TCPSocket
TCPSocket class hierarchy
The TCPSocket class provides the ability to send a stream of data over TCP. TCPSockets maintain a stateful connection that starts with the connect member function. After successfully connecting to a server, you can use the send and recv member functions to send and receive data (similar to writing or reading from a file).
The constructor takes no parameters. To initialize the socket on a specified NetworkInterface, you must call open method, which takes a NetworkStack pointer.
Server socket
You can also use TCP to listen to incoming connections. To do this:
- Bind socket to specific port by calling
TCPSocket::bind(). - Set socket to listening mode by calling
TCPSocket::listen(). - Accept incoming connection by calling
TCPSocket::accept().
Accepting a new connection returns a pointer to a new Socket object that you can use to communicate with the connected peer. Afterward, call this socket's close() function to shut down the connection and clean up the reserved resources.
Accepting a connection leaves the original socket in listening mode. You can continue to accept new connections until you destroy the listening socket, or call its close() method.
TCPSocket class reference
| Public Member Functions | |
| TCPSocket () | |
| Create an uninitialized socket. More... | |
| template<typename S > | |
| TCPSocket (S *stack) | |
| Create a socket on a network interface. More... | |
| virtual | ~TCPSocket () |
| Destroy a socket. More... | |
| virtual int | join_multicast_group (const SocketAddress &address) |
| Override multicast functions to return error for TCP. More... | |
| nsapi_error_t | connect (const char *host, uint16_t port) |
| Connects TCP socket to a remote host. More... | |
| virtual nsapi_error_t | connect (const SocketAddress &address) |
| Connects TCP socket to a remote host. More... | |
| virtual nsapi_size_or_error_t | send (const void *data, nsapi_size_t size) |
| Send data over a TCP socket. More... | |
| virtual nsapi_size_or_error_t | recv (void *data, nsapi_size_t size) |
| Receive data over a TCP socket. More... | |
| virtual nsapi_size_or_error_t | sendto (const SocketAddress &address, const void *data, nsapi_size_t size) |
| Send data on a socket. More... | |
| virtual nsapi_size_or_error_t | recvfrom (SocketAddress *address, void *data, nsapi_size_t size) |
| Receive a data from a socket. More... | |
| virtual TCPSocket * | accept (nsapi_error_t *error=NULL) |
| Accepts a connection on a socket. More... | |
| virtual nsapi_error_t | listen (int backlog=1) |
| Listen for incoming connections. More... | |
| nsapi_error_t | open (NetworkStack *stack) |
| Open a network socket on the network stack of the given network interface. More... | |
| virtual nsapi_error_t | close () |
| defined(DOXYGEN_ONLY) More... | |
| int | leave_multicast_group (const SocketAddress &address) |
| Leave an IP multicast group. More... | |
| int | get_rtt_estimate_to_address (const SocketAddress &address, uint32_t *rtt_estimate) |
| Get estimated round trip time to destination address. More... | |
| int | get_stagger_estimate_to_address (const SocketAddress &address, uint16_t data_amount, uint16_t *stagger_min, uint16_t *stagger_max, uint16_t *stagger_rand) |
| Get estimated stagger value. More... | |
| nsapi_error_t | bind (uint16_t port) |
| Bind the socket to a port on which to receive data. More... | |
| nsapi_error_t | bind (const char *address, uint16_t port) |
| Bind the socket to a specific address and port on which to receive data. More... | |
| virtual nsapi_error_t | bind (const SocketAddress &address) |
| Bind a specific address to a socket. More... | |
| virtual void | set_blocking (bool blocking) |
| Set blocking or non-blocking mode of the socket. More... | |
| virtual void | set_timeout (int timeout) |
| Set timeout on blocking socket operations. More... | |
| virtual nsapi_error_t | setsockopt (int level, int optname, const void *optval, unsigned optlen) |
| Set socket options. More... | |
| virtual nsapi_error_t | getsockopt (int level, int optname, void *optval, unsigned *optlen) |
| Get socket options. More... | |
| virtual void | sigio (mbed::Callback< void()> func) |
| Register a callback on state change of the socket. More... | |
| virtual nsapi_error_t | getpeername (SocketAddress *address) |
| Get the remote-end peer associated with this socket. More... | |
| void | attach (mbed::Callback< void()> func) |
| Register a callback on state change of the socket. More... | |
| template<typename T , typename M > | |
| void | attach (T *obj, M method) |
| Register a callback on state change of the socket. More... | |
TCPSocket example
Here is a client example of HTTP transaction over TCPSocket:
#include "mbed.h"
// Network interface
NetworkInterface *net;
// Socket demo
int main() {
int remaining;
int rcount;
char *p;
char *buffer = new char[256];
nsapi_size_or_error_t result;
// Bring up the ethernet interface
printf("Mbed OS Socket example\n");
#ifdef MBED_MAJOR_VERSION
printf("Mbed OS version: %d.%d.%d\n\n", MBED_MAJOR_VERSION, MBED_MINOR_VERSION, MBED_PATCH_VERSION);
#endif
net = NetworkInterface::get_default_instance();
if (!net) {
printf("Error! No network inteface found.\n");
return 0;
}
result = net->connect();
if (result != 0) {
printf("Error! net->connect() returned: %d\n", result);
return result;
}
// Show the network address
SocketAddress a;
net->get_ip_address(&a);
printf("IP address: %s\n", a.get_ip_address() ? a.get_ip_address() : "None");
net->get_netmask(&a);
printf("Netmask: %s\n", a.get_ip_address() ? a.get_ip_address() : "None");
net->get_gateway(&a);
printf("Gateway: %s\n", a.get_ip_address() ? a.get_ip_address() : "None");
// Open a socket on the network interface, and create a TCP connection to ifconfig.io
TCPSocket socket;
// Send a simple http request
char sbuffer[] = "GET / HTTP/1.1\r\nHost: ifconfig.io\r\nConnection: close\r\n\r\n";
nsapi_size_t size = strlen(sbuffer);
result = socket.open(net);
if (result != 0) {
printf("Error! socket.open() returned: %d\n", result);
}
result = net->gethostbyname("ifconfig.io", &a);
if (result != 0) {
printf("Error! Could not resolve host ifconfig.io. Result: %d\n", result);
}
a.set_port(80);
result = socket.connect(a);
if (result != 0) {
printf("Error! socket.connect() returned: %d\n", result);
goto DISCONNECT;
}
// Loop until whole request sent
while(size) {
result = socket.send(sbuffer+result, size);
if (result < 0) {
printf("Error! socket.send() returned: %d\n", result);
goto DISCONNECT;
}
size -= result;
printf("sent %d [%.*s]\n", result, strstr(sbuffer, "\r\n")-sbuffer, sbuffer);
}
// Receieve an HTTP response and print out the response line
remaining = 256;
rcount = 0;
p = buffer;
while (remaining > 0 && 0 < (result = socket.recv(p, remaining))) {
p += result;
rcount += result;
remaining -= result;
}
if (result < 0) {
printf("Error! socket.recv() returned: %d\n", result);
goto DISCONNECT;
}
// the HTTP response code
printf("recv %d [%.*s]\n", rcount, strstr(buffer, "\r\n")-buffer, buffer);
delete[] buffer;
DISCONNECT:
// Close the socket to return its memory and bring down the network interface
socket.close();
// Bring down the ethernet interface
net->disconnect();
printf("Done\n");
}
Related content
- Socket API reference.