1/***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2022, Daniel Stenberg, <[email protected]>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24
25#include "curl_setup.h"
26
27/***********************************************************************
28 * Only for plain IPv4 builds
29 **********************************************************************/
30#ifdef CURLRES_IPV4 /* plain IPv4 code coming up */
31
32#ifdef HAVE_NETINET_IN_H
33#include <netinet/in.h>
34#endif
35#ifdef HAVE_NETDB_H
36#include <netdb.h>
37#endif
38#ifdef HAVE_ARPA_INET_H
39#include <arpa/inet.h>
40#endif
41#ifdef __VMS
42#include <in.h>
43#include <inet.h>
44#endif
45
46#ifdef HAVE_PROCESS_H
47#include <process.h>
48#endif
49
50#include "urldata.h"
51#include "sendf.h"
52#include "hostip.h"
53#include "hash.h"
54#include "share.h"
55#include "url.h"
56/* The last 3 #include files should be in this order */
57#include "curl_printf.h"
58#include "curl_memory.h"
59#include "memdebug.h"
60
61/*
62 * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
63 * been set and returns TRUE if they are OK.
64 */
65bool Curl_ipvalid(struct Curl_easy *data, struct connectdata *conn)
66{
67 (void)data;
68 if(conn->ip_version == CURL_IPRESOLVE_V6)
69 /* An IPv6 address was requested and we can't get/use one */
70 return FALSE;
71
72 return TRUE; /* OK, proceed */
73}
74
75#ifdef CURLRES_SYNCH
76
77/*
78 * Curl_getaddrinfo() - the IPv4 synchronous version.
79 *
80 * The original code to this function was from the Dancer source code, written
81 * by Bjorn Reese, it has since been patched and modified considerably.
82 *
83 * gethostbyname_r() is the thread-safe version of the gethostbyname()
84 * function. When we build for plain IPv4, we attempt to use this
85 * function. There are _three_ different gethostbyname_r() versions, and we
86 * detect which one this platform supports in the configure script and set up
87 * the HAVE_GETHOSTBYNAME_R_3, HAVE_GETHOSTBYNAME_R_5 or
88 * HAVE_GETHOSTBYNAME_R_6 defines accordingly. Note that HAVE_GETADDRBYNAME
89 * has the corresponding rules. This is primarily on *nix. Note that some unix
90 * flavours have thread-safe versions of the plain gethostbyname() etc.
91 *
92 */
93struct Curl_addrinfo *Curl_getaddrinfo(struct Curl_easy *data,
94 const char *hostname,
95 int port,
96 int *waitp)
97{
98 struct Curl_addrinfo *ai = NULL;
99
100#ifdef CURL_DISABLE_VERBOSE_STRINGS
101 (void)data;
102#endif
103
104 *waitp = 0; /* synchronous response only */
105
106 ai = Curl_ipv4_resolve_r(hostname, port);
107 if(!ai)
108 infof(data, "Curl_ipv4_resolve_r failed for %s", hostname);
109
110 return ai;
111}
112#endif /* CURLRES_SYNCH */
113#endif /* CURLRES_IPV4 */
114
115#if defined(CURLRES_IPV4) && \
116 !defined(CURLRES_ARES) && !defined(CURLRES_AMIGA)
117
118/*
119 * Curl_ipv4_resolve_r() - ipv4 threadsafe resolver function.
120 *
121 * This is used for both synchronous and asynchronous resolver builds,
122 * implying that only threadsafe code and function calls may be used.
123 *
124 */
125struct Curl_addrinfo *Curl_ipv4_resolve_r(const char *hostname,
126 int port)
127{
128#if !defined(HAVE_GETADDRINFO_THREADSAFE) && defined(HAVE_GETHOSTBYNAME_R_3)
129 int res;
130#endif
131 struct Curl_addrinfo *ai = NULL;
132 struct hostent *h = NULL;
133 struct hostent *buf = NULL;
134
135#if defined(HAVE_GETADDRINFO_THREADSAFE)
136 struct addrinfo hints;
137 char sbuf[12];
138 char *sbufptr = NULL;
139
140 memset(&hints, 0, sizeof(hints));
141 hints.ai_family = PF_INET;
142 hints.ai_socktype = SOCK_STREAM;
143 if(port) {
144 msnprintf(sbuf, sizeof(sbuf), "%d", port);
145 sbufptr = sbuf;
146 }
147
148 (void)Curl_getaddrinfo_ex(hostname, sbufptr, &hints, &ai);
149
150#elif defined(HAVE_GETHOSTBYNAME_R)
151 /*
152 * gethostbyname_r() is the preferred resolve function for many platforms.
153 * Since there are three different versions of it, the following code is
154 * somewhat #ifdef-ridden.
155 */
156 int h_errnop;
157
158 buf = calloc(1, CURL_HOSTENT_SIZE);
159 if(!buf)
160 return NULL; /* major failure */
161 /*
162 * The clearing of the buffer is a workaround for a gethostbyname_r bug in
163 * qnx nto and it is also _required_ for some of these functions on some
164 * platforms.
165 */
166
167#if defined(HAVE_GETHOSTBYNAME_R_5)
168 /* Solaris, IRIX and more */
169 h = gethostbyname_r(hostname,
170 (struct hostent *)buf,
171 (char *)buf + sizeof(struct hostent),
172 CURL_HOSTENT_SIZE - sizeof(struct hostent),
173 &h_errnop);
174
175 /* If the buffer is too small, it returns NULL and sets errno to
176 * ERANGE. The errno is thread safe if this is compiled with
177 * -D_REENTRANT as then the 'errno' variable is a macro defined to get
178 * used properly for threads.
