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author | Daniel Stenberg <daniel@haxx.se> | 2003-10-07 21:54:04 +0000 |
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committer | Daniel Stenberg <daniel@haxx.se> | 2003-10-07 21:54:04 +0000 |
commit | 5e847a14bd65383ce65f143c578e120899981fd9 (patch) | |
tree | 0072e647fe22e05aee94cf4e4bf101209e30626c /ares_mkquery.c | |
download | c-ares-5e847a14bd65383ce65f143c578e120899981fd9.tar.gz c-ares-5e847a14bd65383ce65f143c578e120899981fd9.tar.bz2 c-ares-5e847a14bd65383ce65f143c578e120899981fd9.zip |
ares 1.1.1 with collected applied patches
Diffstat (limited to 'ares_mkquery.c')
-rw-r--r-- | ares_mkquery.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/ares_mkquery.c b/ares_mkquery.c new file mode 100644 index 0000000..fda49ee --- /dev/null +++ b/ares_mkquery.c @@ -0,0 +1,161 @@ +/* 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. + */ + +static const char rcsid[] = "$Id$"; + +#include <sys/types.h> + +#ifdef WIN32 +#include "nameser.h" +#else +#include <netinet/in.h> +#include <arpa/nameser.h> +#endif + +#include <stdlib.h> +#include <string.h> +#include "ares.h" +#include "ares_dns.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; + + /* 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++; + + *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); + DNS_HEADER_SET_RD(q, (rd) ? 1 : 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++ = 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; +} |