Difference between revisions of "Unit DNS"

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----
 
----
  
−
Note: DNS Client is IPv4 based, for IPv6 see new Winsock2 functions
+
'''Ultibo DNS Client unit'''
  
 +
Note: DNS Client is IPv4 based, for IPv6 see new Winsock2 functions
  
 
See RFC 1035 Section 4 for details
 
See RFC 1035 Section 4 for details
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<div style="font-size: 14px; padding-left: 12px;">'''DNS flag constants''' <code> DNS_FLAG_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''DNS flag''' <code> DNS_FLAG_* </code></div>
 
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<div style="font-size: 14px; padding-left: 12px;">'''DNS field masks constants''' <code> DNS_OPCODE_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''DNS field masks''' <code> DNS_OPCODE_* </code></div>
 
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<div style="font-size: 14px; padding-left: 12px;">'''DNS query code constants''' <code> DNS_QUERY* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''DNS query code''' <code> DNS_QUERY* </code></div>
 
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−
<div style="font-size: 14px; padding-left: 12px;">'''DNS response code constants''' <code> DNS_NO_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''DNS response code''' <code> DNS_NO_* </code></div>
 
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−
<div style="font-size: 14px; padding-left: 12px;">'''DNS record type constants''' <code> DNS_TYPE_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''DNS record type''' <code> DNS_TYPE_* </code></div>
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
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−
<div style="font-size: 14px; padding-left: 12px;">'''DNS address class constants''' <code> DNS_CLASS_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''DNS address class''' <code> DNS_CLASS_* </code></div>
 
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−
<div style="font-size: 14px; padding-left: 12px;">'''DNS message compression constants''' <code> DNS_POINTER_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''DNS message compression''' <code> DNS_POINTER_* </code></div>
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
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----
 
----
  
−
''To be documented''
+
 
 +
'''DNS specific types'''
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PDNSHeader = ^TDNSHeader;</code>
 +
 
 +
<code>TDNSHeader = packed record</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
|colspan="2"|Note: All Network Order
 +
|-
 +
| <code>Identifier:Word;</code>
 +
| unique identifier
 +
|-
 +
| <code>Flags:Word;</code>
 +
| QD/Opcode/AA/TC/RD/RA/RCODE
 +
|-
 +
| <code>QuestionCount:Word;</code>
 +
| question section, number of entries
 +
|-
 +
| <code>AnswerCount:Word;</code>
 +
| answers, how many
 +
|-
 +
| <code>AuthorityCount:Word;</code>
 +
| count of name server RRs
 +
|-
 +
| <code>AdditionalCount:Word;</code>
 +
| number of "additional" records
 +
|-
 +
|}
 +
</div></div> 
 +
 
 +
'''DNS message'''
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PDNSMessage = ^TDNSMessage;</code>
 +
 
 +
<code>TDNSMessage = packed record</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
| <code>DNS:TDNSHeader;</code>
 +
| style="width: 50%;"|&nbsp;
 +
|-
 +
| <code>Data:array[0..(MAX_DNS_MESSAGE - DNS_HEADER_SIZE) - 1] of Byte;</code>
 +
| &nbsp;
 +
|-
 +
|}
 +
</div></div> 
 +
 +
'''DNS name'''
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PDNSName = ^TDNSName;</code>
 +
 
 +
<code>TDNSName = array[0..MAX_DNS_NAME - 1] of Char;</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
| &nbsp;
 +
| style="width: 50%;"|&nbsp;
 +
|-
 +
|}
 +
</div></div>
 +
 
 +
'''DNS question'''
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PDNSQuestion = ^TDNSQuestion;</code>
 +
 
 +
<code>TDNSQuestion = packed record</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
|colspan="2"|Note: All Network Order
 +
|-
 +
| <code>Name:TDNSName;</code>
 +
| variable length question name
 +
|-
 +
| <code>QuestionType:Word;</code>
 +
| question type (eg DNS_TYPE_A)
 +
|-
 +
| <code>QuestionClass:Word;</code>
 +
| question class (eg DNS_CLASS_IN)
 +
|-
 +
|}
 +
</div></div> 
 +
 
 +
'''DNS resource'''
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PDNSResource = ^TDNSResource;</code>
 +
 
 +
<code>TDNSResource = packed record</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
|colspan="2"|Note: All Network Order
 +
|-
 +
| <code>Name:TDNSName;</code>
 +
| variable length resource name
 +
|-
 +
| <code>RecordType:Word;</code>
 +
| resource record type (eg DNS_TYPE_A)
 +
|-
 +
| <code>RecordClass:Word;</code>
 +
| resource record class (eg DNS_CLASS_IN)
 +
|-
 +
| <code>Ttl:LongWord;</code>
 +
| time-to-live, changed to 32 bits
 +
|-
 +
| <code>DataLength:Word;</code>
 +
| length of data field
 +
|-
 +
| <code>RecordData:array[0..MAX_DNS_MESSAGE - 1] of Byte;</code>
 +
| data field
 +
|-
 +
|}
 +
</div></div> 
 +
 
