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authorRemko Tronçon <git@el-tramo.be>2009-12-03 20:06:33 (GMT)
committerRemko Tronçon <git@el-tramo.be>2009-12-03 20:06:33 (GMT)
commit5df50c35e1baeee517a0895a2c8a2cc2052b087f (patch)
treeb9d90fd123ec251ebb930cfcfaa2ffc805433812 /3rdParty/CAres/src/ares_mkquery.c
parent9b3edba27b8683f1a87ad66ee05802dd93bbbdfc (diff)
downloadswift-contrib-5df50c35e1baeee517a0895a2c8a2cc2052b087f.zip
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Added C-Ares.
Diffstat (limited to '3rdParty/CAres/src/ares_mkquery.c')
-rw-r--r--3rdParty/CAres/src/ares_mkquery.c196
1 files changed, 196 insertions, 0 deletions
diff --git a/3rdParty/CAres/src/ares_mkquery.c b/3rdParty/CAres/src/ares_mkquery.c
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+/* $Id: ares_mkquery.c,v 1.17 2009-11-02 11:55:53 yangtse Exp $ */
+
+/* Copyright 1998 by the Massachusetts Institute of Technology.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is"
+ * without express or implied warranty.
+ */
+
+#include "ares_setup.h"
+
+#ifdef HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+# include <netinet/in.h>
+#endif
+#ifdef HAVE_ARPA_NAMESER_H
+# include <arpa/nameser.h>
+#else
+# include "nameser.h"
+#endif
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+# include <arpa/nameser_compat.h>
+#endif
+
+#include <stdlib.h>
+#include <string.h>
+#include "ares.h"
+#include "ares_dns.h"
+#include "ares_private.h"
+
+/* Header format, from RFC 1035:
+ * 1 1 1 1 1 1
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | ID |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * |QR| Opcode |AA|TC|RD|RA| Z | RCODE |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | QDCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | ANCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | NSCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | ARCOUNT |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ *
+ * AA, TC, RA, and RCODE are only set in responses. Brief description
+ * of the remaining fields:
+ * ID Identifier to match responses with queries
+ * QR Query (0) or response (1)
+ * Opcode For our purposes, always QUERY
+ * RD Recursion desired
+ * Z Reserved (zero)
+ * QDCOUNT Number of queries
+ * ANCOUNT Number of answers
+ * NSCOUNT Number of name server records
+ * ARCOUNT Number of additional records
+ *
+ * Question format, from RFC 1035:
+ * 1 1 1 1 1 1
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | |
+ * / QNAME /
+ * / /
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | QTYPE |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ * | QCLASS |
+ * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+ *
+ * The query name is encoded as a series of labels, each represented
+ * as a one-byte length (maximum 63) followed by the text of the
+ * label. The list is terminated by a label of length zero (which can
+ * be thought of as the root domain).
+ */
+
+int ares_mkquery(const char *name, int dnsclass, int type, unsigned short id,
+ int rd, unsigned char **buf, int *buflen)
+{
+ int len;
+ unsigned char *q;
+ const char *p;
+
+ /* Set our results early, in case we bail out early with an error. */
+ *buflen = 0;
+ *buf = NULL;
+
+ /* Compute the length of the encoded name so we can check buflen.
+ * Start counting at 1 for the zero-length label at the end. */
+ len = 1;
+ for (p = name; *p; p++)
+ {
+ if (*p == '\\' && *(p + 1) != 0)
+ p++;
+ len++;
+ }
+ /* If there are n periods in the name, there are n + 1 labels, and
+ * thus n + 1 length fields, unless the name is empty or ends with a
+ * period. So add 1 unless name is empty or ends with a period.
+ */
+ if (*name && *(p - 1) != '.')
+ len++;
+
+ /* Immediately reject names that are longer than the maximum of 255
+ * bytes that's specified in RFC 1035 ("To simplify implementations,
+ * the total length of a domain name (i.e., label octets and label
+ * length octets) is restricted to 255 octets or less."). We aren't
+ * doing this just to be a stickler about RFCs. For names that are
+ * too long, 'dnscache' closes its TCP connection to us immediately
+ * (when using TCP) and ignores the request when using UDP, and
+ * BIND's named returns ServFail (TCP or UDP). Sending a request
+ * that we know will cause 'dnscache' to close the TCP connection is
+ * painful, since that makes any other outstanding requests on that
+ * connection fail. And sending a UDP request that we know
+ * 'dnscache' will ignore is bad because resources will be tied up
+ * until we time-out the request.
+ */
+ if (len > MAXCDNAME)
+ return ARES_EBADNAME;
+
+ *buflen = len + HFIXEDSZ + QFIXEDSZ;
+ *buf = malloc(*buflen);
+ if (!*buf)
+ return ARES_ENOMEM;
+
+ /* Set up the header. */
+ q = *buf;
+ memset(q, 0, HFIXEDSZ);
+ DNS_HEADER_SET_QID(q, id);
+ DNS_HEADER_SET_OPCODE(q, QUERY);
+ if (rd) {
+ DNS_HEADER_SET_RD(q, 1);
+ }
+ else {
+ DNS_HEADER_SET_RD(q, 0);
+ }
+ DNS_HEADER_SET_QDCOUNT(q, 1);
+
+ /* A name of "." is a screw case for the loop below, so adjust it. */
+ if (strcmp(name, ".") == 0)
+ name++;
+
+ /* Start writing out the name after the header. */
+ q += HFIXEDSZ;
+ while (*name)
+ {
+ if (*name == '.')
+ return ARES_EBADNAME;
+
+ /* Count the number of bytes in this label. */
+ len = 0;
+ for (p = name; *p && *p != '.'; p++)
+ {
+ if (*p == '\\' && *(p + 1) != 0)
+ p++;
+ len++;
+ }
+ if (len > MAXLABEL)
+ return ARES_EBADNAME;
+
+ /* Encode the length and copy the data. */
+ *q++ = (unsigned char)len;
+ for (p = name; *p && *p != '.'; p++)
+ {
+ if (*p == '\\' && *(p + 1) != 0)
+ p++;
+ *q++ = *p;
+ }
+
+ /* Go to the next label and repeat, unless we hit the end. */
+ if (!*p)
+ break;
+ name = p + 1;
+ }
+
+ /* Add the zero-length label at the end. */
+ *q++ = 0;
+
+ /* Finish off the question with the type and class. */
+ DNS_QUESTION_SET_TYPE(q, type);
+ DNS_QUESTION_SET_CLASS(q, dnsclass);
+
+ return ARES_SUCCESS;
+}