text: /*
   *
   * Copyright 2015 gRPC authors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   */
  
  #include <grpc/support/port_platform.h>
  
  #include "src/core/lib/iomgr/port.h"
  
  #ifdef GRPC_POSIX_SOCKET_TCP_CLIENT
  
  #include <errno.h>
  #include <netinet/in.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "absl/strings/str_cat.h"
  
  #include <grpc/support/alloc.h>
  #include <grpc/support/log.h>
  #include <grpc/support/time.h>
  
  #include "src/core/lib/address_utils/sockaddr_utils.h"
  #include "src/core/lib/channel/channel_args.h"
  #include "src/core/lib/gpr/string.h"
  #include "src/core/lib/iomgr/ev_posix.h"
  #include "src/core/lib/iomgr/executor.h"
  #include "src/core/lib/iomgr/iomgr_internal.h"
  #include "src/core/lib/iomgr/sockaddr.h"
  #include "src/core/lib/iomgr/socket_mutator.h"
  #include "src/core/lib/iomgr/socket_utils_posix.h"
  #include "src/core/lib/iomgr/tcp_client_posix.h"
  #include "src/core/lib/iomgr/tcp_posix.h"
  #include "src/core/lib/iomgr/timer.h"
  #include "src/core/lib/iomgr/unix_sockets_posix.h"
  #include "src/core/lib/slice/slice_internal.h"
  
  extern grpc_core::TraceFlag grpc_tcp_trace;
  
  struct async_connect {
    gpr_mu mu;
    grpc_fd* fd;
    grpc_timer alarm;
    grpc_closure on_alarm;
    int refs;
    grpc_closure write_closure;
    grpc_pollset_set* interested_parties;
    std::string addr_str;
    grpc_endpoint** ep;
    grpc_closure* closure;
    grpc_channel_args* channel_args;
    grpc_slice_allocator* slice_allocator;
  };
  
  static grpc_error_handle prepare_socket(const grpc_resolved_address* addr,
                                          int fd,
                                          const grpc_channel_args* channel_args) {
    grpc_error_handle err = GRPC_ERROR_NONE;
  
    GPR_ASSERT(fd >= 0);
  
    err = grpc_set_socket_nonblocking(fd, 1);
    if (err != GRPC_ERROR_NONE) goto error;
    err = grpc_set_socket_cloexec(fd, 1);
    if (err != GRPC_ERROR_NONE) goto error;
    if (!grpc_is_unix_socket(addr)) {
      err = grpc_set_socket_low_latency(fd, 1);
      if (err != GRPC_ERROR_NONE) goto error;
      err = grpc_set_socket_reuse_addr(fd, 1);
      if (err != GRPC_ERROR_NONE) goto error;
      err = grpc_set_socket_tcp_user_timeout(fd, channel_args,
                                             true /* is_client */);
      if (err != GRPC_ERROR_NONE) goto error;
    }
    err = grpc_set_socket_no_sigpipe_if_possible(fd);
    if (err != GRPC_ERROR_NONE) goto error;
  
    err = grpc_apply_socket_mutator_in_args(fd, GRPC_FD_CLIENT_CONNECTION_USAGE,
                                            channel_args);
    if (err != GRPC_ERROR_NONE) goto error;
  
    goto done;
  
  error:
    if (fd >= 0) {
      close(fd);
    }
  done:
    return err;
  }
  
  static void tc_on_alarm(void* acp, grpc_error_handle error) {
    int done;
    async_connect* ac = static_cast<async_connect*>(acp);
    if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
      gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: on_alarm: error=%s",
              ac->addr_str.c_str(), grpc_error_std_string(error).c_str());
    }
    gpr_mu_lock(&ac->mu);
    if (ac->fd != nullptr) {
      grpc_fd_shutdown(
          ac->fd, GRPC_ERROR_CREATE_FROM_STATIC_STRING("connect() timed out"));
    }
    done = (--ac->refs == 0);
    gpr_mu_unlock(&ac->mu);
    if (done) {
      gpr_mu_destroy(&ac->mu);
      if (ac->slice_allocator != nullptr) {
        grpc_slice_allocator_destroy(ac->slice_allocator);
      }
      grpc_channel_args_destroy(ac->channel_args);
      delete ac;
    }
  }
  
  grpc_endpoint* grpc_tcp_client_create_from_fd(
      grpc_fd* fd, const grpc_channel_args* channel_args,
      absl::string_view addr_str, grpc_slice_allocator* slice_allocator) {
    return grpc_tcp_create(fd, channel_args, addr_str, slice_allocator);
  }
  
  static void on_writable(void* acp, grpc_error_handle error) {
    async_connect* ac = static_cast<async_connect*>(acp);
    int so_error = 0;
    socklen_t so_error_size;
    int err;
    int done;
    grpc_endpoint** ep = ac->ep;
    grpc_closure* closure = ac->closure;
    grpc_fd* fd;
  
