src/core/iomgr/tcp_server_posix.c

/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

/* FIXME: "posix" files shouldn't be depending on _GNU_SOURCE */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include <grpc/support/port_platform.h>

#ifdef GPR_POSIX_SOCKET

#include "src/core/iomgr/tcp_server.h"

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>

#include "src/core/iomgr/pollset_posix.h"
#include "src/core/iomgr/resolve_address.h"
#include "src/core/iomgr/sockaddr_utils.h"
#include "src/core/iomgr/socket_utils_posix.h"
#include "src/core/iomgr/tcp_posix.h"
#include "src/core/support/string.h"
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/string_util.h>
#include <grpc/support/sync.h>
#include <grpc/support/time.h>

#define INIT_PORT_CAP 2
#define MIN_SAFE_ACCEPT_QUEUE_SIZE 100

static gpr_once s_init_max_accept_queue_size;
static int s_max_accept_queue_size;

/* one listening port */
typedef struct
{
  int fd;
  grpc_fd *emfd;
  grpc_tcp_server *server;
  union
  {
    gpr_uint8 untyped[GRPC_MAX_SOCKADDR_SIZE];
    struct sockaddr sockaddr;
    struct sockaddr_un un;
  } addr;
  size_t addr_len;
  grpc_closure read_closure;
  grpc_closure destroyed_closure;
} server_port;

static void
unlink_if_unix_domain_socket (const struct sockaddr_un *un)
{
  struct stat st;

  if (stat (un->sun_path, &st) == 0 && (st.st_mode & S_IFMT) == S_IFSOCK)
    {
      unlink (un->sun_path);
    }
}

/* the overall server */
struct grpc_tcp_server
{
  /* Called whenever accept() succeeds on a server port. */
  grpc_tcp_server_cb on_accept_cb;
  void *on_accept_cb_arg;

  gpr_mu mu;

  /* active port count: how many ports are actually still listening */
  size_t active_ports;
  /* destroyed port count: how many ports are completely destroyed */
  size_t destroyed_ports;

  /* is this server shutting down? (boolean) */
  int shutdown;

  /* all listening ports */
  server_port *ports;
  size_t nports;
  size_t port_capacity;

  /* shutdown callback */
  grpc_closure *shutdown_complete;

  /* all pollsets interested in new connections */
  grpc_pollset **pollsets;
  /* number of pollsets in the pollsets array */
  size_t pollset_count;
};

grpc_tcp_server *
grpc_tcp_server_create (void)
{
  grpc_tcp_server *s = gpr_malloc (sizeof (grpc_tcp_server));
  gpr_mu_init (&s->mu);
  s->active_ports = 0;
  s->destroyed_ports = 0;
  s->shutdown = 0;
  s->on_accept_cb = NULL;
  s->on_accept_cb_arg = NULL;
  s->ports = gpr_malloc (sizeof (server_port) * INIT_PORT_CAP);
  s->nports = 0;
  s->port_capacity = INIT_PORT_CAP;
  return s;
}

static void
finish_shutdown (grpc_exec_ctx * exec_ctx, grpc_tcp_server * s)
{
  grpc_closure_list_add (closure_list, s->shutdown_complete, 1);

  gpr_mu_destroy (&s->mu);

  gpr_free (s->ports);
  gpr_free (s);
}

static void
destroyed_port (grpc_exec_ctx * exec_ctx, void *server, int success)
{
  grpc_tcp_server *s = server;
  gpr_mu_lock (&s->mu);
  s->destroyed_ports++;
  if (s->destroyed_ports == s->nports)
    {
      gpr_mu_unlock (&s->mu);
      finish_shutdown (exec_ctx, s);
    }
  else
    {
      GPR_ASSERT (s->destroyed_ports < s->nports);
      gpr_mu_unlock (&s->mu);
    }
}

/* called when all listening endpoints have been shutdown, so no further
   events will be received on them - at this point it's safe to destroy
   things */
static void
deactivated_all_ports (grpc_exec_ctx * exec_ctx, grpc_tcp_server * s)
{
  size_t i;

