Tag Archives: send
C++ || Snippet – How To Send Text Over A Network Using A TCP Connection
The following is sample code which demonstrates the use of the “socket“, “connect“, “bind“, “read“, and “write” function calls for interprocess communication over a network on Unix based systems.
The following example demonstrates a simple network application in which a client sends text to a server, and the server replies (sends text) back to the client. This program demonstrates communication between two programs using a TCP connection.
Click here to examine the UDP version.
Note: The server program must be ran before the client program!
=== 1. SERVER ===
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// ============================================================================ // Author: Kenneth Perkins // Date: Jan 8, 2014 // Taken From: http://programmingnotes.org/ // File: ServerTCP.cpp // Description: This program implements a simple network application in // which a client sends text to a server and the server replies back to the // client. This is the server program, and has the following functionality: // 1. Listen for incoming connections on a specified port. // 2. When a client tries to connect, the connection is accepted. // 3. When a connection is created, text is received from the client. // 4. Text is sent back to the client from the server. // 5. Close the connection and go back to waiting for more connections. // ============================================================================ #include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> #include <ctime> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> using namespace std; // Compile & Run // g++ ServerTCP.cpp -o ServerTCP // ./ServerTCP 1234 // the maximum size for sending/receiving text const int MSG_SIZE = 100; int main(int argc, char* argv[]) { // declare variables // the port number int port = -1; // the integer to store the file descriptor number // which will represent a socket on which the server // will be listening int listenfd = -1; // the file descriptor representing the connection to the client int connfd = -1; // the number of bytes read int numRead = -1; // the buffer to store text char data[MSG_SIZE]; // the structures representing the server and client // addresses respectively sockaddr_in serverAddr, cliAddr; // stores the size of the client's address socklen_t cliLen = sizeof(cliAddr); // make sure the user has provided the port number to listen on if(argc < 2) { cerr<<"\n** ERROR NOT ENOUGH ARGS!\n" <<"USAGE: "<<argv[0]<<" <SERVER PORT #>\n\n"; exit(1); } // get the port number port = atoi(argv[1]); // make sure that the port is within a valid range if(port < 0 || port > 65535) { cerr<<"Invalid port number\n"; exit(1); } // create a socket that uses // IPV4 addressing scheme (AF_INET), // Supports reliable data transfer (SOCK_STREAM), // and choose the default protocol that provides // reliable service (i.e. 0); usually TCP if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { perror("socket"); exit(1); } // set the structure to all zeros memset(&serverAddr, 0, sizeof(serverAddr)); // convert the port number to network representation serverAddr.sin_port = htons(port); // set the server family serverAddr.sin_family = AF_INET; // retrieve packets without having to know your IP address, // and retrieve packets from all network interfaces if the // machine has multiple ones serverAddr.sin_addr.s_addr = htonl(INADDR_ANY); // associate the address with the socket if(bind(listenfd, (sockaddr *) &serverAddr, sizeof(serverAddr)) < 0) { perror("bind"); exit(1); } // listen for connections on socket listenfd. // allow no more than 100 pending clients. if(listen(listenfd, 100) < 0) { perror("listen"); exit(1); } cerr<<"\nServer started!\n"; // wait forever for connections to come while(true) { cerr<<"\nWaiting for someone to connect..\n"; // a structure to store the client address if((connfd = accept(listenfd, (sockaddr *)&cliAddr, &cliLen)) < 0) { perror("accept"); exit(1); } // receive whatever the client sends if((numRead = read(connfd, data, sizeof(data))) < 0) { perror("read"); exit(1); } // NULL terminate the received string data[numRead] = '\0'; cerr<<"\nRECEIVED: '"<<data<<"' from the client\n"; //cerr<<"Bytes read: "<<numRead<<endl; // set the array to all zeros memset(&data, 0, sizeof(data)); // retrieve the time time_t rawtime; time(&rawtime); struct tm* timeinfo; timeinfo = localtime(&rawtime); strftime(data, sizeof(data),"%a, %b %d %Y, %I:%M:%S %p", timeinfo); cerr<<"\nSENDING: '"<<data<<"' to the client\n"; // send the client a message if(write(connfd, data, strlen(data)+1) < 0) { perror("write"); exit(1); } // close the socket close(connfd); } return 0; }// http://programmingnotes.org/ |
