Last active
May 4, 2021 21:12
-
-
Save bgoonz/b90c84fa791c8edaf6487916050d547b to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
''' | |
Generating random strings from regex-like expressions. | |
Generates sequences of random characters derived from a production | |
expression with a grammar approximately identical to that used by Regular | |
Expressions. | |
This is intended for data-driven testing (fuzzing) of input validators and | |
parsers that use regex or regex-like semantics. | |
Example, Generates a Random Email Address: | |
-- fuzzex.generate( "[a-zA-Z0-9._]+@[a-zA-Z0-9._]+\\\\.[a-z]+" ) | |
Where this program Breaks From Regex: | |
-- Fuzzex does not support "non-greedy" repetition. (e.g. "a*?") | |
-- Fuzzex does not currently support "non-capturing" groups. | |
-- Fuzzex is derived from the "Extended Regex" dialect most frequently used. | |
-- Fuzzex is 8-bit ASCII-oriented; this matches Python's RE, but not some others. | |
Where this snippet Is Not The Right Tool: (Go use Sulley or Peach) | |
-- Fuzzing semantic logic; e.g. it might generate data that looks like BASE-64, | |
but it might not decode. | |
''' | |
import re, sys, random | |
def op_dat( data ): | |
def op_dat_fn( vm ): | |
vm.write( data ) | |
return op_dat_fn | |
def op_seq( seq ): | |
def op_seq_fn( vm ): | |
for op in seq: | |
op( vm ) | |
return True | |
return op_seq_fn | |
def op_alt( alt ): | |
def op_alt_fn( vm ): | |
vm.choose( alt )( vm ) | |
return op_alt_fn | |
def op_set( ix, op ): | |
def op_set_fn( vm ): | |
with vm.capture( ix ): op( vm ) | |
return op_set_fn | |
def op_ref( ix ): | |
def op_ref_fn( vm ): | |
vm.write( vm.group( ix ) ) | |
return op_ref_fn | |
def op_nul( ): | |
def op_nul_fn( vm ): | |
pass | |
return op_nul_fn | |
def op_rpt( op, m, n ): | |
if m == n: | |
def op_fix_rpt_fn( vm ): | |
for i in range( 0, m ): | |
op( vm ) | |
return op_fix_rpt_fn | |
if m > n: n, m = m, n | |
r = n - m | |
def op_rpt_fn( vm ): | |
for i in range( 0, m + vm.choose( r ) ): | |
op( vm ) | |
return op_rpt_fn | |
def op_opt( op ): | |
def op_opt_fn( vm ): | |
if vm.choose( 2 ): op( vm ) | |
return op_opt_fn | |
def op_rng( s ): | |
s = ''.join( s ) | |
def op_rng_fn( vm ): | |
vm.write( vm.choose( s ) ) | |
return op_rng_fn | |
any_op = op_rng( map( chr, range( 0, 255 ) ) ) | |
def mk_seq_op( seq ): | |
"unifies a sequence of 0 to N requirements into a minimal operation" | |
if not seq: return op_nul( ) | |
if callable( seq ): return seq | |
if isinstance( seq, str ): return op_dat( seq ) | |
out = []; buf = '' | |
for op in seq: | |
if isinstance( op, str ): | |
buf += op | |
else: | |
if buf: | |
out.append( op_dat( buf ) ) | |
buf = '' | |
if op: | |
out.append( op ) | |
if buf: | |
out.append( op_dat( buf ) ) | |
if len( out ) == 1: | |
return out[0] | |
else: | |
return op_seq( out ) | |
class Error( Exception ): | |
pass | |
escapes = { | |
'n' : '\n', | |
'r' : '\r', | |
't' : '\t', | |
'v' : '\v', | |
'0' : '\0' | |
} | |
rx_octet = re.compile( '([0-8][0-8][0-8]|[0])' ) | |
rx_refer = re.compile( '([0-9][0-9]?)') | |
rx_range = re.compile( '[^\\\\]') | |
rx_repeat = re.compile( '([0-9]+)(,[0-9]+)?\\}' ) | |
class Compiler: | |
def __init__( self, src ): | |
self.src = src | |
self.ofs = 0 | |
self.opens = 0 | |
