Example program with HTTPServer and sensor data streaming over TCPSockets, using Donatien Garnier's Net APIs and services code on top of LWIP. Files StreamServer.h and .cpp encapsulate streaming over TCPSockets. Broadcast is done by sendToAll(), and all incoming data is echoed back to the client. Echo code can be replaced with some remote control of the streaming interface. See main() that shows how to periodically send some data to all subscribed clients. To subscribe, a client should open a socket at <mbed_ip> port 123. I used few lines in TCL code to set up a quick sink for the data. HTTP files are served on port 80 concurrently to the streaming.
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dns.c File Reference
DNS - host name to IP address resolver.
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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. static struct 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]
Call dns_check_entry for each entry in dns_table - check all entries.
Definition at line 718 of file dns.c .
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
Definition at line 645 of file dns.c .
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
Definition at line 502 of file dns.c .
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. Definition at line 860 of file dns.c .
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. Definition at line 935 of file dns.c .
ip_addr_t dns_getserver
(
u8_t
numdns )
Obtain one of the currently configured DNS server.
Parameters:
numdns the index of the DNS server
Returns: IP address of the indexed DNS server or "ip_addr_any" if the DNS server has not been configured. Definition at line 300 of file dns.c .
Initialize the resolver: set up the UDP pcb and configure the default server (DNS_SERVER_ADDRESS).
Definition at line 243 of file dns.c .
err_t dns_local_addhost
(
const char *
hostname ,
const ip_addr_t *
addr
)
Add a hostname/IP address pair to the local host-list.
Duplicates are not checked.
Parameters:
hostname hostname of the new entry addr IP address of the new entry
Returns: ERR_OK if succeeded or ERR_MEM on memory error Definition at line 424 of file dns.c .
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 Definition at line 389 of file dns.c .
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. Definition at line 459 of file dns.c .
static u32_t dns_lookup_local
(
const char *
hostname )
[static]
Scans the local host-list for a hostname.
Parameters:
hostname Hostname to look for in the local host-list
Returns: The first IP address for the hostname in the local host-list or IPADDR_NONE if not found. Definition at line 358 of file dns.c .
static unsigned char* dns_parse_name
(
unsigned char *
query )
[static]
Walk through a compact encoded DNS name and return the end of the name.
Parameters:
query encoded DNS name in the DNS server response
Returns: end of the name
See also: RFC 1035 - 4.1.4. Message compression
Definition at line 537 of file dns.c .
static void dns_recv
(
void *
arg ,
struct udp_pcb *
pcb ,
struct pbuf *
p ,
ip_addr_t *
addr ,
u16_t
port
)
[static]
Receive input function for DNS response packets arriving for the dns UDP pcb.
see udp.h
Definition at line 733 of file dns.c .
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 Definition at line 569 of file dns.c .
void dns_setserver
(
u8_t
numdns ,
ip_addr_t *
dnsserver
)
Initialize one of the DNS servers.
Parameters:
numdns the index of the DNS server to set must be < DNS_MAX_SERVERS dnsserver IP address of the DNS server to set
Definition at line 284 of file dns.c .
The DNS resolver client timer - handle retries and timeouts and should be called every DNS_TMR_INTERVAL milliseconds (every second by default).
Definition at line 314 of file dns.c .
Variable Documentation
Contiguous buffer for processing responses.
Definition at line 235 of file dns.c .
Local host-list.
For hostnames in this list, no external name resolution is performed
Definition at line 199 of file dns.c .
Ilya I
1.7.2