MicroPython
Encountering OSError -203 for sockets...no such error code found in errno #16951
-
|
Hello, I am trying to code an extremely slim webserver with limited feature support. I need a single socket that remains open and serve multiple HTTP requests over that open socket, like a stream. I am encountering a weird issue. Following is my code in a single file main.py. In this skeleton code I have just tried to bind the socket and wait for a connection. I have not even started consuming the socket data. But I get this error I can't find what Exception number -203 means. It is a negative number!!! This code is not present in errno module. I can't find this code in google search either. When I comment out the try-exception block 1, I get same OSError -203 line 21 in this line
Funny thing is if I uncomment this line, But why commenting/uncommenting this line is even affecting the 'bind'? My objective is NOT to close the socket once it is opened. But if I don't have the Another useful information is that I hard-reset my ESP32 board between runs by pressing RST button, and this Error comes 80-90% of the total number of runs. I have seen only few times the code does not throw OSError with Appreciate it if anybody can figure out what's wrong in this piece of code. I have a hunch that it has something to do with Socket options. |
Beta Was this translation helpful? Give feedback.
Replies: 3 comments 5 replies
-
|
Try: |
Beta Was this translation helpful? Give feedback.
-
|
In ESP32 microPython port only the following err codes are available I tried on my Windows machine with python 3.11.0. 203 is not present in errno of both microPytho and CPython. Kinda frustrating!! How can I debug if I don't know what the reason is? |
Beta Was this translation helpful? Give feedback.
-
|
I'm not sure if this is 100% correct. To bind a socket you should use socket.getaddrinfo to get the address. On some ports it's a tuple with a str (ip) and an int (port). On Unix it's a bytestring 16 bytes long. from socket import socket, getaddrinfo, AF_INET, SOCK_STREAM, inet_ntop
try:
from socket import AF_INET6
except ImportError:
AF_INET6 = 10
class socket(socket):
"""
Contextmaager for socket
"""
def __enter__(self):
return self
def __exit__(self, exc_type, exc_obj, exc_tb):
self.close()
def create(ip, port, proto):
sock = socket(proto, SOCK_STREAM)
addr = getaddrinfo(ip, port, proto, SOCK_STREAM)[-1][-1]
sock.bind(addr)
return sock
def decode_addr_port(addr):
proto = int.from_bytes(addr[:1])
if proto == 10:
start = 8
else:
start = 4
ip = inet_ntop(proto, addr[start:])
port = int.from_bytes(addr[2:4], "big")
return ip, port
def new_connection(sock, addr):
print(addr)
print(decode_addr_port(addr))
ip = "0.0.0.0"
port = 8885
with create(ip, port, AF_INET) as sock:
sock.listen()
while True:
new_connection(*sock.accept()) |
Beta Was this translation helpful? Give feedback.
-
|
Thanks for your response. I had taken the code template from microPyServer (https://github.com/troublegum/micropyserver), which has worked in many of my projects. However, this is a basic non-concurrent non-threaded server ...can server one request at a time and closes the connection after sending response to each request. I don't need concurrency. But I need multiple requests to be served over a single TCP connection. This means I can't always close the connection after each request is served. I am attempting to modify the code of microPyServer to implement keep-alive feature. This is my approach,
But, the moment I remove BTW, appreciate it if you can tell me how you got your code to have syntax coloring. |
Beta Was this translation helpful? Give feedback.
-
|
Strange behavior, since I do not see all of your code, I cannot say what may be the problem. I see that you are using MicroPython v1.23.0. You may want to try a newer version. It is up to you. You are free to write your program any way you want. But, I will make it simpler. Set the server and client at If you like, take a look at my suggestion below: import socket
########## Server Class: BEGIN ############
class SlimServer(object):
def __init__(self, host="0.0.0.0", port=80):
# server
self._server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._server.bind((host, port))
self._server.listen(1)
# client - one at a time
self._client = None
def begin(self):
print("SlimServer started")
while True:
try: #try block 2
print("Waiting for new incoming client connection...")
self._client, address = self._server.accept() # this will block !
print("New socket connection arrived...")
print("Client address:", address)
req = {}
req["raw"]= str(self._client.recv(4096), "utf8") #fetch incoming data from socket's rx buffer
#TODO: process the incoming request
print(req["raw"])
except Exception as e: #exception block 2
print("Here 10:")
print(e)
finally: #finally block 2
print("Here 11:")
if self._client:
self._client.close() # close client socket
self._client = None
########## Main: BEGIN ############
server = SlimServer()
server.begin()From another PC (in my case linuxmint) do: $ telnet 192.168.4.73 80
Trying 192.168.4.73...
Connected to 192.168.4.73.
Escape character is '^]'.
12345 I am here
Connection closed by foreign host.
Change the ip to your esp32 ip. You get that from ... or maybe you have a bad esp32 board. |
Beta Was this translation helpful? Give feedback.
-
|
Thanks for the response. I see that you have As I mentioned, I want to implement My concern is about why omitting |
Beta Was this translation helpful? Give feedback.
-
|
You only need to do the bind once. If the We need to close opened client sockets to reclaim resources. The example below will keep the client socket open until the client side closes the socket. import socket
########## Server Class: BEGIN ############
class SlimServer(object):
def __init__(self, host="0.0.0.0", port=80):
# server
self._server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._server.bind((host, port))
self._server.listen(1)
def _client(self, cs):
while True:
try:
req = str(cs.recv(4096), "utf8") # this will block!
#TODO: process the incoming request
if req:
print(req)
cs.send(b'Hello\n')
# check some terminating condition
# if terminate:
# break
else:
break # client close connection
except Exception as e:
print(e)
# close client socket
print('Client terminate!')
cs.close()
def begin(self):
print("SlimServer started")
while True:
try: #try block 2
print("Waiting for new incoming client connection...")
cs, address = self._server.accept() # this will block !
print("New socket connection arrived...")
print("Client address:", address)
self._client(cs)
except Exception as e: #exception block 2
print("Here 10:")
print(e)
########## Main: BEGIN ############
server = SlimServer()
server.begin() |
Beta Was this translation helpful? Give feedback.
-
|
I still don't know why my original code was throwing the -203 error, but moving the bind and listen to Class's init() somehow solved that issue. I extended the code to carefully implement http keep-alive protocol, and now it is working with Curl to do multiple http request-response over same TCP connection. Thank you for providing excellent example code and nudging me to right direction. |
Beta Was this translation helpful? Give feedback.
You only need to do the bind once. If the
server.bind((host, port))then your server is not ready to accept any connection.We need to close opened client sockets to reclaim resources.
The example below will keep the client socket open until the client side closes the socket.