hostip4.c 10 KB

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