Milter-greylist

According to reschauzier:
> > 
> > True, the back reference will also pick up:
> > 
> > 1a4443K23_1
> > 
> > Which may or may not be desirable.
> 
> I must be missing something here; how does
> 
> [0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+
> 
> pick up
> 
> 1a4443K23_1
> 
> ?

it cannot.
\1 refers to the pattern matched (so to 'a'), not to the pattern to match (not to '[^0-9]' so neither 'K' nor '_' could match).

e.g. with perl:

$ perl -e 'print "1a4443K23_1" =~ m/[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+/ ? "ok\n" : "nok\n";'
nok
$ perl -e 'print "1a4443a2a31" =~ m/[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+/ ? "ok\n" : "nok\n";'
ok

explained also by this :

$ perl -e 'use re "debug"; print "1a4443K23_1" =~ m/[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+/ ? "ok\n" : "nok\n";'
Compiling REx `[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+'
size 68 Got 548 bytes for offset annotations.
first at 2
   1: PLUS(13)
   2:   ANYOF[0-9](0)
  13: OPEN1(15)
  15:   ANYOF[\0-/:-\377{unicode_all}](26)
  26: CLOSE1(28)
  28: PLUS(40)
  29:   ANYOF[0-9](0)
  40: REF1(42)
  42: PLUS(54)
  43:   ANYOF[0-9](0)
  54: REF1(56)
  56: PLUS(68)
  57:   ANYOF[0-9](0)
  68: END(0)
stclass "ANYOF[0-9]" plus minlen 5 
Offsets: [68]
        6[1] 1[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 7[1] 0[0] 8[6] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 14[1] 0[0] 20[1] 15[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 21[2] 0[0] 28[1] 23[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 29[2] 0[0] 36[1] 31[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 37[0] 
Matching REx "[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+" against "1a4443K23_1"
Matching stclass "ANYOF[0-9]" against "1a4443K"
  Setting an EVAL scope, savestack=3
   0 <> <1a4443K23_1>     |  1:  PLUS
                           ANYOF[0-9] can match 1 times out of 2147483647...
  Setting an EVAL scope, savestack=3
   1 <1> <a4443K23_1>     | 13:    OPEN1
   1 <1> <a4443K23_1>     | 15:    ANYOF[\0-/:-\377{unicode_all}]
   2 <1a> <4443K23_1>     | 26:    CLOSE1
   2 <1a> <4443K23_1>     | 28:    PLUS
                           ANYOF[0-9] can match 4 times out of 2147483647...
  Setting an EVAL scope, savestack=3
   6 <1a4443> <K23_1>     | 40:      REF1
                                failed...
   5 <1a444> <3K23_1>     | 40:      REF1
                                failed...
   4 <1a44> <43K23_1>     | 40:      REF1
                                failed...
   3 <1a4> <443K23_1>     | 40:      REF1
                                failed...
                              failed...
                            failed...
  Setting an EVAL scope, savestack=3
   2 <1a> <4443K23_1>     |  1:  PLUS
                           ANYOF[0-9] can match 4 times out of 2147483647...
  Setting an EVAL scope, savestack=3
   6 <1a4443> <K23_1>     | 13:    OPEN1
   6 <1a4443> <K23_1>     | 15:    ANYOF[\0-/:-\377{unicode_all}]
   7 <1a4443K> <23_1>     | 26:    CLOSE1
   7 <1a4443K> <23_1>     | 28:    PLUS
                           ANYOF[0-9] can match 2 times out of 2147483647...
  Setting an EVAL scope, savestack=3
   9 <1a4443K23> <_1>     | 40:      REF1
                                failed...
   8 <1a4443K2> <3_1>     | 40:      REF1
                                failed...
                              failed...
   5 <1a444> <3K23_1>     | 13:    OPEN1
   5 <1a444> <3K23_1>     | 15:    ANYOF[\0-/:-\377{unicode_all}]
                              failed...
   4 <1a44> <43K23_1>     | 13:    OPEN1
   4 <1a44> <43K23_1>     | 15:    ANYOF[\0-/:-\377{unicode_all}]
                              failed...
   3 <1a4> <443K23_1>     | 13:    OPEN1
   3 <1a4> <443K23_1>     | 15:    ANYOF[\0-/:-\377{unicode_all}]
                              failed...
                            failed...
Contradicts stclass...
Match failed
nok
Freeing REx: `"[0-9]+([^0-9])[0-9]+\\1[0-9]+\\1[0-9]+"'



while :


$ perl -e 'use re "debug"; print "1a4443a23a1" =~ m/[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+/ ? "ok\n" : "nok\n";'
Compiling REx `[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+'
size 68 Got 548 bytes for offset annotations.
first at 2
   1: PLUS(13)
   2:   ANYOF[0-9](0)
  13: OPEN1(15)
  15:   ANYOF[\0-/:-\377{unicode_all}](26)
  26: CLOSE1(28)
  28: PLUS(40)
  29:   ANYOF[0-9](0)
  40: REF1(42)
  42: PLUS(54)
  43:   ANYOF[0-9](0)
  54: REF1(56)
  56: PLUS(68)
  57:   ANYOF[0-9](0)
  68: END(0)
stclass "ANYOF[0-9]" plus minlen 5 
Offsets: [68]
        6[1] 1[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 7[1] 0[0] 8[6] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 14[1] 0[0] 20[1] 15[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 21[2] 0[0] 28[1] 23[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 29[2] 0[0] 36[1] 31[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 37[0] 
Matching REx "[0-9]+([^0-9])[0-9]+\1[0-9]+\1[0-9]+" against "1a4443a23a1"
Matching stclass "ANYOF[0-9]" against "1a4443a"
  Setting an EVAL scope, savestack=3
   0 <> <1a4443a23a1>     |  1:  PLUS
                           ANYOF[0-9] can match 1 times out of 2147483647...
  Setting an EVAL scope, savestack=3
   1 <1> <a4443a23a1>     | 13:    OPEN1
   1 <1> <a4443a23a1>     | 15:    ANYOF[\0-/:-\377{unicode_all}]
   2 <1a> <4443a23a1>     | 26:    CLOSE1
   2 <1a> <4443a23a1>     | 28:    PLUS
                           ANYOF[0-9] can match 4 times out of 2147483647...
  Setting an EVAL scope, savestack=3
   6 <1a4443> <a23a1>     | 40:      REF1
   7 <1a4443a> <23a1>     | 42:      PLUS
                           ANYOF[0-9] can match 2 times out of 2147483647...
  Setting an EVAL scope, savestack=3
   9 <1a4443a23> <a1>     | 54:        REF1
  10 <1a4443a23a> <1>     | 56:        PLUS
                           ANYOF[0-9] can match 1 times out of 2147483647...
  Setting an EVAL scope, savestack=3
  11 <1a4443a23a1> <>     | 68:          END
Match successful!
ok
Freeing REx: `"[0-9]+([^0-9])[0-9]+\\1[0-9]+\\1[0-9]+"'



/Fabien