ARES_PARSE_TXT_REPLY(3) Introduction to Library Functions
NAME
ares_parse_txt_reply - Parse a reply to a DNS query of type TXT
SYNOPSIS
#include <ares.h>
int ares_parse_txt_reply(const unsigned char*
abuf, int
alen,
struct ares_txt_reply **
txt_out);
int ares_parse_txt_reply_ext(const unsigned char*
abuf, int
alen,
struct ares_txt_ext **
txt_out);
DESCRIPTION
The
ares_parse_txt_reply(3) and
ares_parse_txt_reply_ext(3) functions
parse the response to a query of type TXT into a linked list (one
element per sub-string) of
struct ares_txt_reply (
struct ares_txt_ext) The parameters
abuf and
alen give the contents of the
response. The result is stored in allocated memory and a pointer to
it stored into the variable pointed to by
txt_out. It is the
caller's responsibility to free the resulting
txt_out structure when
it is no longer needed using the function
ares_free_data(3).
The structure
ares_txt_reply contains the following fields:
struct ares_txt_reply {
struct ares_txt_reply *next;
unsigned int length;
unsigned char *txt;
};
The structure
ares_txt_ext contains the following fields:
struct ares_txt_ext {
struct ares_txt_ext *next;
unsigned int length;
unsigned char *txt;
unsigned char record_start;
};
The
record_start field in
struct ares_txt_ext is 1 if this structure
is a start of a TXT record, and 0 if the structure is a continuation
of a previous record. The linked list of the
struct ares_txt_ext will
have at least one item with
record_start equal to 1, and may have
some items with
record_start equal to 0 between them.
These sequences of
struct ares_txt_ext (starting from the item with
record_start equal to 1, and ending right before the record start
item) may be treated as either components of a single TXT record or
as a multi-parted TXT record, depending on particular use case.
RETURN VALUES
ares_parse_txt_reply (
ares_parse_txt_reply_ext) can return any of the
following values:
ARES_SUCCESS The response was successfully parsed.
ARES_EBADRESP The response was malformatted.
ARES_ENODATA The response did not contain an answer to the query.
ARES_ENOMEM Memory was exhausted.
AVAILABILITY
This function was first introduced in c-ares version 1.7.0.
SEE ALSO
ares_query(3) ares_free_data(3) 27 October 2009 ARES_PARSE_TXT_REPLY(3)
