cl3.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#define DFL_PORT 8006
#define BACKLOG 10
#define BUFLEN 120



void make_server_addr(struct sockaddr_in * addr, unsigned short int port) {
  addr->sin_family = AF_INET;
  addr->sin_addr.s_addr = htonl(INADDR_ANY);
  addr->sin_port = htons(port);
  memset(&(addr->sin_zero), '\0', 8);

}

void out(int client_fd, char * buf, size_t len) {
  size_t sent;

  while (len > 0) {
    sent = write(client_fd, buf, len);
    if (sent < 0) {
      perror("out: write");
      close(client_fd);
      exit(EXIT_FAILURE);
    }
    len -= sent;
  }

}

void ls_cmd(int client_fd, char* buf){
  pid_t pid;
  char ls_cmd[] = "/bin/ls";
  char * ls_args[] = {"ls", "-lh", 0};
  int retval;
  printf("ls_cmd buf %s\n", buf);
  if((pid = fork()) < 0){
    perror("ls_cmd: fork");
    close(client_fd);
    exit(EXIT_FAILURE);
  }else if(!pid){
    /* child */
    if(dup2(client_fd, 1) < 0 ){
      perror("ls_cmd: dup2");
      close(client_fd);
      exit(EXIT_FAILURE);
    }

    if(execv(ls_cmd, ls_args)){
      perror("ls_cmd: execv");
      close(client_fd);
      exit(EXIT_FAILURE);
    }

  }else{
    waitpid(pid, &retval, 0);
    if(retval != EXIT_SUCCESS){
      out(client_fd, "Internal server error.\n", 24);
      close(client_fd);
      exit(EXIT_FAILURE);
    }
  }

}


void get_cmd(int client_fd, char* buf){

    int isfileopen = 0;
    int filesize;
    int readcount;
    char* filename = malloc(sizeof(char)*120);
    if(filename == NULL){
        perror("get_cmd malloc");
    }

    strncpy(filename, strchr(buf, ' ')+1, strlen(buf));

    printf("file name %s_\n", filename);
    FILE *fp;
    fp = fopen(filename, "rb");


    if(!fp){
        buf = "Error opening file\n";
        out(client_fd, buf, strlen(buf)+1);
        perror("get_cmd file open");
    }else{
        isfileopen = 1;

        while(1){
            if(feof(fp)){
                printf("done sending file, last slice length: %d\n", readcount);
                break;
            }

            readcount = fread(buf, 1, BUFLEN, fp);
            out(client_fd, buf, readcount);

        }
    }


    if(isfileopen){
        fclose(fp);
    }

free(filename);
}


void serve(int client_fd,char* buf) {
    char* error = malloc(120);
    size_t readcount;
    while ( (readcount = read(client_fd, buf, BUFLEN)) > 0) {
            printf("buf %c_ %s strlen(buf) %d_ \n", buf[0] , buf, readcount);

        if(buf[0] == 'g'){
            printf("serve: file %s_\n", buf);
            get_cmd(client_fd, buf);
        }else if(buf[0] == 'l'){
            puts("Serve: ls");
            ls_cmd(client_fd, buf);
        }else{
            int i;

            printf(error, "Unknown command: %c, %d, %s_\n", buf[0], buf[0], buf);
            sprintf(error, "Unknown command: %c, %d, %s_\n\0", buf[0], buf[0], buf);
            out(client_fd, error, strlen(error)+1);
        }

    }
    close(client_fd);
    free(error);
}

int main(int argc, char ** argv) {
    char buf[BUFLEN];

  int listen_fd;
  struct sockaddr_in client_addr;
  socklen_t client_addr_len = sizeof(struct sockaddr_in);
  struct sockaddr_in local_address;
  int on = 1;
  int client_fd;
  pid_t pid;


  /* make a listening socket */
  listen_fd = socket(PF_INET, SOCK_STREAM, 0);
  if ( listen_fd < 0 ) {
    perror("main: socket");
    exit(EXIT_FAILURE);
  }

  make_server_addr(&local_address, DFL_PORT);

  if( bind(listen_fd, (struct sockaddr *)&local_address,
                                    sizeof(local_address)) ){
    perror("main: bind");
    exit(EXIT_FAILURE);
  }


  if( listen(listen_fd, BACKLOG) ){
    perror("main: listen");
    exit(EXIT_FAILURE);
  }


  if( setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) ){
    perror("main: setsockopt:");
    exit(EXIT_FAILURE);
  }

  puts("Started listening");

  while(1){

    client_fd = accept(listen_fd, (struct sockaddr *)&client_addr,
                                                    &client_addr_len );
    if (client_fd < 0 ) {
      perror("main: accept");
      exit(EXIT_FAILURE);
    }

    printf("Client connected!\n");

    if( (pid = fork()) < 0 ) {
      perror("myserver: fork");
      exit(EXIT_FAILURE);
    } else if(!pid) {
      /* child */

      close(listen_fd);

      serve(client_fd, buf);

      printf("Client disconnected!\n");
      exit(EXIT_SUCCESS);

    } else {
      /* parent*/
      close(client_fd);
    }


  }

  close(listen_fd);
  exit(EXIT_SUCCESS);
}