dn_find()--Search for Compressed Domain Name

 #include <sys/types.h>
 #include <netinet/in.h>
 #include <arpa/nameser.h>
 #include <resolv.h>

 int dn_find(unsigned char *expanded_domain_name,
             unsigned char *message_pointer,
             unsigned char **domain_name_pointers,  
             unsigned char **last_domain_name)

The dn_find() function is used to search for an expanded domain name in a list of compressed domain names.

Authorities and Locks

None.

Parameters

expanded_domain_name

(Input) The pointer to the expanded domain name.

message_pointer_name

(Input) A pointer to the DNS packet that contains the compressed names pointed to by the elements of domain_name_pointers.

domain_name_pointers

(Input) The pointer to an array of pointers to previously compressed names in the current message.

last_domain_name

(Input) The pointer to the end of the array of domain_name_pointers.

Return Value

dn_find() returns an integer. Possible values are:

• -1 (unsuccessful)
  
  
• n (successful), where n is an offset into the message_pointer where domain name was found.

Error Conditions

When the dn_find() function fails, it does not set specific errno or h_errno values. An error occurs under the following conditions:

• NULL pointer(s) passed to the function.
  
  
• Invalid pointer(s) passed to the function.
  
  
• Expanded domain name not found in the DNS packet.

Usage Notes

1. dn_find() locates an expanded name in an array of previously compressed names.
   
   
2. Usually dn_find() is called from dn_comp() but can be called directly.
   
   
3. dn_find() expects EBCDIC data as input.

Related Information

• dn_expand()--Expand Domain Name
  
  
• dn_comp()--Compress Domain Name
  
  
• dn_skipname()--Skip over Compressed Domain Name

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