Enhance timeclnt.c and timeserv.c to enable them to display which connection number of the client.

Compile the timeserv.c as described in Step 1.

1. compile the program

>gcc timeserv.c -o timeserv

2. run it as a server ( If the port number is being used, try different port number. In this case, you have change the port nuber in the timeserv.c file (#define PORTNUM 13000).) The telnet command in 3. needs to use the same port number assigned in timeserv.c.

>timeserv &

3. open another shell and compile the timeclnt.c:

> gcc timeclnt.c -o timeclnt

4. From client connect to the server

>timeclnt 13999

5. Modify the timeserv.c so that the client side will receive a message stating "You are the Number 5 user!" It means that the server will be tracking how many connections have been accepted

Thing to submit:

1. Submit a .c file of updated timeslnt.c

2. A screen shot that shows the running result.

3. Describe all the system calls used to enable the client program to receive messages from server.

/* timeclnt.c - a client for timeserv.c * * usage: timeclnt hostname portnumber * */ #include #include #include #include #include #include /* for exit()*/ #include /*bzero */ #include /* read() */ #include /* read() */ #define oops(msg) { perror(msg); exit(1); }

main(int ac, char *av[]) { struct sockaddr_in servadd; /* the number to call */ struct hostent *hp; /* used to get number */ int sock_id, sock_fd; /* the socket and fd */ char message[BUFSIZ]; /* to receive message */ int messlen; /* for message length */

/* * * Step 1: Get a socket * */

sock_id = socket( AF_INET, SOCK_STREAM, 0 ); /* get a line */ if ( sock_id == -1 ) oops( "socket" ); /* or fail */

/* * * Step 2: connect to server * * need to build address (host,port) of server first * */

bzero( &servadd, sizeof( servadd ) ); /* zero the address */

hp = gethostbyname( av[1] ); /* lookup host's ip # */ if (hp == NULL) oops(av[1]); /* or die */ bcopy(hp->h_addr, (struct sockaddr *)&servadd.sin_addr, hp->h_length);

servadd.sin_port = htons(atoi(av[2])); /* fill in port number */

servadd.sin_family = AF_INET ; /* fill in socket type */

/* now dial */ if ( connect(sock_id,(struct sockaddr *)&servadd, sizeof(servadd)) !=0) oops( "connect" );

/* * * Step 3: transfer data from server, then hangup * */

messlen = read(sock_id, message, BUFSIZ); /* read stuff */ if ( messlen == - 1 ) oops("read") ; if ( write( 1, message, messlen ) != messlen ) /* and write to */ oops( "write" ); /* stdout */ close( sock_id ); }

timeserv.c

#include  #include  #include  #include  #include  #include  #include  #include  #include  #define PORTNUM 13000 /* our time service phone number */ #define HOSTLEN 256 #define oops(msg) { perror(msg) ; exit(1) ; } int main(int ac, char *av[]) { struct sockaddr_in saddr; /* build our address here */ struct hostent *hp; /* this is part of our */ char hostname[HOSTLEN]; /* address */ int sock_id,sock_fd; /* line id, file desc */ FILE *sock_fp; /* use socket as stream */ /*char *ctime(); */ /* convert secs to string */ time_t thetime; /* the time we report */ /* * Step 1: ask kernel for a socket */ sock_id = socket( PF_INET, SOCK_STREAM, 0 ); /* get a socket */ if ( sock_id == -1 ) oops( "socket" ); /* * Step 2: bind address to socket. Address is host,port */ bzero( (void *)&saddr, sizeof(saddr) ); /* clear out struct */ gethostname( hostname, HOSTLEN ); /* where am I ? */ hp = gethostbyname( hostname ); /* get info about host */ /* fill in host part */ bcopy( (void *)hp->h_addr, (void *)&saddr.sin_addr, hp->h_length); saddr.sin_port = htons(PORTNUM); /* fill in socket port */ saddr.sin_family = AF_INET ; /* fill in addr family */ if ( bind(sock_id, (struct sockaddr *)&saddr, sizeof(saddr)) != 0 ) oops( "bind" ); /* * Step 3: allow incoming calls with Qsize=1 on socket */ if ( listen(sock_id, 1) != 0 ) oops( "listen" ); /* * main loop: accept(), write(), close() */ while ( 1 ){ sock_fd = accept(sock_id, NULL, NULL); /* wait for call */ printf("Wow! got a call! "); if ( sock_fd == -1 ) oops( "accept" ); /* error getting calls */ sock_fp = fdopen(sock_fd,"w"); /* we'll write to the */ if ( sock_fp == NULL ) /* socket as a stream */ oops( "fdopen" ); /* unless we can't */ thetime = time(NULL); /* get time */ /* and convert to strng */ fprintf( sock_fp, "The time here is .." ); fprintf( sock_fp, "%s", ctime(&thetime) ); fclose( sock_fp ); /* release connection */ } }