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Gift server demonstration
Standard Libraries and other headers example from a Well House Consultants training course
More on Standard Libraries and other headers [link]
Source code: g2.c Module: C211
/* Originally based on an original from
http://en.wikibooks.org/wiki/C_Programming/Networking_in_UNIX available under creative commons license. Gift server demonstration */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <arpa/inet.h> #include <sys/types.h> #include <netinet/in.h> #include <sys/socket.h> #include <signal.h> #include <time.h> #define PORTNUM 13579 int hitter = 0; /* Yuk - global! - done for the signal handler*/ int mysocket = 0 ; /* ditto! */ int consocket = 0 ; /* ditto! */ /* Signal handler - run this if ^C is entered on server */ void cc(int sig) { signal(sig, SIG_IGN); /* Not sure why we briefly ignore! */ printf("Can't kill me this way ;-) (but if you persist, perhaps ...)\n"); hitter++; if (hitter > 5) { /* ALSO need to make sure we've read anything buffered before close? */ printf("Persistant, aren't you!\n"); if (mysocket) close(mysocket); if (consocket) close(consocket); exit(EXIT_SUCCESS); } signal(SIGINT, cc); /* re-enable ^C trap to here again if needed */ } int main(int argc, char *argv[]) { int ncr ; /* number chars read */ FILE *logfile; char *greeting = "Please enter your gift: "; char *youget = "In return you receive: "; char giftstore[257] = "Two pints of lager and a packet of pork scratchings\n"; char giftbox[257]; struct sockaddr_in dest; /* socket info about the machine connecting to us */ struct sockaddr_in serv; /* socket info about our server */ socklen_t socksize = sizeof(struct sockaddr_in); signal(SIGINT, cc); /* Handler for ^C on the server */ memset(&serv, 0, sizeof(serv)); /* zero the struct before filling the fields */ serv.sin_family = AF_INET; /* set the type of connection to TCP/IP */ serv.sin_addr.s_addr = htonl(INADDR_ANY); /* set our address to any interface */ serv.sin_port = htons(PORTNUM); /* set the server port number */ /* create a socket, bind to it, listen (up to 5 Q'd request) and accept */ mysocket = socket(AF_INET, SOCK_STREAM, 0); bind(mysocket, (struct sockaddr *)&serv, sizeof(struct sockaddr)); listen(mysocket, 5); consocket = accept(mysocket, (struct sockaddr *)&dest, &socksize); while(consocket) { logfile = fopen("logmehere.txt","a"); /* log who connected and when (two alternatives in this demo) */ time_t now; now = time(NULL); fprintf(logfile,"%s- Incoming connection from %s\n", ctime(&now), inet_ntoa(dest.sin_addr)); struct timeval details; gettimeofday(&details); fprintf(logfile,"%s- Incoming connection from %s\n", ctime(&(details.tv_sec)), inet_ntoa(dest.sin_addr)); /* protocol exchange with client */ send(consocket, greeting, strlen(greeting), 0); ncr = read(consocket, giftbox, sizeof(giftbox)-1); giftbox[ncr] = '\0'; send(consocket, youget, strlen(youget), 0); send(consocket, giftstore, strlen(giftstore), 0); /* server closes connection when it has sent */ close(consocket); /* complete logging to file */ fprintf(logfile,"-sent: %s-received: %s\n",giftstore,giftbox); fclose(logfile); /* Save the new gift into the giftstore */ strcpy(giftstore,giftbox); /* Await next connection */ consocket = accept(mysocket, (struct sockaddr *)&dest, &socksize); } close(mysocket); return EXIT_SUCCESS; } /* Sample output - server trainee@kingston:~/cmar15$ make g2 cc g2.c -o g2 trainee@kingston:~/cmar15$ ./g2 ^CCan't kill me this way ;-) (but if you persist, perhaps ...) ^CCan't kill me this way ;-) (but if you persist, perhaps ...) ^CCan't kill me this way ;-) (but if you persist, perhaps ...) ^CCan't kill me this way ;-) (but if you persist, perhaps ...) ^CCan't kill me this way ;-) (but if you persist, perhaps ...) ^CCan't kill me this way ;-) (but if you persist, perhaps ...) Persistant, aren't you! trainee@kingston:~/cmar15$ ---------------------------------------------------------------------------------- Sample output - a client trainee@kingston:~/cmar15$ telnet localhost 13579 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Please enter your gift: Sticky Toffee Pudding In return you receive: Two pints of lager and a packet of pork scratchings Connection closed by foreign host. trainee@kingston:~/cmar15$ telnet localhost 13579 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Please enter your gift: Pea Pie In return you receive: Sticky Toffee Pudding Connection closed by foreign host. trainee@kingston:~/cmar15$ Sample log file Fri Mar 27 12:26:42 2015 - Incoming connection from 192.168.200.37 Fri Mar 27 12:26:42 2015 - Incoming connection from 192.168.200.37 -sent: Feet -received: hands Sat Mar 28 07:06:16 2015 - Incoming connection from 127.0.0.1 Sat Mar 28 07:06:16 2015 - Incoming connection from 127.0.0.1 -sent: Two pints of lager and a packet of pork scratchings -received: Sticky Toffee Pudding Sat Mar 28 07:07:06 2015 - Incoming connection from 127.0.0.1 Sat Mar 28 07:07:06 2015 - Incoming connection from 127.0.0.1 -sent: Sticky Toffee Pudding -received: Pea Pie */ Learn about this subject
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