Advanced request configuration

It is possible to not use the default DNS configuration when resolving a specific host such as specifying a particular DNS server, different number of request retries and so on. When calling DNSc_GetHost() it is possible to specify a request configuration in the parameter p_cfg.

µC/DNSc request configuration is based on a structure that contains different configuration sections with many parameter settings.This section describes the request configuration settings, and should provide you an in-depth understanding of all parameters configuration. You will also discover which settings to modify in order to enhance the functionalities. Refer to the configuration field description section for further details.

Request Configuration

µC/DNS uses the following structure to configure requests:

typedef  struct  DNSc_req_cfg {
    DNSc_ADDR_OBJ  *ServerAddrPtr;
    NET_PORT_NBR    ServerPort;
    CPU_INT16U      TaskDly_ms;
    CPU_INT16U      ReqTimeout_ms;
    CPU_INT08U      ReqRetry;
    DNSc_REQ_TYPE   ReqType;
    DNSc_FLAGS      ReqFlags;
} DNSc_REQ_CFG;

Structure Fields

Structure Field	Type	Description	Possible Values
ServerAddrPtr	CPU_CHAR	Server IP address	DEF_NULL to use the default server Pointer to a string that contains the IP address.
ServerPort	NET_PORT_NBR	Port number	NET_PORT_NBR_NONE Default DNS port MUST be >= NET_PORT_NBR_MIN Must be <= NET_PORT_NBR_MAX
TaskDly_ms	CPU_INT16U	Configure task delay in integer milliseconds	Default value: [DNSc_DFLT_TASK_DLY_MS] = 50ms MUST be >= 1
ReqTimeout_ms	CPU_INT16U	Configure timeout before a request resolution retry	Default value: [DNSc_DFLT_REQ_RETRY_TIMEOUT_MS] = 1000ms MUST be >= 100
ReqRetry	CPU_INT08U	Configure maximum of request resolution retry.	Default value: [DNSc_DFLT_REQ_RETRY_NBR_MAX] = 2 MUST be >= 1
ReqType	DNSc_REQ_TYPE	Instructs the DNS request state machine if the request is a forward request (type A, AAAA), or a reverse request (type PTR IPv4 or PTR IPv6).	Meant for internal use by uC/DNSc. Any values passed are ignored.
ReqFlags	DNSc_FLAGS	Contains a copy of DNSc_GetHost()'s 'flags' argument to keep track of them internally. Enables DNSc to use its internal flags DNSc_FLAG_UPDATE_PREF and DNSc_FLAG_RESET_REQ without modifying the 'flags' argument.	Meant for internal use by uC/DNSc. Any values passed are ignored.