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SimplestServer.c
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SimplestServer.c
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#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
void clean_exit(int rc, int fd, char *message){
if (rc == -1 || fd == -1){
if (fd != -1){
close(fd);
}
perror(message);
exit(EXIT_FAILURE);
}
}
int main(int argc, char * argv[]){
int server_fd, client_fd, rc, client_addr_len, opt;
struct sockaddr_in server_addr, client_addr;
char client_msg[1024], *server_msg = "Message";
//determine port number to listen on
if (argc != 2){
fprintf(stderr, "[Usage]: %s PORT\n", argv[0]);
exit(EXIT_FAILURE);
}
//create server address struct
memset(&server_addr, 0, sizeof(struct sockaddr_in));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(atoi(argv[1]));
//bind to available ip on machine
server_addr.sin_addr.s_addr = INADDR_ANY;
//open socket
server_fd = socket(AF_INET, SOCK_STREAM, 0);
clean_exit(server_fd, server_fd, "[Server socket error]: ");
//allow reusable port after disconnect or termination of server
rc = setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, (socklen_t)sizeof(int));
clean_exit(rc, server_fd, "[Server setsockopt error]: ");
//bind socket to address and PORT
rc = bind(server_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr_in));
clean_exit(rc, server_fd, "[Server bind error]");
//listen on the socket for up to 5 connections and check perror
rc = listen(server_fd, 5);
clean_exit(rc, server_fd, "[Server listen error]: ");
//Accept connections forever
fprintf(stdout, "Server at %s:%d Listening for connections\n", inet_ntoa(server_addr.sin_addr), ntohs(server_addr.sin_port));
while(1){
client_fd = accept(server_fd, (struct sockaddr *)&client_addr, (socklen_t *)&client_addr_len);
clean_exit(client_fd, server_fd, "[Server accept error]: ");
//process requests
fprintf(stdout, "Received connection from %s:%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
read(client_fd, client_msg, 1024);
fprintf(stdout, "%s said: %s", inet_ntoa(client_addr.sin_addr), client_msg);
write(client_fd, server_msg, strlen(server_msg));
//close client
close(client_fd);
}
}