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