  /* delete ALL the things */
  gpr_mu_lock (&s->mu);

  if (!s->shutdown)
    {
      gpr_mu_unlock (&s->mu);
      return;
    }

  if (s->nports)
    {
      for (i = 0; i < s->nports; i++)
	{
	  server_port *sp = &s->ports[i];
	  if (sp->addr.sockaddr.sa_family == AF_UNIX)
	    {
	      unlink_if_unix_domain_socket (&sp->addr.un);
	    }
	  sp->destroyed_closure.cb = destroyed_port;
	  sp->destroyed_closure.cb_arg = s;
	  grpc_fd_orphan (exec_ctx, sp->emfd, &sp->destroyed_closure, "tcp_listener_shutdown");
	}
      gpr_mu_unlock (&s->mu);
    }
  else
    {
      gpr_mu_unlock (&s->mu);
      finish_shutdown (exec_ctx, s);
    }
}

void
grpc_tcp_server_destroy (grpc_exec_ctx * exec_ctx, grpc_tcp_server * s, grpc_closure * closure)
{
  size_t i;
  gpr_mu_lock (&s->mu);

  GPR_ASSERT (!s->shutdown);
  s->shutdown = 1;

  s->shutdown_complete = closure;

  /* shutdown all fd's */
  if (s->active_ports)
    {
      for (i = 0; i < s->nports; i++)
	{
	  grpc_fd_shutdown (exec_ctx, s->ports[i].emfd);
	}
      gpr_mu_unlock (&s->mu);
    }
  else
    {
      gpr_mu_unlock (&s->mu);
      deactivated_all_ports (exec_ctx, s);
    }
}

/* get max listen queue size on linux */
static void
init_max_accept_queue_size (void)
{
  int n = SOMAXCONN;
  char buf[64];
  FILE *fp = fopen ("/proc/sys/net/core/somaxconn", "r");
  if (fp == NULL)
    {
      /* 2.4 kernel. */
      s_max_accept_queue_size = SOMAXCONN;
      return;
    }
  if (fgets (buf, sizeof buf, fp))
    {
      char *end;
      long i = strtol (buf, &end, 10);
      if (i > 0 && i <= INT_MAX && end && *end == 0)
	{
	  n = (int) i;
	}
    }
  fclose (fp);
  s_max_accept_queue_size = n;

  if (s_max_accept_queue_size < MIN_SAFE_ACCEPT_QUEUE_SIZE)
    {
      gpr_log (GPR_INFO, "Suspiciously small accept queue (%d) will probably lead to " "connection drops", s_max_accept_queue_size);
    }
}

static int
get_max_accept_queue_size (void)
{
  gpr_once_init (&s_init_max_accept_queue_size, init_max_accept_queue_size);
  return s_max_accept_queue_size;
}

/* Prepare a recently-created socket for listening. */
static int
prepare_socket (int fd, const struct sockaddr *addr, size_t addr_len)
{
  struct sockaddr_storage sockname_temp;
  socklen_t sockname_len;

  if (fd < 0)
    {
      goto error;
    }

  if (!grpc_set_socket_nonblocking (fd, 1) || !grpc_set_socket_cloexec (fd, 1) || (addr->sa_family != AF_UNIX && (!grpc_set_socket_low_latency (fd, 1) || !grpc_set_socket_reuse_addr (fd, 1))) || !grpc_set_socket_no_sigpipe_if_possible (fd))
    {
      gpr_log (GPR_ERROR, "Unable to configure socket %d: %s", fd, strerror (errno));
      goto error;
    }

  GPR_ASSERT (addr_len < ~(socklen_t) 0);
  if (bind (fd, addr, (socklen_t) addr_len) < 0)
    {
      char *addr_str;
      grpc_sockaddr_to_string (&addr_str, addr, 0);
      gpr_log (GPR_ERROR, "bind addr=%s: %s", addr_str, strerror (errno));
      gpr_free (addr_str);
      goto error;
    }

  if (listen (fd, get_max_accept_queue_size ()) < 0)
    {
      gpr_log (GPR_ERROR, "listen: %s", strerror (errno));
      goto error;
    }

  sockname_len = sizeof (sockname_temp);
  if (getsockname (fd, (struct sockaddr *) &sockname_temp, &sockname_len) < 0)
    {
      goto error;
    }

  return grpc_sockaddr_get_port ((struct sockaddr *) &sockname_temp);

error:
  if (fd >= 0)
    {
      close (fd);
    }
  return -1;
}

/* event manager callback when reads are ready */
static void
on_read (grpc_exec_ctx * exec_ctx, void *arg, int success)
{
  server_port *sp = arg;
  grpc_fd *fdobj;
  size_t i;

