| // Copyright 2013 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. |
| |
| #ifndef NET_QUIC_PORT_SUGGESTER_H_ |
| #define NET_QUIC_PORT_SUGGESTER_H_ |
| |
| #include "base/basictypes.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/sha1.h" |
| #include "net/base/net_export.h" |
| |
| namespace net { |
| |
| class HostPortPair; |
| |
| // We provide a pseudo-random number generator that is always seeded the same |
| // way for a given destination host-port pair. The generator is used to |
| // consistently suggest (for that host-port pair) an ephemeral source port, |
| // and hence increase the likelihood that a server's load balancer will direct |
| // a repeated connection to the same server (with QUIC, further increasing the |
| // chance of connection establishment with 0-RTT). |
| class NET_EXPORT_PRIVATE PortSuggester |
| : public base::RefCounted<PortSuggester> { |
| public: |
| PortSuggester(const HostPortPair& server, uint64 seed); |
| |
| // Generate a pseudo-random int in the inclusive range from |min| to |max|. |
| // Will (probably) return different numbers when called repeatedly. |
| int SuggestPort(int min, int max); |
| |
| uint32 call_count() const { return call_count_; } |
| int previous_suggestion() const; |
| |
| private: |
| friend class base::RefCounted<PortSuggester>; |
| |
| virtual ~PortSuggester() {} |
| |
| // We maintain the first 8 bytes of a hash as our seed_ state. |
| uint64 seed_; |
| uint32 call_count_; // Number of suggestions made. |
| int previous_suggestion_; |
| |
| DISALLOW_COPY_AND_ASSIGN(PortSuggester); |
| }; |
| |
| } // namespace net |
| |
| #endif // NET_QUIC_PORT_SUGGESTER_H_ |