问题
I would like to know how Reusing HttpWebRequests works to avoid SSL handshake process everytime.
I use the keep alive headr in the request and the first handshake is successfull but i would like to reuse the request in order to avoid future handshakes against the same certificate.
Think is i dont know if i had to reuse the HttpWebRequest object instance or even if i create a new request object it will use the same connection since the keep alive is already on place and working.
Should i store the existing request object lets say at class level and reuse it? or i can safely dispose the object and next time i create a request it will be under the effect of the keep alive connection?
I am asking this cause i need to lower the timings in an application, and worst part is always ssl handshake, that can take over 3seconds in a phone with medium signal from carrier.
I am using C# to develop. I have tried to look for this kind of information but all i read over internet is how to set up the SSL Server and enabling certain settings but not how to make the client work with these features.
EDIT: FINDINGS RESULTS I created a sample program in .NET C# whith the following code:
Stopwatch sw = new Stopwatch();
sw.Start();
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(@"https:\\www.gmail.com"));
request.KeepAlive = true;
request.Method = "GET";
request.ContentType = "application/json";
request.ContentLength = 0;
request.ConnectionGroupName = "test";
//request.UnsafeAuthenticatedConnectionSharing = true;
//request.PreAuthenticate = true;
var response = request.GetResponse();
//response.Close();
request.Abort();
sw.Stop();
listBox1.Items.Add("Connection in : " + sw.Elapsed.ToString());
sw.Reset();
sw.Start();
HttpWebRequest request2 = (HttpWebRequest)WebRequest.Create(new Uri(@"https:\\www.gmail.com"));
request2.KeepAlive = true;
request2.Method = "GET";
//request2.UnsafeAuthenticatedConnectionSharing = true;
//request2.PreAuthenticate = true;
request2.ContentType = "application/json";
request2.ContentLength = 0;
request2.ConnectionGroupName = "test";
var response2 = request2.GetResponse();
//response2.Close();
request2.Abort();
sw.Stop();
listBox1.Items.Add("Connection 2 in : " + sw.Elapsed.ToString());
Results was that the first connection triggered the CertificatevalidationCallback 3 times (one for each certificate) and then the second connection only once, but when i CLOSED THE RESPONSE before performing the next request, no callback was triggered.
I suppose that keeping a response open keeps the socket open and thats why the partial handshake takes place (not the full certificate chain).
Sorry if I sound kind of noob in this matter, SSL and timings was coded by a work mate and the code was not clear to follow. But i think i have the answer. Thanks Poupou for your tremendous help
回答1:
This is already built-in the the SSL/TLS stack shipped with Xamarin.iOS (i.e. at a lower level than HttpWebRequest). There's nothing to set up to enabled this. In fact you would need extra code if you wanted to disable it.
If the server supports it then subsequent handshake will already faster because a Session ID cache will be used (see TLS 1.0 RFC page 30).
However the server does not have to honor the session id (given to it). In such case a full handshake will need be done again. IOW you cannot force this from the client (only offer).
You can verify this using a network analyzer, e.g. wireshark, by looking at the exchanges (and comparing them to the RFC).
来源：https://stackoverflow.com/questions/24202530/how-to-reuse-connection-request-to-avoid-handshake