root/net/http/http_stream_parser.cc

DEFINITIONS

1. GetResponseHeaderLines
2. HeadersContainMultipleCopiesOfField
3. NetLogSendRequestBodyCallback
4. used_
5. DidConsume
6. BytesRemaining
7. SetOffset
8. DidAppend
9. Clear
10. size
11. capacity
12. SeekableIOBuffer
13. weak_ptr_factory_
14. SendRequest
15. ReadResponseHeaders
16. Close
17. ReadResponseBody
18. OnIOComplete
19. DoLoop
20. DoSendHeaders
21. DoSendBody
22. DoSendRequestReadingBody
23. DoReadHeaders
24. DoReadHeadersComplete
25. DoReadBody
26. DoReadBodyComplete
27. ParseResponseHeaders
28. DoParseResponseHeaders
29. CalculateResponseBodySize
30. GetUploadProgress
31. GetResponseInfo
32. IsResponseBodyComplete
33. CanFindEndOfResponse
34. IsMoreDataBuffered
35. IsConnectionReused
36. SetConnectionReused
37. IsConnectionReusable
38. GetSSLInfo
39. GetSSLCertRequestInfo
40. EncodeChunk
41. ShouldMergeRequestHeadersAndBody

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/http/http_stream_parser.h"

#include "base/bind.h"
#include "base/compiler_specific.h"
#include "base/strings/string_util.h"
#include "base/values.h"
#include "net/base/io_buffer.h"
#include "net/base/ip_endpoint.h"
#include "net/base/upload_data_stream.h"
#include "net/http/http_chunked_decoder.h"
#include "net/http/http_request_headers.h"
#include "net/http/http_request_info.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_util.h"
#include "net/socket/client_socket_handle.h"
#include "net/socket/ssl_client_socket.h"

namespace {

const size_t kMaxMergedHeaderAndBodySize = 1400;
const size_t kRequestBodyBufferSize = 1 << 14;  // 16KB

std::string GetResponseHeaderLines(const net::HttpResponseHeaders& headers) {
  std::string raw_headers = headers.raw_headers();
  const char* null_separated_headers = raw_headers.c_str();
  const char* header_line = null_separated_headers;
  std::string cr_separated_headers;
  while (header_line[0] != 0) {
    cr_separated_headers += header_line;
    cr_separated_headers += "\n";
    header_line += strlen(header_line) + 1;
  }
  return cr_separated_headers;
}

// Return true if |headers| contain multiple |field_name| fields with different
// values.
bool HeadersContainMultipleCopiesOfField(
    const net::HttpResponseHeaders& headers,
    const std::string& field_name) {
  void* it = NULL;
  std::string field_value;
  if (!headers.EnumerateHeader(&it, field_name, &field_value))
    return false;
  // There's at least one |field_name| header.  Check if there are any more
  // such headers, and if so, return true if they have different values.
  std::string field_value2;
  while (headers.EnumerateHeader(&it, field_name, &field_value2)) {
    if (field_value != field_value2)
      return true;
  }
  return false;
}

base::Value* NetLogSendRequestBodyCallback(
    int length,
    bool is_chunked,
    bool did_merge,
    net::NetLog::LogLevel /* log_level */) {
  base::DictionaryValue* dict = new base::DictionaryValue();
  dict->SetInteger("length", length);
  dict->SetBoolean("is_chunked", is_chunked);
  dict->SetBoolean("did_merge", did_merge);
  return dict;
}

}  // namespace

namespace net {

// Similar to DrainableIOBuffer(), but this version comes with its own
// storage. The motivation is to avoid repeated allocations of
// DrainableIOBuffer.
//
// Example:
//
// scoped_refptr<SeekableIOBuffer> buf = new SeekableIOBuffer(1024);
// // capacity() == 1024. size() == BytesRemaining() == BytesConsumed() == 0.
// // data() points to the beginning of the buffer.
//
// // Read() takes an IOBuffer.
// int bytes_read = some_reader->Read(buf, buf->capacity());
// buf->DidAppend(bytes_read);
// // size() == BytesRemaining() == bytes_read. data() is unaffected.
//
// while (buf->BytesRemaining() > 0) {
//   // Write() takes an IOBuffer. If it takes const char*, we could
///  // simply use the regular IOBuffer like buf->data() + offset.
//   int bytes_written = Write(buf, buf->BytesRemaining());
//   buf->DidConsume(bytes_written);
// }
// // BytesRemaining() == 0. BytesConsumed() == size().
// // data() points to the end of the consumed bytes (exclusive).
//
// // If you want to reuse the buffer, be sure to clear the buffer.
// buf->Clear();
// // size() == BytesRemaining() == BytesConsumed() == 0.
// // data() points to the beginning of the buffer.
//
class HttpStreamParser::SeekableIOBuffer : public net::IOBuffer {
 public:
  explicit SeekableIOBuffer(int capacity)
    : IOBuffer(capacity),
      real_data_(data_),
      capacity_(capacity),
      size_(0),
      used_(0) {
  }

