? NULL : result.h_name;
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got_canon = true;
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(*pat)->family = result.h_addrtype;
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memcpy ((*pat)->addr, result.h_addr_list[0], result.h_length);
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(*pat)->scopeid = 0;
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pat = &((*pat)->next);
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/* If we only look for the first matching entry we are done. */
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if ((_res_hconf.flags & HCONF_FLAG_MULTI) == 0)
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break;
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}
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/* If we have to look for multiple records and found one, this
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is a success. */
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if (status == NSS_STATUS_NOTFOUND && any)
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{
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assert ((_res_hconf.flags & HCONF_FLAG_MULTI) != 0);
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status = NSS_STATUS_SUCCESS;
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}
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fclose (stream);
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}
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else if (status == NSS_STATUS_TRYAGAIN)
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{
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*errnop = errno;
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*herrnop = TRY_AGAIN;
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}
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else
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{
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*errnop = errno;
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*herrnop = NO_DATA;
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}
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return status;
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}
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libc_hidden_def (_nss_files_gethostbyname4_r)
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