text: // 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.
  //
  // HttpStream provides an abstraction for a basic http streams, SPDY, and QUIC.
  // The HttpStream subtype is expected to manage the underlying transport
  // appropriately.  For example, a basic http stream will return the transport
  // socket to the pool for reuse.  SPDY streams on the other hand leave the
  // transport socket management to the SpdySession.
  
  #ifndef NET_HTTP_HTTP_STREAM_H_
  #define NET_HTTP_HTTP_STREAM_H_
  
  #include <stdint.h>
  
  #include "base/macros.h"
  #include "base/memory/scoped_ptr.h"
  #include "net/base/completion_callback.h"
  #include "net/base/net_error_details.h"
  #include "net/base/net_export.h"
  #include "net/base/request_priority.h"
  #include "net/base/upload_progress.h"
  
  namespace net {
  
  class BoundNetLog;
  class HttpNetworkSession;
  class HttpRequestHeaders;
  struct HttpRequestInfo;
  class HttpResponseInfo;
  class IOBuffer;
  class IPEndPoint;
  struct LoadTimingInfo;
  class SSLCertRequestInfo;
  class SSLInfo;
  
  class NET_EXPORT_PRIVATE HttpStream {
   public:
    HttpStream() {}
    virtual ~HttpStream() {}
  
    // Initialize stream.  Must be called before calling SendRequest().
    // |request_info| must outlive the HttpStream.
    // Returns a net error code, possibly ERR_IO_PENDING.
    virtual int InitializeStream(const HttpRequestInfo* request_info,
                                 RequestPriority priority,
                                 const BoundNetLog& net_log,
                                 const CompletionCallback& callback) = 0;
  
    // Writes the headers and uploads body data to the underlying socket.
    // ERR_IO_PENDING is returned if the operation could not be completed
    // synchronously, in which case the result will be passed to the callback
    // when available. Returns OK on success.
    //
    // The callback will only be invoked once the first full set of headers have
    // been received, at which point |response| will have been populated with that
    // set of headers, and is safe to read, until/unless ReadResponseHeaders is
    // called.
    //
    // |response| must remain valid until all sets of headers has been read, or
    // the HttpStream is destroyed. There's typically only one set of
    // headers, except in the case of 1xx responses (See ReadResponseHeaders).
    virtual int SendRequest(const HttpRequestHeaders& request_headers,
                            HttpResponseInfo* response,
                            const CompletionCallback& callback) = 0;
  
    // Reads from the underlying socket until the next set of response headers
    // have been completely received.  This may only be called on 1xx responses
    // after SendRequest has completed successfully, to read the next set of
    // headers.
    //
    // ERR_IO_PENDING is returned if the operation could not be completed
    // synchronously, in which case the result will be passed to the callback when
    // available. Returns OK on success. The response headers are available in
    // the HttpResponseInfo passed in to original call to SendRequest.
    virtual int ReadResponseHeaders(const CompletionCallback& callback) = 0;
  
    // Reads response body data, up to |buf_len| bytes. |buf_len| should be a
    // reasonable size (<2MB). The number of bytes read is returned, or an
    // error is returned upon failure.  0 indicates that the request has been
    // fully satisfied and there is no more data to read.
    // ERR_CONNECTION_CLOSED is returned when the connection has been closed
    // prematurely.  ERR_IO_PENDING is returned if the operation could not be
    // completed synchronously, in which case the result will be passed to the
    // callback when available. If the operation is not completed immediately,
    // the socket acquires a reference to the provided buffer until the callback
    // is invoked or the socket is destroyed.
    virtual int ReadResponseBody(IOBuffer* buf, int buf_len,
                                 const CompletionCallback& callback) = 0;
  
    // Closes the stream.
    // |not_reusable| indicates if the stream can be used for further requests.
    // In the case of HTTP, where we re-use the byte-stream (e.g. the connection)
    // this means we need to close the connection; in the case of SPDY, where the
    // underlying stream is never reused, it has no effect.
    // TODO(mmenke): We should fold the |not_reusable| flag into the stream
    //               implementation itself so that the caller does not need to
    //               pass it at all.  Ideally we'd be able to remove
    //               CanReuseConnection() and IsResponseBodyComplete().
    // TODO(mmenke): We should try and merge Drain() into this method as well.
    virtual void Close(bool not_reusable) = 0;
  