  // DidConsume() changes the |data_| pointer so that |data_| always points
  // to the first unconsumed byte.
  void DidConsume(int bytes) {
    SetOffset(used_ + bytes);
  }

  // Returns the number of unconsumed bytes.
  int BytesRemaining() const {
    return size_ - used_;
  }

  // Seeks to an arbitrary point in the buffer. The notion of bytes consumed
  // and remaining are updated appropriately.
  void SetOffset(int bytes) {
    DCHECK_GE(bytes, 0);
    DCHECK_LE(bytes, size_);
    used_ = bytes;
    data_ = real_data_ + used_;
  }

  // Called after data is added to the buffer. Adds |bytes| added to
  // |size_|. data() is unaffected.
  void DidAppend(int bytes) {
    DCHECK_GE(bytes, 0);
    DCHECK_GE(size_ + bytes, 0);
    DCHECK_LE(size_ + bytes, capacity_);
    size_ += bytes;
  }

  // Changes the logical size to 0, and the offset to 0.
  void Clear() {
    size_ = 0;
    SetOffset(0);
  }

  // Returns the logical size of the buffer (i.e the number of bytes of data
  // in the buffer).
  int size() const { return size_; }

  // Returns the capacity of the buffer. The capacity is the size used when
  // the object is created.
  int capacity() const { return capacity_; };

 private:
  virtual ~SeekableIOBuffer() {
    // data_ will be deleted in IOBuffer::~IOBuffer().
    data_ = real_data_;
  }

  char* real_data_;
  const int capacity_;
  int size_;
  int used_;
};

// 2 CRLFs + max of 8 hex chars.
const size_t HttpStreamParser::kChunkHeaderFooterSize = 12;

HttpStreamParser::HttpStreamParser(ClientSocketHandle* connection,
                                   const HttpRequestInfo* request,
                                   GrowableIOBuffer* read_buffer,
                                   const BoundNetLog& net_log)
    : io_state_(STATE_NONE),
      request_(request),
      request_headers_(NULL),
      read_buf_(read_buffer),
      read_buf_unused_offset_(0),
      response_header_start_offset_(-1),
      received_bytes_(0),
      response_body_length_(-1),
      response_body_read_(0),
      user_read_buf_(NULL),
      user_read_buf_len_(0),
      connection_(connection),
      net_log_(net_log),
      sent_last_chunk_(false),
      weak_ptr_factory_(this) {
  io_callback_ = base::Bind(&HttpStreamParser::OnIOComplete,
                            weak_ptr_factory_.GetWeakPtr());
}

HttpStreamParser::~HttpStreamParser() {
}

int HttpStreamParser::SendRequest(const std::string& request_line,
                                  const HttpRequestHeaders& headers,
                                  HttpResponseInfo* response,
                                  const CompletionCallback& callback) {
  DCHECK_EQ(STATE_NONE, io_state_);
  DCHECK(callback_.is_null());
  DCHECK(!callback.is_null());
  DCHECK(response);

  net_log_.AddEvent(
      NetLog::TYPE_HTTP_TRANSACTION_SEND_REQUEST_HEADERS,
      base::Bind(&HttpRequestHeaders::NetLogCallback,
                 base::Unretained(&headers),
                 &request_line));

  DVLOG(1) << __FUNCTION__ << "()"
           << " request_line = \"" << request_line << "\""
           << " headers = \"" << headers.ToString() << "\"";
  response_ = response;

  // Put the peer's IP address and port into the response.
  IPEndPoint ip_endpoint;
  int result = connection_->socket()->GetPeerAddress(&ip_endpoint);
  if (result != OK)
    return result;
  response_->socket_address = HostPortPair::FromIPEndPoint(ip_endpoint);

  std::string request = request_line + headers.ToString();

  if (request_->upload_data_stream != NULL) {
    request_body_send_buf_ = new SeekableIOBuffer(kRequestBodyBufferSize);
    if (request_->upload_data_stream->is_chunked()) {
      // Read buffer is adjusted to guarantee that |request_body_send_buf_| is
      // large enough to hold the encoded chunk.
      request_body_read_buf_ =
          new SeekableIOBuffer(kRequestBodyBufferSize - kChunkHeaderFooterSize);
    } else {
      // No need to encode request body, just send the raw data.
      request_body_read_buf_ = request_body_send_buf_;
    }
  }

  io_state_ = STATE_SENDING_HEADERS;

