1 /* Copyright (C) 1996-2022 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. */
80 extern 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. */
89 libc_freeres_ptr (static char *buffer);
90
91
92 LOOKUP_TYPE *
FUNCTION_NAME(ADD_PARAMS)93 FUNCTION_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
160 done:
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
177 nss_interface_function (FUNCTION_NAME)
178