[asterisk-bugs] [Asterisk 0018060]: [patch] func_string FILTER contains an infinite loop

[Asterisk Bug Tracker]

The following issue has been UPDATED. 
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https://issues.asterisk.org/view.php?id=18060 
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Reported By:                wdoekes
Assigned To:                
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Project:                    Asterisk
Issue ID:                   18060
Category:                   Functions/func_strings
Reproducibility:            always
Severity:                   trivial
Priority:                   normal
Status:                     new
Asterisk Version:           1.6.2.13 
JIRA:                        
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-09-27 08:41 CDT
Last Modified:              2010-09-28 10:57 CDT
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Summary:                    [patch] func_string FILTER contains an infinite loop
Description: 
Hi,

func_strings FILTER() contains an infinite loop when you're using
characters
above \x7f or invalid character escapes (e.g. \xgg).


Dialplan:

Set(var=abc "dëf)
NoOp(var = ${var})
Set(filtered=${FILTER(\x30-\xff,${var})}) ;; no wrapping
NoOp(filtered = ${filtered})
Set(filtered=${FILTER(\x30-\x10,${var})}) ;; wrapping 
NoOp(filtered = ${filtered})
Hangup()

Output:

Set("var=abc "dëf") in new stack
NoOp("var = abc "dëf") in new stack
WARNING[21708]: func_strings.c:466 filter: Range wrapping in
FILTER(\x20-\xff,abc "dëf).  This may not be what you want.
<-- Infinite loop

Expected output:

Set("var=abc "dëf") in new stack
NoOp("var = abc "dëf") in new stack
Set("filtered=abcdëf") in new stack
NoOp("filtered = abcdëf") in new stack
[2010-09-27 15:25:14] WARNING[23206]: func_strings.c:466 filter: Range
wrapping in FILTER(\x30-\x10,abc "dëf).  This may not be what you want.
Set("Local/+31852100586 at osvpi_world-1268;2", "filtered=abcdëf") in new
stack
NoOp("Local/+31852100586 at osvpi_world-1268;2", "filtered = abcdëf") in new
stack
Hangup("") in new stack



I've patched func_strings.c to add a couple of (unsigned char) casts, so
that
ac != c2 is actually false at one point. Otherwise ac loops from 0 to 255
while
c2 is negative.

I've also added a backwards incompatible change of setting c2 to c1 when
a
parse error (invalid character escape) occurs. Otherwise I'd get the
aforementioned warning when using a range that ends at \xff.


Regards,
Walter Doekes
OSSO B.V.
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---------------------------------------------------------------------- 
 (0127466) lmadsen (administrator) - 2010-09-28 10:57
 https://issues.asterisk.org/view.php?id=18060#c127466 
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Update description per your note. Thanks! 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-09-28 10:57 lmadsen        Note Added: 0127466                          
2010-09-28 10:57 lmadsen        Description Updated                          
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