// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// 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
//
//     https://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 <openssl/bio.h>

#if !defined(OPENSSL_NO_SOCK)

#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <string.h>

#if !defined(OPENSSL_WINDOWS)
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#else
#include <winsock2.h>
#include <ws2tcpip.h>
#endif

#include <algorithm>
#include <utility>

#include <openssl/err.h>
#include <openssl/mem.h>

#include "../internal.h"
#include "../mem_internal.h"
#include "internal.h"


using namespace bssl;

enum {
  BIO_CONN_S_BEFORE,
  BIO_CONN_S_BLOCKED_CONNECT,
  BIO_CONN_S_OK,
};

namespace {
struct BIO_CONNECT {
  int state = BIO_CONN_S_BEFORE;

  UniquePtr<char> param_hostname;
  UniquePtr<char> param_port;
  int nbio = 0;

  unsigned short port = 0;

  sockaddr_storage them;
  socklen_t them_length = 0;

  // The file descriptor is kept in bio->num in order to match the socket BIO.

  // info_callback is called when the connection is initially made
  // callback(BIO,state,ret);  The callback should return 'ret', state is for
  // compatibility with the SSL info_callback.
  int (*info_callback)(BIO *bio, int state, int ret) = nullptr;
};
}  // namespace

#if !defined(OPENSSL_WINDOWS)
static int closesocket(int sock) { return close(sock); }
#endif

// split_host_and_port sets `*out_host` and `*out_port` to the host and port
// parsed from `name`. It returns one on success or zero on error. Even when
// successful, `*out_port` may be NULL on return if no port was specified.
static int split_host_and_port(UniquePtr<char> *out_host,
                               UniquePtr<char> *out_port, const char *name) {
  const char *host, *port = nullptr;
  size_t host_len = 0;

  *out_host = nullptr;
  *out_port = nullptr;

  if (name[0] == '[') {  // bracketed IPv6 address
    const char *close = strchr(name, ']');
    if (close == nullptr) {
      return 0;
    }
    host = name + 1;
    host_len = close - host;
    if (close[1] == ':') {  // [IP]:port
      port = close + 2;
    } else if (close[1] != 0) {
      return 0;
    }
  } else {
    const char *colon = strchr(name, ':');
    if (colon == nullptr ||
        strchr(colon + 1, ':') != nullptr) {  // IPv6 address
      host = name;
      host_len = strlen(name);
    } else {  // host:port
      host = name;
      host_len = colon - name;
      port = colon + 1;
    }
  }

  out_host->reset(OPENSSL_strndup(host, host_len));
  if (*out_host == nullptr) {
    return 0;
  }
  if (port == nullptr) {
    *out_port = nullptr;
    return 1;
  }
  out_port->reset(OPENSSL_strdup(port));
  if (*out_port == nullptr) {
    *out_host = nullptr;
    return 0;
  }
  return 1;
}

static int conn_state(BIO *bio, BIO_CONNECT *c) {
  int ret = -1, i;
  int (*cb)(BIO *, int, int) = nullptr;

  if (c->info_callback != nullptr) {
    cb = c->info_callback;
  }

  for (;;) {
    switch (c->state) {
      case BIO_CONN_S_BEFORE:
        // If there's a hostname and a port, assume that both are
        // exactly what they say. If there is only a hostname, try
        // (just once) to split it into a hostname and port.

        if (c->param_hostname == nullptr) {
          OPENSSL_PUT_ERROR(BIO, BIO_R_NO_HOSTNAME_SPECIFIED);
          goto exit_loop;
        }

        if (c->param_port == nullptr) {
          UniquePtr<char> host, port;
          if (!split_host_and_port(&host, &port, c->param_hostname.get()) ||
              port == nullptr) {
            OPENSSL_PUT_ERROR(BIO, BIO_R_NO_PORT_SPECIFIED);
            ERR_add_error_data(2, "host=", c->param_hostname.get());
            goto exit_loop;
          }

          c->param_port = std::move(port);
          c->param_hostname = std::move(host);
        }

        if (!bio_ip_and_port_to_socket_and_addr(
                &FromOpaque(bio)->num, &c->them, &c->them_length,
                c->param_hostname.get(), c->param_port.get())) {
          OPENSSL_PUT_ERROR(BIO, BIO_R_UNABLE_TO_CREATE_SOCKET);
          ERR_add_error_data(4, "host=", c->param_hostname.get(), ":",
                             c->param_port.get());
          goto exit_loop;
        }

        if (c->nbio) {
          if (!bio_socket_nbio(FromOpaque(bio)->num, 1)) {
            OPENSSL_PUT_ERROR(BIO, BIO_R_ERROR_SETTING_NBIO);
            ERR_add_error_data(4, "host=", c->param_hostname.get(), ":",
                               c->param_port.get());
            goto exit_loop;
          }
        }

        i = 1;
        ret = setsockopt(FromOpaque(bio)->num, SOL_SOCKET, SO_KEEPALIVE,
                         (char *)&i, sizeof(i));
        if (ret < 0) {
          OPENSSL_PUT_SYSTEM_ERROR();
          OPENSSL_PUT_ERROR(BIO, BIO_R_KEEPALIVE);
          ERR_add_error_data(4, "host=", c->param_hostname.get(), ":",
                             c->param_port.get());
          goto exit_loop;
        }

