Using uasyncio server as HTTP Server: closing trouble

[milo1987]

Hello Micropython community.
I hope you can help me.

I'm new on Python and programming for a esp8266 and esp32 device. I'm programming a smartdevices, that connects to iobroker and has a webinterface for config.
I'm using a few loops from uasyncio, that handle the different tasks.

One of them is a uasyncio.start_server instance, which calls my function httpLoop:

async def httpLoop(self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter):
        try:
            self.ms.log("HTTP-Client Connected...")
            s = str(await reader.read(30))
            self.ms.log(s)

            if s.startswith("b'GET / "):
                self.ms.log("Verzeichnis / erkannt. Sende...")
                await writer.awrite('HTTP/1.1 200 OK\r\n')
                await writer.awrite('Content-Type: text/html\r\n\r\n')
                await asyncio.sleep(0.1)
                await self.generateHTML(writer)
                self.ms.log("Verbindung 200 getrennt")

            else:
                await writer.awrite('HTTP/1.1 404 Not Found\r\n')
                await writer.awrite('Content-Type: text/html\r\n\r\n')
                await writer.awrite('<>')
                self.ms.log("Verbindung 404 getrennt")

            reader.close()
            await asyncio.sleep(1)
            await reader.wait_closed()
            await asyncio.sleep(0.2)
            await writer.drain()
            await asyncio.sleep(0.2)
            writer.close()
            await asyncio.sleep(0.2)
            await writer.wait_closed()

        except Exception as e:
            self.ms.log("Fehler in HTTP Loop: " + str(e))

The routines works fine on microsoft edge or with wget. But on Firefox the site generates successful but every time writer.close() will be called Firefox stop the site with "ERR_CONNECTION_RESET" (See Picture)

The asycio.sleep() methods are only for debugging and trys to get fixed.

I hope you can help me.
Thank you alot!

[peterhinch]

You might like to look at the uasyncio source. writer.close does nothing. It's more likely that the fault occurs on

await writer.wait_closed()

This closes the socket. However at this point the writer has completed its work because you waited on .drain so I don't understand why closing the socket is problematic.

[milo1987]

Ah good to know.. then i can delete this...

But why Firefox makes a problem with that, i dont know :(
I got the hole Page, see it and when the httpstatus changes to 200 OK the page changes to connection reset.

I will try to change the http page next into a easy hello world page.

[karfas]

In my opinion it is bad practice to close sockets (or other resources) in a function that didn't open it.
Just leave the socket handling to the async server function.

You can analyze FF's behaviour using it's web console.

BTW, I don't understand all these asyncio.sleep() calls sprinkled around. I'm pretty sure asyncio will work as well without. There is no need to schedule other tasks before you await the completion of another function.

[milo1987]

asyncio.sleep() was just another try to get it work. On google were some solutions, so i just tried it... but that doesn't change anything...

if i won't close the connection the firefox will never stop the connection. it's running the hole time :(
I will try to debug with the webconsole today

[milo1987]

OK - i found a solution.

s = str(await reader.read(30))

MUST for firefox be:

s = str(await reader.read(-1))

If you won't get everything from the clientbuffer. Firefox will stop with this error, because his connection will not be closed.

The hole code to handle the HTML Request is:

async def httpLoop(self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter):
        try:
            self.ms.log("HTTP-Client Connected...")
            s = str(await reader.read(-1))
            self.ms.log(s)

            if s.startswith("b'GET / "):
                self.ms.log("Reading Path / . Send: ")
                await writer.awrite('HTTP/1.1 200 OK\r\n')
                await writer.awrite('Connection: close\r\n')
                await writer.awrite('Content-Type: text/html\r\n\r\n')
                await self.generateHTML(writer)
                self.ms.log("Connection 200 finished")

            else:
                await writer.awrite('HTTP/1.1 404 Not Found\r\n')
                await writer.awrite('Connection: close\r\n')
                await writer.awrite('Content-Type: text/html\r\n\r\n')
                await writer.awrite('<>')
                self.ms.log("Connection 404 finished")

            await reader.wait_closed()
            await writer.drain()
            await writer.wait_closed()

        except Exception as e:
            self.ms.log("Error in HTTP Loop: " + str(e))