res_getservers()--Get Name Server Addresses

 #include <resolv.h>

 int res_getservers(state* res,
                    union res_sockaddr_union *addresses,
                    int num_addresses)

The res_getservers() function gets the list of name server addresses that will be used on resolver or network APIs that use the state structure.

Parameters

res

(Input) The pointer to the state structure.

addresses

(Input/Output) A pointer to storage for the list of name server addresses to return. The structure of each address entry is:

union res_sockaddr_union {
    struct sockaddr_in  sin;
    struct sockaddr_in6 sin6;
    int64_t         __align64;  /* 64bit alignment */
    char            __space[128];   /* max size */
};

num_addresses

(Input) The number of addresses to return in the list. The maximum number of addresses is MAXNS.

Authorities:

No authorization is required.

Return Value

• -1 (unsuccessful)
  
  
• n (successful, where n is the number of addresses returned in the name server address list

Error Conditions

When the res_getservers() 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]

res appears to have been previously initialized but the reserved field is not set to zeros.

Usage Notes

1. If num_addresses is not large enough to contain the entire list, it will be truncated without error.

Related Information

• res_ninit()--Initialize res Structure
  
  
• res_nclose()--Close Socket and Reset res Structure
  
  
• res_setservers()--Set Name Server Addresses

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