Annotation of embedaddon/curl/lib/hostip4.c, revision 1.1.1.1
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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