bird/flock/hypervisor.c

#include "lib/birdlib.h"

#include "lib/cbor.h"
#include "lib/hash.h"
#include "lib/io-loop.h"
#include "lib/resource.h"
#include "lib/socket.h"

#include "flock/flock.h"

#include <stdlib.h>
#include <sys/socket.h>

/**
 * Main control socket
 **/

static struct birdloop *hcs_loop;
static pool *hcs_pool;

OBSREF(struct shutdown_placeholder) hcs_shutdown_placeholder;

static int
hcs_rx(sock *s, uint size)
{
  s64 sz = hcs_parse(s->data, s->rbuf, size);
  if (sz < 0)
  {
    log(L_INFO "CLI parser error at position %ld: %s", -sz-1, hcs_error(s->data));
    sk_close(s);
    return 0; /* Must return 0 when closed */
  }

  if (!hcs_complete(s->data))
  {
    ASSERT_DIE(sz == size);
    return 1;
  }

  log(L_INFO "Parsed command.");

  /* TODO do something more */
  if (sz < size)
    memmove(s->rbuf, s->rbuf + sz, size - sz);
  if (!s->rx_hook)
    return (sz == size);

  hcs_parser_cleanup(s->data);
  s->data = hcs_parser_init(s);

  return (sz < size) ? hcs_rx(s, size - sz) : 1;
}

static void
hcs_err(sock *s, int err)
{
  log(L_INFO "CLI dropped: %s", strerror(err));
  hcs_parser_cleanup(s->data);
  sk_close(s);
}

static int
hcs_connect(sock *s, uint size UNUSED)
{
  log(L_INFO "CLI connected: %p", s);

  s->rx_hook = hcs_rx;
  s->err_hook = hcs_err;
  s->data = hcs_parser_init(s);
  return 1;
}

static void
hcs_connect_err(sock *s UNUSED, int err)
{
  ASSERT_DIE(err);
  log(L_INFO "Failed to accept CLI connection: %s", strerror(err));
}

static void
hcs_stopped(void *data)
{
  ASSERT_DIE(data == hcs_loop);
  hcs_pool = NULL;
  hcs_loop = NULL;
  OBSREF_CLEAR(hcs_shutdown_placeholder);

  unlink(flock_config.control_socket_path);
}

static void
hcs_shutdown(void *_data UNUSED)
{
  birdloop_stop(hcs_loop, hcs_stopped, hcs_loop);
}

void
hypervisor_control_socket(void)
{
  struct birdloop *loop = hcs_loop = birdloop_new(&root_pool, DOMAIN_ORDER(control), 0, "Control socket");
  birdloop_enter(loop);

  pool *p = hcs_pool = rp_new(birdloop_pool(loop), birdloop_domain(loop), "Control socket pool");
  sock *s = sk_new(p);
  s->type = SK_UNIX_PASSIVE;
  s->rx_hook = hcs_connect;
  s->err_hook = hcs_connect_err;
  s->rbsize = 1024;
  s->tbsize = 1024;

  if (sk_open_unix(s, loop, flock_config.control_socket_path) < 0)
    die("Can't create control socket %s: %m", flock_config.control_socket_path);

  ev_send(&shutdown_event_list, ev_new_init(p, hcs_shutdown, NULL));

  birdloop_leave(loop);

  OBSREF_SET(hcs_shutdown_placeholder, &shutdown_placeholder);
}



/**
 * Exposed process' communication structure
 **/
static struct hypervisor_exposed {
  pool *p;
  sock *s;
  struct birdloop *loop;
  const char *port_name;
  sock *port_sreq;
} he;

/**
 * Exposed process' parent side (requestor)
 **/

static void hexp_received_telnet(void *);
struct hexp_received_telnet {
  event e;
  int fd;
  u16 port;
};

static int
hypervisor_telnet_connected(sock *sk, uint size UNUSED)
{
  int fd = accept(sk->fd, NULL, 0);
  if (fd < 0)
  {
    if (errno == EAGAIN)
      return 1;

    log(L_ERR "failed to accept telnet connection: %m");
    return 0;
  }

  int e = fork();
  if (e < 0)
  {
    log(L_ERR "failed to fork: %m");
    return 0;
  }

  if (e)
  {
    log(L_INFO "telnet connected");
    close(fd);
    sk_close(sk);
    return 1;
  }

  close(0);
  close(1);
  close(2);
  dup2(fd, 0);
  dup2(fd, 1);

  e = execl("/usr/sbin/telnetd", "telnetd", "-E", "/bin/bash", NULL);
  log(L_ERR "failed to execl: %m");
  exit(42);
}

static int
hypervisor_exposed_parent_rx(sock *sk, uint size)
{
  if ((size != 5) || (sk->rxfd < 0))
  {
    log(L_ERR "Exposed parent RX %d bytes, fd %d, what the hell", size, sk->rxfd);
    sk_close(sk);
    ev_send_loop(&main_birdloop, &poweroff_event);
    return 0;
  }