  // If we have a small request body, then we'll merge with the headers into a
  // single write.
  bool did_merge = false;
  if (ShouldMergeRequestHeadersAndBody(request, request_->upload_data_stream)) {
    size_t merged_size = request.size() + request_->upload_data_stream->size();
    scoped_refptr<IOBuffer> merged_request_headers_and_body(
        new IOBuffer(merged_size));
    // We'll repurpose |request_headers_| to store the merged headers and
    // body.
    request_headers_ = new DrainableIOBuffer(
        merged_request_headers_and_body.get(), merged_size);

    memcpy(request_headers_->data(), request.data(), request.size());
    request_headers_->DidConsume(request.size());

    size_t todo = request_->upload_data_stream->size();
    while (todo) {
      int consumed = request_->upload_data_stream
          ->Read(request_headers_.get(), todo, CompletionCallback());
      DCHECK_GT(consumed, 0);  // Read() won't fail if not chunked.
      request_headers_->DidConsume(consumed);
      todo -= consumed;
    }
    DCHECK(request_->upload_data_stream->IsEOF());
    // Reset the offset, so the buffer can be read from the beginning.
    request_headers_->SetOffset(0);
    did_merge = true;

    net_log_.AddEvent(
        NetLog::TYPE_HTTP_TRANSACTION_SEND_REQUEST_BODY,
        base::Bind(&NetLogSendRequestBodyCallback,
                   request_->upload_data_stream->size(),
                   false, /* not chunked */
                   true /* merged */));
  }

  if (!did_merge) {
    // If we didn't merge the body with the headers, then |request_headers_|
    // contains just the HTTP headers.
    scoped_refptr<StringIOBuffer> headers_io_buf(new StringIOBuffer(request));
    request_headers_ =
        new DrainableIOBuffer(headers_io_buf.get(), headers_io_buf->size());
  }

  result = DoLoop(OK);
  if (result == ERR_IO_PENDING)
    callback_ = callback;

  return result > 0 ? OK : result;
}

int HttpStreamParser::ReadResponseHeaders(const CompletionCallback& callback) {
  DCHECK(io_state_ == STATE_REQUEST_SENT || io_state_ == STATE_DONE);
  DCHECK(callback_.is_null());
  DCHECK(!callback.is_null());
  DCHECK_EQ(0, read_buf_unused_offset_);

  // This function can be called with io_state_ == STATE_DONE if the
  // connection is closed after seeing just a 1xx response code.
  if (io_state_ == STATE_DONE)
    return ERR_CONNECTION_CLOSED;

  int result = OK;
  io_state_ = STATE_READ_HEADERS;

  if (read_buf_->offset() > 0) {
    // Simulate the state where the data was just read from the socket.
    result = read_buf_->offset();
    read_buf_->set_offset(0);
  }
  if (result > 0)
    io_state_ = STATE_READ_HEADERS_COMPLETE;

  result = DoLoop(result);
  if (result == ERR_IO_PENDING)
    callback_ = callback;

  return result > 0 ? OK : result;
}

void HttpStreamParser::Close(bool not_reusable) {
  if (not_reusable && connection_->socket())
    connection_->socket()->Disconnect();
  connection_->Reset();
}

int HttpStreamParser::ReadResponseBody(IOBuffer* buf, int buf_len,
                                       const CompletionCallback& callback) {
  DCHECK(io_state_ == STATE_BODY_PENDING || io_state_ == STATE_DONE);
  DCHECK(callback_.is_null());
  DCHECK(!callback.is_null());
  DCHECK_LE(buf_len, kMaxBufSize);

  if (io_state_ == STATE_DONE)
    return OK;

  user_read_buf_ = buf;
  user_read_buf_len_ = buf_len;
  io_state_ = STATE_READ_BODY;

  int result = DoLoop(OK);
  if (result == ERR_IO_PENDING)
    callback_ = callback;

  return result;
}

void HttpStreamParser::OnIOComplete(int result) {
  result = DoLoop(result);