    (void)GRPC_ERROR_REF(error);
  
    if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
      gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: on_writable: error=%s",
              ac->addr_str.c_str(), grpc_error_std_string(error).c_str());
    }
  
    gpr_mu_lock(&ac->mu);
    GPR_ASSERT(ac->fd);
    fd = ac->fd;
    ac->fd = nullptr;
    gpr_mu_unlock(&ac->mu);
  
    grpc_timer_cancel(&ac->alarm);
  
    gpr_mu_lock(&ac->mu);
    if (error != GRPC_ERROR_NONE) {
      error =
          grpc_error_set_str(error, GRPC_ERROR_STR_OS_ERROR, "Timeout occurred");
      goto finish;
    }
  
    do {
      so_error_size = sizeof(so_error);
      err = getsockopt(grpc_fd_wrapped_fd(fd), SOL_SOCKET, SO_ERROR, &so_error,
                       &so_error_size);
    } while (err < 0 && errno == EINTR);
    if (err < 0) {
      error = GRPC_OS_ERROR(errno, "getsockopt");
      goto finish;
    }
  
    switch (so_error) {
      case 0:
        grpc_pollset_set_del_fd(ac->interested_parties, fd);
        *ep = grpc_tcp_client_create_from_fd(fd, ac->channel_args, ac->addr_str,
                                             ac->slice_allocator);
        ac->slice_allocator = nullptr;
        fd = nullptr;
        break;
      case ENOBUFS:
        /* We will get one of these errors if we have run out of
           memory in the kernel for the data structures allocated
           when you connect a socket.  If this happens it is very
           likely that if we wait a little bit then try again the
           connection will work (since other programs or this
           program will close their network connections and free up
           memory).  This does _not_ indicate that there is anything
           wrong with the server we are connecting to, this is a
           local problem.
  
           If you are looking at this code, then chances are that
           your program or another program on the same computer
           opened too many network connections.  The "easy" fix:
           don't do that! */
        gpr_log(GPR_ERROR, "kernel out of buffers");
        gpr_mu_unlock(&ac->mu);
        grpc_fd_notify_on_write(fd, &ac->write_closure);
        return;
      case ECONNREFUSED:
        /* This error shouldn't happen for anything other than connect(). */
        error = GRPC_OS_ERROR(so_error, "connect");
        break;
      default:
        /* We don't really know which syscall triggered the problem here,
           so punt by reporting getsockopt(). */
        error = GRPC_OS_ERROR(so_error, "getsockopt(SO_ERROR)");
        break;
    }
  
  finish:
    if (fd != nullptr) {
      grpc_pollset_set_del_fd(ac->interested_parties, fd);
      grpc_fd_orphan(fd, nullptr, nullptr, "tcp_client_orphan");
      fd = nullptr;
    }
    done = (--ac->refs == 0);
    gpr_mu_unlock(&ac->mu);
    if (error != GRPC_ERROR_NONE) {
      std::string str;
      bool ret = grpc_error_get_str(error, GRPC_ERROR_STR_DESCRIPTION, &str);
      GPR_ASSERT(ret);
      std::string description =
          absl::StrCat("Failed to connect to remote host: ", str);
      error = grpc_error_set_str(error, GRPC_ERROR_STR_DESCRIPTION, description);
      error =
          grpc_error_set_str(error, GRPC_ERROR_STR_TARGET_ADDRESS, ac->addr_str);
    }
    if (done) {
      // This is safe even outside the lock, because "done", the sentinel, is
      // populated *inside* the lock.
      gpr_mu_destroy(&ac->mu);
      if (ac->slice_allocator != nullptr) {
        grpc_slice_allocator_destroy(ac->slice_allocator);
        ac->slice_allocator = nullptr;
      }
      grpc_channel_args_destroy(ac->channel_args);
      delete ac;
    }
    // Push async connect closure to the executor since this may actually be
    // called during the shutdown process, in which case a deadlock could form
    // between the core shutdown mu and the connector mu (b/188239051)
    grpc_core::Executor::Run(closure, error);
  }
  
