1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, 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 #include "urldata.h"
47 #include "sendf.h"
48 #include "hostip.h"
49 #include "hash.h"
50 #include "share.h"
51 #include "url.h"
52 /* The last 3 #include files should be in this order */
53 #include "curl_printf.h"
54 #include "curl_memory.h"
55 #include "memdebug.h"
56
57 /*
58 * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
59 * been set and returns TRUE if they are OK.
60 */
Curl_ipvalid(struct Curl_easy * data,struct connectdata * conn)61 bool Curl_ipvalid(struct Curl_easy *data, struct connectdata *conn)
62 {
63 (void)data;
64 if(conn->ip_version == CURL_IPRESOLVE_V6)
65 /* An IPv6 address was requested and we cannot get/use one */
66 return FALSE;
67
68 return TRUE; /* OK, proceed */
69 }
70
71 #ifdef CURLRES_SYNCH
72
73 /*
74 * Curl_getaddrinfo() - the IPv4 synchronous version.
75 *
76 * The original code to this function was from the Dancer source code, written
77 * by Bjorn Reese, it has since been patched and modified considerably.
78 *
79 * gethostbyname_r() is the thread-safe version of the gethostbyname()
80 * function. When we build for plain IPv4, we attempt to use this
81 * function. There are _three_ different gethostbyname_r() versions, and we
82 * detect which one this platform supports in the configure script and set up
83 * the HAVE_GETHOSTBYNAME_R_3, HAVE_GETHOSTBYNAME_R_5 or
84 * HAVE_GETHOSTBYNAME_R_6 defines accordingly. Note that HAVE_GETADDRBYNAME
85 * has the corresponding rules. This is primarily on *nix. Note that some Unix
86 * flavours have thread-safe versions of the plain gethostbyname() etc.
87 *
88 */
Curl_getaddrinfo(struct Curl_easy * data,const char * hostname,int port,int * waitp)89 struct Curl_addrinfo *Curl_getaddrinfo(struct Curl_easy *data,
90 const char *hostname,
91 int port,
92 int *waitp)
93 {
94 struct Curl_addrinfo *ai = NULL;
95
96 #ifdef CURL_DISABLE_VERBOSE_STRINGS
97 (void)data;
98 #endif
99
100 *waitp = 0; /* synchronous response only */
101
102 ai = Curl_ipv4_resolve_r(hostname, port);
103 if(!ai)
104 infof(data, "Curl_ipv4_resolve_r failed for %s", hostname);
105
106 return ai;
107 }
108 #endif /* CURLRES_SYNCH */
109 #endif /* CURLRES_IPV4 */
110
111 #if defined(CURLRES_IPV4) && \
112 !defined(CURLRES_ARES) && !defined(CURLRES_AMIGA)
113
114 /*
115 * Curl_ipv4_resolve_r() - ipv4 threadsafe resolver function.
116 *
117 * This is used for both synchronous and asynchronous resolver builds,
118 * implying that only threadsafe code and function calls may be used.
119 *
120 */
Curl_ipv4_resolve_r(const char * hostname,int port)121 struct Curl_addrinfo *Curl_ipv4_resolve_r(const char *hostname,
122 int port)
123 {
124 #if !(defined(HAVE_GETADDRINFO) && defined(HAVE_GETADDRINFO_THREADSAFE)) && \
125 defined(HAVE_GETHOSTBYNAME_R_3)
126 int res;
127 #endif
128 struct Curl_addrinfo *ai = NULL;
129 #if !(defined(HAVE_GETADDRINFO) && defined(HAVE_GETADDRINFO_THREADSAFE))
130 struct hostent *h = NULL;
131 struct hostent *buf = NULL;
132 #endif
133
134 #if defined(HAVE_GETADDRINFO) && defined(HAVE_GETADDRINFO_THREADSAFE)
135 struct addrinfo hints;
136 char sbuf[12];
137 char *sbufptr = NULL;
138
139 memset(&hints, 0, sizeof(hints));
140 hints.ai_family = PF_INET;
141 hints.ai_socktype = SOCK_STREAM;
142 if(port) {
143 msnprintf(sbuf, sizeof(sbuf), "%d", port);
144 sbufptr = sbuf;
145 }
146
147 (void)Curl_getaddrinfo_ex(hostname, sbufptr, &hints, &ai);
148
149 #elif defined(HAVE_GETHOSTBYNAME_R)
150 /*
151 * gethostbyname_r() is the preferred resolve function for many platforms.
152 * Since there are three different versions of it, the following code is
153 * somewhat #ifdef-ridden.
154 */
155 int h_errnop;
156
157 buf = calloc(1, CURL_HOSTENT_SIZE);
158 if(!buf)
159 return NULL; /* major failure */
160 /*
161 * The clearing of the buffer is a workaround for a gethostbyname_r bug in
162 * qnx nto and it is also _required_ for some of these functions on some
163 * platforms.
164 */
165
166 #if defined(HAVE_GETHOSTBYNAME_R_5)
167 /* Solaris, IRIX and more */
168 h = gethostbyname_r(hostname,
169 (struct hostent *)buf,
170 (char *)buf + sizeof(struct hostent),
171 CURL_HOSTENT_SIZE - sizeof(struct hostent),
172 &h_errnop);
173
174 /* If the buffer is too small, it returns NULL and sets errno to
175 * ERANGE. The errno is thread safe if this is compiled with
176 * -D_REENTRANT as then the 'errno' variable is a macro defined to get
177 * used properly for threads.