  // The client callback can do anything, including destroying this class,
  // so any pending callback must be issued after everything else is done.
  if (result != ERR_IO_PENDING && !callback_.is_null()) {
    CompletionCallback c = callback_;
    callback_.Reset();
    c.Run(result);
  }
}

int HttpStreamParser::DoLoop(int result) {
  bool can_do_more = true;
  do {
    switch (io_state_) {
      case STATE_SENDING_HEADERS:
        if (result < 0)
          can_do_more = false;
        else
          result = DoSendHeaders(result);
        break;
      case STATE_SENDING_BODY:
        if (result < 0)
          can_do_more = false;
        else
          result = DoSendBody(result);
        break;
      case STATE_SEND_REQUEST_READING_BODY:
        result = DoSendRequestReadingBody(result);
        break;
      case STATE_REQUEST_SENT:
        DCHECK(result != ERR_IO_PENDING);
        can_do_more = false;
        break;
      case STATE_READ_HEADERS:
        net_log_.BeginEvent(NetLog::TYPE_HTTP_STREAM_PARSER_READ_HEADERS);
        result = DoReadHeaders();
        break;
      case STATE_READ_HEADERS_COMPLETE:
        result = DoReadHeadersComplete(result);
        net_log_.EndEventWithNetErrorCode(
            NetLog::TYPE_HTTP_STREAM_PARSER_READ_HEADERS, result);
        break;
      case STATE_BODY_PENDING:
        DCHECK(result != ERR_IO_PENDING);
        can_do_more = false;
        break;
      case STATE_READ_BODY:
        result = DoReadBody();
        // DoReadBodyComplete handles error conditions.
        break;
      case STATE_READ_BODY_COMPLETE:
        result = DoReadBodyComplete(result);
        break;
      case STATE_DONE:
        DCHECK(result != ERR_IO_PENDING);
        can_do_more = false;
        break;
      default:
        NOTREACHED();
        can_do_more = false;
        break;
    }
  } while (result != ERR_IO_PENDING && can_do_more);

  return result;
}

int HttpStreamParser::DoSendHeaders(int result) {
  request_headers_->DidConsume(result);
  int bytes_remaining = request_headers_->BytesRemaining();
  if (bytes_remaining > 0) {
    // Record our best estimate of the 'request time' as the time when we send
    // out the first bytes of the request headers.
    if (bytes_remaining == request_headers_->size()) {
      response_->request_time = base::Time::Now();
    }
    result = connection_->socket()
        ->Write(request_headers_.get(), bytes_remaining, io_callback_);
  } else if (request_->upload_data_stream != NULL &&
             (request_->upload_data_stream->is_chunked() ||
              // !IsEOF() indicates that the body wasn't merged.
              (request_->upload_data_stream->size() > 0 &&
               !request_->upload_data_stream->IsEOF()))) {
    net_log_.AddEvent(
        NetLog::TYPE_HTTP_TRANSACTION_SEND_REQUEST_BODY,
        base::Bind(&NetLogSendRequestBodyCallback,
                   request_->upload_data_stream->size(),
                   request_->upload_data_stream->is_chunked(),
                   false /* not merged */));
    io_state_ = STATE_SENDING_BODY;
    result = OK;
  } else {
    io_state_ = STATE_REQUEST_SENT;
  }
  return result;
}

int HttpStreamParser::DoSendBody(int result) {
  // |result| is the number of bytes sent from the last call to
  // DoSendBody(), or 0 (i.e. OK).

  // Send the remaining data in the request body buffer.
  request_body_send_buf_->DidConsume(result);
  if (request_body_send_buf_->BytesRemaining() > 0) {
    return connection_->socket()
        ->Write(request_body_send_buf_.get(),
                request_body_send_buf_->BytesRemaining(),
                io_callback_);
  }

  if (request_->upload_data_stream->is_chunked() && sent_last_chunk_) {
    io_state_ = STATE_REQUEST_SENT;
    return OK;
  }

  request_body_read_buf_->Clear();
  io_state_ = STATE_SEND_REQUEST_READING_BODY;
  return request_->upload_data_stream->Read(request_body_read_buf_.get(),
                                            request_body_read_buf_->capacity(),
                                            io_callback_);
}

int HttpStreamParser::DoSendRequestReadingBody(int result) {
  // |result| is the result of read from the request body from the last call to
  // DoSendBody().
  DCHECK_GE(result, 0);  // There won't be errors.

