I noted that fiddler sends "connection:close" header when the client sends a CONNECT request to initiate secure connection along with the "200 connection established" message.
CONNECT request to a forward HTTP proxy over an SSL connection?
As explained in above question, the connection should be kept-alive between the client and the proxy so that the client can subsequently sent the actual request.
Why does fiddler sends the close header? wouldn't the client close the connection because of the header instead?.
Any Connection header in the successful response to the CONNECT request does not make any sense and gets ignored. CONNECT will establish a tunnel, which only ends with the end of the TCP connection. But a Connection header would make sense with an unsuccessful CONNECT, because with close the client would need to start a new TCP connection and with keep-alive (implicit with HTTP/1.1 response) it can reuse it with another request.
Connection: Close means that the connection will be closed after the request completes. Since the request in this scenario only completes when the HTTPS connection is closed, this is exactly the behavior you want for this sort of request.
Arguably, using Connection: keep-alive on a CONNECT request is invalid, since there's no legal way for the connection to be kept-alive after the tunnel is closed.
Related
Below is the configured thread group
Thread Group
|
|--> HTTP SAMPLE
I am opening 5 threads in 5 seconds with loop count is 5. It means in each thread 5 HHTP request will be sent, so total 25 request.
Thread 1 : TCP CONNECTION OPENED --> HTTP REQUEST SENT ---> HTTP RESPONSE RECEIVED.
Question: After receiving response whether TCP connection will be closed and again TCP connection will be opened and then HTTP request will be sent?
Or once response is received in same TCP connection next HTTP request will be sent?
It depends on what do you set in the HTTP Request sampler, if you tick Use KeepAlive box - then JMeter will send Connection header with the value of keep-alive
it means that the underlying TCP connection will remain open and the next HTTP Request sampler(s) will be reusing this connection.
If you untick the box JMeter will send Connection header with the value of close and next HTTP Request sampler will re-establish the connection.
You need to check what's going on in reality using your browser developer tools or an external sniffer tool like Wireshark and configure JMeter to behave exactly like the real browser does
I'm building a HTTP client(for embedded devices) and I was wondering,
If I receive a HTTP 3xx response, and in the location header I get a hostname different from the one I had in the request. Should I disconnect the TCP connection and reconnect to the new host, or I just need to send a new request with a new host header and keep the old TCP connection alive.
Thank you
It doesn't make sense to reuse the original TCP connection if you're being redirected elsewhere. If my webserver only hosts example.com and I redirect you to elsewhere.net, my webserver will probably not respond to a request for elsewhere.net.
Worse, this also potentially sets you up for a great man-in-the-middle attack if my server redirects you to http://bank.com and you reuse the same TCP connection when sending a request to bank.com. My server can maliciously respond to requests with Host: bank.com, which isn't something you want to happen.
You can't assume the original connection can be reused unless the redirect is to the same same host with the same protocol.
Persistent HTTP connections are a little tricky with the number of client/server combinations. You can avoid the complexity by just wasting time closing and re-establishing each connection:
If you're implementing a HTTP/1.0 client, Connection: keep-alive isn't something you have to implement. Compliant servers should just close the connection after every request if you don't negotiate that you support persistent connections.
If you're implementing a HTTP/1.1 client and don't want to persist the connection, just send Connection: close with your request and a HTTP/1.1 server should close the connection.
We are trying to make a secure communication between our embedded system and web server.Firstly we implement HTTP connection to in our microcontroller. I am just connecting to 80 port of my web server and send simple GET request to this port as example below :
GET /foo.php?msg=test HTTP/1.1
HOST: foo.com
My questions is,How we will turn this to HTTPS ? Which port i should connect ?
Will be any difference on structure of GET request above ? Will i have to do some encryption manually or connect to "https" link instead "http" is enuogh for secure communication.
Thanks for any information
The only difference between a HTTP request and a HTTPS request is that the first is send over a plain TCP connection while the other is send over a TLS connection, i.e.:
with HTTP you establish a TCP connection and send the request over this connection
with HTTPS you establish a TCP connection, upgrade this connection to TLS (including proper certificate validation etc!) and then send the same request as you did with HTTP over this connection.
Apart from that I recommend to either use an established library for HTTP or carefully read the standard. Although HTTP looks simply it is actually not and there are many questions here where users try to do a simply HTTP request and trip over behavior they did not expect.
For example in your case the server might send the response with chunked encoding, with content-length or simply end it with connection close. And it might wait for further requests on the same connection since HTTP/1.1 implicitly enables HTTP keep-alive. Does your code really account for all these cases?
I have two questions on HTTP Connection close:
If a client sends a HTTP request with Connection: close to HTTP Server, Is it the HTTP Server or client responsibility to send TCP FIN after response is received by client?
If a client sends a bad formatted HTTP request, and server sends a 400 BAD REQUEST, is it best practice to close the connection by server (even though the HTTP request has connection: keep-alive) or is it good practice to keep the connection still active?
Thanks in advance for answering my queries?
When the server receives a 400 Bad Request, it is going to send the response with the keep-alive header because if the client feels like sending another request, then they can use a pre-existing connection (this connection is shut down within a certain amount of time, it has an expiration date). The Keep-Alive Header is more about not saturating the network with TCP connection demands. You basically say "I am going to talk to you, for 2 minutes, whatever you send me, I'll answer you though this connection"
The server is only an object that receives commands from an user. You ask him, he does or not. The TCP FIN is something you send to the server to shut down the connection, but you choose when you don't want to communicate with him anymore. The client transmits the first FIN, and receives an ACK to ensure that the server got it. Then the server launches its own FIN, and waits for the ACK. If everything is okay, you and your server are no longer friends.
I have a HTTP client that sets the Connection header to the following value when I make a request:
Connection: close
However when the server sends a response, it is setting the header to Keep-Alive:
Connection: Keep-Alive
This seems intuitively wrong to me, and I am wondering how the client should handle such a response from the server? Also why would a server respond with Keep-Alive, when the client has asked for the connection to be closed, is this valid?
According to the HTTP RFC:
"HTTP/1.1 defines the "close" connection option for the sender to signal that the connection will be closed after completion of the response. For example,
Connection: close
in either the request or the response header fields indicates that the connection SHOULD NOT be considered `persistent' (section 8.1) after the current request/response is complete."
That's fine. You are telling the server you don't support persistent connections and it's telling you it does. Either party is completely valid in closing the connection - it's more of a message about what both supports rather then a YOU MUST CLOSE THIS CONNECTION command.
The client says I will close the connection when the current request/response is finished,or in other words , said you don't support persisten connections. That is, it doesn't tell the server to close the connection. The server replies that it supports persistent connections(keep-alive).
As you've told the server that you don't support persistent connection, you should close the connection when you've read the response.