1/* Copyright (C) 1996-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <assert.h>
19#include <errno.h>
20#include <libc-lock.h>
21#include <stdlib.h>
22#include <resolv.h>
23
24#include "nsswitch.h"
25
26/*******************************************************************\
27|* Here we assume several symbols to be defined: *|
28|* *|
29|* LOOKUP_TYPE - the return type of the function *|
30|* *|
31|* FUNCTION_NAME - name of the non-reentrant function *|
32|* *|
33|* DATABASE_NAME - name of the database the function accesses *|
34|* (e.g., host, services, ...) *|
35|* *|
36|* ADD_PARAMS - additional parameter, can vary in number *|
37|* *|
38|* ADD_VARIABLES - names of additional parameter *|
39|* *|
40|* BUFLEN - length of buffer allocated for the non *|
41|* reentrant version *|
42|* *|
43|* Optionally the following vars can be defined: *|
44|* *|
45|* NEED_H_ERRNO - an extra parameter will be passed to point to *|
46|* the global `h_errno' variable. *|
47|* *|
48\*******************************************************************/
49
50
51#ifdef HANDLE_DIGITS_DOTS
52# include <resolv/resolv_context.h>
53#endif
54
55/* To make the real sources a bit prettier. */
56#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
57#define APPEND_R(name) APPEND_R1 (name)
58#define APPEND_R1(name) name##_r
59#define INTERNAL(name) INTERNAL1 (name)
60#define INTERNAL1(name) __##name
61
62/* Sometimes we need to store error codes in the `h_errno' variable. */
63#ifdef NEED_H_ERRNO
64# define H_ERRNO_PARM , int *h_errnop
65# define H_ERRNO_VAR , &h_errno_tmp
66# define H_ERRNO_VAR_P &h_errno_tmp
67#else
68# define H_ERRNO_PARM
69# define H_ERRNO_VAR
70# define H_ERRNO_VAR_P NULL
71#endif
72
73#ifdef HAVE_AF
74# define AF_VAL af
75#else
76# define AF_VAL AF_INET
77#endif
78
79/* Prototype for reentrant version we use here. */
80extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
81 char *buffer, size_t buflen,
82 LOOKUP_TYPE **result H_ERRNO_PARM)
83 attribute_hidden;
84
85/* We need to protect the dynamic buffer handling. */
86__libc_lock_define_initialized (static, lock);
87
88/* This points to the static buffer used. */
89libc_freeres_ptr (static char *buffer);
90
91
92LOOKUP_TYPE *
93FUNCTION_NAME (ADD_PARAMS)
94{
95 static size_t buffer_size;
96 static LOOKUP_TYPE resbuf;
97 LOOKUP_TYPE *result;
98#ifdef NEED_H_ERRNO
99 int h_errno_tmp = 0;
100#endif
101
102#ifdef HANDLE_DIGITS_DOTS
103 /* Wrap both __nss_hostname_digits_dots and the actual lookup
104 function call in the same context. */
105 struct resolv_context *res_ctx = __resolv_context_get ();
106 if (res_ctx == NULL)
107 {
108# if NEED_H_ERRNO
109 __set_h_errno (NETDB_INTERNAL);
110# endif
111 return NULL;
112 }
113#endif
114
115 /* Get lock. */
116 __libc_lock_lock (lock);
117
118 if (buffer == NULL)
119 {
120 buffer_size = BUFLEN;
121 buffer = (char *) malloc (buffer_size);
122 }
123
124#ifdef HANDLE_DIGITS_DOTS
125 if (buffer != NULL)
126 {
127 if (__nss_hostname_digits_dots_context
128 (res_ctx, name, &resbuf, &buffer, &buffer_size, 0, &result, NULL,
129 AF_VAL, H_ERRNO_VAR_P))
130 goto done;
131 }
132#endif
133
134 while (buffer != NULL
135 && (INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, &resbuf, buffer,
136 buffer_size, &result H_ERRNO_VAR)
137 == ERANGE)
138#ifdef NEED_H_ERRNO
139 && h_errno_tmp == NETDB_INTERNAL
140#endif
141 )
142 {
143 char *new_buf;
144 buffer_size *= 2;
145 new_buf = (char *) realloc (buffer, buffer_size);
146 if (new_buf == NULL)
147 {
148 /* We are out of memory. Free the current buffer so that the
149 process gets a chance for a normal termination. */
150 free (buffer);
151 __set_errno (ENOMEM);
152 }
153 buffer = new_buf;
154 }
155
156 if (buffer == NULL)
157 result = NULL;
158
159#ifdef HANDLE_DIGITS_DOTS
160done:
161#endif
162 /* Release lock. */
163 __libc_lock_unlock (lock);
164
165#ifdef HANDLE_DIGITS_DOTS
166 __resolv_context_put (res_ctx);
167#endif
168
169#ifdef NEED_H_ERRNO
170 if (h_errno_tmp != 0)
171 __set_h_errno (h_errno_tmp);
172#endif
173
174 return result;
175}
176
177nss_interface_function (FUNCTION_NAME)
178