  if (!success)
    {
      goto error;
    }

  /* loop until accept4 returns EAGAIN, and then re-arm notification */
  for (;;)
    {
      struct sockaddr_storage addr;
      socklen_t addrlen = sizeof (addr);
      char *addr_str;
      char *name;
      /* Note: If we ever decide to return this address to the user, remember to
         strip off the ::ffff:0.0.0.0/96 prefix first. */
      int fd = grpc_accept4 (sp->fd, (struct sockaddr *) &addr, &addrlen, 1, 1);
      if (fd < 0)
	{
	  switch (errno)
	    {
	    case EINTR:
	      continue;
	    case EAGAIN:
	      grpc_fd_notify_on_read (exec_ctx, sp->emfd, &sp->read_closure);
	      return;
	    default:
	      gpr_log (GPR_ERROR, "Failed accept4: %s", strerror (errno));
	      goto error;
	    }
	}

      grpc_set_socket_no_sigpipe_if_possible (fd);

      addr_str = grpc_sockaddr_to_uri ((struct sockaddr *) &addr);
      gpr_asprintf (&name, "tcp-server-connection:%s", addr_str);

      if (grpc_tcp_trace)
	{
	  gpr_log (GPR_DEBUG, "SERVER_CONNECT: incoming connection: %s", addr_str);
	}

      fdobj = grpc_fd_create (fd, name);
      /* TODO(ctiller): revise this when we have server-side sharding
         of channels -- we certainly should not be automatically adding every
         incoming channel to every pollset owned by the server */
      for (i = 0; i < sp->server->pollset_count; i++)
	{
	  grpc_pollset_add_fd (exec_ctx, sp->server->pollsets[i], fdobj);
	}
      sp->server->on_accept_cb (sp->server->on_accept_cb_arg, grpc_tcp_create (exec_ctx, fdobj, GRPC_TCP_DEFAULT_READ_SLICE_SIZE, addr_str));

      gpr_free (name);
      gpr_free (addr_str);
    }

  abort ();

error:
  gpr_mu_lock (&sp->server->mu);
  if (0 == --sp->server->active_ports)
    {
      gpr_mu_unlock (&sp->server->mu);
      deactivated_all_ports (exec_ctx, sp->server);
    }
  else
    {
      gpr_mu_unlock (&sp->server->mu);
    }
}

static int
add_socket_to_server (grpc_tcp_server * s, int fd, const struct sockaddr *addr, size_t addr_len)
{
  server_port *sp;
  int port;
  char *addr_str;
  char *name;

  port = prepare_socket (fd, addr, addr_len);
  if (port >= 0)
    {
      grpc_sockaddr_to_string (&addr_str, (struct sockaddr *) &addr, 1);
      gpr_asprintf (&name, "tcp-server-listener:%s", addr_str);
      gpr_mu_lock (&s->mu);
      GPR_ASSERT (!s->on_accept_cb && "must add ports before starting server");
      /* append it to the list under a lock */
      if (s->nports == s->port_capacity)
	{
	  s->port_capacity *= 2;
	  s->ports = gpr_realloc (s->ports, sizeof (server_port) * s->port_capacity);
	}
      sp = &s->ports[s->nports++];
      sp->server = s;
      sp->fd = fd;
      sp->emfd = grpc_fd_create (fd, name);
      memcpy (sp->addr.untyped, addr, addr_len);
      sp->addr_len = addr_len;
      GPR_ASSERT (sp->emfd);
      gpr_mu_unlock (&s->mu);
      gpr_free (addr_str);
      gpr_free (name);
    }

  return port;
}

int
grpc_tcp_server_add_port (grpc_tcp_server * s, const void *addr, size_t addr_len)
{
  int allocated_port1 = -1;
  int allocated_port2 = -1;
  unsigned i;
  int fd;
  grpc_dualstack_mode dsmode;
  struct sockaddr_in6 addr6_v4mapped;
  struct sockaddr_in wild4;
  struct sockaddr_in6 wild6;
  struct sockaddr_in addr4_copy;
  struct sockaddr *allocated_addr = NULL;
  struct sockaddr_storage sockname_temp;
  socklen_t sockname_len;
  int port;

  if (((struct sockaddr *) addr)->sa_family == AF_UNIX)
    {
      unlink_if_unix_domain_socket (addr);
    }