    // Indicates if the response body has been completely read.
    virtual bool IsResponseBodyComplete() const = 0;
  
    // A stream exists on top of a connection.  If the connection has been used
    // to successfully exchange data in the past, error handling for the
    // stream is done differently.  This method returns true if the underlying
    // connection is reused or has been connected and idle for some time.
    virtual bool IsConnectionReused() const = 0;
    // TODO(mmenke): We should fold this into RenewStreamForAuth(), and make that
    //    method drain the stream as well, if needed (And return asynchronously).
    virtual void SetConnectionReused() = 0;
  
    // Checks whether the underlying connection can be reused.  The stream's
    // connection can be reused if the response headers allow for it, the socket
    // is still connected, and the stream exclusively owns the underlying
    // connection.  SPDY and QUIC streams don't own their own connections, so
    // always return false.
    virtual bool CanReuseConnection() const = 0;
  
    // Get the total number of bytes received from network for this stream.
    virtual int64_t GetTotalReceivedBytes() const = 0;
  
    // Get the total number of bytes sent over the network for this stream.
    virtual int64_t GetTotalSentBytes() const = 0;
  
    // Populates the connection establishment part of |load_timing_info|, and
    // socket ID.  |load_timing_info| must have all null times when called.
    // Returns false and does nothing if there is no underlying connection, either
    // because one has yet to be assigned to the stream, or because the underlying
    // socket has been closed.
    //
    // In practice, this means that this function will always succeed any time
    // between when the full headers have been received and the stream has been
    // closed.
    virtual bool GetLoadTimingInfo(LoadTimingInfo* load_timing_info) const = 0;
  
    // Get the SSLInfo associated with this stream's connection.  This should
    // only be called for streams over SSL sockets, otherwise the behavior is
    // undefined.
    virtual void GetSSLInfo(SSLInfo* ssl_info) = 0;
  
    // Get the SSLCertRequestInfo associated with this stream's connection.
    // This should only be called for streams over SSL sockets, otherwise the
    // behavior is undefined.
    virtual void GetSSLCertRequestInfo(SSLCertRequestInfo* cert_request_info) = 0;
  
    // Gets the remote endpoint of the socket that the HTTP stream is using, if
    // any. Returns true and fills in |endpoint| if it is available; returns false
    // and does not modify |endpoint| if it is unavailable.
    virtual bool GetRemoteEndpoint(IPEndPoint* endpoint) = 0;
  
    // In the case of an HTTP error or redirect, flush the response body (usually
    // a simple error or "this page has moved") so that we can re-use the
    // underlying connection. This stream is responsible for deleting itself when
    // draining is complete.
    virtual void Drain(HttpNetworkSession* session) = 0;
  
    // Get the network error details this stream is encountering.
    // Fills in |details| if it is available; leaves |details| unchanged if it
    // is unavailable.
    virtual void PopulateNetErrorDetails(NetErrorDetails* details) = 0;
  
    // Called when the priority of the parent transaction changes.
    virtual void SetPriority(RequestPriority priority) = 0;
  
    // Queries the UploadDataStream for its progress (bytes sent).
    virtual UploadProgress GetUploadProgress() const = 0;
  
    // Returns a new (not initialized) stream using the same underlying
    // connection and invalidates the old stream - no further methods should be
    // called on the old stream.  The caller should ensure that the response body
    // from the previous request is drained before calling this method.  If the
    // subclass does not support renewing the stream, NULL is returned.
    virtual HttpStream* RenewStreamForAuth() = 0;
  
   private:
    DISALLOW_COPY_AND_ASSIGN(HttpStream);
  };
  
  }  // namespace net
  
  #endif  // NET_HTTP_HTTP_STREAM_H_
  