DNS

Get ip from domain name

example：demo/dns

1. Enumerated type

1.1. DNS_Status_t

DNS status

typedef enum{
    DNS_STATUS_ERROR = -1,
    DNS_STATUS_OK    =  0,
    DNS_STATUS_WAIT  =  1,
    DNS_STATUS_MAX
}DNS_Status_t;

2. Function

2.1. DNS_CALLBACK_FUNC_T

typedef VOID (*DNS_CALLBACK_FUNC_T)(DNS_Status_t status, void* param);

Function

DNS callback funtion

Parameters

• status:DNS status
• param：parameter

Return

None

2.2. DNS_GetHostByName

DNS_Status_t     DNS_GetHostByName(const char* domain, char* ip);

Function

Resolve domain names to IP addresses, because domain name resolution sometimes takes a long time. In order not to block programs, the return value may be DNS_STATUS_WAIT, that is, domain name resolution has not yet been completed, and events will happen after completion.

Parameters

• domain： domain name
• ip：ip address output, ensure array have enough length, e.g:127.0.0.1

Return

• DNS_STATUS_OK：success, DNS_STATUS_ERROR: error, DNS_STATUS_WAIT：wait for resolve

2.3. DNS_GetHostByNameEX

DNS_Status_t     DNS_GetHostByNameEX(const char *hostname, char* ip, DNS_CALLBACK_FUNC_T func, void* param);

Function

Resolve the domain name to the IP address, and call the callback function after success.

Parameters

• hostname：domain name
• ip：ip address output, ensure array have enough length, e.g:127.0.0.1
• fuc: callback function
• param:the parameter to callback function

Return

• DNS_STATUS_OK: success, DNS_STATUS_ERROR: error, DNS_STATUS_WAIT:wait for result

2.4. DNS_GetHostByName2

int32_t          DNS_GetHostByName2(const char* domain, char* ip);

Function

Parsing domain name to IP address with block way, easy to use, but poor performance.

Parameters

• hostname：domain name
• ip：ip address output, ensure array have enough length, e.g:127.0.0.1

Return

• 0: success, other:error code