public class ProxyMiddleware 
{
//private ProxyHttpClient _proxyHttpClient; 
Private const string CDN_HEADER_NAME="cache-control"; 
NotForwardedHttpHeaders=new private static readonly string [] [] {" Connection ", "the Host"};////Http header files used in the two attributes in the following code, the two state attribute is what meaning, if there are no these two properties in a header file, represent what meaning? 
Private readonly RequestDelegate _next; 
Private readonly ILogger _logger; 

Public ProxyMiddleware (
RequestDelegate next, 
ILogger The logger 

) 
{
_next=next; 
_logger=logger; 
//_proxyHttpClient=proxyHttpClient; 
} 

///& lt; Summary> 
///by middleware, intercept access, detection prefix, and forward 
///& lt;/summary> 
///& lt; Param name="context" & gt;  
///& lt; Param name="urlRewriter & gt;"  
///& lt; Returns>  
Public async Task Invoke (HttpContext context, IUrlRewriter urlRewriter, ProxyHttpClient ProxyHttpClient) 
{
Var targetUri=await urlRewriter. RewriteUri (context); 

If (targetUri!=null) 
{
Var requestMessage=GenerateProxifiedRequest (context, targetUri); 
Await SendAsync (context, requestMessage proxyHttpClient); 

return; 
} 

Await _next (context); 
} 

Private async Task SendAsync (HttpContext context, HttpRequestMessage requestMessage, ProxyHttpClient ProxyHttpClient) 
{


Using (var responseMessage=await proxyHttpClient. Client. SendAsync (requestMessage, HttpCompletionOption ResponseHeadersRead, context, RequestAborted)) 
{
The context. The Response. StatusCode=(int) responseMessage. StatusCode; 

Foreach (var header in responseMessage. Headers) 
{
Context, the Response Headers [header. Key]=header. The Value. The ToArray (); 
} 

Foreach (var header in responseMessage content. Headers) 
{
Context, the Response Headers [header. Key]=header. The Value. The ToArray (); 
} 

The context, the Response Headers. Remove (" transfer - the encoding "); 

if (! The context, the Response Headers. Either ContainsKey (CDN_HEADER_NAME)) 
{
The context, the Response Headers. The Add (CDN_HEADER_NAME, "no - the cache, the no - the store"); 
} 

Await responseMessage. Content. CopyToAsync (context. The Response. The Body); 
} 
} 

Private static HttpRequestMessage GenerateProxifiedRequest (HttpContext context, Uri targetUri) 
{
Var requestMessage=new HttpRequestMessage (); 
CopyRequestContentAndHeaders (context, requestMessage); 
RequestMessage. RequestUri=targetUri; 
RequestMessage. Headers. Host=targetUri. Host; 
RequestMessage. Method=GetMethod (context) Request) Method). 
Return requestMessage; 
} 

Private static void CopyRequestContentAndHeaders (HttpContext context, HttpRequestMessage requestMessage) 
{
Var requestMethod=context. Request. Method; 
if (! HttpMethods. IsGet (requestMethod) & amp; & 
! HttpMethods. IsHead (requestMethod) & amp; & 
! HttpMethods. IsDelete (requestMethod) & amp; & 
! HttpMethods. IsTrace (requestMethod)) 
{
Var streamContent=new streamContent (context. Request. Body); 
RequestMessage. The Content=streamContent; 
} 

Foreach (var header in the context, the Request Headers) 
{
if (! NotForwardedHttpHeaders. The Contains (header. Key))////Http header file these two properties (connection, the Host) state of the two attributes is what meaning, if there are no these two properties in a header file, represent what meaning? 
{
If (header. The Key!="the user-agent")//////the judgment, what does that mean? 
{
if (! RequestMessage. Headers. TryAddWithoutValidation (header. The Key, the header. The Value. ToArray ()) & amp; & RequestMessage. The Content!=null) 
{
RequestMessage. The Content? . Headers. TryAddWithoutValidation (header. The Key, the header. The Value. ToArray ()); 
} 
} 
The else 
{
String userAgent=header. The Value. The Count & gt; 0? (the header. The Value [0] + "" + context. TraceIdentifier) : string. The Empty; 

if (! RequestMessage. Headers. TryAddWithoutValidation (header. The Key, the userAgent) & amp; & RequestMessage. The Content!=null) 
{
RequestMessage. The Content? . Headers. TryAddWithoutValidation (header. The Key, the userAgent);////in the main file attributes are more the size attribute, the head of attributes and what meaning, please combined with code to help explain, 
} 
} 

} 
} 
} 

Private static HttpMethod GetMethod (string method) 
{
If (HttpMethods IsDelete (method)) return HttpMethod. Delete; 
If (HttpMethods IsGet (method)) return HttpMethod. Get; 
If (HttpMethods IsHead (method)) return HttpMethod. Head; 
If (HttpMethods IsOptions (method)) return HttpMethod. The Options; 
If (HttpMethods IsPost (method)) return HttpMethod. Post; 
If (HttpMethods IsPut (method)) return HttpMethod. Put; 
If (HttpMethods IsTrace (method)) return HttpMethod. Trace; 
Return new HttpMethod (method); 
} 

CodePudding user response:

NotForwardedHttpHeaders=new private static readonly string [] [] {" Connection ", "the Host"};////Http header files used in the two attributes in the following code, the two state attribute is what meaning, if there are no these two properties in a header file, represent what meaning?

CodePudding user response:

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