  // Chunked data needs to be encoded.
  if (request_->upload_data_stream->is_chunked()) {
    if (result == 0) {  // Reached the end.
      DCHECK(request_->upload_data_stream->IsEOF());
      sent_last_chunk_ = true;
    }
    // Encode the buffer as 1 chunk.
    const base::StringPiece payload(request_body_read_buf_->data(), result);
    request_body_send_buf_->Clear();
    result = EncodeChunk(payload,
                         request_body_send_buf_->data(),
                         request_body_send_buf_->capacity());
  }

  if (result == 0) {  // Reached the end.
    // Reaching EOF means we can finish sending request body unless the data is
    // chunked. (i.e. No need to send the terminal chunk.)
    DCHECK(request_->upload_data_stream->IsEOF());
    DCHECK(!request_->upload_data_stream->is_chunked());
    io_state_ = STATE_REQUEST_SENT;
  } else if (result > 0) {
    request_body_send_buf_->DidAppend(result);
    result = 0;
    io_state_ = STATE_SENDING_BODY;
  }
  return result;
}

int HttpStreamParser::DoReadHeaders() {
  io_state_ = STATE_READ_HEADERS_COMPLETE;

  // Grow the read buffer if necessary.
  if (read_buf_->RemainingCapacity() == 0)
    read_buf_->SetCapacity(read_buf_->capacity() + kHeaderBufInitialSize);

  // http://crbug.com/16371: We're seeing |user_buf_->data()| return NULL.
  // See if the user is passing in an IOBuffer with a NULL |data_|.
  CHECK(read_buf_->data());

  return connection_->socket()
      ->Read(read_buf_.get(), read_buf_->RemainingCapacity(), io_callback_);
}

int HttpStreamParser::DoReadHeadersComplete(int result) {
  DCHECK_EQ(0, read_buf_unused_offset_);

  if (result == 0)
    result = ERR_CONNECTION_CLOSED;

  if (result < 0 && result != ERR_CONNECTION_CLOSED) {
    io_state_ = STATE_DONE;
    return result;
  }
  // If we've used the connection before, then we know it is not a HTTP/0.9
  // response and return ERR_CONNECTION_CLOSED.
  if (result == ERR_CONNECTION_CLOSED && read_buf_->offset() == 0 &&
      connection_->is_reused()) {
    io_state_ = STATE_DONE;
    return result;
  }

  // Record our best estimate of the 'response time' as the time when we read
  // the first bytes of the response headers.
  if (read_buf_->offset() == 0 && result != ERR_CONNECTION_CLOSED)
    response_->response_time = base::Time::Now();

  if (result == ERR_CONNECTION_CLOSED) {
    // The connection closed before we detected the end of the headers.
    if (read_buf_->offset() == 0) {
      // The connection was closed before any data was sent. Likely an error
      // rather than empty HTTP/0.9 response.
      io_state_ = STATE_DONE;
      return ERR_EMPTY_RESPONSE;
    } else if (request_->url.SchemeIsSecure()) {
      // The connection was closed in the middle of the headers. For HTTPS we
      // don't parse partial headers. Return a different error code so that we
      // know that we shouldn't attempt to retry the request.
      io_state_ = STATE_DONE;
      return ERR_RESPONSE_HEADERS_TRUNCATED;
    }
    // Parse things as well as we can and let the caller decide what to do.
    int end_offset;
    if (response_header_start_offset_ >= 0) {
      io_state_ = STATE_READ_BODY_COMPLETE;
      end_offset = read_buf_->offset();
    } else {
      io_state_ = STATE_BODY_PENDING;
      end_offset = 0;
    }
    int rv = DoParseResponseHeaders(end_offset);
    if (rv < 0)
      return rv;
    return result;
  }

  read_buf_->set_offset(read_buf_->offset() + result);
  DCHECK_LE(read_buf_->offset(), read_buf_->capacity());
  DCHECK_GE(result,  0);

  int end_of_header_offset = ParseResponseHeaders();

  // Note: -1 is special, it indicates we haven't found the end of headers.
  // Anything less than -1 is a net::Error, so we bail out.
  if (end_of_header_offset < -1)
    return end_of_header_offset;

  if (end_of_header_offset == -1) {
    io_state_ = STATE_READ_HEADERS;
    // Prevent growing the headers buffer indefinitely.
    if (read_buf_->offset() >= kMaxHeaderBufSize) {
      io_state_ = STATE_DONE;
      return ERR_RESPONSE_HEADERS_TOO_BIG;
    }
  } else {
    CalculateResponseBodySize();
    // If the body is zero length, the caller may not call ReadResponseBody,
    // which is where any extra data is copied to read_buf_, so we move the
    // data here.
    if (response_body_length_ == 0) {
      int extra_bytes = read_buf_->offset() - end_of_header_offset;
      if (extra_bytes) {
        CHECK_GT(extra_bytes, 0);
        memmove(read_buf_->StartOfBuffer(),
                read_buf_->StartOfBuffer() + end_of_header_offset,
                extra_bytes);
      }
      read_buf_->SetCapacity(extra_bytes);
      if (response_->headers->response_code() / 100 == 1) {
        // After processing a 1xx response, the caller will ask for the next
        // header, so reset state to support that. We don't completely ignore a
        // 1xx response because it cannot be returned in reply to a CONNECT
        // request so we return OK here, which lets the caller inspect the
        // response and reject it in the event that we're setting up a CONNECT
        // tunnel.
        response_header_start_offset_ = -1;
        response_body_length_ = -1;
        io_state_ = STATE_REQUEST_SENT;
      } else {
        io_state_ = STATE_DONE;
      }
      return OK;
    }

