cant make it work
this is a server client “rsh”program.This rsh (remote shell) allows me to execute a series of sh commands on a remote Unix system.
something like: if the command on client is
client linux03 uname -a
it should get an answer like:
Linux linux03 2.4.9-12 #1 Tue Oct 30 18:41:57 EST 2001 i686 unknown
the program is upposed to support till 3 pipes.
am spending so much time on it and i cant think clearly anymore.
any suggest please
server code:
client code which works fineCode:#include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> //#include <iostream.h> #include <unistd.h> #define SADDR struct sockaddr * #define MAXCMDS 3 #define MAXARGS 3 //function to output err to stderr and exit void xerror(char msg[]) { perror(msg); exit(1); } //function to parse char array into tokens based on passed delimiters int parse (char *line, char *delimitor, char *token[]) { int i=1; strtok(line, delimitor); token[0]=line; while((token[i]=(char *)strtok(NULL, delimitor))!=NULL) { while (*token[i] == ' ') token[i]++; /* eliminate leading spaces */ i++; } return i; } int execute_cmds(char commands[], char buffer[]) { int i, k; //loop variables int no_cmds, no_args, op_size; //number of commands, arguments, & output size char *cmd[MAXCMDS]; //pointer to array of command 'strings' char *args[MAXARGS]; // pointer to array of arguments int pfds[MAXCMDS][2]; //array of pipe file descriptors //debug printf("in execute_cmds \n"); for(i=0 ; i<MAXCMDS ; i++) pipe(pfds[i]); //setup pipes //debug printf("pipes done \n"); for(i=0 ; i<MAXCMDS ; i++) cmd[i] = NULL; no_cmds = parse(commands, "|", cmd); //null cmd array, parse command string printf("Number of commands = %d\n", no_cmds); for (i=0 ; i<no_cmds ; i++) printf("cmd[%d]=%s\n", i, cmd[i]); for(i=0 ; i<no_cmds ; i++) //loop for numebr of commands' times { if(!fork()) //fork new child { //debug printf("in child pid %d \n", getpid()); close(1); //close child stdout no_args = parse(cmd[i], " ", args); //parse each command args[no_args]=NULL; dup(pfds[i][1]); //make stdout = pfds[i][1] - input of pipe i close(pfds[i][0]); //close input of same pipe if(i!=0) //if not child 1 connect child stdin to o/p of previous pipe { close(0); //close child stdin dup(pfds[i-1][0]); //make stdin = pfds[i-1][0] - output of pipe before close(pfds[i-1][1]); //close input of pipe before } for(k=0 ; k<MAXCMDS ; k++) { if(k!=i && k!=i-1) { close(pfds[k][0]); close(pfds[k][1]);} } no_args = parse(cmd[i], " ", args); //parse each command args[no_args]=NULL; //debug fprintf(stderr, "%s\n", cmd[i]); for(i=0 ; i<no_args ; i++) fprintf(stderr, "%s\n", args[i]); execvp(cmd[i], args); //execute command i with args exit(0); } } for(i=0 ; i<MAXCMDS ; i++){ //close all unwanted pipes in parent if(i!=(no_cmds-1)) { close(pfds[i][0]); close(pfds[i][1]);} } close(pfds[no_cmds-1][1]); op_size = read(pfds[no_cmds-1][0],buffer,500); //store o/p in last pipe in buffer buffer[op_size] = '\0'; close(pfds[no_cmds-1][0]); //debug printf("buffer = %s ; size = %d\n", buffer, op_size); printf("leaving execute_cmds\n"); return op_size; } int main(int argc, char *argv[]) { struct sockaddr_in sa; //struct to hold socket address variables char cmd_line[501], buf[501]; //arrays for command line and data buffer int s, new_s, length_recv, length_send, n = sizeof(sa); //debug printf("start\n"); if ((s=socket(AF_INET,SOCK_STREAM,0)) < 0) xerror("socket"); // make socket sa.sin_family = AF_INET; // set type sa.sin_addr.s_addr = htonl(INADDR_ANY); // set wildcard sa.sin_port = htons(6001); // set port if ( bind(s, (SADDR)&sa, n) < 0 ) xerror("bind"); // bind address listen(s, 5); // queue callers for( ; ; ) { if ( ( new_s = accept(s, (SADDR)0, 0) ) < 0 ) xerror("accept");// accept call if(!fork()) { // child process printf("in child server pid %d \n", getpid()); close(s); length_recv = recv(new_s, cmd_line, 501, 0); // read cmd_line[length_recv] = '\0'; // delimit string printf("Command string recieved\n"); length_send = execute_cmds(cmd_line, buf); //execute commands, store results in buffer buf[] printf("Message being returned - %s\n", buf); send(new_s, buf, length_send, 0); // return message //debug //send(new_s, "done something \0", 20, 0); printf("Returned result\n"); close(new_s); //close server socket exit(0); } // parent process close(new_s); //close server socket } printf("Have exited forever loop!!!\n"); }
thanksCode:#include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <unistd.h> int main(int argc, char *argv[]) { struct hostent *hp; struct sockaddr_in sa; int s, n_chars, n = sizeof(struct sockaddr_in); char buf[501]; if ((s=socket(AF_INET,SOCK_STREAM,0)) < 0) exit(1);// make socket if ( (hp = gethostbyname(argv[1])) == 0 ) exit(1); // get host struct memset(&sa, 0, n); // init struct memcpy(&sa.sin_addr, hp->h_addr, hp->h_length); // set host sa.sin_port = htons(6001); // set port sa.sin_family = AF_INET; // set type if (connect(s,(struct sockaddr *)&sa,n)<0) exit(1);// connect send(s, argv[2], strlen(argv[2]), 0); // write message printf("\nSent command string\n"); n_chars=recv(s, buf, 500, 0); buf[n_chars]='\0'; printf("%d chars output returned, o/p=%s\n", n_chars, buf); }
