/* portbind.c: Tim Hollebeek, Oct 28, 1996 */
#include "base/std.h"

#include <arpa/inet.h>   // for inet_addr
#include <netinet/in.h>  // for sockaddr_in, INADDR_ANY, INADDR_NONE, htons
#include <cstdio>        // for perror, fprintf, sscanf, stderr
#include <cstdlib>       // for exit
#include <cstring>       // for strcmp
#include <sys/socket.h>  // for bind, setsockopt, socket, AF_INET, SOCK_STREAM
#include <unistd.h>      // for close, dup2, execv, setgid, setuid

#define HANDLE_ERROR(routine, call) \
  if ((call) == -1) {               \
    perror(#routine);               \
    exit(-1);                       \
  }

int main(int argc, char **argv) {
  int port = -1;
  char *ipaddress = nullptr;
  const char *driver_name = "./driver";
  int uid = -1;
  int gid = -1;

  int fd;
  int optval = 1;
  struct sockaddr_in sin;

  /*Args are passed down to the driver, but we process the following options:
   *
   * -p <port number>
   * -d <driver path>
   * -u <uid>
   * -g <gid>
   * -i <ip address>
   *
   * anything else causes us to quit scanning options.
   */
  while (argc > 1) {
    if (strcmp(argv[1], "-p") == 0) {
      if (argc == 2 || sscanf(argv[2], "%d", &port) != 1) {
        fprintf(stderr, "%s: -p must be followed by a port number.\n", argv[0]);
        exit(-1);
      }
      argc -= 2;
      argv += 2;
    } else if (strcmp(argv[1], "-d") == 0) {
      if (argc == 2) {
        fprintf(stderr, "%s: -d must be followed by the driver pathname.\n", argv[0]);
        exit(-1);
      }
      driver_name = argv[2];
      argc -= 2;
      argv += 2;
    } else if (strcmp(argv[1], "-u") == 0) {
      if (argc == 2 || sscanf(argv[2], "%d", &uid) != 1) {
        fprintf(stderr, "%s: -u must be followed by a valid numeric uid.\n", argv[0]);
        exit(-1);
      }
      argc -= 2;
      argv += 2;
    } else if (strcmp(argv[1], "-g") == 0) {
      if (argc == 2 || sscanf(argv[2], "%d", &gid) != 1) {
        fprintf(stderr, "%s: -g must be followed by a valid numeric gid.\n", argv[0]);
        exit(-1);
      }
      argc -= 2;
      argv += 2;
    } else if (strcmp(argv[1], "-i") == 0) {
      if (argc == 2 || inet_addr(argv[2]) == INADDR_NONE) {
        fprintf(stderr, "%s: -i must be followed by a valid dotted decimal ip address.\n", argv[0]);
        exit(-1);
      }
      ipaddress = argv[2];
      argc -= 2;
      argv += 2;
    } else {
      break;
    }
  }

  if (port == -1) {
    fprintf(stderr, "%s: a port must be specified with -p.\n", argv[0]);
    exit(-1);
  }

  /* create the socket */
  HANDLE_ERROR(socket, fd = socket(AF_INET, SOCK_STREAM, 0));

  /* move to fd #6 */
  HANDLE_ERROR(dup2, dup2(fd, 6));

  /* close the old copy */
  HANDLE_ERROR(close, close(fd));

  /* set local address reuse */
  HANDLE_ERROR(setsockopt,
               setsockopt(6, SOL_SOCKET, SO_REUSEADDR, (char *)&optval, sizeof(optval)));

  /* setup our address */
  sin.sin_family = AF_INET;
  sin.sin_addr.s_addr = (ipaddress ? inet_addr(ipaddress) : INADDR_ANY);
  sin.sin_port = htons(static_cast<unsigned short>(port));

  /* bind to our address */
  HANDLE_ERROR(bind, bind(6, (struct sockaddr *)&sin, sizeof(sin)));

  /* change our uid and gid */
  if (gid != -1) {
    HANDLE_ERROR(setgid, setgid(gid));
  }

  if (uid != -1) {
    HANDLE_ERROR(setuid, setuid(uid));
  }

  argv[0] = const_cast<char *>(driver_name);
  /* exec the driver */
  HANDLE_ERROR(execv, execv(driver_name, argv));
  return 0;
}
