https://www.tutorialspoint.com/unix_sockets/socket_server_example.htm
https://www.tutorialspoint.com/unix_sockets/socket_client_example.htm
Part 1: source code:
server.c:
#include <stdio.h> #include <stdlib.h> #include <netdb.h> #include <netinet/in.h> #include <string.h> int main( int argc, char *argv[] ) { int sockfd, newsockfd, portno, clilen; char buffer[256]; struct sockaddr_in serv_addr, cli_addr; int n; /* First call to socket() function */ sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) { perror("ERROR opening socket"); exit(1); } /* Initialize socket structure */ bzero((char *) &serv_addr, sizeof(serv_addr)); portno = 5001; serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = INADDR_ANY; serv_addr.sin_port = htons(portno); /* Now bind the host address using bind() call.*/ if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) { perror("ERROR on binding"); exit(1); } /* Now start listening for the clients, here process will * go in sleep mode and will wait for the incoming connection */ listen(sockfd,5); clilen = sizeof(cli_addr); /* Accept actual connection from the client */ newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen); if (newsockfd < 0) { perror("ERROR on accept"); exit(1); } /* If connection is established then start communicating */ bzero(buffer,256); n = read( newsockfd,buffer,255 ); if (n < 0) { perror("ERROR reading from socket"); exit(1); } printf("Here is the message: %s\n",buffer); /* Write a response to the client */ n = write(newsockfd,"I got your message",18); if (n < 0) { perror("ERROR writing to socket"); exit(1); } return 0; }
client.c:
#include <stdio.h> #include <stdlib.h> #include <netdb.h> #include <netinet/in.h> #include <string.h> int main(int argc, char *argv[]) { int sockfd, portno, n; struct sockaddr_in serv_addr; struct hostent *server; char buffer[256]; if (argc < 3) { fprintf(stderr,"usage %s hostname port\n", argv[0]); exit(0); } portno = atoi(argv[2]); /* Create a socket point */ sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) { perror("ERROR opening socket"); exit(1); } server = gethostbyname(argv[1]); if (server == NULL) { fprintf(stderr,"ERROR, no such host\n"); exit(0); } bzero((char *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length); serv_addr.sin_port = htons(portno); /* Now connect to the server */ if (connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) { perror("ERROR connecting"); exit(1); } /* Now ask for a message from the user, this message * will be read by server */ printf("Please enter the message: "); bzero(buffer,256); fgets(buffer,255,stdin); /* Send message to the server */ n = write(sockfd, buffer, strlen(buffer)); if (n < 0) { perror("ERROR writing to socket"); exit(1); } /* Now read server response */ bzero(buffer,256); n = read(sockfd, buffer, 255); if (n < 0) { perror("ERROR reading from socket"); exit(1); } printf("%s\n",buffer); return 0; }
Part 2: compile:
gcc server.c -o server
gcc client.c -o client
Part 3: execution:
Step 1: execute server command
./server
Step 2: execute client command
./client 127.0.0.1 5001
Please enter the message: hello world
I got your message
Step 3: check the result on server
Here is the message: hello world
