Utilities/cmcurl/hostip4.c

   1 /***************************************************************************
   2  *                                  _   _ ____  _
   3  *  Project                     ___| | | |  _ \| |
   4  *                             / __| | | | |_) | |
   5  *                            | (__| |_| |  _ <| |___
   6  *                             \___|\___/|_| \_\_____|
   7  *
   8  * Copyright (C) 1998 - 2006, 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 http://curl.haxx.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  * $Id: hostip4.c,v 1.2 2007-03-15 19:22:13 andy Exp $
  22  ***************************************************************************/
  23
  24 #include "setup.h"
  25
  26 #include <string.h>
  27 #include <errno.h>
  28
  29 #ifdef NEED_MALLOC_H
  30 #include <malloc.h>
  31 #endif
  32 #ifdef HAVE_SYS_TYPES_H
  33 #include <sys/types.h>
  34 #endif
  35 #ifdef HAVE_SYS_SOCKET_H
  36 #include <sys/socket.h>
  37 #endif
  38 #ifdef HAVE_NETINET_IN_H
  39 #include <netinet/in.h>
  40 #endif
  41 #ifdef HAVE_NETDB_H
  42 #include <netdb.h>
  43 #endif
  44 #ifdef HAVE_ARPA_INET_H
  45 #include <arpa/inet.h>
  46 #endif
  47 #ifdef HAVE_STDLIB_H
  48 #include <stdlib.h>     /* required for free() prototypes */
  49 #endif
  50 #ifdef HAVE_UNISTD_H
  51 #include <unistd.h>     /* for the close() proto */
  52 #endif
  53 #ifdef  VMS
  54 #include <in.h>
  55 #include <inet.h>
  56 #include <stdlib.h>
  57 #endif
  58
  59 #ifdef HAVE_SETJMP_H
  60 #include <setjmp.h>
  61 #endif
  62
  63 #ifdef HAVE_PROCESS_H
  64 #include <process.h>
  65 #endif
  66
  67 #include "urldata.h"
  68 #include "sendf.h"
  69 #include "hostip.h"
  70 #include "hash.h"
  71 #include "share.h"
  72 #include "strerror.h"
  73 #include "url.h"
  74 #include "inet_pton.h"
  75
  76 #define _MPRINTF_REPLACE /* use our functions only */
  77 #include <curl/mprintf.h>
  78
  79 #if defined(HAVE_INET_NTOA_R) && !defined(HAVE_INET_NTOA_R_DECL)
  80 #include "inet_ntoa_r.h"
  81 #endif
  82
  83 #include "memory.h"
  84 /* The last #include file should be: */
  85 #include "memdebug.h"
  86
  87 /***********************************************************************
  88  * Only for plain-ipv4 builds
  89  **********************************************************************/
  90 #ifdef CURLRES_IPV4 /* plain ipv4 code coming up */
  91 /*
  92  * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
  93  * been set and returns TRUE if they are OK.
  94  */
  95 bool Curl_ipvalid(struct SessionHandle *data)
  96 {
  97   if(data->set.ip_version == CURL_IPRESOLVE_V6)
  98     /* an ipv6 address was requested and we can't get/use one */
  99     return FALSE;
 100
 101   return TRUE; /* OK, proceed */
 102 }
 103
 104 #ifdef CURLRES_SYNCH /* the functions below are for synchronous resolves */
 105
 106 /*
 107  * Curl_getaddrinfo() - the ipv4 synchronous version.
 108  *
 109  * The original code to this function was from the Dancer source code, written
 110  * by Bjorn Reese, it has since been patched and modified considerably.
 111  *
 112  * gethostbyname_r() is the thread-safe version of the gethostbyname()
 113  * function. When we build for plain IPv4, we attempt to use this
 114  * function. There are _three_ different gethostbyname_r() versions, and we
 115  * detect which one this platform supports in the configure script and set up
 116  * the HAVE_GETHOSTBYNAME_R_3, HAVE_GETHOSTBYNAME_R_5 or
 117  * HAVE_GETHOSTBYNAME_R_6 defines accordingly. Note that HAVE_GETADDRBYNAME
 118  * has the corresponding rules. This is primarily on *nix. Note that some unix
 119  * flavours have thread-safe versions of the plain gethostbyname() etc.
 120  *
 121  */
 122 Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
 123                                 const char *hostname,
 124                                 int port,
 125                                 int *waitp)
 126 {
 127   Curl_addrinfo *ai = NULL;
 128   struct hostent *h = NULL;
 129   in_addr_t in;
 130   struct SessionHandle *data = conn->data;
 131   struct hostent *buf = NULL;
 132
 133   (void)port; /* unused in IPv4 code */
 134
 135   *waitp = 0; /* don't wait, we act synchronously */
 136
 137   if(1 == Curl_inet_pton(AF_INET, hostname, &in))
 138     /* This is a dotted IP address 123.123.123.123-style */
 139     return Curl_ip2addr(in, hostname, port);
 140
 141 #if defined(HAVE_GETHOSTBYNAME_R)
 142   /*
 143    * gethostbyname_r() is the preferred resolve function for many platforms.
