// Copyright 2018 The Crashpad 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
//
//     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 "util/net/http_transport.h"

#include <fcntl.h>
#include <netdb.h>
#include <poll.h>
#include <sys/socket.h>

#include "base/logging.h"
#include "base/macros.h"
#include "base/numerics/safe_conversions.h"
#include "base/posix/eintr_wrapper.h"
#include "base/scoped_generic.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "util/file/file_io.h"
#include "util/net/http_body.h"
#include "util/net/url.h"
#include "util/stdlib/string_number_conversion.h"
#include "util/string/split_string.h"

namespace crashpad {

namespace {

constexpr const char kCRLFTerminator[] = "\r\n";

class HTTPTransportSocket final : public HTTPTransport {
 public:
  HTTPTransportSocket() = default;
  ~HTTPTransportSocket() override = default;

  bool ExecuteSynchronously(std::string* response_body) override;

 private:
  DISALLOW_COPY_AND_ASSIGN(HTTPTransportSocket);
};

struct ScopedAddrinfoTraits {
  static addrinfo* InvalidValue() { return nullptr; }
  static void Free(addrinfo* ai) { freeaddrinfo(ai); }
};
using ScopedAddrinfo =
    base::ScopedGeneric<addrinfo*, ScopedAddrinfoTraits>;

bool WaitUntilSocketIsReady(int sock) {
  pollfd pollfds;
  pollfds.fd = sock;
  pollfds.events = POLLIN | POLLPRI | POLLOUT;
  constexpr int kTimeoutMS = 1000;
  int ret = HANDLE_EINTR(poll(&pollfds, 1, kTimeoutMS));
  if (ret < 0) {
    PLOG(ERROR) << "poll";
    return false;
  } else if (ret == 1) {
    if (pollfds.revents & POLLERR) {
      int err;
      socklen_t err_len = sizeof(err);
      if (getsockopt(sock, SOL_SOCKET, SO_ERROR, &err, &err_len) != 0) {
        PLOG(ERROR) << "getsockopt";
      } else {
        errno = err;
        PLOG(ERROR) << "POLLERR";
      }
      return false;
    }
    if (pollfds.revents & POLLHUP) {
      return false;
    }
    return (pollfds.revents & POLLIN) != 0 || (pollfds.revents & POLLOUT) != 0;
  }

  // Timeout.
  return false;
}

class ScopedSetNonblocking {
 public:
  explicit ScopedSetNonblocking(int sock) : sock_(sock) {
    int flags = fcntl(sock, F_GETFL, 0);
    if (flags < 0) {
      PLOG(ERROR) << "fcntl";
      sock_ = -1;
      return;
    }

    if (fcntl(sock_, F_SETFL, flags | O_NONBLOCK) < 0) {
      PLOG(ERROR) << "fcntl";
      sock_ = -1;
    }
  }

  ~ScopedSetNonblocking() {
    if (sock_ >= 0) {
      int flags = fcntl(sock_, F_GETFL, 0);
      if (flags < 0) {
        PLOG(ERROR) << "fcntl";
        return;
      }

      if (fcntl(sock_, F_SETFL, flags & (~O_NONBLOCK)) < 0) {
        PLOG(ERROR) << "fcntl";
      }
    }
  }

 private:
  int sock_;

  DISALLOW_COPY_AND_ASSIGN(ScopedSetNonblocking);
};

base::ScopedFD CreateSocket(const std::string& hostname,
                            const std::string& port) {
  addrinfo hints = {};
  hints.ai_family = AF_UNSPEC;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_protocol = 0;
  hints.ai_flags = 0;

  addrinfo* addrinfo_raw;
  if (getaddrinfo(hostname.c_str(), port.c_str(), &hints, &addrinfo_raw) < 0) {
    PLOG(ERROR) << "getaddrinfo";
    return base::ScopedFD();
  }
  ScopedAddrinfo addrinfo(addrinfo_raw);

  for (const auto* ap = addrinfo.get(); ap; ap = ap->ai_next) {
    base::ScopedFD result(
        socket(ap->ai_family, ap->ai_socktype, ap->ai_protocol));
    if (!result.is_valid()) {
      continue;
    }