  grpc_error_handle grpc_tcp_client_prepare_fd(
      const grpc_channel_args* channel_args, const grpc_resolved_address* addr,
      grpc_resolved_address* mapped_addr, int* fd) {
    grpc_dualstack_mode dsmode;
    grpc_error_handle error;
    *fd = -1;
    /* Use dualstack sockets where available. Set mapped to v6 or v4 mapped to
       v6. */
    if (!grpc_sockaddr_to_v4mapped(addr, mapped_addr)) {
      /* addr is v4 mapped to v6 or v6. */
      memcpy(mapped_addr, addr, sizeof(*mapped_addr));
    }
    error =
        grpc_create_dualstack_socket(mapped_addr, SOCK_STREAM, 0, &dsmode, fd);
    if (error != GRPC_ERROR_NONE) {
      return error;
    }
    if (dsmode == GRPC_DSMODE_IPV4) {
      /* Original addr is either v4 or v4 mapped to v6. Set mapped_addr to v4. */
      if (!grpc_sockaddr_is_v4mapped(addr, mapped_addr)) {
        memcpy(mapped_addr, addr, sizeof(*mapped_addr));
      }
    }
    if ((error = prepare_socket(mapped_addr, *fd, channel_args)) !=
        GRPC_ERROR_NONE) {
      return error;
    }
    return GRPC_ERROR_NONE;
  }
  
  void grpc_tcp_client_create_from_prepared_fd(
      grpc_pollset_set* interested_parties, grpc_closure* closure, const int fd,
      const grpc_channel_args* channel_args, const grpc_resolved_address* addr,
      grpc_millis deadline, grpc_endpoint** ep,
      grpc_slice_allocator* slice_allocator) {
    int err;
    do {
      err = connect(fd, reinterpret_cast<const grpc_sockaddr*>(addr->addr),
                    addr->len);
    } while (err < 0 && errno == EINTR);
  
    std::string name = absl::StrCat("tcp-client:", grpc_sockaddr_to_uri(addr));
    grpc_fd* fdobj = grpc_fd_create(fd, name.c_str(), true);
  
    if (err >= 0) {
      *ep = grpc_tcp_client_create_from_fd(
          fdobj, channel_args, grpc_sockaddr_to_uri(addr), slice_allocator);
      grpc_core::ExecCtx::Run(DEBUG_LOCATION, closure, GRPC_ERROR_NONE);
      return;
    }
    if (errno != EWOULDBLOCK && errno != EINPROGRESS) {
      grpc_slice_allocator_destroy(slice_allocator);
      grpc_error_handle error = GRPC_OS_ERROR(errno, "connect");
      error = grpc_error_set_str(error, GRPC_ERROR_STR_TARGET_ADDRESS,
                                 grpc_sockaddr_to_uri(addr));
      grpc_fd_orphan(fdobj, nullptr, nullptr, "tcp_client_connect_error");
      grpc_core::ExecCtx::Run(DEBUG_LOCATION, closure, error);
      return;
    }
  
    grpc_pollset_set_add_fd(interested_parties, fdobj);
  
    async_connect* ac = new async_connect();
    ac->closure = closure;
    ac->ep = ep;
    ac->fd = fdobj;
    ac->interested_parties = interested_parties;
    ac->addr_str = grpc_sockaddr_to_uri(addr);
    gpr_mu_init(&ac->mu);
    ac->refs = 2;
    ac->slice_allocator = slice_allocator;
    GRPC_CLOSURE_INIT(&ac->write_closure, on_writable, ac,
                      grpc_schedule_on_exec_ctx);
    ac->channel_args = grpc_channel_args_copy(channel_args);
  
    if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
      gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: asynchronously connecting fd %p",
              ac->addr_str.c_str(), fdobj);
    }
  
    gpr_mu_lock(&ac->mu);
    GRPC_CLOSURE_INIT(&ac->on_alarm, tc_on_alarm, ac, grpc_schedule_on_exec_ctx);
    grpc_timer_init(&ac->alarm, deadline, &ac->on_alarm);
    grpc_fd_notify_on_write(ac->fd, &ac->write_closure);
    gpr_mu_unlock(&ac->mu);
  }
  
  static void tcp_connect(grpc_closure* closure, grpc_endpoint** ep,
                          grpc_slice_allocator* slice_allocator,
                          grpc_pollset_set* interested_parties,
                          const grpc_channel_args* channel_args,
                          const grpc_resolved_address* addr,
                          grpc_millis deadline) {
    grpc_resolved_address mapped_addr;
    int fd = -1;
    grpc_error_handle error;
    *ep = nullptr;
    if ((error = grpc_tcp_client_prepare_fd(channel_args, addr, &mapped_addr,
                                            &fd)) != GRPC_ERROR_NONE) {
      grpc_slice_allocator_destroy(slice_allocator);
      grpc_core::ExecCtx::Run(DEBUG_LOCATION, closure, error);
      return;
    }
    grpc_tcp_client_create_from_prepared_fd(interested_parties, closure, fd,
                                            channel_args, &mapped_addr, deadline,
                                            ep, slice_allocator);
  }
  
  grpc_tcp_client_vtable grpc_posix_tcp_client_vtable = {tcp_connect};
  #endif
  