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TCPSocket

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 in the NetworkStack pointer to open the socket on the specified NetworkInterface. If you do not pass in the constructor, then you must call open to initialize the socket.

Refer to TCPServer class for TCP server functionality.

TCPSocket class reference

Public Member Functions
 TCPSocket ()
template<typename S >
 TCPSocket (S *stack)
virtual ~TCPSocket ()
nsapi_error_t connect (const char *host, uint16_t port)
nsapi_error_t connect (const SocketAddress &address)
nsapi_size_or_error_t send (const void *data, nsapi_size_t size)
nsapi_size_or_error_t recv (void *data, nsapi_size_t size)
 Public Member Functions inherited from Socket
virtual ~Socket ()
nsapi_error_t open (NetworkStack *stack)
template<typename S >
nsapi_error_t open (S *stack)
nsapi_error_t close ()
nsapi_error_t bind (uint16_t port)
nsapi_error_t bind (const char *address, uint16_t port)
nsapi_error_t bind (const SocketAddress &address)
void set_blocking (bool blocking)
void set_timeout (int timeout)
nsapi_error_t setsockopt (int level, int optname, const void *optval, unsigned optlen)
nsapi_error_t getsockopt (int level, int optname, void *optval, unsigned *optlen)
void sigio (mbed::Callback< void()> func)
void attach (mbed::Callback< void()> func)
template<typename T , typename M >
void attach (T *obj, M method)
Protected Member Functions
virtual nsapi_protocol_t get_proto ()
virtual void event ()
Protected Attributes
volatile unsigned _pending
rtos::EventFlags _event_flag
bool _read_in_progress
bool _write_in_progress
 Protected Attributes inherited from Socket
NetworkStack_stack
nsapi_socket_t _socket
uint32_t _timeout
mbed::Callback< void()> _event
mbed::Callback< void()> _callback
rtos::Mutex _lock
Friends
class TCPServer

TCPSocket Example

Here is a TCP client example of HTTP transaction using the ESP8266 module.

/* WiFi Example
 * Copyright (c) 2016 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "mbed.h"
#include "TCPSocket.h"

#if TARGET_UBLOX_EVK_ODIN_W2
#include "OdinWiFiInterface.h"
OdinWiFiInterface wifi;
#else
#if !TARGET_FF_ARDUINO
#error [NOT_SUPPORTED] Only Arduino form factor devices are supported at this time
#endif
#include "ESP8266Interface.h"
ESP8266Interface wifi(D1, D0);
#endif

const char *sec2str(nsapi_security_t sec)
{
    switch (sec) {
        case NSAPI_SECURITY_NONE:
            return "None";
        case NSAPI_SECURITY_WEP:
            return "WEP";
        case NSAPI_SECURITY_WPA:
            return "WPA";
        case NSAPI_SECURITY_WPA2:
            return "WPA2";
        case NSAPI_SECURITY_WPA_WPA2:
            return "WPA/WPA2";
        case NSAPI_SECURITY_UNKNOWN:
        default:
            return "Unknown";
    }
}

void scan_demo(WiFiInterface *wifi)
{
    WiFiAccessPoint *ap;

    printf("Scan:\r\n");

    int count = wifi->scan(NULL,0);

    /* Limit number of network arbitrary to 15 */
    count = count < 15 ? count : 15;

    ap = new WiFiAccessPoint[count];
    count = wifi->scan(ap, count);
    for (int i = 0; i < count; i++)
    {
        printf("Network: %s secured: %s BSSID: %hhX:%hhX:%hhX:%hhx:%hhx:%hhx RSSI: %hhd Ch: %hhd\r\n", ap[i].get_ssid(),
               sec2str(ap[i].get_security()), ap[i].get_bssid()[0], ap[i].get_bssid()[1], ap[i].get_bssid()[2],
               ap[i].get_bssid()[3], ap[i].get_bssid()[4], ap[i].get_bssid()[5], ap[i].get_rssi(), ap[i].get_channel());
    }
    printf("%d networks available.\r\n", count);

    delete[] ap;
}

void http_demo(NetworkInterface *net)
{
    TCPSocket socket;

    printf("Sending HTTP request to www.arm.com...\r\n");

    // Open a socket on the network interface, and create a TCP connection to www.arm.com
    socket.open(net);
    socket.connect("www.arm.com", 80);

    // Send a simple http request
    char sbuffer[] = "GET / HTTP/1.1\r\nHost: www.arm.com\r\n\r\n";
    int scount = socket.send(sbuffer, sizeof sbuffer);
    printf("sent %d [%.*s]\r\n", scount, strstr(sbuffer, "\r\n")-sbuffer, sbuffer);

    // Recieve a simple http response and print out the response line
    char rbuffer[64];
    int rcount = socket.recv(rbuffer, sizeof rbuffer);
    printf("recv %d [%.*s]\r\n", rcount, strstr(rbuffer, "\r\n")-rbuffer, rbuffer);

    // Close the socket to return its memory and bring down the network interface
    socket.close();
}

int main()
{
    printf("WiFi example\r\n\r\n");

    scan_demo(&wifi);

    printf("\r\nConnecting...\r\n");
    int ret = wifi.connect(MBED_CONF_APP_WIFI_SSID, MBED_CONF_APP_WIFI_PASSWORD, NSAPI_SECURITY_WPA_WPA2);
    if (ret != 0) {
        printf("\r\nConnection error\r\n");
        return -1;
    }

    printf("Success\r\n\r\n");
    printf("MAC: %s\r\n", wifi.get_mac_address());
    printf("IP: %s\r\n", wifi.get_ip_address());
    printf("Netmask: %s\r\n", wifi.get_netmask());
    printf("Gateway: %s\r\n", wifi.get_gateway());
    printf("RSSI: %d\r\n\r\n", wifi.get_rssi());

    http_demo(&wifi);

    wifi.disconnect();

    printf("\r\nDone\r\n");
}

Here is a TCP client example of HTTP transaction over Ethernet interface.

#include "mbed.h"
#include "EthernetInterface.h"

// Network interface
EthernetInterface net;

// Socket demo
int main() {
    // Bring up the ethernet interface
    printf("Ethernet socket example\n");
    net.connect();

    // Show the network address
    const char *ip = net.get_ip_address();
    printf("IP address is: %s\n", ip ? ip : "No IP");

    // Open a socket on the network interface, and create a TCP connection to mbed.org
    TCPSocket socket;
    socket.open(&net);
    socket.connect("developer.mbed.org", 80);

    // Send a simple http request
    char sbuffer[] = "GET / HTTP/1.1\r\nHost: developer.mbed.org\r\n\r\n";
    int scount = socket.send(sbuffer, sizeof sbuffer);
    printf("sent %d [%.*s]\n", scount, strstr(sbuffer, "\r\n")-sbuffer, sbuffer);

    // Recieve a simple http response and print out the response line
    char rbuffer[64];
    int rcount = socket.recv(rbuffer, sizeof rbuffer);
    printf("recv %d [%.*s]\n", rcount, strstr(rbuffer, "\r\n")-rbuffer, rbuffer);

    // 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");
}

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