/*********************
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* simple TCP-server *
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*********************/
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <netdb.h>
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#include <string.h>
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int main(int argc, char **argv) {
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unsigned short port; /* port to bind to */
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char buffer[80]; /* i/o buffer */
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struct sockaddr_in client; /* ip address of client */
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struct sockaddr_in server; /* ip address of server */
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struct hostent *hostnm; /* dest-hostname to connect to */
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int s; /* socket */
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int ns; /* socket connected to client */
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int namelen; /* length of client name */
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int optval=1;
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int s_optlen=0;
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ssize_t recvbytes; /* received bytes */
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/* check for needed parameters */
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if(argc!=3) {
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fprintf(stderr, "%s portnumber\n", argv[0]);
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exit(1);
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}
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hostnm=gethostbyname(argv[1]);
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/* port to int */
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port=(unsigned short) atoi(argv[2]);
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/* generating socket */
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if((s=socket(AF_INET, SOCK_STREAM,0))<0){
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perror("Error:");
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exit(2);
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}
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/* set socket options so that we can reuse the port */
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setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &optval, s_optlen);
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/* bind to socket */
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server.sin_family = AF_INET;
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server.sin_port = htons(port);
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server.sin_addr.s_addr = *((unsigned long *)hostnm->h_addr);
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if(bind(s, (struct sockaddr *)&server, sizeof(server))<0){
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perror("Error:");
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exit(3);
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}
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/* waiting for connections */
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if(listen(s,1)!=0){
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perror("Error:");
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exit(4);
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}
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/* get connection */
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namelen=sizeof(client);
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/* we loop forever here to avoid stopping the server */
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while(1) {
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if((ns=accept(s, (struct sockaddr *)&client, &namelen))==-1){
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perror("Error:");
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exit(5);
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}
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/* write welcome banner to user */
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snprintf(buffer, 54, "Welcome to the echo server, type a single x to quit.\n");
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send(ns, buffer, 54, 0);
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/* loop until we get an x as first char */
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do {
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/* get messages */
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recvbytes=recv(ns, buffer, sizeof(buffer), 0);
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if(recvbytes == -1){
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perror("Error:");
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exit(6);
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}
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/* send answer */
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if(send(ns, buffer, recvbytes, 0) <0){
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perror("Error:");
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exit(7);
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}
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} while (buffer[0] != 'x');
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/* client session closed on request, say bye bye */
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snprintf(buffer, 30, "Good bye, see you next time.\n");
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send(ns, buffer, 30, 0);
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/* close connection */
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close(ns);
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}
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/* close listener */
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close(s);
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printf("server exiting\n");
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return(0);
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}
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