1 /* Copyright (C) 1996-2023 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 #include <set-freeres.h>
24
25 #include "nsswitch.h"
26
27 /*******************************************************************\
28 |* Here we assume several symbols to be defined: *|
29 |* *|
30 |* LOOKUP_TYPE - the return type of the function *|
31 |* *|
32 |* FUNCTION_NAME - name of the non-reentrant function *|
33 |* *|
34 |* DATABASE_NAME - name of the database the function accesses *|
35 |* (e.g., host, services, ...) *|
36 |* *|
37 |* ADD_PARAMS - additional parameter, can vary in number *|
38 |* *|
39 |* ADD_VARIABLES - names of additional parameter *|
40 |* *|
41 |* BUFLEN - length of buffer allocated for the non *|
42 |* reentrant version *|
43 |* *|
44 |* Optionally the following vars can be defined: *|
45 |* *|
46 |* NEED_H_ERRNO - an extra parameter will be passed to point to *|
47 |* the global `h_errno' variable. *|
48 |* *|
49 \*******************************************************************/
50
51
52 #ifdef HANDLE_DIGITS_DOTS
53 # include <resolv/resolv_context.h>
54 #endif
55
56 /* To make the real sources a bit prettier. */
57 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
58 #define APPEND_R(name) APPEND_R1 (name)
59 #define APPEND_R1(name) name##_r
60 #define INTERNAL(name) INTERNAL1 (name)
61 #define INTERNAL1(name) __##name
62 #define APPEND_FREEMEM_NAME1(name) __libc_##name##_freemem_ptr
63 #define APPEND_FREEMEM_NAME(name) APPEND_FREEMEM_NAME1(name)
64 #define FREEMEM_NAME APPEND_FREEMEM_NAME (FUNCTION_NAME)
65
66 /* Sometimes we need to store error codes in the `h_errno' variable. */
67 #ifdef NEED_H_ERRNO
68 # define H_ERRNO_PARM , int *h_errnop
69 # define H_ERRNO_VAR , &h_errno_tmp
70 # define H_ERRNO_VAR_P &h_errno_tmp
71 #else
72 # define H_ERRNO_PARM
73 # define H_ERRNO_VAR
74 # define H_ERRNO_VAR_P NULL
75 #endif
76
77 #ifdef HAVE_AF
78 # define AF_VAL af
79 #else
80 # define AF_VAL AF_INET
81 #endif
82
83 /* Prototype for reentrant version we use here. */
84 extern int INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf,
85 char *buffer, size_t buflen,
86 LOOKUP_TYPE **result H_ERRNO_PARM)
87 attribute_hidden;
88
89 /* We need to protect the dynamic buffer handling. */
90 __libc_lock_define_initialized (static, lock);
91
92 /* This points to the static buffer used. */
93 static char *buffer;
94
95 weak_alias (buffer, FREEMEM_NAME)
96
97 LOOKUP_TYPE *
98 FUNCTION_NAME (ADD_PARAMS)
99 {
100 static size_t buffer_size;
101 static LOOKUP_TYPE resbuf;
102 LOOKUP_TYPE *result;
103 #ifdef NEED_H_ERRNO
104 int h_errno_tmp = 0;
105 #endif
106
107 #ifdef HANDLE_DIGITS_DOTS
108 /* Wrap both __nss_hostname_digits_dots and the actual lookup
109 function call in the same context. */
110 struct resolv_context *res_ctx = __resolv_context_get ();
111 if (res_ctx == NULL)
112 {
113 # if NEED_H_ERRNO
114 __set_h_errno (NETDB_INTERNAL);
115 # endif
116 return NULL;
117 }
118 #endif
119
120 /* Get lock. */
121 __libc_lock_lock (lock);
122
123 if (buffer == NULL)
124 {
125 buffer_size = BUFLEN;
126 buffer = (char *) malloc (buffer_size);
127 }
128
129 #ifdef HANDLE_DIGITS_DOTS
130 if (buffer != NULL)
131 {
132 if (__nss_hostname_digits_dots_context
133 (res_ctx, name, &resbuf, &buffer, &buffer_size, 0, &result, NULL,
134 AF_VAL, H_ERRNO_VAR_P))
135 goto done;
136 }
137 #endif
138
139 while (buffer != NULL
140 && (INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, &resbuf, buffer,
141 buffer_size, &result H_ERRNO_VAR)
142 == ERANGE)
143 #ifdef NEED_H_ERRNO
144 && h_errno_tmp == NETDB_INTERNAL
145 #endif
146 )
147 {
148 char *new_buf;
149 buffer_size *= 2;
150 new_buf = (char *) realloc (buffer, buffer_size);
151 if (new_buf == NULL)
152 {
153 /* We are out of memory. Free the current buffer so that the
154 process gets a chance for a normal termination. */
155 free (buffer);
156 __set_errno (ENOMEM);
157 }
158 buffer = new_buf;
159 }
160
161 if (buffer == NULL)
162 result = NULL;
163
164 #ifdef HANDLE_DIGITS_DOTS
165 done:
166 #endif
167 /* Release lock. */
168 __libc_lock_unlock (lock);
169
170 #ifdef HANDLE_DIGITS_DOTS
171 __resolv_context_put (res_ctx);
172 #endif
173
174 #ifdef NEED_H_ERRNO
175 if (h_errno_tmp != 0)
176 __set_h_errno (h_errno_tmp);
177 #endif
178
179 return result;
180 }
181
182 nss_interface_function (FUNCTION_NAME)