 144    * Since there are three different versions of it, the following code is
 145    * somewhat #ifdef-ridden.
 146    */
 147   else {
 148     int h_errnop;
 149     int res=ERANGE;
 150
 151     buf = (struct hostent *)calloc(CURL_HOSTENT_SIZE, 1);
 152     if(!buf)
 153       return NULL; /* major failure */
 154     /*
 155      * The clearing of the buffer is a workaround for a gethostbyname_r bug in
 156      * qnx nto and it is also _required_ for some of these functions on some
 157      * platforms.
 158      */
 159
 160 #ifdef HAVE_GETHOSTBYNAME_R_5
 161     /* Solaris, IRIX and more */
 162     (void)res; /* prevent compiler warning */
 163     h = gethostbyname_r(hostname,
 164                         (struct hostent *)buf,
 165                         (char *)buf + sizeof(struct hostent),
 166                         CURL_HOSTENT_SIZE - sizeof(struct hostent),
 167                         &h_errnop);
 168
 169     /* If the buffer is too small, it returns NULL and sets errno to
 170      * ERANGE. The errno is thread safe if this is compiled with
 171      * -D_REENTRANT as then the 'errno' variable is a macro defined to get
 172      * used properly for threads.
 173      */
 174
 175     if(h) {
 176       ;
 177     }
 178     else
 179 #endif /* HAVE_GETHOSTBYNAME_R_5 */
 180 #ifdef HAVE_GETHOSTBYNAME_R_6
 181     /* Linux */
 182
 183     res=gethostbyname_r(hostname,
 184                         (struct hostent *)buf,
 185                         (char *)buf + sizeof(struct hostent),
 186                         CURL_HOSTENT_SIZE - sizeof(struct hostent),
 187                         &h, /* DIFFERENCE */
 188                         &h_errnop);
 189     /* Redhat 8, using glibc 2.2.93 changed the behavior. Now all of a
 190      * sudden this function returns EAGAIN if the given buffer size is too
 191      * small. Previous versions are known to return ERANGE for the same
 192      * problem.
 193      *
 194      * This wouldn't be such a big problem if older versions wouldn't
 195      * sometimes return EAGAIN on a common failure case. Alas, we can't
 196      * assume that EAGAIN *or* ERANGE means ERANGE for any given version of
 197      * glibc.
 198      *
 199      * For now, we do that and thus we may call the function repeatedly and
 200      * fail for older glibc versions that return EAGAIN, until we run out of
 201      * buffer size (step_size grows beyond CURL_HOSTENT_SIZE).
 202      *
 203      * If anyone has a better fix, please tell us!
 204      *
 205      * -------------------------------------------------------------------
 206      *
 207      * On October 23rd 2003, Dan C dug up more details on the mysteries of
 208      * gethostbyname_r() in glibc:
 209      *
 210      * In glibc 2.2.5 the interface is different (this has also been
 211      * discovered in glibc 2.1.1-6 as shipped by Redhat 6). What I can't
 212      * explain, is that tests performed on glibc 2.2.4-34 and 2.2.4-32
 213      * (shipped/upgraded by Redhat 7.2) don't show this behavior!
 214      *
 215      * In this "buggy" version, the return code is -1 on error and 'errno'
 216      * is set to the ERANGE or EAGAIN code. Note that 'errno' is not a
 217      * thread-safe variable.
 218      */
 219
 220     if(!h) /* failure */
 221 #endif/* HAVE_GETHOSTBYNAME_R_6 */
 222 #ifdef HAVE_GETHOSTBYNAME_R_3
 223     /* AIX, Digital Unix/Tru64, HPUX 10, more? */
 224
 225     /* For AIX 4.3 or later, we don't use gethostbyname_r() at all, because of
 226      * the plain fact that it does not return unique full buffers on each
 227      * call, but instead several of the pointers in the hostent structs will
 228      * point to the same actual data! This have the unfortunate down-side that
 229      * our caching system breaks down horribly. Luckily for us though, AIX 4.3
 230      * and more recent versions have a "completely thread-safe"[*] libc where
 231      * all the data is stored in thread-specific memory areas making calls to
 232      * the plain old gethostbyname() work fine even for multi-threaded
 233      * programs.
 234      *
 235      * This AIX 4.3 or later detection is all made in the configure script.
 236      *
 237      * Troels Walsted Hansen helped us work this out on March 3rd, 2003.
 238      *
 239      * [*] = much later we've found out that it isn't at all "completely
 240      * thread-safe", but at least the gethostbyname() function is.
 241      */
 242
 243     if(CURL_HOSTENT_SIZE >=
 244        (sizeof(struct hostent)+sizeof(struct hostent_data))) {
 245
 246       /* August 22nd, 2000: Albert Chin-A-Young brought an updated version
 247        * that should work! September 20: Richard Prescott worked on the buffer
 248        * size dilemma.