  /* Check if this is a wildcard port, and if so, try to keep the port the same
     as some previously created listener. */
  if (grpc_sockaddr_get_port (addr) == 0)
    {
      for (i = 0; i < s->nports; i++)
	{
	  sockname_len = sizeof (sockname_temp);
	  if (0 == getsockname (s->ports[i].fd, (struct sockaddr *) &sockname_temp, &sockname_len))
	    {
	      port = grpc_sockaddr_get_port ((struct sockaddr *) &sockname_temp);
	      if (port > 0)
		{
		  allocated_addr = malloc (addr_len);
		  memcpy (allocated_addr, addr, addr_len);
		  grpc_sockaddr_set_port (allocated_addr, port);
		  addr = allocated_addr;
		  break;
		}
	    }
	}
    }

  if (grpc_sockaddr_to_v4mapped (addr, &addr6_v4mapped))
    {
      addr = (const struct sockaddr *) &addr6_v4mapped;
      addr_len = sizeof (addr6_v4mapped);
    }

  /* Treat :: or 0.0.0.0 as a family-agnostic wildcard. */
  if (grpc_sockaddr_is_wildcard (addr, &port))
    {
      grpc_sockaddr_make_wildcards (port, &wild4, &wild6);

      /* Try listening on IPv6 first. */
      addr = (struct sockaddr *) &wild6;
      addr_len = sizeof (wild6);
      fd = grpc_create_dualstack_socket (addr, SOCK_STREAM, 0, &dsmode);
      allocated_port1 = add_socket_to_server (s, fd, addr, addr_len);
      if (fd >= 0 && dsmode == GRPC_DSMODE_DUALSTACK)
	{
	  goto done;
	}

      /* If we didn't get a dualstack socket, also listen on 0.0.0.0. */
      if (port == 0 && allocated_port1 > 0)
	{
	  grpc_sockaddr_set_port ((struct sockaddr *) &wild4, allocated_port1);
	}
      addr = (struct sockaddr *) &wild4;
      addr_len = sizeof (wild4);
    }

  fd = grpc_create_dualstack_socket (addr, SOCK_STREAM, 0, &dsmode);
  if (fd < 0)
    {
      gpr_log (GPR_ERROR, "Unable to create socket: %s", strerror (errno));
    }
  if (dsmode == GRPC_DSMODE_IPV4 && grpc_sockaddr_is_v4mapped (addr, &addr4_copy))
    {
      addr = (struct sockaddr *) &addr4_copy;
      addr_len = sizeof (addr4_copy);
    }
  allocated_port2 = add_socket_to_server (s, fd, addr, addr_len);

done:
  gpr_free (allocated_addr);
  return allocated_port1 >= 0 ? allocated_port1 : allocated_port2;
}

int
grpc_tcp_server_get_fd (grpc_tcp_server * s, unsigned index)
{
  return (index < s->nports) ? s->ports[index].fd : -1;
}

void
grpc_tcp_server_start (grpc_exec_ctx * exec_ctx, grpc_tcp_server * s, grpc_pollset ** pollsets, size_t pollset_count, grpc_tcp_server_cb on_accept_cb, void *on_accept_cb_arg)
{
  size_t i, j;
  GPR_ASSERT (on_accept_cb);
  gpr_mu_lock (&s->mu);
  GPR_ASSERT (!s->on_accept_cb);
  GPR_ASSERT (s->active_ports == 0);
  s->on_accept_cb = on_accept_cb;
  s->on_accept_cb_arg = on_accept_cb_arg;
  s->pollsets = pollsets;
  s->pollset_count = pollset_count;
  for (i = 0; i < s->nports; i++)
    {
      for (j = 0; j < pollset_count; j++)
	{
	  grpc_pollset_add_fd (exec_ctx, pollsets[j], s->ports[i].emfd);
	}
      s->ports[i].read_closure.cb = on_read;
      s->ports[i].read_closure.cb_arg = &s->ports[i];
      grpc_fd_notify_on_read (exec_ctx, s->ports[i].emfd, &s->ports[i].read_closure);
      s->active_ports++;
    }
  gpr_mu_unlock (&s->mu);
}

#endif