osd-contiki/doc/example-psock-server.c

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/*
* This is a small example of how to write a TCP server using
* Contiki's protosockets. It is a simple server that accepts one line
* of text from the TCP connection, and echoes back the first 10 bytes
* of the string, and then closes the connection.
*
* The server only handles one connection at a time.
*
*/
#include <string.h>
/*
* We include "contiki-net.h" to get all network definitions and
* declarations.
*/
#include "contiki-net.h"
/*
* We define one protosocket since we've decided to only handle one
* connection at a time. If we want to be able to handle more than one
* connection at a time, each parallell connection needs its own
* protosocket.
*/
static struct psock ps;
/*
* We must have somewhere to put incoming data, and we use a 10 byte
* buffer for this purpose.
*/
static uint8_t buffer[10];
/*---------------------------------------------------------------------------*/
/*
* A protosocket always requires a protothread. The protothread
* contains the code that uses the protosocket. We define the
* protothread here.
*/
static
PT_THREAD(handle_connection(struct psock *p))
{
/*
* A protosocket's protothread must start with a PSOCK_BEGIN(), with
* the protosocket as argument.
*
* Remember that the same rules as for protothreads apply: do NOT
* use local variables unless you are very sure what you are doing!
* Local (stack) variables are not preserved when the protothread
* blocks.
*/
PSOCK_BEGIN(p);
/*
* We start by sending out a welcoming message. The message is sent
* using the PSOCK_SEND_STR() function that sends a null-terminated
* string.
*/
PSOCK_SEND_STR(p, "Welcome, please type something and press return.\n");
/*
* Next, we use the PSOCK_READTO() function to read incoming data
* from the TCP connection until we get a newline character. The
* number of bytes that we actually keep is dependant of the length
* of the input buffer that we use. Since we only have a 10 byte
* buffer here (the buffer[] array), we can only remember the first
* 10 bytes received. The rest of the line up to the newline simply
* is discarded.
*/
PSOCK_READTO(p, '\n');
/*
* And we send back the contents of the buffer. The PSOCK_DATALEN()
* function provides us with the length of the data that we've
* received. Note that this length will not be longer than the input
* buffer we're using.
*/
PSOCK_SEND_STR(p, "Got the following data: ");
PSOCK_SEND(p, buffer, PSOCK_DATALEN(p));
PSOCK_SEND_STR(p, "Good bye!\r\n");
/*
* We close the protosocket.
*/
PSOCK_CLOSE(p);
/*
* And end the protosocket's protothread.
*/
PSOCK_END(p);
}
/*---------------------------------------------------------------------------*/
/*
* We declare the process and specify that it should be automatically started.
*/
PROCESS(example_psock_server_process, "Example protosocket server");
AUTOSTART_PROCESSES(&example_psock_server_process);
/*---------------------------------------------------------------------------*/
/*
* The definition of the process.
*/
PROCESS_THREAD(example_psock_server_process, ev, data)
{
/*
* The process begins here.
*/
PROCESS_BEGIN();
/*
* We start with setting up a listening TCP port. Note how we're
* using the UIP_HTONS() macro to convert the port number (1010) to
* network byte order as required by the tcp_listen() function.
*/
tcp_listen(UIP_HTONS(1010));
/*
* We loop for ever, accepting new connections.
*/
while(1) {
/*
* We wait until we get the first TCP/IP event, which probably
* comes because someone connected to us.
*/
PROCESS_WAIT_EVENT_UNTIL(ev == tcpip_event);
/*
* If a peer connected with us, we'll initialize the protosocket
* with PSOCK_INIT().
*/
if(uip_connected()) {
/*
* The PSOCK_INIT() function initializes the protosocket and
* binds the input buffer to the protosocket.
*/
PSOCK_INIT(&ps, buffer, sizeof(buffer));
/*
* We loop until the connection is aborted, closed, or times out.
*/
while(!(uip_aborted() || uip_closed() || uip_timedout())) {
/*
* We wait until we get a TCP/IP event. Remember that we
* always need to wait for events inside a process, to let
* other processes run while we are waiting.
*/
PROCESS_WAIT_EVENT_UNTIL(ev == tcpip_event);
/*
* Here is where the real work is taking place: we call the
* handle_connection() protothread that we defined above. This
* protothread uses the protosocket to receive the data that
* we want it to.
*/
handle_connection(&ps);
}
}
}
/*
* We must always declare the end of a process.
*/
PROCESS_END();
}
/*---------------------------------------------------------------------------*/