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15837681
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2013-04-05T15:23:55.817
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Basically, you have three different issue in your code: <ol> <li>the string comparison (fixed by K Scott Piel). </li> <li>The print of the received message are not coming out. You need to add <code>'\n'</code> in all your <code>printf</code> functions.</li> <li>This is the most important issue: after the first communication between the server and the client, you are calling the <code>accept</code> function in the server code. From the <a href="http://linux.die.net/man/3/accept" rel="nofollow">man <code>accept</code> page</a>, we can read </li> </ol> <blockquote> The <code>accept()</code> function shall extract the first connection on the queue of pending connections, create a new socket with the same socket type protocol and address family as the specified socket, and allocate a new file descriptor for that socket. </blockquote> So, after the first communication, your server is waiting for a new connection and your client is waiting for a message from the server. The second communication will never happen. To solve this issue, you can use <a href="http://linux.die.net/man/3/fork" rel="nofollow"><code>fork()</code></a> API. Here is a fix proposal using the <code>fork()</code>: clientsocket.c <pre><code>#include <sys/socket.h> #include <sys/types.h> #include <netinet/in.h> #include <netdb.h> #include <stdio.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <arpa/inet.h> int main(int argc, char *argv[]) { int sockfd = 0, n = 0,m=2; char recvBuff[1024]; struct sockaddr_in serv_addr; if(argc != 2) { printf("\n Usage: %s <ip of server> \n",argv[0]); return 1; } memset(recvBuff, '0',sizeof(recvBuff)); if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { printf("\n Error : Could not create socket \n"); return 1; } memset(&serv_addr, '0', sizeof(serv_addr)); serv_addr.sin_family = AF_INET; serv_addr.sin_port = htons(5000); if(inet_pton(AF_INET, argv[1], &serv_addr.sin_addr)<=0) { printf("\n inet_pton error occured\n"); return 1; } if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) { printf("\n Error : Connect Failed \n"); return 1; } //m is 2 initially,I want that sending and receiving should be done 2 times while(m--) { printf("Waiting from the server ...\n"); n = recv(sockfd,recvBuff,1024,0); recvBuff[n]= '\0'; //"hi" is received printf("%s\n", recvBuff); if(!strncmp(recvBuff, "hi\n", strlen("hi\n"))) { printf("Send ACK\n"); n = send(sockfd,"Message Received",strlen("Message Received\n"),0); printf("%d Sent ... \n", n); } } //sending "Message received" return 0; } </code></pre> serversocket.c <pre><code>#include <sys/socket.h> #include <stdio.h> #include <stdlib.h> #include <netinet/in.h> #include <arpa/inet.h> #include <unistd.h> #include <error.h> #include <string.h> #include <sys/types.h> #include <time.h> int main(int argc,char *argv[]) { int listenfd = 0,qlength=10,connfd = 0,t=5; int n; struct sockaddr_in serv; struct sockaddr_in dest; socklen_t socksize = sizeof(struct sockaddr_in); char sendBuff[1024]="hi\n"; pid_t pid; int m = 2; //time_t ticks; listenfd = socket(AF_INET,SOCK_STREAM,0); //socket for listening to connection requests memset(&serv,'0',sizeof(serv)); serv.sin_family = AF_INET; serv.sin_addr.s_addr = htonl(INADDR_ANY); serv.sin_port=htons(5000); bind(listenfd,(struct sockaddr *)&serv,sizeof(serv)); //binding the socket to a port printf("Server started ...\n"); listen(listenfd,2); connfd=accept(listenfd,(struct sockaddr *)&dest,&socksize); //another socket for sending and receiving on the previously built socket while(connfd > 0) { printf("Incoming connection from %s-sending a hi...\n",inet_ntoa(dest.sin_addr)); pid = fork(); if(pid) { /* shall continue to listen to new client */ printf("Parent shall continue listening ... \n"); connfd=accept(listenfd,(struct sockaddr *)&dest,&socksize); } else { printf("Chlid process: Communication with the client ... \n"); while(m--) { printf("try %d - Sending %s ... \n", m, sendBuff); send(connfd,sendBuff,strlen(sendBuff),0); //at first my server sends a hi sleep(3); n=recv(connfd, sendBuff, 1024, 0); //if hi received by the client,then server should receive "Message Received" from the client sendBuff[n]='\0'; printf("Data received: [%s]\n", sendBuff); /* need to add '\n' so the print will be displayed */ strcpy(sendBuff, "hi\n"); } printf("Child process will exit\n"); return 0; } } return 0; } </code></pre>
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1. POServer not able to receive message from client
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