Annotation of embedaddon/curl/lib/hostip4.c, revision 1.1
1.1 ! misho 1: /***************************************************************************
! 2: * _ _ ____ _
! 3: * Project ___| | | | _ \| |
! 4: * / __| | | | |_) | |
! 5: * | (__| |_| | _ <| |___
! 6: * \___|\___/|_| \_\_____|
! 7: *
! 8: * Copyright (C) 1998 - 2020, 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.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: ***************************************************************************/
! 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: */
! 64: bool Curl_ipvalid(struct connectdata *conn)
! 65: {
! 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: */
! 91: Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
! 92: const char *hostname,
! 93: int port,
! 94: int *waitp)
! 95: {
! 96: Curl_addrinfo *ai = NULL;
! 97:
! 98: #ifdef CURL_DISABLE_VERBOSE_STRINGS
! 99: (void)conn;
! 100: #endif
! 101:
! 102: *waitp = 0; /* synchronous response only */
! 103:
! 104: ai = Curl_ipv4_resolve_r(hostname, port);
! 105: if(!ai)
! 106: infof(conn->data, "Curl_ipv4_resolve_r failed for %s\n", 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: */
! 122: 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: 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) */
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