178 */
179
180 if(h) {
181 ;
182 }
183 else
184 #elif defined(HAVE_GETHOSTBYNAME_R_6)
185 /* Linux */
186
187 (void)gethostbyname_r(hostname,
188 (struct hostent *)buf,
189 (char *)buf + sizeof(struct hostent),
190 CURL_HOSTENT_SIZE - sizeof(struct hostent),
191 &h, /* DIFFERENCE */
192 &h_errnop);
193 /* Redhat 8, using glibc 2.2.93 changed the behavior. Now all of a
194 * sudden this function returns EAGAIN if the given buffer size is too
195 * small. Previous versions are known to return ERANGE for the same
196 * problem.
197 *
198 * This would not be such a big problem if older versions would not
199 * sometimes return EAGAIN on a common failure case. Alas, we cannot
200 * assume that EAGAIN *or* ERANGE means ERANGE for any given version of
201 * glibc.
202 *
203 * For now, we do that and thus we may call the function repeatedly and
204 * fail for older glibc versions that return EAGAIN, until we run out of
205 * buffer size (step_size grows beyond CURL_HOSTENT_SIZE).
206 *
207 * If anyone has a better fix, please tell us!
208 *
209 * -------------------------------------------------------------------
210 *
211 * On October 23rd 2003, Dan C dug up more details on the mysteries of
212 * gethostbyname_r() in glibc:
213 *
214 * In glibc 2.2.5 the interface is different (this has also been
215 * discovered in glibc 2.1.1-6 as shipped by Redhat 6). What I cannot
216 * explain, is that tests performed on glibc 2.2.4-34 and 2.2.4-32
217 * (shipped/upgraded by Redhat 7.2) do not show this behavior!
218 *
219 * In this "buggy" version, the return code is -1 on error and 'errno'
220 * is set to the ERANGE or EAGAIN code. Note that 'errno' is not a
221 * thread-safe variable.
222 */
223
224 if(!h) /* failure */
225 #elif defined(HAVE_GETHOSTBYNAME_R_3)
226 /* AIX, Digital UNIX/Tru64, HP-UX 10, more? */
227
228 /* For AIX 4.3 or later, we do not use gethostbyname_r() at all, because of
229 * the plain fact that it does not return unique full buffers on each
230 * call, but instead several of the pointers in the hostent structs will
231 * point to the same actual data! This have the unfortunate down-side that
232 * our caching system breaks down horribly. Luckily for us though, AIX 4.3
233 * and more recent versions have a "completely thread-safe"[*] libc where
234 * all the data is stored in thread-specific memory areas making calls to
235 * the plain old gethostbyname() work fine even for multi-threaded
236 * programs.
237 *
238 * This AIX 4.3 or later detection is all made in the configure script.
239 *
240 * Troels Walsted Hansen helped us work this out on March 3rd, 2003.
241 *
242 * [*] = much later we have found out that it is not at all "completely
243 * thread-safe", but at least the gethostbyname() function is.
244 */
245
246 if(CURL_HOSTENT_SIZE >=
247 (sizeof(struct hostent) + sizeof(struct hostent_data))) {
248
249 /* August 22nd, 2000: Albert Chin-A-Young brought an updated version
250 * that should work! September 20: Richard Prescott worked on the buffer
251 * size dilemma.
252 */
253
254 res = gethostbyname_r(hostname,
255 (struct hostent *)buf,
256 (struct hostent_data *)((char *)buf +
257 sizeof(struct hostent)));
258 h_errnop = SOCKERRNO; /* we do not deal with this, but set it anyway */
259 }
260 else
261 res = -1; /* failure, too smallish buffer size */
262
263 if(!res) { /* success */
264
265 h = buf; /* result expected in h */
266
267 /* This is the worst kind of the different gethostbyname_r() interfaces.
268 * Since we do not know how big buffer this particular lookup required,
269 * we cannot realloc down the huge alloc without doing closer analysis of
270 * the returned data. Thus, we always use CURL_HOSTENT_SIZE for every
271 * name lookup. Fixing this would require an extra malloc() and then
272 * calling Curl_addrinfo_copy() that subsequent realloc()s down the new
273 * memory area to the actually used amount.
274 */
275 }
276 else
277 #endif /* HAVE_...BYNAME_R_5 || HAVE_...BYNAME_R_6 || HAVE_...BYNAME_R_3 */
278 {
279 h = NULL; /* set return code to NULL */
280 free(buf);
281 }
282 #else /* (HAVE_GETADDRINFO && HAVE_GETADDRINFO_THREADSAFE) ||
283 HAVE_GETHOSTBYNAME_R */
284 /*
285 * Here is code for platforms that do not 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 && HAVE_GETADDRINFO_THREADSAFE) ||
291 HAVE_GETHOSTBYNAME_R */
292
293 #if !(defined(HAVE_GETADDRINFO) && defined(HAVE_GETADDRINFO_THREADSAFE))
294 if(h) {
295 ai = Curl_he2ai(h, port);
296
297 if(buf) /* used a *_r() function */
298 free(buf);
299 }
300 #endif
301
302 return ai;
303 }
304 #endif /* defined(CURLRES_IPV4) && !defined(CURLRES_ARES) &&
305 !defined(CURLRES_AMIGA) */
306