        BIO_clear_retry_flags(bio);
        ret = connect(FromOpaque(bio)->num, (struct sockaddr *)&c->them,
                      c->them_length);
        if (ret < 0) {
          if (bio_socket_should_retry(ret)) {
            BIO_set_retry_special(bio);
            c->state = BIO_CONN_S_BLOCKED_CONNECT;
            BIO_set_retry_reason(bio, BIO_RR_CONNECT);
          } else {
            OPENSSL_PUT_SYSTEM_ERROR();
            OPENSSL_PUT_ERROR(BIO, BIO_R_CONNECT_ERROR);
            ERR_add_error_data(4, "host=", c->param_hostname.get(), ":",
                               c->param_port.get());
          }
          goto exit_loop;
        } else {
          c->state = BIO_CONN_S_OK;
        }
        break;

      case BIO_CONN_S_BLOCKED_CONNECT:
        if (!bio_socket_finish_connect(FromOpaque(bio)->num)) {
          if (bio_socket_should_retry(-1)) {
            BIO_set_retry_special(bio);
            c->state = BIO_CONN_S_BLOCKED_CONNECT;
            BIO_set_retry_reason(bio, BIO_RR_CONNECT);
          } else {
            BIO_clear_retry_flags(bio);
            OPENSSL_PUT_SYSTEM_ERROR();
            OPENSSL_PUT_ERROR(BIO, BIO_R_NBIO_CONNECT_ERROR);
            ERR_add_error_data(4, "host=", c->param_hostname.get(), ":",
                               c->param_port.get());
          }
          ret = -1;
          goto exit_loop;
        } else {
          c->state = BIO_CONN_S_OK;
        }
        break;

      case BIO_CONN_S_OK:
        ret = 1;
        goto exit_loop;
      default:
        assert(0);
        goto exit_loop;
    }

    if (cb != nullptr) {
      ret = cb((BIO *)bio, c->state, ret);
      if (ret == 0) {
        goto end;
      }
    }
  }

exit_loop:
  if (cb != nullptr) {
    ret = cb((BIO *)bio, c->state, ret);
  }

end:
  return ret;
}

static int conn_new(BIO *bio) {
  BIO_set_init(bio, 0);
  FromOpaque(bio)->num = -1;
  FromOpaque(bio)->flags = 0;
  BIO_set_data(bio, New<BIO_CONNECT>());
  return BIO_get_data(bio) != nullptr;
}

static void conn_close_socket(BIO *bio) {
  BIO_CONNECT *c = (BIO_CONNECT *)BIO_get_data(bio);

  if (FromOpaque(bio)->num == -1) {
    return;
  }

  // Only do a shutdown if things were established
  if (c->state == BIO_CONN_S_OK) {
    shutdown(FromOpaque(bio)->num, 2);
  }
  closesocket(FromOpaque(bio)->num);
  FromOpaque(bio)->num = -1;
}

static int conn_free(BIO *bio) {
  if (BIO_get_shutdown(bio)) {
    conn_close_socket(bio);
  }

  Delete(static_cast<BIO_CONNECT *>(BIO_get_data(bio)));
  return 1;
}

static int conn_read(BIO *bio, char *out, int out_len) {
  int ret = 0;
  BIO_CONNECT *data;

  data = (BIO_CONNECT *)BIO_get_data(bio);
  if (data->state != BIO_CONN_S_OK) {
    ret = conn_state(bio, data);
    if (ret <= 0) {
      return ret;
    }
  }

  bio_clear_socket_error();
  ret = (int)recv(FromOpaque(bio)->num, out, out_len, 0);
  BIO_clear_retry_flags(bio);
  if (ret <= 0) {
    if (bio_socket_should_retry(ret)) {
      BIO_set_retry_read(bio);
    }
  }

  return ret;
}

static int conn_write_ex(BIO *bio, const char *in, size_t in_len,
                         size_t *out_written) {
  BIO_CONNECT *data = (BIO_CONNECT *)BIO_get_data(bio);
  if (data->state != BIO_CONN_S_OK) {
    if (conn_state(bio, data) <= 0) {
      return 0;
    }
  }

  bio_clear_socket_error();
#if defined(OPENSSL_WINDOWS)
  in_len = std::min(in_len, size_t{INT_MAX});
  int ret = send(FromOpaque(bio)->num, in, static_cast<int>(in_len), 0);
#else
  ssize_t ret = send(FromOpaque(bio)->num, in, in_len, 0);
#endif
  BIO_clear_retry_flags(bio);
  if (ret <= 0) {
    if (bio_socket_should_retry(ret)) {
      BIO_set_retry_write(bio);
    }
    return 0;
  }