    {
      // Set socket to non-blocking to avoid hanging for a long time if the
      // network is down.
      ScopedSetNonblocking nonblocking(result.get());

      if (HANDLE_EINTR(connect(result.get(), ap->ai_addr, ap->ai_addrlen)) <
          0) {
        if (errno != EINPROGRESS) {
          PLOG(ERROR) << "connect";
        } else if (WaitUntilSocketIsReady(result.get())) {
          return result;
        }
        return base::ScopedFD();
      }

      return result;
    }
  }

  return base::ScopedFD();
}

bool WriteRequest(int sock,
                  const std::string& method,
                  const std::string& resource,
                  const HTTPHeaders& headers,
                  HTTPBodyStream* body_stream) {
  std::string request_line = base::StringPrintf(
      "%s %s HTTP/1.0\r\n", method.c_str(), resource.c_str());
  if (!LoggingWriteFile(sock, request_line.data(), request_line.size()))
    return false;

  // Write headers, and determine if Content-Length has been specified.
  bool chunked = true;
  size_t content_length = 0;
  for (const auto& header : headers) {
    std::string header_str = base::StringPrintf(
        "%s: %s\r\n", header.first.c_str(), header.second.c_str());
    if (header.first == kContentLength) {
      chunked = !base::StringToSizeT(header.second, &content_length);
      DCHECK(!chunked);
    }

    if (!LoggingWriteFile(sock, header_str.data(), header_str.size()))
      return false;
  }

  // If no Content-Length, then encode as chunked, so add that header too.
  if (chunked) {
    static constexpr const char kTransferEncodingChunked[] =
        "Transfer-Encoding: chunked\r\n";
    if (!LoggingWriteFile(
            sock, kTransferEncodingChunked, strlen(kTransferEncodingChunked))) {
      return false;
    }
  }

  if (!LoggingWriteFile(sock, kCRLFTerminator, strlen(kCRLFTerminator))) {
    return false;
  }

  FileOperationResult data_bytes;
  do {
    constexpr size_t kCRLFSize = arraysize(kCRLFTerminator) - 1;
    struct __attribute__((packed)) {
      char size[8];
      char crlf[2];
      uint8_t data[32 * 1024 + kCRLFSize];
    } buf;
    static_assert(
        sizeof(buf) == sizeof(buf.size) + sizeof(buf.crlf) + sizeof(buf.data),
        "buf should not have padding");

    // Read a block of data.
    data_bytes =
        body_stream->GetBytesBuffer(buf.data, sizeof(buf.data) - kCRLFSize);
    if (data_bytes == -1) {
      return false;
    }
    DCHECK_GE(data_bytes, 0);
    DCHECK_LE(static_cast<size_t>(data_bytes), sizeof(buf.data) - kCRLFSize);

    void* write_start;
    size_t write_size;

    if (chunked) {
      // Chunked encoding uses the entirety of buf. buf.size is presented in
      // hexadecimal without any leading "0x". The terminating CR and LF will be
      // placed immediately following the used portion of buf.data, even if
      // buf.data is not full.

      // Not snprintf because non-null terminated is desired.
      int rv = sprintf(
          buf.size, "%08x", base::checked_cast<unsigned int>(data_bytes));
      DCHECK_GE(rv, 0);
      DCHECK_EQ(static_cast<size_t>(rv), sizeof(buf.size));
      DCHECK_NE(buf.size[sizeof(buf.size) - 1], '\0');

      memcpy(&buf.crlf[0], kCRLFTerminator, kCRLFSize);
      memcpy(&buf.data[data_bytes], kCRLFTerminator, kCRLFSize);

      // Skip leading zeroes in the chunk size.
      size_t size_len;
      for (size_len = sizeof(buf.size); size_len > 1; --size_len) {
        if (buf.size[sizeof(buf.size) - size_len] != '0') {
          break;
        }
      }

      write_start = buf.crlf - size_len;
      write_size = size_len + sizeof(buf.crlf) + data_bytes + kCRLFSize;
    } else {
      // When not using chunked encoding, only use buf.data.
      write_start = buf.data;
      write_size = data_bytes;
    }