self.closes = 0 | |
self.limit = 4 | |
def parse_rpt( self, op ): | |
m = rx_repeat.match( self.src, self.ofs ) | |
if not m: | |
raise Error( '"{" followed without matching "}"') #TODO: Python ignores this silently. | |
self.ofs = m.end( ) | |
if not m.group(2): | |
n = int( m.group( 1 ) ) | |
return op_rpt( op, n, n ) | |
n = int( m.group(2)[1:] ) | |
m = int( m.group(1) ) | |
return op_rpt( op, m, n ) | |
def parse_rng( self ): | |
end = len( self.src ) | |
if self.ofs >= end: | |
raise Error( '"[" at end of expression' ) | |
if self.src[self.ofs] == '^': | |
self.ofs += 1 | |
x = self.parse_rng_items( ) | |
s = set( ) | |
for i in range( 0, 127 ): #TODO: configurable | |
c = chr( i ) | |
if c not in x: s.add( c ) | |
else: | |
s = self.parse_rng_items( ) | |
return op_rng( s ) | |
def parse_rng_items( self ): | |
end = len( self.src ) | |
s = set() | |
while self.ofs < end: | |
ch = self.src[ self.ofs ] | |
if ch == ']': | |
self.ofs += 1 | |
return s | |
a = self.parse_rng_item( ) | |
if self.src[ self.ofs ] == '-': | |
self.ofs += 1 | |
b = self.parse_rng_item( ) | |
for i in range( ord( a ), ord( b ) + 1 ): | |
ch = chr( i ) | |
s.add( ch ) | |
else: | |
s.add( a ) | |
raise Error( 'unmatched "["' ) | |
def parse_rng_item( self ): | |
end = len( self.src ) | |
if self.ofs >= end: raise Error( '"[" at end of expression' ) | |
ch = self.src[ self.ofs ] | |
self.ofs += 1 | |
if ch == '\\': | |
if self.ofs >= end: raise Error( '"\\" at end of expression' ) | |
m = rx_octet.match( self.src, self.ofs ) | |
if m: | |
self.ofs = m.end( ) | |
return chr( int( m.group(1), 8 ) ) | |
else: | |
return ch | |
def parse_esc( self ): | |
if self.ofs >= len( self.src ): | |
raise Error( '"\\" at end of expression' ) | |
m = rx_octet.match( self.src, self.ofs ) | |
if m: | |
self.ofs = m.end( ) | |
return op_data( chr( int( m.group(1), 8 ) ) ) | |
m = rx_refer.match( self.src, self.ofs ) | |
if m: | |
self.ofs = m.end( ) | |
ix = int( m.group( 1 ), 8 ) | |
if ix > self.closes: | |
raise Error( 'illegal forward reference' ) # not that there are any legal ones. | |
return op_ref( ix ) | |
ch = self.src[self.ofs] | |
self.ofs += 1 | |
return escapes.get( ch, ch ) | |
def parse_expr( self, inner = False ): | |
"parses a possibly branched expression yielding none or an operation" | |
opt = [] # We start with an empty sequence of requirements. | |
opts = [opt] # And a empty list of branches. | |
end = len( self.src ) | |
while self.ofs < end: | |
ch = self.src[ self.ofs ] | |
self.ofs += 1 | |
if ch == '|': | |
opt = [] | |
opts.append( opt ) | |
elif ch =='(': | |
self.opens += 1 | |
opt.append( op_set( self.opens, self.parse_expr( True ) ) ) | |
self.closes += 1 | |
elif ch == ')': | |
if not inner: raise Error( 'unmatched ")"' ) | |
inner = False | |
break | |
elif ch == '\\': | |
opt.append( self.parse_esc( ) ) | |
elif ch == '.': | |
opt.append( any_op ) | |
elif ch == '*': | |
if not opt: raise Error( 'nothing to repeat' ) | |
#TODO: Catch and Report multiple-repeat. | |
opt[-1] = op_rpt( mk_seq_op( opt[-1] ), 0, self.limit ) | |
elif ch == '+': | |
if not opt: raise Error( 'nothing to repeat' ) | |
#TODO: Catch and Report multiple-repeat. | |
opt[-1] = op_rpt( mk_seq_op( opt[-1] ), 1, self.limit ) | |
elif ch == '?': | |