  ASSERT_DIE(sk->rbuf[0] == 0xa1);
  ASSERT_DIE(sk->rbuf[1] == 0x21);
  ASSERT_DIE(sk->rbuf[2] == 0x19);

  u16 port = ntohs(*((u16 *) &sk->rbuf[3]));
  log(L_INFO "RX %d bytes, fd %d, port %u", size, sk->rxfd, port);

  struct hexp_received_telnet *hrt = mb_allocz(he.p, sizeof *hrt);
  *hrt = (struct hexp_received_telnet) {
    .e = {
      .hook = hexp_received_telnet,
      .data = hrt,
    },
    .port = port,
    .fd = sk->rxfd,
  };
  ev_send_loop(hcs_loop, &hrt->e);

  sk->rxfd = -1;

  return 0;
}

static void
hypervisor_exposed_parent_err(sock *sk, int e UNUSED)
{
  sk_close(sk);
}

/**
 * Exposed process' child side (executor)
 **/
static int
hypervisor_exposed_child_rx(sock *sk, uint size)
{
  if (size != 3)
  {
    log(L_ERR "Got something strange: %d, %m", size);
    abort();
    sk_close(sk);
    return 0;
  }

  /* Only one thing is actually supported for now: opening a listening socket */
  int sfd = socket(AF_INET6, SOCK_STREAM | SOCK_CLOEXEC, 0);
  if (sfd < 0)
  {
    log(L_ERR "Failed to socket(): %m");
    return 0;
  }

  while (1)
  {
    u32 r = (random_u32() % (32768-1024) + 1024);
    union {
      struct sockaddr_in6 sin;
      struct sockaddr a;
    } sin = {
      .sin = {
	.sin6_family = AF_INET6,
	.sin6_port = htons(r),
	.sin6_addr.s6_addr[15] = 1,
      },
    };

    int e = bind(sfd, &sin.a, sizeof sin);
    if (e < 0)
      if (errno == EADDRINUSE)
      {
	log(L_INFO "Tried to bind to %u but already in use", r);
	continue;
      } else {
	log(L_ERR "Failed to bind to %u: %m", r);
	close(sfd);
	return 0;
      }

    e = listen(sfd, 10);
    if (e < 0)
    {
      log(L_ERR "Failed to listen(): %m", e);
      close(sfd);
      return 0;
    }

    log(L_INFO "SUCCESS");

    sk->txfd = sfd;

    linpool *lp = lp_new(sk->pool);
    struct cbor_writer *cw = cbor_init(sk->tbuf, sk->tbsize, lp);
    cbor_open_block_with_length(cw, 1);
    cbor_add_int(cw, -2);
    cbor_add_int(cw, r);

    e = sk_send(sk, cw->pt);
    if (e < 0)
      log(L_ERR "Failed to send socket: %m");

    close(sfd);

    return 0;
  }
}

static void
hypervisor_exposed_child_err(sock *sk, int e)
{
  if (e == 0)
    log(L_INFO "Exposed child exiting OK");
  else
    log(L_ERR "Exposed child control socket failure: %s", strerror(e));

  sk_close(sk);
  exit(!!e);
}

/**
 * Common init code
 */
void
hypervisor_exposed_fork(void)
{
  int fds[2], e;

  /* create socketpair before forking to do communication */
  e = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, fds);
  if (e < 0)
    die("Failed to create internal socketpair: %m");

  e = fork();
  if (e < 0)
    die("Failed to fork exposed: %m");

  if (!e) this_thread_id |= 0xe000;

  /* Create the communication channel (this runs twice!) */
  he.loop = birdloop_new(&root_pool, DOMAIN_ORDER(proto), 0, "Exposed interlink");

  birdloop_enter(he.loop);
  he.p = rp_new(birdloop_pool(he.loop), birdloop_domain(he.loop), "Exposed interlink pool");
  he.s = sk_new(he.p);
  he.s->type = SK_MAGIC; /* because we already have the fd */

  /* Set the hooks and fds according to the side we are at */
  he.s->rx_hook = e ? hypervisor_exposed_parent_rx : hypervisor_exposed_child_rx;
  he.s->err_hook = e ? hypervisor_exposed_parent_err : hypervisor_exposed_child_err;
  he.s->fd = fds[!!e];
  he.s->flags = e ? SKF_FD_RX : SKF_FD_TX;
  close(fds[!e]);

  if (sk_open(he.s, he.loop) < 0)
    bug("Exposed parent: sk_open failed");

  sk_set_rbsize(he.s, 128);
  sk_set_tbsize(he.s, 128);

  he.s->type = SK_UNIX_MSG; /* now we can reveal who we are */

  birdloop_leave(he.loop);