 +
'''DNS client data'''
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PDNSClientData = ^TDNSClientData;</code>
 +
 
 +
<code>TDNSClientData = record</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
|colspan="2"|Note: Used for TLS Data
 +
|-
 +
|colspan="2"|''Host Ent''
 +
|-
 +
| <code>HostEnt:THostEnt;</code>
 +
| style="width: 50%;"|&nbsp;
 +
|-
 +
| <code>HostEntName:array[0..MAX_NAME_SIZE - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
| <code>HostAliasesPtr:PChar;</code>
 +
| &nbsp;
 +
|-
 +
| <code>HostAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
| <code>HostAddrListPtr:PChar;</code>
 +
| &nbsp;
 +
|-
 +
| <code>HostAddrList:array[0..MAX_HOST_ALIASES - 1] of TInAddr;</code>
 +
| &nbsp;
 +
|-
 +
|colspan="2"|''Net Ent''
 +
|-
 +
| <code>NetEnt:TNetEnt;</code>
 +
| &nbsp;
 +
|-
 +
| <code>NetEntName:array[0..MAX_NAME_SIZE - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
| <code>NetAliasesPtr:PChar;</code>
 +
| &nbsp;
 +
|-
 +
| <code>NetAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
|colspan="2"|''Serv Ent''
 +
|-
 +
| <code>ServEnt:TServEnt;</code>
 +
| &nbsp;
 +
|-
 +
| <code>ServEntName:array[0..MAX_NAME_SIZE - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
| <code>ServAliasesPtr:PChar;</code>
 +
| &nbsp;
 +
|-
 +
| <code>ServAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
| <code>ServEntProto:array[0..MAX_NAME_SIZE - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
|colspan="2"|''Proto Ent''
 +
|-
 +
| <code>ProtoEnt:TProtoEnt;</code>
 +
| &nbsp;
 +
|-
 +
| <code>ProtoEntName:array[0..MAX_NAME_SIZE - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
| <code>ProtoAliasesPtr:PChar;</code>
 +
| &nbsp;
 +
|-
 +
| <code>ProtoAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;</code>
 +
| &nbsp;
 +
|-
 +
|}
 +
</div></div>
 +
<br />
 +
 
 +
=== Class definitions ===
 +
----
 +
 
 +
 
 +
'''DNS specific classes'''
 +
 
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TDNSClient|<code>TDNSClient = class(TNetworkClient)</code>]]
 +
|-
 +
|}
 +
<br />
  
 
=== Public variables ===
 
=== Public variables ===
 
----
 
----
  
−
''To be documented''
+
''None defined''
  
 
=== Function declarations ===
 
=== Function declarations ===
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|-
 
|-
−
! '''Note'''
+
! Note
 
| None documented
 
| None documented
 
|-
 
|-
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! '''Note'''
+
! Note
 
| None documented
 
| None documented
 
|-
 
|-
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|-
 
|-
−
! '''Note'''
+
! Note
 
| None documented
 
| None documented
 
|-
 
|-

Latest revision as of 05:21, 31 August 2021

Return to Unit Reference


Description

Ultibo DNS Client unit

Note: DNS Client is IPv4 based, for IPv6 see new Winsock2 functions

See RFC 1035 Section 4 for details

Constants


DNS specific constants DNS_*
DNS_TIMEOUT = 5000; We wait for 5 seconds for a DNS reply
DNS_RETRIES = 4; Try the request 4 times
 
DNS_HEADER_SIZE = 12; SizeOf(TDNSHeader);
 
DNS_QUESTION_SIZE = 4; SizeOf(TDNSQuestion);
DNS_RESOURCE_SIZE = 10; SizeOf(TDNSResource); Not including Record Data
 
MAX_DNS_NAME = 255;  
MAX_DNS_LABEL = 63;  
MAX_DNS_MESSAGE = 512; Maximum Size of DNS Message


DNS flag DNS_FLAG_*
DNS_FLAG_RESPONSE = $8000; query = 0, response = 1
DNS_FLAG_AUTHORITY = $0400; Authoritative answer
DNS_FLAG_TRUNCATED = $0200; Truncation, response was cut off at 512
DNS_FLAG_DO_RECURSE = $0100; Recursion desired
DNS_FLAG_CAN_RECURSE = $0080; Recursion available


DNS field masks DNS_OPCODE_*
DNS_OPCODE_MASK = $7800; Opcode
DNS_RESPONSE_MASK = $000F; Response code


