1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2021, 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 ***************************************************************************/
22
23 #include "curl_setup.h"
24
25 /***********************************************************************
26 * Only for plain IPv4 builds
27 **********************************************************************/
28 #ifdef CURLRES_IPV4 /* plain IPv4 code coming up */
29
30 #ifdef HAVE_NETINET_IN_H
31 #include <netinet/in.h>
32 #endif
33 #ifdef HAVE_NETDB_H
34 #include <netdb.h>
35 #endif
36 #ifdef HAVE_ARPA_INET_H
37 #include <arpa/inet.h>
38 #endif
39 #ifdef __VMS
40 #include <in.h>
41 #include <inet.h>
42 #endif
43
44 #ifdef HAVE_PROCESS_H
45 #include <process.h>
46 #endif
47
48 #include "urldata.h"
49 #include "sendf.h"
50 #include "hostip.h"
51 #include "hash.h"
52 #include "share.h"
53 #include "strerror.h"
54 #include "url.h"
55 /* The last 3 #include files should be in this order */
56 #include "curl_printf.h"
57 #include "curl_memory.h"
58 #include "memdebug.h"
59
60 /*
61 * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
62 * been set and returns TRUE if they are OK.
63 */
Curl_ipvalid(struct Curl_easy * data,struct connectdata * conn)64 bool Curl_ipvalid(struct Curl_easy *data, struct connectdata *conn)
65 {
66 (void)data;
67 if(conn->ip_version == CURL_IPRESOLVE_V6)
68 /* An IPv6 address was requested and we can't get/use one */
69 return FALSE;
70
71 return TRUE; /* OK, proceed */
72 }
73
74 #ifdef CURLRES_SYNCH
75
76 /*
77 * Curl_getaddrinfo() - the IPv4 synchronous version.
78 *
79 * The original code to this function was from the Dancer source code, written
80 * by Bjorn Reese, it has since been patched and modified considerably.
81 *
82 * gethostbyname_r() is the thread-safe version of the gethostbyname()
83 * function. When we build for plain IPv4, we attempt to use this
84 * function. There are _three_ different gethostbyname_r() versions, and we
85 * detect which one this platform supports in the configure script and set up
86 * the HAVE_GETHOSTBYNAME_R_3, HAVE_GETHOSTBYNAME_R_5 or
87 * HAVE_GETHOSTBYNAME_R_6 defines accordingly. Note that HAVE_GETADDRBYNAME
88 * has the corresponding rules. This is primarily on *nix. Note that some unix
89 * flavours have thread-safe versions of the plain gethostbyname() etc.
90 *
91 */
Curl_getaddrinfo(struct Curl_easy * data,const char * hostname,int port,int * waitp)92 struct Curl_addrinfo *Curl_getaddrinfo(struct Curl_easy *data,
93 const char *hostname,
94 int port,
95 int *waitp)
96 {
97 struct Curl_addrinfo *ai = NULL;
98
99 #ifdef CURL_DISABLE_VERBOSE_STRINGS
100 (void)data;
101 #endif
102
103 *waitp = 0; /* synchronous response only */
104
105 ai = Curl_ipv4_resolve_r(hostname, port);
106 if(!ai)
107 infof(data, "Curl_ipv4_resolve_r failed for %s\n", hostname);
108
109 return ai;
110 }
111 #endif /* CURLRES_SYNCH */
112 #endif /* CURLRES_IPV4 */
113
114 #if defined(CURLRES_IPV4) && !defined(CURLRES_ARES)
115
116 /*
117 * Curl_ipv4_resolve_r() - ipv4 threadsafe resolver function.
118 *
119 * This is used for both synchronous and asynchronous resolver builds,
120 * implying that only threadsafe code and function calls may be used.
121 *
122 */
Curl_ipv4_resolve_r(const char * hostname,int port)123 struct Curl_addrinfo *Curl_ipv4_resolve_r(const char *hostname,
124 int port)
125 {
126 #if !defined(HAVE_GETADDRINFO_THREADSAFE) && defined(HAVE_GETHOSTBYNAME_R_3)
127 int res;
128 #endif
129 struct Curl_addrinfo *ai = NULL;
130 struct hostent *h = NULL;
131 struct hostent *buf = NULL;
132
133 #if defined(HAVE_GETADDRINFO_THREADSAFE)
134 struct addrinfo hints;
135 char sbuf[12];
136 char *sbufptr = NULL;
137
138 memset(&hints, 0, sizeof(hints));
139 hints.ai_family = PF_INET;
140 hints.ai_socktype = SOCK_STREAM;
141 if(port) {
142 msnprintf(sbuf, sizeof(sbuf), "%d", port);
143 sbufptr = sbuf;
144 }
145
146 (void)Curl_getaddrinfo_ex(hostname, sbufptr, &hints, &ai);
147
148 #elif defined(HAVE_GETHOSTBYNAME_R)
149 /*
150 * gethostbyname_r() is the preferred resolve function for many platforms.
151 * Since there are three different versions of it, the following code is
152 * somewhat #ifdef-ridden.
153 */
154 int h_errnop;
155
156 buf = calloc(1, CURL_HOSTENT_SIZE);
157 if(!buf)
158 return NULL; /* major failure */
159 /*
160 * The clearing of the buffer is a workaround for a gethostbyname_r bug in
161 * qnx nto and it is also _required_ for some of these functions on some
162 * platforms.
