Issue410046
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Created on 2001-03-20 16:32 by dougfort, last changed 2022-04-10 16:03 by admin. This issue is now closed.
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msg36136 - (view) | Author: Doug Fort (dougfort) | Date: 2001-03-20 16:32 | |
When reading with a numeric terminator, asynchat assumes that if the server didn't send fewer bytes than requested, that it sent exactly the number of bytes requested. This is normally the case, but an overloaded server can return an error message that is larger than the number of bytes requested. When this happens asynchttp.handle_read() goes into a tight loop, returning an empty string for data and zero for a terminator. This patch raises an exception if the number of bytes returned exceeds the number requested. It's kind of an ugly fix, because asynchttp doesn't raise any other exceptions, and passes on those it catches to handle_error. However, this really is an exceptional case, and the results of not handling it are disastrous. |
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msg36137 - (view) | Author: Doug Fort (dougfort) | Date: 2001-03-20 16:36 | |
Logged In: YES user_id=6399 *** asynchat.pyTue Mar 20 11:11:58 2001 --- asynchat.py.originalTue Mar 20 10:43:01 2001 *************** *** 49,60 **** import socket import asyncore - class async_chat_exception(Exception): - def __init__(self, message): - self._message = message - def __str__(self): - return self._message - class async_chat (asyncore.dispatcher): """This is an abstract class. You must derive from this class, and add the two methods collect_incoming_data() and found_terminator()""" --- 49,54 ---- *************** *** 111,128 **** self.collect_incoming_data (self.ac_in_buffer) self.ac_in_buffer = '' self.terminator = self.terminator - lb ! elif lb == n: self.collect_incoming_data (self.ac_in_buffer[:n]) ! self.ac_in_buffer = '' self.terminator = 0 self.found_terminator() - else: - # if we got back more than we asked for, the server - # is badly confused - raise async_chat_exception( - "Unexpect response: requested %s bytes got %s. %s" % ( - n, lb, self.ac_in_buffer - )) else: # 3 cases: # 1) end of buffer matches terminator exactly: --- 105,115 ---- self.collect_incoming_data (self.ac_in_buffer) self.ac_in_buffer = '' self.terminator = self.terminator - lb ! else: self.collect_incoming_data (self.ac_in_buffer[:n]) ! self.ac_in_buffer = self.ac_in_buffer[n:] self.terminator = 0 self.found_terminator() else: # 3 cases: # 1) end of buffer matches terminator exactly: |
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msg36138 - (view) | Author: Doug Fort (dougfort) | Date: 2001-03-25 14:22 | |
Logged In: YES user_id=6399 I have discovered that there are real cases where the server sends back more bytes than requested: specifically in Trannsfer-mode: chunked. Here is a revised, much simpler patch that passes on the data. *** asynchat.py.original Tue Mar 20 10:43:01 2001 --- asynchat.py Sun Mar 25 09:13:56 2001 *************** *** 106,113 **** self.ac_in_buffer = '' self.terminator = self.terminator - lb else: ! self.collect_incoming_data (self.ac_in_buffer[:n]) ! self.ac_in_buffer = self.ac_in_buffer[n:] self.terminator = 0 self.found_terminator() else: --- 106,113 ---- self.ac_in_buffer = '' self.terminator = self.terminator - lb else: ! self.collect_incoming_data (self.ac_in_buffer) ! self.ac_in_buffer = '' self.terminator = 0 self.found_terminator() else: |
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msg36139 - (view) | Author: Guido van Rossum (gvanrossum) * | Date: 2001-04-10 22:16 | |
Logged In: YES user_id=6380 Doug, I'm hesitant to apply this right before releasing 2.1 -- I have no way to test this code. Can you ask for a review by Sam Rushing, asynchat.py's author? |
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msg36140 - (view) | Author: Doug Fort (dougfort) | Date: 2001-04-22 13:26 | |
Logged In: YES user_id=6399 I have sent a copy of the patch to Sam Rushing with a request for review. |
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msg36141 - (view) | Author: Doug Fort (dougfort) | Date: 2001-04-22 20:34 | |
Logged In: YES user_id=6399 Sam Rushing thinks that this patch will break other protocols. I have to admit, I was only concerned with HTTP. I can work around them problem by overloading handle_read(), so why don't we forget the whole thing? |
History | |||
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Date | User | Action | Args |
2022-04-10 16:03:53 | admin | set | github: 34198 |
2001-03-20 16:32:23 | dougfort | create |