    // Note where the headers stop.
    read_buf_unused_offset_ = end_of_header_offset;
    io_state_ = STATE_BODY_PENDING;
  }
  return result;
}

int HttpStreamParser::DoReadBody() {
  io_state_ = STATE_READ_BODY_COMPLETE;

  // There may be some data left over from reading the response headers.
  if (read_buf_->offset()) {
    int available = read_buf_->offset() - read_buf_unused_offset_;
    if (available) {
      CHECK_GT(available, 0);
      int bytes_from_buffer = std::min(available, user_read_buf_len_);
      memcpy(user_read_buf_->data(),
             read_buf_->StartOfBuffer() + read_buf_unused_offset_,
             bytes_from_buffer);
      read_buf_unused_offset_ += bytes_from_buffer;
      if (bytes_from_buffer == available) {
        read_buf_->SetCapacity(0);
        read_buf_unused_offset_ = 0;
      }
      return bytes_from_buffer;
    } else {
      read_buf_->SetCapacity(0);
      read_buf_unused_offset_ = 0;
    }
  }

  // Check to see if we're done reading.
  if (IsResponseBodyComplete())
    return 0;

  DCHECK_EQ(0, read_buf_->offset());
  return connection_->socket()
      ->Read(user_read_buf_.get(), user_read_buf_len_, io_callback_);
}

int HttpStreamParser::DoReadBodyComplete(int result) {
  // When the connection is closed, there are numerous ways to interpret it.
  //
  //  - If a Content-Length header is present and the body contains exactly that
  //    number of bytes at connection close, the response is successful.
  //
  //  - If a Content-Length header is present and the body contains fewer bytes
  //    than promised by the header at connection close, it may indicate that
  //    the connection was closed prematurely, or it may indicate that the
  //    server sent an invalid Content-Length header. Unfortunately, the invalid
  //    Content-Length header case does occur in practice and other browsers are
  //    tolerant of it. We choose to treat it as an error for now, but the
  //    download system treats it as a non-error, and URLRequestHttpJob also
  //    treats it as OK if the Content-Length is the post-decoded body content
  //    length.
  //
  //  - If chunked encoding is used and the terminating chunk has been processed
  //    when the connection is closed, the response is successful.
  //
  //  - If chunked encoding is used and the terminating chunk has not been
  //    processed when the connection is closed, it may indicate that the
  //    connection was closed prematurely or it may indicate that the server
  //    sent an invalid chunked encoding. We choose to treat it as
  //    an invalid chunked encoding.
  //
  //  - If a Content-Length is not present and chunked encoding is not used,
  //    connection close is the only way to signal that the response is
  //    complete. Unfortunately, this also means that there is no way to detect
  //    early close of a connection. No error is returned.
  if (result == 0 && !IsResponseBodyComplete() && CanFindEndOfResponse()) {
    if (chunked_decoder_.get())
      result = ERR_INCOMPLETE_CHUNKED_ENCODING;
    else
      result = ERR_CONTENT_LENGTH_MISMATCH;
  }

  if (result > 0)
    received_bytes_ += result;

  // Filter incoming data if appropriate.  FilterBuf may return an error.
  if (result > 0 && chunked_decoder_.get()) {
    result = chunked_decoder_->FilterBuf(user_read_buf_->data(), result);
    if (result == 0 && !chunked_decoder_->reached_eof()) {
      // Don't signal completion of the Read call yet or else it'll look like
      // we received end-of-file.  Wait for more data.
      io_state_ = STATE_READ_BODY;
      return OK;
    }
  }

  if (result > 0)
    response_body_read_ += result;

  if (result <= 0 || IsResponseBodyComplete()) {
    io_state_ = STATE_DONE;