DNS query code DNS_QUERY*
DNS_QUERY = 0; A standard query
DNS_INV_QUERY = 1; An inverse query
DNS_COMP_QUERY_MULTI = 2; A completion query, multiple reply (Obsolete)
DNS_COMP_QUERY_SINGLE = 3; A completion query, single reply (Obsolete)


DNS response code DNS_NO_*
DNS_NO_ERROR = 0;  
DNS_FORMAT_ERROR = 1;  
DNS_SERVER_FAILURE = 2;  
DNS_NAME_ERROR = 3;  
DNS_NOT_IMPLEMENTED = 4;  
DNS_REFUSED = 5;  


DNS record type DNS_TYPE_*
DNS_TYPE_A = 1; Host address resource record (RR)
DNS_TYPE_NS = 2;  
DNS_TYPE_MD = 3;  
DNS_TYPE_MF = 4;  
DNS_TYPE_CNAME = 5;  
DNS_TYPE_SOA = 6;  
DNS_TYPE_MB = 7;  
DNS_TYPE_MG = 8;  
DNS_TYPE_MR = 9;  
DNS_TYPE_RT_NULL = 10;  
DNS_TYPE_WKS = 11;  
DNS_TYPE_PTR = 12; A domain name ptr
DNS_TYPE_HINFO = 13;  
DNS_TYPE_MINFO = 14;  
DNS_TYPE_MX = 15; Mail exchange


DNS address class DNS_CLASS_*
DNS_CLASS_IN = 1; ARPA internet class
DNS_CLASS_CS = 2;  
DNS_CLASS_WILD = 255; Wildcard for several of the classifications


DNS message compression DNS_POINTER_*
DNS_POINTER_MASK = $C0; Mask to indicate pointer to previously used name


Type definitions


DNS specific types

PDNSHeader = ^TDNSHeader;

TDNSHeader = packed record

Note: All Network Order
Identifier:Word; unique identifier
Flags:Word; QD/Opcode/AA/TC/RD/RA/RCODE
QuestionCount:Word; question section, number of entries
AnswerCount:Word; answers, how many
AuthorityCount:Word; count of name server RRs
AdditionalCount:Word; number of "additional" records

DNS message

PDNSMessage = ^TDNSMessage;

TDNSMessage = packed record

DNS:TDNSHeader;  
Data:array[0..(MAX_DNS_MESSAGE - DNS_HEADER_SIZE) - 1] of Byte;  

DNS name

PDNSName = ^TDNSName;

TDNSName = array[0..MAX_DNS_NAME - 1] of Char;

   

DNS question

PDNSQuestion = ^TDNSQuestion;

TDNSQuestion = packed record

Note: All Network Order
Name:TDNSName; variable length question name
QuestionType:Word; question type (eg DNS_TYPE_A)
QuestionClass:Word; question class (eg DNS_CLASS_IN)

DNS resource

PDNSResource = ^TDNSResource;

TDNSResource = packed record

Note: All Network Order
Name:TDNSName; variable length resource name
RecordType:Word; resource record type (eg DNS_TYPE_A)
RecordClass:Word; resource record class (eg DNS_CLASS_IN)
Ttl:LongWord; time-to-live, changed to 32 bits
DataLength:Word; length of data field
RecordData:array[0..MAX_DNS_MESSAGE - 1] of Byte; data field

DNS client data

PDNSClientData = ^TDNSClientData;

TDNSClientData = record

Note: Used for TLS Data
Host Ent
HostEnt:THostEnt;  
HostEntName:array[0..MAX_NAME_SIZE - 1] of Char;  
HostAliasesPtr:PChar;  
HostAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;  
HostAddrListPtr:PChar;  
HostAddrList:array[0..MAX_HOST_ALIASES - 1] of TInAddr;  
Net Ent
NetEnt:TNetEnt;  
NetEntName:array[0..MAX_NAME_SIZE - 1] of Char;  
NetAliasesPtr:PChar;  
NetAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;  
Serv Ent
ServEnt:TServEnt;  
ServEntName:array[0..MAX_NAME_SIZE - 1] of Char;  
ServAliasesPtr:PChar;  
ServAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;  
ServEntProto:array[0..MAX_NAME_SIZE - 1] of Char;  
Proto Ent
ProtoEnt:TProtoEnt;  
ProtoEntName:array[0..MAX_NAME_SIZE - 1] of Char;  
ProtoAliasesPtr:PChar;  
ProtoAliases:array[0..(MAX_NAME_SIZE * MAX_NAME_ALIASES) - 1] of Char;  


Class definitions


DNS specific classes

TDNSClient = class(TNetworkClient)


Public variables

None defined

Function declarations


Initialization functions 

procedure DNSInit;
Description: To be documented
Note None documented 


function DNSStart:LongWord;
Description: To be documented
Note None documented 


function DNSStop:LongWord;
Description: To be documented
Note None documented


Return to Unit Reference

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