Donatien Garnier
NetServices Stack source
Dependents: HelloWorld ServoInterfaceBoardExample1 4180_Lab4
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DNS - host name to IP address resolver. More...
Go to the source code of this file.
Functions | |
| static void | dns_recv (void *arg, struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *addr, u16_t port) |
| Receive input function for DNS response packets arriving for the dns UDP pcb. | |
| static void | dns_check_entries (void) |
| Call dns_check_entry for each entry in dns_table - check all entries. | |
| void | dns_init () |
| Initialize the resolver: set up the UDP pcb and configure the default server (DNS_SERVER_ADDRESS). | |
| void | dns_setserver (u8_t numdns, ip_addr_t *dnsserver) |
| Initialize one of the DNS servers. | |
| ip_addr_t | dns_getserver (u8_t numdns) |
| Obtain one of the currently configured DNS server. | |
| void | dns_tmr (void) |
| The DNS resolver client timer - handle retries and timeouts and should be called every DNS_TMR_INTERVAL milliseconds (every second by default). | |
| static u32_t | dns_lookup_local (const char *hostname) |
| Scans the local host-list for a hostname. | |
| int | dns_local_removehost (const char *hostname, const ip_addr_t *addr) |
| Remove all entries from the local host-list for a specific hostname and/or IP addess. | |
| err_t | dns_local_addhost (const char *hostname, const ip_addr_t *addr) |
| Add a hostname/IP address pair to the local host-list. | |
| static u32_t | dns_lookup (const char *name) |
| Look up a hostname in the array of known hostnames. | |
| static u8_t | dns_compare_name (unsigned char *query, unsigned char *response) |
| Compare the "dotted" name "query" with the encoded name "response" to make sure an answer from the DNS server matches the current dns_table entry (otherwise, answers might arrive late for hostname not on the list any more). | |
| static unsigned char * | dns_parse_name (unsigned char *query) |
| Walk through a compact encoded DNS name and return the end of the name. | |
| static err_t | dns_send (u8_t numdns, const char *name, u8_t id) |
| Send a DNS query packet. | |
| static void | dns_check_entry (u8_t i) |
| dns_check_entry() - see if pEntry has not yet been queried and, if so, sends out a query. | |
| static err_t | dns_enqueue (const char *name, dns_found_callback found, void *callback_arg) |
| Queues a new hostname to resolve and sends out a DNS query for that hostname. | |
| err_t | dns_gethostbyname (const char *hostname, ip_addr_t *addr, dns_found_callback found, void *callback_arg) |
| Resolve a hostname (string) into an IP address. | |
Variables | |
| static struct local_hostlist_entry * | local_hostlist_dynamic |
| Local host-list. | |
| static u8_t | dns_payload_buffer [LWIP_MEM_ALIGN_BUFFER(DNS_MSG_SIZE)] |
| Contiguous buffer for processing responses. | |
Detailed Description
DNS - host name to IP address resolver.
Definition in file dns.c.
Function Documentation
| static void dns_check_entries | ( | void | ) | [static] |
| static void dns_check_entry | ( | u8_t | i ) | [static] |
dns_check_entry() - see if pEntry has not yet been queried and, if so, sends out a query.
Check an entry in the dns_table:
- send out query for new entries
- retry old pending entries on timeout (also with different servers)
- remove completed entries from the table if their TTL has expired
- Parameters:
-
i index of the dns_table entry to check
| static u8_t dns_compare_name | ( | unsigned char * | query, |
| unsigned char * | response | ||
| ) | [static] |
Compare the "dotted" name "query" with the encoded name "response" to make sure an answer from the DNS server matches the current dns_table entry (otherwise, answers might arrive late for hostname not on the list any more).
- Parameters:
-
query hostname (not encoded) from the dns_table response encoded hostname in the DNS response
- Returns:
- 0: names equal; 1: names differ
- See also:
- RFC 1035 - 4.1.4. Message compression
| static err_t dns_enqueue | ( | const char * | name, |
| dns_found_callback | found, | ||
| void * | callback_arg | ||
| ) | [static] |
Queues a new hostname to resolve and sends out a DNS query for that hostname.
- Parameters:
-
name the hostname that is to be queried found a callback founction to be called on success, failure or timeout callback_arg argument to pass to the callback function
- Returns:
- a err_t return code.
| err_t dns_gethostbyname | ( | const char * | hostname, |
| ip_addr_t * | addr, | ||
| dns_found_callback | found, | ||
| void * | callback_arg | ||
| ) |
Resolve a hostname (string) into an IP address.
NON-BLOCKING callback version for use with raw API!!!
Returns immediately with one of err_t return codes:
- ERR_OK if hostname is a valid IP address string or the host name is already in the local names table.
- ERR_INPROGRESS enqueue a request to be sent to the DNS server for resolution if no errors are present.
- Parameters:
-
hostname the hostname that is to be queried addr pointer to a ip_addr_t where to store the address if it is already cached in the dns_table (only valid if ERR_OK is returned!) found a callback function to be called on success, failure or timeout (only if ERR_INPROGRESS is returned!) callback_arg argument to pass to the callback function
- Returns:
- a err_t return code.
| ip_addr_t dns_getserver | ( | u8_t | numdns ) |
| void dns_init | ( | void | ) |
| err_t dns_local_addhost | ( | const char * | hostname, |
| const ip_addr_t * | addr | ||
| ) |
| int dns_local_removehost | ( | const char * | hostname, |
| const ip_addr_t * | addr | ||
| ) |
Remove all entries from the local host-list for a specific hostname and/or IP addess.
- Parameters:
-
hostname hostname for which entries shall be removed from the local host-list addr address for which entries shall be removed from the local host-list
- Returns:
- the number of removed entries
| static u32_t dns_lookup | ( | const char * | name ) | [static] |
Look up a hostname in the array of known hostnames.
- Note:
- This function only looks in the internal array of known hostnames, it does not send out a query for the hostname if none was found. The function dns_enqueue() can be used to send a query for a hostname.
- Parameters:
-
name the hostname to look up
- Returns:
- the hostname's IP address, as u32_t (instead of ip_addr_t to better check for failure: != IPADDR_NONE) or IPADDR_NONE if the hostname was not found in the cached dns_table.
| static u32_t dns_lookup_local | ( | const char * | hostname ) | [static] |
| static unsigned char* dns_parse_name | ( | unsigned char * | query ) | [static] |
| static void dns_recv | ( | void * | arg, |
| struct udp_pcb * | pcb, | ||
| struct pbuf * | p, | ||
| ip_addr_t * | addr, | ||
| u16_t | port | ||
| ) | [static] |
| static err_t dns_send | ( | u8_t | numdns, |
| const char * | name, | ||
| u8_t | id | ||
| ) | [static] |
Send a DNS query packet.
- Parameters:
-
numdns index of the DNS server in the dns_servers table name hostname to query id index of the hostname in dns_table, used as transaction ID in the DNS query packet
- Returns:
- ERR_OK if packet is sent; an err_t indicating the problem otherwise
| void dns_setserver | ( | u8_t | numdns, |
| ip_addr_t * | dnsserver | ||
| ) |
| void dns_tmr | ( | void | ) |
Variable Documentation
u8_t dns_payload_buffer[LWIP_MEM_ALIGN_BUFFER(DNS_MSG_SIZE)] [static] |
struct local_hostlist_entry* local_hostlist_dynamic [static] |
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