    // Save the overflow data, which can be in two places.  There may be
    // some left over in |user_read_buf_|, plus there may be more
    // in |read_buf_|.  But the part left over in |user_read_buf_| must have
    // come from the |read_buf_|, so there's room to put it back at the
    // start first.
    int additional_save_amount = read_buf_->offset() - read_buf_unused_offset_;
    int save_amount = 0;
    if (chunked_decoder_.get()) {
      save_amount = chunked_decoder_->bytes_after_eof();
    } else if (response_body_length_ >= 0) {
      int64 extra_data_read = response_body_read_ - response_body_length_;
      if (extra_data_read > 0) {
        save_amount = static_cast<int>(extra_data_read);
        if (result > 0)
          result -= save_amount;
      }
    }

    CHECK_LE(save_amount + additional_save_amount, kMaxBufSize);
    if (read_buf_->capacity() < save_amount + additional_save_amount) {
      read_buf_->SetCapacity(save_amount + additional_save_amount);
    }

    if (save_amount) {
      received_bytes_ -= save_amount;
      memcpy(read_buf_->StartOfBuffer(), user_read_buf_->data() + result,
             save_amount);
    }
    read_buf_->set_offset(save_amount);
    if (additional_save_amount) {
      memmove(read_buf_->data(),
              read_buf_->StartOfBuffer() + read_buf_unused_offset_,
              additional_save_amount);
      read_buf_->set_offset(save_amount + additional_save_amount);
    }
    read_buf_unused_offset_ = 0;
  } else {
    io_state_ = STATE_BODY_PENDING;
    user_read_buf_ = NULL;
    user_read_buf_len_ = 0;
  }

  return result;
}

int HttpStreamParser::ParseResponseHeaders() {
  int end_offset = -1;
  DCHECK_EQ(0, read_buf_unused_offset_);

  // Look for the start of the status line, if it hasn't been found yet.
  if (response_header_start_offset_ < 0) {
    response_header_start_offset_ = HttpUtil::LocateStartOfStatusLine(
        read_buf_->StartOfBuffer(), read_buf_->offset());
  }

  if (response_header_start_offset_ >= 0) {
    end_offset = HttpUtil::LocateEndOfHeaders(read_buf_->StartOfBuffer(),
                                              read_buf_->offset(),
                                              response_header_start_offset_);
  } else if (read_buf_->offset() >= 8) {
    // Enough data to decide that this is an HTTP/0.9 response.
    // 8 bytes = (4 bytes of junk) + "http".length()
    end_offset = 0;
  }

  if (end_offset == -1)
    return -1;

  int rv = DoParseResponseHeaders(end_offset);
  if (rv < 0)
    return rv;
  return end_offset;
}

int HttpStreamParser::DoParseResponseHeaders(int end_offset) {
  scoped_refptr<HttpResponseHeaders> headers;
  DCHECK_EQ(0, read_buf_unused_offset_);

  if (response_header_start_offset_ >= 0) {
    received_bytes_ += end_offset;
    headers = new HttpResponseHeaders(HttpUtil::AssembleRawHeaders(
        read_buf_->StartOfBuffer(), end_offset));
  } else {
    // Enough data was read -- there is no status line.
    headers = new HttpResponseHeaders(std::string("HTTP/0.9 200 OK"));
  }

  // Check for multiple Content-Length headers with no Transfer-Encoding header.
  // If they exist, and have distinct values, it's a potential response
  // smuggling attack.
  if (!headers->HasHeader("Transfer-Encoding")) {
    if (HeadersContainMultipleCopiesOfField(*headers.get(), "Content-Length"))
      return ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_LENGTH;
  }

  // Check for multiple Content-Disposition or Location headers.  If they exist,
  // it's also a potential response smuggling attack.
  if (HeadersContainMultipleCopiesOfField(*headers.get(),
                                          "Content-Disposition"))
    return ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION;
  if (HeadersContainMultipleCopiesOfField(*headers.get(), "Location"))
    return ERR_RESPONSE_HEADERS_MULTIPLE_LOCATION;

  response_->headers = headers;
  response_->connection_info = HttpResponseInfo::CONNECTION_INFO_HTTP1;
  response_->vary_data.Init(*request_, *response_->headers.get());
  DVLOG(1) << __FUNCTION__ << "()"
           << " content_length = \"" << response_->headers->GetContentLength()
           << "\n\""
           << " headers = \""
           << GetResponseHeaderLines(*response_->headers.get()) << "\"";
  return OK;
}

void HttpStreamParser::CalculateResponseBodySize() {
  // Figure how to determine EOF:

