res_nisourserver()--Check Server Address

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

 int res_nisourserver(state* res,
                       const struct sockaddr_in* server)

The res_nisourserver() looks up the specified server address in the ns_addr_list[] of the specified res structure.

Parameters

res

(Input) The pointer to the state structure.

server

(Input) The pointer to the server address to check. Although it is declared as a const struct sockaddr_in*, it may be either a const struct sockaddr_in* or a const struct sockaddr_in6*.

Authorities:

No authorization is required.

Return Value

(0) Server not found in ns_addr_list[].

(>0) Server found in ns_addr_list[].

(<0) Error.

Error Conditions

When the res_nisourserver() function returns an error, errno will be set to one of the following:

[EFAULT]

The system detected a pointer that was invalid while attempting to access an input pointer.

[EINVAL]

One of the following reasons:

• A NULL pointer was passed to res_nisourserver()
  
  
• The res appears to be initialized but the reserved field is not set to zeros.

Related Information

• res_findzonecut()--Find the Enclosing Zone and Servers
  
  
• res_init()--Initialize res Structure
  
  
• res_nclose()--Close Socket and Reset res Structure
  
  
• res_nmkquery()--Place Domain Query in Buffer
  
  
• res_nquery()--Send Domain Query
  
  
• res_nsearch()--Search for Domain Name
  
  
• res_nsend()--Send Buffered Domain Query
  
  
• res_xlate()--Translate DNS Packets

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