179 */
180
181 if(h) {
182 ;
183 }
184 else
185#elif defined(HAVE_GETHOSTBYNAME_R_6)
186 /* Linux */
187
188 (void)gethostbyname_r(hostname,
189 (struct hostent *)buf,
190 (char *)buf + sizeof(struct hostent),
191 CURL_HOSTENT_SIZE - sizeof(struct hostent),
192 &h, /* DIFFERENCE */
193 &h_errnop);
194 /* Redhat 8, using glibc 2.2.93 changed the behavior. Now all of a
195 * sudden this function returns EAGAIN if the given buffer size is too
196 * small. Previous versions are known to return ERANGE for the same
197 * problem.
198 *
199 * This wouldn't be such a big problem if older versions wouldn't
200 * sometimes return EAGAIN on a common failure case. Alas, we can't
201 * assume that EAGAIN *or* ERANGE means ERANGE for any given version of
202 * glibc.
203 *
204 * For now, we do that and thus we may call the function repeatedly and
205 * fail for older glibc versions that return EAGAIN, until we run out of
206 * buffer size (step_size grows beyond CURL_HOSTENT_SIZE).
207 *
208 * If anyone has a better fix, please tell us!
209 *
210 * -------------------------------------------------------------------
211 *
212 * On October 23rd 2003, Dan C dug up more details on the mysteries of
213 * gethostbyname_r() in glibc:
214 *
215 * In glibc 2.2.5 the interface is different (this has also been
216 * discovered in glibc 2.1.1-6 as shipped by Redhat 6). What I can't
217 * explain, is that tests performed on glibc 2.2.4-34 and 2.2.4-32
218 * (shipped/upgraded by Redhat 7.2) don't show this behavior!
219 *
220 * In this "buggy" version, the return code is -1 on error and 'errno'
221 * is set to the ERANGE or EAGAIN code. Note that 'errno' is not a
222 * thread-safe variable.
223 */
224
225 if(!h) /* failure */
226#elif defined(HAVE_GETHOSTBYNAME_R_3)
227 /* AIX, Digital Unix/Tru64, HPUX 10, more? */
228
229 /* For AIX 4.3 or later, we don't use gethostbyname_r() at all, because of
230 * the plain fact that it does not return unique full buffers on each
231 * call, but instead several of the pointers in the hostent structs will
232 * point to the same actual data! This have the unfortunate down-side that
233 * our caching system breaks down horribly. Luckily for us though, AIX 4.3
234 * and more recent versions have a "completely thread-safe"[*] libc where
235 * all the data is stored in thread-specific memory areas making calls to
236 * the plain old gethostbyname() work fine even for multi-threaded
237 * programs.
238 *
239 * This AIX 4.3 or later detection is all made in the configure script.
240 *
241 * Troels Walsted Hansen helped us work this out on March 3rd, 2003.
242 *
243 * [*] = much later we've found out that it isn't at all "completely
244 * thread-safe", but at least the gethostbyname() function is.
245 */
246
247 if(CURL_HOSTENT_SIZE >=
248 (sizeof(struct hostent) + sizeof(struct hostent_data))) {
249
250 /* August 22nd, 2000: Albert Chin-A-Young brought an updated version
251 * that should work! September 20: Richard Prescott worked on the buffer
252 * size dilemma.
253 */
254
255 res = gethostbyname_r(hostname,
256 (struct hostent *)buf,
257 (struct hostent_data *)((char *)buf +
258 sizeof(struct hostent)));
259 h_errnop = SOCKERRNO; /* we don't deal with this, but set it anyway */
260 }
261 else
262 res = -1; /* failure, too smallish buffer size */
263
264 if(!res) { /* success */
265
266 h = buf; /* result expected in h */
267
268 /* This is the worst kind of the different gethostbyname_r() interfaces.
269 * Since we don't know how big buffer this particular lookup required,
270 * we can't realloc down the huge alloc without doing closer analysis of
271 * the returned data. Thus, we always use CURL_HOSTENT_SIZE for every
272 * name lookup. Fixing this would require an extra malloc() and then
273 * calling Curl_addrinfo_copy() that subsequent realloc()s down the new
274 * memory area to the actually used amount.
275 */
276 }
277 else
278#endif /* HAVE_...BYNAME_R_5 || HAVE_...BYNAME_R_6 || HAVE_...BYNAME_R_3 */
279 {
280 h = NULL; /* set return code to NULL */
281 free(buf);
282 }
283#else /* HAVE_GETADDRINFO_THREADSAFE || HAVE_GETHOSTBYNAME_R */
284 /*
285 * Here is code for platforms that don't have a thread safe
286 * getaddrinfo() nor gethostbyname_r() function or for which
287 * gethostbyname() is the preferred one.
288 */
289 h = gethostbyname((void *)hostname);
290#endif /* HAVE_GETADDRINFO_THREADSAFE || HAVE_GETHOSTBYNAME_R */
291
292 if(h) {
293 ai = Curl_he2ai(h, port);
294
295 if(buf) /* used a *_r() function */
296 free(buf);
297 }
298
299 return ai;
300}
301#endif /* defined(CURLRES_IPV4) && !defined(CURLRES_ARES) &&
302 !defined(CURLRES_AMIGA) */
303