=== 2. CLIENT ===
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// ============================================================================ // Author: Kenneth Perkins // Date: Jan 8, 2014 // Taken From: http://programmingnotes.org/ // File: ClientTCP.cpp // Description: This program implements a simple network application in // which a client sends text to a server and the server replies back to the // client. This is the client program, and has the following functionality: // 1. Establish a connection to the server. // 2. Send text to the server. // 3. Recieve text from the server. // 4. Close the connection and exit. // ============================================================================ #include <iostream> #include <cstdio> #include <ctime> #include <cstdlib> #include <cstring> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> using namespace std; // Compile & Run // g++ ClientTCP.cpp -o ClientTCP // ./ClientTCP 127.0.0.1 1234 // the maximum size for sending/receiving text const int MSG_SIZE = 100; int main(int argc, char* argv[]) { // declare variables // the port number int port = -1; // the file descriptor representing the connection to the client int connfd = -1; // the buffer to store text char data[MSG_SIZE] = "Server, what time is it?"; // the number of bytes read int numRead = -1; // the structures representing the server address sockaddr_in serverAddr; // stores the size of the client's address socklen_t servLen = sizeof(serverAddr); // make sure the user has provided the port number to listen on if(argc < 3) { cerr<<"\n** ERROR NOT ENOUGH ARGS!\n" <<"USAGE: "<<argv[0]<<" <SERVER IP> <SERVER PORT #>\n\n"; exit(1); } // get the port number port = atoi(argv[2]); // make sure that the port is within a valid range if(port < 0 || port > 65535) { cerr<<"Invalid port number\n"; exit(1); } // connect to the server if((connfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { perror("socket"); exit(1); } // set the structure to all zeros memset(&serverAddr, 0, sizeof(serverAddr)); // set the server family serverAddr.sin_family = AF_INET; // convert the port number to network representation serverAddr.sin_port = htons(port); // convert the IP from the presentation format (i.e. string) // to the format in the serverAddr structure. if(!inet_pton(AF_INET, argv[1], &serverAddr.sin_addr)) { perror("inet_pton"); exit(1); } // connect to the server. This call will return a socket used // used for communications between the server and the client. if(connect(connfd, (sockaddr*)&serverAddr, sizeof(sockaddr)) < 0) { perror("connect"); exit(1); } cerr<<"\nSENDING: '"<<data<<"' to the server\n"; // send the server a message if(write(connfd, data, strlen(data)+1) < 0) { perror("write"); exit(1); } // receive whatever the server sends if((numRead = read(connfd, data, sizeof(data))) < 0) { perror("read"); exit(1); } // NULL terminate the received string data[numRead] = '\0'; cerr<<"\nRECEIVED: '"<<data<<"' from the server\n"; //cerr<<"Bytes read: "<<numRead<<endl; // close the connection socket close(connfd); return 0; }// http://programmingnotes.org/ |
QUICK NOTES:
The highlighted lines are sections of interest to look out for.
The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.
The following is sample output.
SERVER OUTPUT:
Server started!
Waiting for someone to connect..
RECEIVED: "Server, what time is it?" from the client
SENDING: "Wed, Jan 08 2014, 07:51:53 PM" to the client
CLIENT OUTPUT:
SENDING: "Server, what time is it?" to the server
RECEIVED: "Wed, Jan 08 2014, 07:51:53 PM" from the server
Python || Snippet – How To Send Text Over A Network Using Socket, Send, & Recv
The following is sample code which demonstrates the use of the “socket“, “connect“, “send“, and “recv” function calls for interprocess communication over a network.
