| yuezonghe | 824eb0c | 2024-06-27 02:32:26 -0700 | [diff] [blame] | 1 | .\" |
| 2 | .\" Copyright 1998 by the Massachusetts Institute of Technology. |
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| 12 | .\" M.I.T. makes no representations about the suitability of |
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| 15 | .\" |
| 16 | .TH ARES_PARSE_TXT_REPLY 3 "27 October 2009" |
| 17 | .SH NAME |
| 18 | ares_parse_txt_reply \- Parse a reply to a DNS query of type TXT |
| 19 | .SH SYNOPSIS |
| 20 | .nf |
| 21 | .B #include <ares.h> |
| 22 | .PP |
| 23 | .B int ares_parse_txt_reply(const unsigned char* \fIabuf\fP, int \fIalen\fP, |
| 24 | .B struct ares_txt_reply **\fItxt_out\fP); |
| 25 | .PP |
| 26 | .B int ares_parse_txt_reply_ext(const unsigned char* \fIabuf\fP, int \fIalen\fP, |
| 27 | .B struct ares_txt_ext **\fItxt_out\fP); |
| 28 | .fi |
| 29 | .SH DESCRIPTION |
| 30 | The |
| 31 | .BR "ares_parse_txt_reply" " (" "ares_parse_txt_reply_ext" ")" |
| 32 | function parses the response to a query of type TXT into a |
| 33 | linked list (one element per sub-string) of |
| 34 | .IR "struct ares_txt_reply" " (" "struct ares_txt_ext" ")" |
| 35 | The parameters |
| 36 | .I abuf |
| 37 | and |
| 38 | .I alen |
| 39 | give the contents of the response. The result is stored in allocated |
| 40 | memory and a pointer to it stored into the variable pointed to by |
| 41 | .IR txt_out . |
| 42 | It is the caller's responsibility to free the resulting |
| 43 | .IR txt_out |
| 44 | structure when it is no longer needed using the function |
| 45 | .B ares_free_data |
| 46 | .PP |
| 47 | The structure |
| 48 | .I ares_txt_reply |
| 49 | contains the following fields: |
| 50 | .sp |
| 51 | .in +4n |
| 52 | .nf |
| 53 | struct ares_txt_reply { |
| 54 | struct ares_txt_reply *next; |
| 55 | unsigned int length; |
| 56 | unsigned char *txt; |
| 57 | }; |
| 58 | .fi |
| 59 | .in |
| 60 | .PP |
| 61 | The structure |
| 62 | .I ares_txt_ext |
| 63 | contains the following fields: |
| 64 | .sp |
| 65 | .in +4n |
| 66 | .nf |
| 67 | struct ares_txt_ext { |
| 68 | struct ares_txt_ext *next; |
| 69 | unsigned int length; |
| 70 | unsigned char *txt; |
| 71 | unsigned char record_start; |
| 72 | }; |
| 73 | .fi |
| 74 | .in |
| 75 | .PP |
| 76 | The |
| 77 | .I record_start |
| 78 | field in |
| 79 | .I struct ares_txt_ext |
| 80 | is 1 if this structure is a start of a TXT record, and 0 if the structure is a |
| 81 | continuation of a previous record. The linked list of the |
| 82 | .I struct ares_txt_ext |
| 83 | will have at least one item with |
| 84 | .I record_start |
| 85 | equal to 1, and may have some items with |
| 86 | .I record_start |
| 87 | equal to 0 between them. |
| 88 | .PP |
| 89 | These sequences of |
| 90 | .I struct ares_txt_ext |
| 91 | (starting from the item with |
| 92 | .I record_start |
| 93 | equal to 1, and ending right before the record start item) may be treated as |
| 94 | either components of a single TXT record or as a multi-parted TXT record, |
| 95 | depending on particular use case. |
| 96 | .PP |
| 97 | .SH RETURN VALUES |
| 98 | .BR "ares_parse_txt_reply" " (" "ares_parse_txt_reply_ext" ")" |
| 99 | can return any of the following values: |
| 100 | .TP 15 |
| 101 | .B ARES_SUCCESS |
| 102 | The response was successfully parsed. |
| 103 | .TP 15 |
| 104 | .B ARES_EBADRESP |
| 105 | The response was malformatted. |
| 106 | .TP 15 |
| 107 | .B ARES_ENODATA |
| 108 | The response did not contain an answer to the query. |
| 109 | .TP 15 |
| 110 | .B ARES_ENOMEM |
| 111 | Memory was exhausted. |
| 112 | .SH AVAILABILITY |
| 113 | This function was first introduced in c-ares version 1.7.0. |
| 114 | .SH SEE ALSO |
| 115 | .BR ares_query (3) |
| 116 | .BR ares_free_data (3) |
| 117 | .SH AUTHOR |
| 118 | Written by Jakub Hrozek <jhrozek@redhat.com>, on behalf of Red Hat, Inc http://www.redhat.com |
| 119 | .PP |
| 120 | Amended by Fedor Indutny <fedor@indutny.com>, on behalf of PayPal, Inc https://www.paypal.com |