  // For certain responses, we know the content length is always 0. From
  // RFC 2616 Section 4.3 Message Body:
  //
  // For response messages, whether or not a message-body is included with
  // a message is dependent on both the request method and the response
  // status code (section 6.1.1). All responses to the HEAD request method
  // MUST NOT include a message-body, even though the presence of entity-
  // header fields might lead one to believe they do. All 1xx
  // (informational), 204 (no content), and 304 (not modified) responses
  // MUST NOT include a message-body. All other responses do include a
  // message-body, although it MAY be of zero length.
  if (response_->headers->response_code() / 100 == 1) {
    response_body_length_ = 0;
  } else {
    switch (response_->headers->response_code()) {
      case 204:  // No Content
      case 205:  // Reset Content
      case 304:  // Not Modified
        response_body_length_ = 0;
        break;
    }
  }
  if (request_->method == "HEAD")
    response_body_length_ = 0;

  if (response_body_length_ == -1) {
    // "Transfer-Encoding: chunked" trumps "Content-Length: N"
    if (response_->headers->IsChunkEncoded()) {
      chunked_decoder_.reset(new HttpChunkedDecoder());
    } else {
      response_body_length_ = response_->headers->GetContentLength();
      // If response_body_length_ is still -1, then we have to wait
      // for the server to close the connection.
    }
  }
}

UploadProgress HttpStreamParser::GetUploadProgress() const {
  if (!request_->upload_data_stream)
    return UploadProgress();

  return UploadProgress(request_->upload_data_stream->position(),
                        request_->upload_data_stream->size());
}

HttpResponseInfo* HttpStreamParser::GetResponseInfo() {
  return response_;
}

bool HttpStreamParser::IsResponseBodyComplete() const {
  if (chunked_decoder_.get())
    return chunked_decoder_->reached_eof();
  if (response_body_length_ != -1)
    return response_body_read_ >= response_body_length_;

  return false;  // Must read to EOF.
}

bool HttpStreamParser::CanFindEndOfResponse() const {
  return chunked_decoder_.get() || response_body_length_ >= 0;
}

bool HttpStreamParser::IsMoreDataBuffered() const {
  return read_buf_->offset() > read_buf_unused_offset_;
}

bool HttpStreamParser::IsConnectionReused() const {
  ClientSocketHandle::SocketReuseType reuse_type = connection_->reuse_type();
  return connection_->is_reused() ||
         reuse_type == ClientSocketHandle::UNUSED_IDLE;
}

void HttpStreamParser::SetConnectionReused() {
  connection_->set_reuse_type(ClientSocketHandle::REUSED_IDLE);
}

bool HttpStreamParser::IsConnectionReusable() const {
  return connection_->socket() && connection_->socket()->IsConnectedAndIdle();
}

void HttpStreamParser::GetSSLInfo(SSLInfo* ssl_info) {
  if (request_->url.SchemeIsSecure() && connection_->socket()) {
    SSLClientSocket* ssl_socket =
        static_cast<SSLClientSocket*>(connection_->socket());
    ssl_socket->GetSSLInfo(ssl_info);
  }
}

void HttpStreamParser::GetSSLCertRequestInfo(
    SSLCertRequestInfo* cert_request_info) {
  if (request_->url.SchemeIsSecure() && connection_->socket()) {
    SSLClientSocket* ssl_socket =
        static_cast<SSLClientSocket*>(connection_->socket());
    ssl_socket->GetSSLCertRequestInfo(cert_request_info);
  }
}

int HttpStreamParser::EncodeChunk(const base::StringPiece& payload,
                                  char* output,
                                  size_t output_size) {
  if (output_size < payload.size() + kChunkHeaderFooterSize)
    return ERR_INVALID_ARGUMENT;

  char* cursor = output;
  // Add the header.
  const int num_chars = base::snprintf(output, output_size,
                                       "%X\r\n",
                                       static_cast<int>(payload.size()));
  cursor += num_chars;
  // Add the payload if any.
  if (payload.size() > 0) {
    memcpy(cursor, payload.data(), payload.size());
    cursor += payload.size();
  }
  // Add the trailing CRLF.
  memcpy(cursor, "\r\n", 2);
  cursor += 2;

  return cursor - output;
}

// static
bool HttpStreamParser::ShouldMergeRequestHeadersAndBody(
    const std::string& request_headers,
    const UploadDataStream* request_body) {
  if (request_body != NULL &&
      // IsInMemory() ensures that the request body is not chunked.
      request_body->IsInMemory() &&
      request_body->size() > 0) {
    size_t merged_size = request_headers.size() + request_body->size();
    if (merged_size <= kMaxMergedHeaderAndBodySize)
      return true;
  }
  return false;
}

}  // namespace net