  *out_written = ret;
  return 1;
}

static long conn_ctrl(BIO *bio, int cmd, long num, void *ptr) {
  BIO_CONNECT *data = static_cast<BIO_CONNECT *>(BIO_get_data(bio));
  switch (cmd) {
    case BIO_CTRL_RESET:
      data->state = BIO_CONN_S_BEFORE;
      conn_close_socket(bio);
      FromOpaque(bio)->flags = 0;
      return 0;
    case BIO_C_DO_STATE_MACHINE:
      // use this one to start the connection
      if (data->state != BIO_CONN_S_OK) {
        return conn_state(bio, data);
      } else {
        return 1;
      }
    case BIO_C_SET_CONNECT:
      if (ptr == nullptr) {
        return 0;
      }
      BIO_set_init(bio, 1);
      if (num == 0) {
        data->param_hostname.reset(
            OPENSSL_strdup(reinterpret_cast<const char *>(ptr)));
        if (data->param_hostname == nullptr) {
          return 0;
        }
      } else if (num == 1) {
        data->param_port.reset(
            OPENSSL_strdup(reinterpret_cast<const char *>(ptr)));
        if (data->param_port == nullptr) {
          return 0;
        }
      } else {
        return 0;
      }
      return 1;
    case BIO_C_SET_NBIO:
      data->nbio = static_cast<int>(num);
      return 1;
    case BIO_C_GET_FD:
      if (BIO_get_init(bio)) {
        int *out = static_cast<int *>(ptr);
        if (out != nullptr) {
          *out = FromOpaque(bio)->num;
        }
        return FromOpaque(bio)->num;
      } else {
        return -1;
      }
    case BIO_CTRL_GET_CLOSE:
      return BIO_get_shutdown(bio);
    case BIO_CTRL_SET_CLOSE:
      BIO_set_shutdown(bio, static_cast<int>(num));
      return 1;
    case BIO_CTRL_FLUSH:
      return 1;
    case BIO_CTRL_GET_CALLBACK: {
      auto out = reinterpret_cast<int (**)(BIO *bio, int state, int xret)>(ptr);
      *out = data->info_callback;
      return 1;
    }
    default:
      return 0;
  }
}

static long conn_callback_ctrl(BIO *bio, int cmd, BIO_info_cb *fp) {
  BIO_CONNECT *data = static_cast<BIO_CONNECT *>(BIO_get_data(bio));
  switch (cmd) {
    case BIO_CTRL_SET_CALLBACK:
      data->info_callback = fp;
      return 1;
    default:
      return 0;
  }
}

BIO *BIO_new_connect(const char *hostname) {
  BIO *ret;

  ret = BIO_new(BIO_s_connect());
  if (ret == nullptr) {
    return nullptr;
  }
  if (!BIO_set_conn_hostname(ret, hostname)) {
    BIO_free(ret);
    return nullptr;
  }
  return ret;
}

static const BIO_METHOD methods_connectp = {
    BIO_TYPE_CONNECT, "socket connect",   /*bwrite=*/nullptr, conn_write_ex,
    conn_read,        /*gets=*/nullptr,   conn_ctrl,          conn_new,
    conn_free,        conn_callback_ctrl,
};

const BIO_METHOD *BIO_s_connect() { return &methods_connectp; }

int BIO_set_conn_hostname(BIO *bio, const char *name) {
  return (int)BIO_ctrl(bio, BIO_C_SET_CONNECT, 0, (void *)name);
}

int BIO_set_conn_port(BIO *bio, const char *port_str) {
  return (int)BIO_ctrl(bio, BIO_C_SET_CONNECT, 1, (void *)port_str);
}

int BIO_set_conn_int_port(BIO *bio, const int *port) {
  char buf[DECIMAL_SIZE(int) + 1];
  snprintf(buf, sizeof(buf), "%d", *port);
  return BIO_set_conn_port(bio, buf);
}

int BIO_set_nbio(BIO *bio, int on) {
  return (int)BIO_ctrl(bio, BIO_C_SET_NBIO, on, nullptr);
}

int BIO_do_connect(BIO *bio) {
  return (int)BIO_ctrl(bio, BIO_C_DO_STATE_MACHINE, 0, nullptr);
}

#endif  // OPENSSL_NO_SOCK