  /* Now there is a loop both in child and parent, prepared to read the socket.
   * There is only one difference. Whereas the parent has to continue its run
   * to do other duties, the child is stuck here forever. */
  if (e)
    return;

  /**
   * Child only
   **/

  /* Run worker threads */
  struct thread_config tc = {};
  bird_thread_commit(&tc);

  /* Wait for Godot */
  birdloop_minimalist_main();
}

void
hexp_cleanup_after_fork(void)
{
  birdloop_enter(he.loop);
  rp_free(he.p);
  rem_node((node *) he.loop); /* FIXME: this is terrible but i'm lazy now */
  birdloop_leave(he.loop);
  birdloop_free(he.loop);
}

/**
 * Hypervisor's mapping between external ports and names
 */

static void
hexp_sock_err(sock *s, int err UNUSED)
{
  ASSERT_DIE(s == he.port_sreq);
  he.port_name = NULL;
  he.port_sreq = NULL;
}

void
hexp_get_telnet(sock *s, const char *name)
{
  ASSERT_DIE(!he.port_name);
  he.port_name = name ?: "";
  he.port_sreq = s;

  uint8_t buf[64];
  linpool *lp = lp_new(s->pool);
  struct cbor_writer *cw = cbor_init(buf, sizeof buf, lp);
  cbor_open_block_with_length(cw, 1);
  cbor_add_int(cw, 1);
  cw->cbor[cw->pt++] = 0xf6;

  int e = write(he.s->fd, buf, cw->pt);
  if (e != cw->pt)
    bug("write error handling not implemented, got %d (%m)", e);

  rfree(lp);

  s->err_paused = hexp_sock_err;
  sk_pause_rx(s->loop, s);
}

static void hexp_received_telnet(void *_data)
{
  struct hexp_received_telnet *hrt = _data;

  ASSERT_DIE(he.port_name);
  const char *name = he.port_name;
  he.port_name = NULL;

  sock *s = he.port_sreq;
  he.port_sreq = NULL;

  if (name[0])
  {
    /* Transferring the received listening socket to the container */
    int fd = container_ctl_fd(name);

    /* TODO: unduplicate this code */
    byte outbuf[128];
    linpool *lp = lp_new(hcs_pool);
    struct cbor_writer *cw = cbor_init(outbuf, sizeof outbuf, lp);
    cbor_open_block_with_length(cw, 1);
    cbor_add_int(cw, -2);
    write_item(cw, 7, 22);
    struct iovec v = {
      .iov_base = outbuf,
      .iov_len = cw->pt,
    };
    byte cbuf[CMSG_SPACE(sizeof hrt->fd)];
    struct msghdr m = {
      .msg_iov = &v,
      .msg_iovlen = 1,
      .msg_control = &cbuf,
      .msg_controllen = sizeof cbuf,
    };
    struct cmsghdr *c = CMSG_FIRSTHDR(&m);
    c->cmsg_level = SOL_SOCKET;
    c->cmsg_type = SCM_RIGHTS;
    c->cmsg_len = CMSG_LEN(sizeof hrt->fd);
    memcpy(CMSG_DATA(c), &hrt->fd, sizeof hrt->fd);

    int e = sendmsg(fd, &m, 0);
    if (e < 0)
      log(L_ERR "Failed to send socket: %m");

    close(hrt->fd);
  }
  else
  {
    /* Opening listener here */

    sock *skl = sk_new(hcs_pool);
    skl->type = SK_MAGIC;
    skl->rx_hook = hypervisor_telnet_connected;
    skl->data = skl;
    skl->fd = hrt->fd;
    if (sk_open(skl, hcs_loop) < 0)
      bug("Telnet listener: sk_open failed");
  }

  if (s)
  {
    linpool *lp = lp_new(hcs_pool);
    struct cbor_writer *cw = cbor_init(s->tbuf, s->tbsize, lp);
    cbor_open_block_with_length(cw, 1);
    cbor_add_int(cw, -2);
    cbor_add_int(cw, hrt->port);

    sk_send(s, cw->pt);
    sk_resume_rx(hcs_loop, s);

    hcs_parser_cleanup(s->data);
    s->data = hcs_parser_init(s);

    rfree(lp);
  }

  birdloop_enter(he.loop);
  mb_free(hrt);
  birdloop_leave(he.loop);
}