    // write_size will be 0 at EOF in non-chunked mode. Skip the write in that
    // case. In contrast, at EOF in chunked mode, a zero-length chunk must be
    // sent to signal EOF. This will happen when processing the EOF indicated by
    // a 0 return from body_stream()->GetBytesBuffer() above.
    if (write_size != 0) {
      if (!LoggingWriteFile(sock, write_start, write_size))
        return false;
    }
  } while (data_bytes > 0);

  return true;
}

bool ReadLine(int sock, std::string* line) {
  line->clear();
  for (;;) {
    char byte;
    if (!LoggingReadFileExactly(sock, &byte, 1)) {
      return false;
    }

    line->append(&byte, 1);
    if (byte == '\n')
      return true;
  }
}

bool StartsWith(const std::string& str, const char* with, size_t len) {
  return str.compare(0, len, with) == 0;
}

bool ReadResponseLine(int sock) {
  std::string response_line;
  if (!ReadLine(sock, &response_line)) {
    LOG(ERROR) << "ReadLine";
    return false;
  }
  static constexpr const char kHttp10[] = "HTTP/1.0 200 ";
  static constexpr const char kHttp11[] = "HTTP/1.1 200 ";
  return StartsWith(response_line, kHttp10, strlen(kHttp10)) ||
         StartsWith(response_line, kHttp11, strlen(kHttp11));
}

bool ReadResponseHeaders(int sock, HTTPHeaders* headers) {
  for (;;) {
    std::string line;
    if (!ReadLine(sock, &line)) {
      return false;
    }

    if (line == kCRLFTerminator) {
      return true;
    }

    std::string left, right;
    if (!SplitStringFirst(line, ':', &left, &right)) {
      LOG(ERROR) << "SplitStringFirst";
      return false;
    }
    DCHECK_EQ(right[right.size() - 1], '\n');
    DCHECK_EQ(right[right.size() - 2], '\r');
    DCHECK_EQ(right[0], ' ');
    DCHECK_NE(right[1], ' ');
    right = right.substr(1, right.size() - 3);
    (*headers)[left] = right;
  }
}

bool ReadContentChunked(int sock, std::string* body) {
  // TODO(scottmg): https://crashpad.chromium.org/bug/196.
  LOG(ERROR) << "TODO(scottmg): chunked response read";
  return false;
}

bool ReadResponse(int sock, std::string* response_body) {
  response_body->clear();

  if (!ReadResponseLine(sock)) {
    return false;
  }

  HTTPHeaders response_headers;
  if (!ReadResponseHeaders(sock, &response_headers)) {
    return false;
  }

  auto it = response_headers.find("Content-Length");
  size_t len = 0;
  if (it != response_headers.end()) {
    if (!base::StringToSizeT(it->second, &len)) {
      LOG(ERROR) << "invalid Content-Length";
      return false;
    }
  }

  if (len) {
    response_body->resize(len, 0);
    return ReadFileExactly(sock, &(*response_body)[0], len);
  }

  it = response_headers.find("Transfer-Encoding");
  bool chunked = false;
  if (it != response_headers.end() && it->second == "chunked") {
    chunked = true;
  }

  return chunked ? ReadContentChunked(sock, response_body)
                 : LoggingReadToEOF(sock, response_body);
}

bool HTTPTransportSocket::ExecuteSynchronously(std::string* response_body) {
  std::string scheme, hostname, port, resource;
  if (!CrackURL(url(), &scheme, &hostname, &port, &resource)) {
    return false;
  }

  base::ScopedFD sock(CreateSocket(hostname, port));
  if (!sock.is_valid()) {
    return false;
  }

  if (!WriteRequest(sock.get(), method(), resource, headers(), body_stream())) {
    return false;
  }

  if (!ReadResponse(sock.get(), response_body)) {
    return false;
  }

  return true;
}

}  // namespace

// static
std::unique_ptr<HTTPTransport> HTTPTransport::Create() {
  return std::unique_ptr<HTTPTransportSocket>(new HTTPTransportSocket);
}

}  // namespace crashpad