The following example demonstrates a simple network application in which a client sends text to a server, and the server replies (sends text) back to the client.
Note: The server program must be ran before the client program!
=== 1. SERVER ===
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# ============================================================================= # Author: Kenneth Perkins # Date: Jan 8, 2014 # Taken From: http://programmingnotes.org/ # File: Server.py # Description: This program implements a simple network application in # which a client sends text to a server and the server replies back to the # client. This is the server program, which has the following functionality: # 1. Listen for incoming connections on a specified port. # 2. When a client tries to connect, the connection is accepted. # 3. When a connection is created, text is received from the client. # 4. Text is sent back to the client from the server. # 5. Close the connection and go back to waiting for more connections. # ============================================================================= import socket, sys, datetime # Run # python3 Server.py 1234 # the client message size MAX_MSG_LEN = 4096 def main(argc, argv): # check the command line arguments if(argc < 2): print("\n** ERROR NOT ENOUGH ARGS!\n" "USAGE: %s <SERVER PORT #>\n" %(argv[0])) sys.exit(1) # get the port number port = int(argv[1]) # the backlog backlog = 100 # create A TCP socket listenSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # bind the socket to the port listenSocket.bind(("", port)) # start listening for incoming connections listenSocket.listen(backlog) print("\nServer started!") # service clients forever while(True): print("\nWaiting for someone to connect..") # accept a connection from the client client, address = listenSocket.accept() # get the data from the client data = client.recv(MAX_MSG_LEN) print("\nRECEIVED: '%s' from the client" %(data.decode("UTF-8"))) # make sure the data was successfully received if(data): # get the current date and time now = datetime.datetime.now() dateAndTime = now.strftime("%a, %b %d %Y, %I:%M:%S %p") # send the date and time to the client print("\nSENDING: '%s' to the client" %(dateAndTime)) client.send(dateAndTime.encode("UTF-8")) # close the connection to the client client.close() if __name__ == "__main__": main(len(sys.argv), sys.argv) # http://programmingnotes.org/ |
=== 2. CLIENT ===
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# ============================================================================= # Author: Kenneth Perkins # Date: Jan 8, 2014 # Taken From: http://programmingnotes.org/ # File: Client.py # Description: This program implements a simple network application in # which a client sends text to a server and the server replies back to the # client. This is the client program, which has the following functionality: # 1. Establish a connection to the server. # 2. Send text to the server. # 3. Recieve text from the server. # 4. Close the connection and exit. # ============================================================================= import socket, sys # Run # python3 Client.py localhost 1234 # the size of the message sent by server MAX_MSG_LEN = 4096 def main(argc, argv): # check the command line arguments if(argc < 3): print("\n** ERROR NOT ENOUGH ARGS!\n" "USAGE: %s <SERVER IP> <SERVER PORT #>\n" %(argv[0])) sys.exit(1) # get the host name (or IP) host = argv[1] # get the server's port number port = int(argv[2]) # the client socket clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # connect to the server clientSocket.connect((host,port)) # send a string to the server data = "Server, what time is it?" print("\nSENDING: '%s' to the server" %(data)) clientSocket.send(data.encode("UTF-8")) # get the date from the server data = clientSocket.recv(MAX_MSG_LEN) print("\nRECEIVED: '%s' from the server\n" %(data.decode("UTF-8"))) # close the connection to the server clientSocket.close() if __name__ == "__main__": main(len(sys.argv), sys.argv) # http://programmingnotes.org/ |
QUICK NOTES:
The highlighted lines are sections of interest to look out for.
The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.
The following is sample output.
SERVER OUTPUT:
Server started!
Waiting for someone to connect..
RECEIVED: "Server, what time is it?" from the client
SENDING: "Wed, Jan 08 2014, 04:02:13 PM" to the client
CLIENT OUTPUT:
SENDING: "Server, what time is it?" to the server
RECEIVED: "Wed, Jan 08 2014, 04:02:13 PM" from the server