if not opt: raise Error( 'nothing to repeat' ) | |
#TODO: Catch and Report multiple-repeat. | |
opt[-1] = op_opt( mk_seq_op( opt[-1] ) ) | |
elif ch == '[': | |
opt.append( self.parse_rng( ) ) | |
elif ch == '{': | |
if not opt: raise Error( 'nothing to repeat' ) | |
#TODO: Catch and Report multiple-repeat. | |
opt[-1] = self.parse_rpt( mk_seq_op( opt[-1] ) ) | |
else: | |
opt.append( ch ) | |
if inner: | |
raise Error( 'unmatched "("' ) | |
opts = filter( lambda x:x, opts ) | |
if not opts: | |
return op_nul( ) | |
elif len( opts ) == 1: | |
return mk_seq_op( opt ) | |
else: | |
return op_alt( map( mk_seq_op, opts ) ) | |
class Generator: | |
def __init__( self, root ): | |
if not root: raise Exception #TODO | |
self.root = root | |
def generate( self, seed = None, vm = None ): | |
if vm is None: vm = Vm( seed ) | |
self.root( vm ) | |
return str( vm ) | |
class Vm: | |
def __init__( self, seed = None ): | |
self.rng = random.WichmannHill( seed ) | |
self.out = [] | |
self.groups = {} | |
def choose( self, field ): | |
"selects a random value from 0 .. field - 1, or the list" | |
if isinstance( field, int ): | |
return self.rng.randint( 0, field ) | |
else: | |
return self.rng.choice( field ) | |
def write( self, data ): | |
self.out.append( data ) | |
def group( self, tag ): | |
return self.groups.get( tag, '' ) | |
def capture( self, tag ): | |
return Capture( self, tag ) | |
def __str__( self ): | |
return ''.join( self.out ) | |
def __repr__( self ): | |
return '<fuzzex.vm %r>' % str( self ) | |
class Capture: | |
def __init__( self, vm, ref ): | |
self.vm = vm | |
self.ref = ref | |
def __enter__( self ): | |
self.out = self.vm.out | |
self.vm.out = [] | |
def __exit__( self, errtyp, errval, errtb ): | |
if errtyp or errval: return False | |
vm = self.vm | |
data = ''.join( vm.out ) | |
vm.out = self.out | |
vm.write( data ) | |
vm.groups[self.ref] = data | |
def generate( fx, seed = None, vm = None ): | |
if isinstance( fx, str ): | |
fx = compile( fx ) | |
return fx.generate( seed, vm ) | |
def compile( data ): | |
return Generator( Compiler( data ).parse_expr( ) ) | |
def test( ex, seed = None ): | |
r = re.compile( '^' + ex + '$' ) | |
data = generate( ex, seed ) | |
k = r.match( data ) | |
print >>sys.stderr, 'TESTING: %s, RESULT: %r, %s' % ( | |
ex, data, "PASSED" if k else "FAILED" | |
) | |
return k | |
def test_batch( seed = None ): | |
return ( test( 'a' ) | |
and test( 'a|b', seed ) | |
and test( 'a|b|c', seed ) | |
and test( 'aa', seed ) | |
and test( 'aa|b', seed ) | |
and test( 'aa|bb', seed ) | |
and test( 'aa|bb|c', seed ) | |
and test( 'a|bb|c', seed ) | |
and test( 'a|bb|cc', seed ) | |
and test( '(a|bb|cc)z\\1', seed ) | |
and test( 'a?b', seed ) | |
and test( 'a*b', seed ) | |
and test( 'a+b', seed ) | |
and test( '[a]', seed ) | |
and test( '[-a-c]', seed ) | |
and test( '[^a-zA-Z0-9]', seed ) | |
and test( "^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)([?]([^#]*))?(#(.*))?", seed ) | |
and test( "[a-zA-Z0-9._]+@[a-z0-9._]+\\.[a-z]+", seed ) | |
and test( "[a-z]{3,8}", seed ) | |
and test( ".{3,8}", seed ) | |
) | |
__all__ = [ | |
'compile', 'generate', 'Generator' | |
] | |
if __name__ == '__main__': | |
test_batch( ) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment