Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Net / System / Net / _ProxyChain.cs / 1 / _ProxyChain.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //----------------------------------------------------------------------------- namespace System.Net { using System.Collections; using System.Collections.Generic; internal interface IAutoWebProxy : IWebProxy { ProxyChain GetProxies(Uri destination); } internal abstract class ProxyChain : IEnumerable, IDisposable { private List m_Cache = new List (); private bool m_CacheComplete; private ProxyEnumerator m_MainEnumerator; private Uri m_Destination; private HttpAbortDelegate m_HttpAbortDelegate; protected ProxyChain(Uri destination) { m_Destination = destination; } public IEnumerator GetEnumerator() { ProxyEnumerator enumerator = new ProxyEnumerator(this); if (m_MainEnumerator == null) { m_MainEnumerator = enumerator; } return enumerator; } IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } public virtual void Dispose() { } internal IEnumerator Enumerator { get { return m_MainEnumerator == null ? GetEnumerator() : m_MainEnumerator; } } internal Uri Destination { get { return m_Destination; } } // MoveNext can be time-consuming (download proxy script). This lets you abort it. internal virtual void Abort() { } internal bool HttpAbort(HttpWebRequest request, WebException webException) { Abort(); return true; } internal HttpAbortDelegate HttpAbortDelegate { get { if (m_HttpAbortDelegate == null) { m_HttpAbortDelegate = new HttpAbortDelegate(HttpAbort); } return m_HttpAbortDelegate; } } protected abstract bool GetNextProxy(out Uri proxy); // This implementation prevents DIRECT (null) from being returned more than once. private class ProxyEnumerator : IEnumerator { private ProxyChain m_Chain; private bool m_Finished; private int m_CurrentIndex = -1; private bool m_TriedDirect; internal ProxyEnumerator(ProxyChain chain) { m_Chain = chain; } public Uri Current { get { if (m_Finished || m_CurrentIndex < 0) { throw new InvalidOperationException(SR.GetString(SR.InvalidOperation_EnumOpCantHappen)); } GlobalLog.Assert(m_Chain.m_Cache.Count > m_CurrentIndex, "ProxyEnumerator::Current|Not all proxies made it to the cache."); return m_Chain.m_Cache[m_CurrentIndex]; } } object IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (m_Finished) { return false; } checked{m_CurrentIndex++;} if (m_Chain.m_Cache.Count > m_CurrentIndex) { return true; } if (m_Chain.m_CacheComplete) { m_Finished = true; return false; } lock (m_Chain.m_Cache) { if (m_Chain.m_Cache.Count > m_CurrentIndex) { return true; } if (m_Chain.m_CacheComplete) { m_Finished = true; return false; } Uri nextProxy; while (true) { if (!m_Chain.GetNextProxy(out nextProxy)) { m_Finished = true; m_Chain.m_CacheComplete = true; return false; } if (nextProxy == null) { if (m_TriedDirect) { continue; } m_TriedDirect = true; } break; } m_Chain.m_Cache.Add(nextProxy); GlobalLog.Assert(m_Chain.m_Cache.Count > m_CurrentIndex, "ProxyEnumerator::MoveNext|Not all proxies made it to the cache."); return true; } } public void Reset() { m_Finished = false; m_CurrentIndex = -1; } public void Dispose() { } } } // This class implements failover logic for proxy scripts. internal class ProxyScriptChain : ProxyChain { private WebProxy m_Proxy; private Uri[] m_ScriptProxies; private int m_CurrentIndex; private int m_SyncStatus; internal ProxyScriptChain(WebProxy proxy, Uri destination) : base(destination) { m_Proxy = proxy; } protected override bool GetNextProxy(out Uri proxy) { if (m_CurrentIndex < 0) { proxy = null; return false; } if (m_CurrentIndex == 0) { AutoWebProxyState state; m_ScriptProxies = m_Proxy.GetProxiesAuto(Destination, out state, ref m_SyncStatus); if (state != AutoWebProxyState.ExecutionSuccess) { m_ScriptProxies = null; } } if (m_ScriptProxies == null || m_CurrentIndex >= m_ScriptProxies.Length) { proxy = m_Proxy.GetProxyAutoFailover(Destination); m_CurrentIndex = -1; return true; } proxy = m_ScriptProxies[m_CurrentIndex++]; return true; } internal override void Abort() { m_Proxy.AbortGetProxiesAuto(ref m_SyncStatus); } } // This class says to use no proxy. internal class DirectProxy : ProxyChain { private bool m_ProxyRetrieved; internal DirectProxy(Uri destination) : base(destination) { } protected override bool GetNextProxy(out Uri proxy) { proxy = null; if (m_ProxyRetrieved) { return false; } m_ProxyRetrieved = true; return true; } } // This class says to use a single fixed proxy. internal class StaticProxy : ProxyChain { private Uri m_Proxy; internal StaticProxy(Uri destination, Uri proxy) : base(destination) { if (proxy == null) { throw new ArgumentNullException("proxy"); } m_Proxy = proxy; } protected override bool GetNextProxy(out Uri proxy) { proxy = m_Proxy; if (proxy == null) { return false; } m_Proxy = null; return true; } } }
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