 249        */
 250
 251       res = gethostbyname_r(hostname,
 252                             (struct hostent *)buf,
 253                             (struct hostent_data *)((char *)buf +
 254                                                     sizeof(struct hostent)));
 255       h_errnop= errno; /* we don't deal with this, but set it anyway */
 256     }
 257     else
 258       res = -1; /* failure, too smallish buffer size */
 259
 260     if(!res) { /* success */
 261
 262       h = buf; /* result expected in h */
 263
 264       /* This is the worst kind of the different gethostbyname_r() interfaces.
 265        * Since we don't know how big buffer this particular lookup required,
 266        * we can't realloc down the huge alloc without doing closer analysis of
 267        * the returned data. Thus, we always use CURL_HOSTENT_SIZE for every
 268        * name lookup. Fixing this would require an extra malloc() and then
 269        * calling Curl_addrinfo_copy() that subsequent realloc()s down the new
 270        * memory area to the actually used amount.
 271        */
 272     }
 273     else
 274 #endif /* HAVE_GETHOSTBYNAME_R_3 */
 275       {
 276       infof(data, "gethostbyname_r(2) failed for %s\n", hostname);
 277       h = NULL; /* set return code to NULL */
 278       free(buf);
 279     }
 280 #else /* HAVE_GETHOSTBYNAME_R */
 281     /*
 282      * Here is code for platforms that don't have gethostbyname_r() or for
 283      * which the gethostbyname() is the preferred() function.
 284      */
 285   else {
 286     h = gethostbyname(hostname);
 287     if (!h)
 288       infof(data, "gethostbyname(2) failed for %s\n", hostname);
 289 #endif /*HAVE_GETHOSTBYNAME_R */
 290   }
 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
 302 #endif /* CURLRES_SYNCH */
 303 #endif /* CURLRES_IPV4 */
 304
 305 /*
 306  * Curl_he2ai() translates from a hostent struct to a Curl_addrinfo struct.
 307  * The Curl_addrinfo is meant to work like the addrinfo struct does for IPv6
 308  * stacks, but for all hosts and environments.
 309  *
 310  *   Curl_addrinfo defined in "lib/hostip.h"
 311  *
 312  *     struct Curl_addrinfo {
 313  *       int                   ai_flags;
 314  *       int                   ai_family;
 315  *       int                   ai_socktype;
 316  *       int                   ai_protocol;
 317  *       socklen_t             ai_addrlen;   * Follow rfc3493 struct addrinfo *
 318  *       char                 *ai_canonname;
 319  *       struct sockaddr      *ai_addr;
 320  *       struct Curl_addrinfo *ai_next;
 321  *     };
 322  *
 323  *   hostent defined in <netdb.h>
 324  *
 325  *     struct hostent {
 326  *       char    *h_name;
 327  *       char    **h_aliases;
 328  *       int     h_addrtype;
 329  *       int     h_length;
 330  *       char    **h_addr_list;
 331  *     };
 332  *
 333  *   for backward compatibility:
 334  *
 335  *     #define h_addr  h_addr_list[0]
 336  */
 337
 338 Curl_addrinfo *Curl_he2ai(const struct hostent *he, int port)
 339 {
 340   Curl_addrinfo *ai;
 341   Curl_addrinfo *prevai = NULL;
 342   Curl_addrinfo *firstai = NULL;
 343   struct sockaddr_in *addr;
 344   int i;
 345   struct in_addr *curr;
 346
 347   if(!he)
 348     /* no input == no output! */
 349     return NULL;
 350
 351   for(i=0; (curr = (struct in_addr *)he->h_addr_list[i]) != NULL; i++) {
 352
 353     ai = calloc(1, sizeof(Curl_addrinfo) + sizeof(struct sockaddr_in));
 354
 355     if(!ai)
 356       break;
 357
 358     if(!firstai)
 359       /* store the pointer we want to return from this function */
 360       firstai = ai;
 361
 362     if(prevai)
 363       /* make the previous entry point to this */
 364       prevai->ai_next = ai;
 365
 366     ai->ai_family = AF_INET;              /* we only support this */
 367
 368     /* we return all names as STREAM, so when using this address for TFTP
 369        the type must be ignored and conn->socktype be used instead! */
 370     ai->ai_socktype = SOCK_STREAM;
 371
 372     ai->ai_addrlen = sizeof(struct sockaddr_in);
 373     /* make the ai_addr point to the address immediately following this struct
 374        and use that area to store the address */
 375     ai->ai_addr = (struct sockaddr *) ((char*)ai + sizeof(Curl_addrinfo));
 376
 377     /* leave the rest of the struct filled with zero */
 378
 379     addr = (struct sockaddr_in *)ai->ai_addr; /* storage area for this info */
 380
 381     memcpy((char *)&(addr->sin_addr), curr, sizeof(struct in_addr));
 382     addr->sin_family = he->h_addrtype;
 383     addr->sin_port = htons((unsigned short)port);
 384
 385     prevai = ai;
 386   }
 387   return firstai;
 388 }
 389