本人大四在做毕设，马上答辩。急需知道下面这段程序的作用，忘高手前来帮助啊
我的c语言基础为0000000/*
* SSSSimpleSocketServerTask()
*
* This MicroC/OS-II thread spins forever after first establishing a listening
* socket for our sss connection, binding it, and listening. Once setup,
* it perpetually waits for incoming data to either the listening socket, or
* (if a connection is active), the sss data socket. When data arrives,
* the approrpriate routine is called to either accept/reject a connection
* request, or process incoming data.
*/
void SSSSimpleSocketServerTask()
{
int fd_listen, max_socket;
struct sockaddr_in addr;
static SSSConn conn;
fd_set readfds;
/*
* Sockets primer...
* The socket() call creates an endpoint for TCP of UDP communication. It
* returns a descriptor (similar to a file descriptor) that we call fd_listen,
* or, "the socket we're listening on for connection requests" in our sss
* server example.
*/
if ((fd_listen = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Socket creation failed");
}
/*
* Sockets primer, continued...
* Calling bind() associates a socket created with socket() to a particular IP
* port and incoming address. In this case we're binding to SSS_PORT and to
* INADDR_ANY address (allowing anyone to connect to us. Bind may fail for
* various reasons, but the most common is that some other socket is bound to
* the port we're requesting.
*/
addr.sin_family = AF_INET;
addr.sin_port = htons(SSS_PORT);
addr.sin_addr.s_addr = INADDR_ANY;
if ((bind(fd_listen,(struct sockaddr *)&addr,sizeof(addr))) < 0)
{
alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Bind failed");
}
/*
* Sockets primer, continued...
* The listen socket is a socket which is waiting for incoming connections.
* This call to listen will block (i.e. not return) until someone tries to
* connect to this port.
*/
if ((listen(fd_listen,1)) < 0)
{
alt_NetworkErrorHandler(EXPANDED_DIAGNOSIS_CODE,"[sss_task] Listen failed");
}
/* At this point we have successfully created a socket which is listening
* on SSS_PORT for connection requests from any remote address.
*/
sss_reset_connection(&conn);
printf("[sss_task] Simple Socket Server listening on port %d\n", SSS_PORT);
while(1)
{
/*
* For those not familiar with sockets programming...
* The select() call below basically tells the TCPIP stack to return
* from this call when any of the events I have expressed an interest
* in happen (it blocks until our call to select() is satisfied).
*
* In the call below we're only interested in either someone trying to
* connect to us, or data being available to read on a socket, both of
* these are a read event as far as select is called.
*
* The sockets we're interested in are passed in in the readfds
* parameter, the format of the readfds is implementation dependant
* Hence there are standard MACROs for setting/reading the values:
*
* FD_ZERO - Zero's out the sockets we're interested in
* FD_SET - Adds a socket to those we're interested in
* FD_ISSET - Tests whether the chosen socket is set
*/
FD_ZERO(&readfds);
FD_SET(fd_listen, &readfds);
max_socket = fd_listen+1;
if (conn.fd != -1)
{
FD_SET(conn.fd, &readfds);
if (max_socket <= conn.fd)
{
max_socket = conn.fd+1;
}
}
select(max_socket, &readfds, NULL, NULL, NULL);
/*
* If fd_listen (the listening socket we originally created in this thread
* is "set" in readfs, then we have an incoming connection request. We'll
* call a routine to explicitly accept or deny the incoming connection
* request (in this example, we accept a single connection and reject any
* others that come in while the connection is open).
*/
if (FD_ISSET(fd_listen, &readfds))
{
sss_handle_accept(fd_listen, &conn);
}
/*
* If sss_handle_accept() accepts the connection, it creates *another*
* socket for sending/receiving data over sss. Note that this socket is
* independant of the listening socket we created above. This socket's
* descriptor is stored in conn.fd. If conn.fs is set in readfs... we have
* incoming data for our sss server, and we call our receiver routine
* to process it.
*/
else
{
if ((conn.fd != -1) && FD_ISSET(conn.fd, &readfds))
{
sss_handle_receive(&conn);
}
}
} /* while(1) */
}
chinese please