163 */
164
165 #if defined(HAVE_GETHOSTBYNAME_R_5)
166 /* Solaris, IRIX and more */
167 h = gethostbyname_r(hostname,
168 (struct hostent *)buf,
169 (char *)buf + sizeof(struct hostent),
170 CURL_HOSTENT_SIZE - sizeof(struct hostent),
171 &h_errnop);
172
173 /* If the buffer is too small, it returns NULL and sets errno to
174 * ERANGE. The errno is thread safe if this is compiled with
175 * -D_REENTRANT as then the 'errno' variable is a macro defined to get
176 * used properly for threads.
177 */
178
179 if(h) {
180 ;
181 }
182 else
183 #elif defined(HAVE_GETHOSTBYNAME_R_6)
184 /* Linux */
185
186 (void)gethostbyname_r(hostname,
187 (struct hostent *)buf,
188 (char *)buf + sizeof(struct hostent),
189 CURL_HOSTENT_SIZE - sizeof(struct hostent),
190 &h, /* DIFFERENCE */
191 &h_errnop);
192 /* Redhat 8, using glibc 2.2.93 changed the behavior. Now all of a
193 * sudden this function returns EAGAIN if the given buffer size is too
194 * small. Previous versions are known to return ERANGE for the same
195 * problem.
196 *
197 * This wouldn't be such a big problem if older versions wouldn't
198 * sometimes return EAGAIN on a common failure case. Alas, we can't
199 * assume that EAGAIN *or* ERANGE means ERANGE for any given version of
200 * glibc.
201 *
202 * For now, we do that and thus we may call the function repeatedly and
203 * fail for older glibc versions that return EAGAIN, until we run out of
204 * buffer size (step_size grows beyond CURL_HOSTENT_SIZE).
205 *
206 * If anyone has a better fix, please tell us!
207 *
208 * -------------------------------------------------------------------
209 *
210 * On October 23rd 2003, Dan C dug up more details on the mysteries of
211 * gethostbyname_r() in glibc:
212 *
213 * In glibc 2.2.5 the interface is different (this has also been
214 * discovered in glibc 2.1.1-6 as shipped by Redhat 6). What I can't
215 * explain, is that tests performed on glibc 2.2.4-34 and 2.2.4-32
216 * (shipped/upgraded by Redhat 7.2) don't show this behavior!
217 *
218 * In this "buggy" version, the return code is -1 on error and 'errno'
219 * is set to the ERANGE or EAGAIN code. Note that 'errno' is not a
220 * thread-safe variable.
221 */
222
223 if(!h) /* failure */
224 #elif defined(HAVE_GETHOSTBYNAME_R_3)
225 /* AIX, Digital Unix/Tru64, HPUX 10, more? */
226
227 /* For AIX 4.3 or later, we don't use gethostbyname_r() at all, because of
228 * the plain fact that it does not return unique full buffers on each
229 * call, but instead several of the pointers in the hostent structs will
230 * point to the same actual data! This have the unfortunate down-side that
231 * our caching system breaks down horribly. Luckily for us though, AIX 4.3
232 * and more recent versions have a "completely thread-safe"[*] libc where
233 * all the data is stored in thread-specific memory areas making calls to
234 * the plain old gethostbyname() work fine even for multi-threaded
235 * programs.
236 *
237 * This AIX 4.3 or later detection is all made in the configure script.
238 *
239 * Troels Walsted Hansen helped us work this out on March 3rd, 2003.
240 *
241 * [*] = much later we've found out that it isn't at all "completely
242 * thread-safe", but at least the gethostbyname() function is.
243 */
244
245 if(CURL_HOSTENT_SIZE >=
246 (sizeof(struct hostent) + sizeof(struct hostent_data))) {
247
248 /* August 22nd, 2000: Albert Chin-A-Young brought an updated version
249 * that should work! September 20: Richard Prescott worked on the buffer
250 * size dilemma.
251 */
252
253 res = gethostbyname_r(hostname,
254 (struct hostent *)buf,
255 (struct hostent_data *)((char *)buf +
256 sizeof(struct hostent)));
257 h_errnop = SOCKERRNO; /* we don't deal with this, but set it anyway */
258 }
259 else
260 res = -1; /* failure, too smallish buffer size */
261
262 if(!res) { /* success */
263
264 h = buf; /* result expected in h */
265
266 /* This is the worst kind of the different gethostbyname_r() interfaces.
267 * Since we don't know how big buffer this particular lookup required,
268 * we can't realloc down the huge alloc without doing closer analysis of
269 * the returned data. Thus, we always use CURL_HOSTENT_SIZE for every
270 * name lookup. Fixing this would require an extra malloc() and then
271 * calling Curl_addrinfo_copy() that subsequent realloc()s down the new
272 * memory area to the actually used amount.
273 */
274 }
275 else
276 #endif /* HAVE_...BYNAME_R_5 || HAVE_...BYNAME_R_6 || HAVE_...BYNAME_R_3 */
277 {
278 h = NULL; /* set return code to NULL */
279 free(buf);
280 }
281 #else /* HAVE_GETADDRINFO_THREADSAFE || HAVE_GETHOSTBYNAME_R */
282 /*
283 * Here is code for platforms that don't have a thread safe
284 * getaddrinfo() nor gethostbyname_r() function or for which
285 * gethostbyname() is the preferred one.
286 */
287 h = gethostbyname((void *)hostname);
288 #endif /* HAVE_GETADDRINFO_THREADSAFE || HAVE_GETHOSTBYNAME_R */
289
290 if(h) {
291 ai = Curl_he2ai(h, port);
292
293 if(buf) /* used a *_r() function */
294 free(buf);
295 }
296
297 return ai;
298 }
299 #endif /* defined(CURLRES_IPV4) && !defined(CURLRES_ARES) */
300