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Socket

Table of Contents

  1. TCP Socket
  2. UDP Socket

Network Interfaces

  1. Socket API
  2. Ethernet Interface
  3. VodafoneK3770 Interface

The mbed C++ Socket API is a simple abstraction on top of the Berkeley sockets API.

The Socket library is included within the Networking libraries (Ethernet Interface and VodafoneK3770 Interface).

TCP Socket

/media/uploads/emilmont/sockets.png

TCP Echo Server

Import program
TCPEchoServer - main.cpp

00001 #include "mbed.h"
00002 #include "EthernetInterface.h"
00003 
00004 int main (void) {
00005     EthernetInterface eth;
00006     eth.init(); //Use DHCP
00007     eth.connect();
00008     printf("IP Address is %s\n", eth.getIPAddress());
00009     
00010     TCPSocketServer server;
00011     server.bind(7);
00012     server.listen(1);
00013     
00014     while (true) {
00015         printf("\nWait for new connection...\n");
00016         TCPSocketConnection client;
00017         server.accept(client);
00018         
00019         printf("Connection from: %s\n", client.get_address());
00020         char buffer[256];
00021         while (true) {
00022             int n = client.receive(buffer, 256, 3000);
00023             if (n <= 0) break;
00024             
00025             client.send_all(buffer, n, 3000);
00026             if (n <= 0) break;
00027         }
00028         client.close();
00029     }
00030 }

You can test the above server running on your mbed, with the following Python script running on your PC:

import socket

ECHO_SERVER_ADDRESS = "10.2.131.195"
ECHO_PORT = 7

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
s.connect((ECHO_SERVER_ADDRESS, ECHO_PORT))

s.sendall('Hello, world')
data = s.recv(1024)
s.close()
print 'Received', repr(data)

TCP Echo Client

Import program
TCPEchoClient - main.cpp

00001 #include "mbed.h"
00002 #include "EthernetInterface.h"
00003 
00004 const char* ECHO_SERVER_ADDRESS = "10.2.131.73";
00005 const int ECHO_PORT = 7;
00006 
00007 int main() {
00008     EthernetInterface eth;
00009     eth.init(); //Use DHCP
00010     eth.connect();
00011     printf("IP Address is %s\n", eth.getIPAddress());
00012     
00013     TCPSocketConnection sock;
00014     while (sock.connect(ECHO_SERVER_ADDRESS, ECHO_PORT) < 0) {
00015         printf("Unable to connect to (%s) on port (%d)\n", ECHO_SERVER_ADDRESS, ECHO_PORT);
00016         wait(1);
00017     }
00018     
00019     char hello[] = "Hello World\n";
00020     sock.send_all(hello, sizeof(hello) - 1);
00021     
00022     char buf[256];
00023     int n = sock.receive(buf, 256);
00024     // buf[n] = '\0';
00025     printf("%s", buf);
00026     
00027     sock.close();
00028     eth.disconnect();
00029     
00030     while(true) {}
00031 }

You can test the above Client running on your mbed, with the following Python script running on your PC:

import socket

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('', 7))
s.listen(1)

while True:
    conn, addr = s.accept()
    print 'Connected by', addr
    while True:
        data = conn.recv(1024)
        if not data: break
        conn.sendall(data)
    conn.close()

UDP Socket

UDP Echo Server

Import program
UDPEchoServer - main.cpp

00001 #include "mbed.h"
00002 #include "EthernetInterface.h"
00003 
00004 int main (void) {
00005     EthernetInterface eth;
00006     eth.init(); //Use DHCP
00007     eth.connect();
00008     printf("IP Address is %s\n", eth.getIPAddress());
00009     
00010     UDPSocket server;
00011     server.bind(7);
00012     
00013     char buffer[256];
00014     while (true) {
00015         printf("\nWait for packet...\n");
00016         
00017         UDPPacket packet(buffer, sizeof(buffer));
00018         int n = server.receiveFrom(packet);
00019         
00020         printf("Received packet from: %s\n", packet.get_address());
00021         packet.set_data(buffer, n);
00022         server.sendTo(packet);
00023     }
00024 }

You can test the above Server running on your mbed, with the following Python script running on your PC:

import socket
 
ECHO_SERVER_ADDRESS = '10.2.131.195'
ECHO_PORT = 7

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

sock.sendto("Hello World\n", (ECHO_SERVER_ADDRESS, ECHO_PORT))
response = sock.recv(256)
sock.close()

print response
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