Brendan Cully <[EMAIL PROTECTED]> writes:
> On Sunday, 18 March 2007 at 17:36, Rocco Rutte wrote:
>> I was looking at some mutt code for this issue and other issues that
>> report broken threading upon invalid message-ids. It seems that mutt
>> happily accepts the following syntax: '<.*>' which is just plain wrong.
>>
>> I looked at rfc822.c to try to reuse address parsing for parsing
>> message-ids but failed since I didn't have much time and the quote is
>> quite complex.
>>
>> Even though adopting your code for mutt would be quite easy, I'm not
>> yet sure what to do in case of validation errors.
>>
>> Say we get '<foobar>' during APOP authentication; should be really
>> reject that and report failed authentication? If a message has
>> '<foobar>' as message-id and others have it in their References:
>> header, should we really ignore it and break threading?
>
> Here's a patch that does a really minimal check that the message ID is
> of the form <[EMAIL PROTECTED]> where x and y are between ASCII 0 and 127. I
> hope
> that it's enough to thwart the MD5 collision attack, but liberal
> enough to tolerate the range of broken POP servers out there. The @y
> test could be easily removed if necessary.
May I again offer to use my code here which I deem a *COMPLETE*
RFC822-validation:
<http://mknod.org/svn/fetchmail/branches/BRANCH_6-3/rfc822valid.c>
Any complaints my way. It is lightly-documented ad-hoc code implementing
RFC-822 tokens more or less in a hardwired way. I didn't bother to read
RFC-2822, because that's not what RFC-1939 references :-P
The code expects the timestamp as C string with the angle brackets
included, you'd call for instance
res = rfc822_valid_msgid((const unsigned char *)"<[EMAIL PROTECTED]>");
if (!res) {
barf("noncompliant timestamp, APOP not available.\n");
}
so we can share & fix code together rather than all go reinventing
wheels with dents or something like that...
The code at the URL above is part of fetchmail 6.3.8, so if someone
spots a bug, let me know.
It's GPL v2, but I'm willing to license under different terms for
OSI-compliant software if needed.
I'm attaching it for your convenience (I hope it passes through the list
driver...)
--
Matthias Andree
/* rfc822valid.c -- validators for RFC-822 syntax
* (C) Copyright 2007 Matthias Andree <[EMAIL PROTECTED]>
* GNU General Public License v2 */
/* This works only on ASCII-based computers. */
#include "fetchmail.h"
#include <string.h>
/* CHAR except specials, SPACE, CTLs */
static const char *atomchar = "!#$%&'*+-/0123456789=?ABCDEFGHIJKLMNOPQRSTUVWXYZ^_`abcdefghijklmnopqrstuvwxyz{|}~";
static int quotedpair(unsigned char const **x) {
if (**x != '\\') return 0;
++ *x;
if ((int)* *x > 127 || * *x == '\0')
/* XXX FIXME: 0 is a legal CHAR, so the == '\0' is sort of bogus
* above, but fetchmail does not currently deal with NUL inputs
* so we don't need to make the distinction between
* end-of-string and quoted NUL. */
return 0;
++ *x;
return 1;
}
static int quotedstring(unsigned char const **x) {
if (* *x != '"') return 0;
++ *x;
for(;;) {
switch (* *x) {
case '"':
++ *x;
return 1;
case '\\':
if (quotedpair(x) == 0) return 0;
continue;
case '\r':
case '\0':
return 0;
}
if ((int)* *x >= 128) {
return 0;
}
++ *x;
}
}
static int atom(unsigned char const **x) {
/* atom */
if (strchr(atomchar, (const char)**x)) {
*x += strspn((const char *)*x, atomchar);
return 1;
}
/* invalid character */
return 0;
}
static int word(unsigned char const **x) {
if (**x == '"')
return quotedstring(x);
return atom(x);
}
static int domain_literal(unsigned char const **x) {
if (**x != '[') return 0;
++ *x;
for(;;) {
switch (* *x) {
case '\0':
case '\r':
case '[':
return 0;
case ']':
++ *x;
return 1;
case '\\':
if (quotedpair(x) == 0) return 0;
continue;
}
if ((int)* *x > 127) return 0;
++ *x;
}
}
static int subdomain(unsigned char const **x) {
if (* *x == '[') return domain_literal(x);
return atom(x);
}
int rfc822_valid_msgid(const unsigned char *x) {
/* expect "<" */
if (*x != '<') return 0;
++ x;
/* expect local-part = word *("." word)
* where
* word = atom/quoted-string
* atom = 1*ATOMCHAR
* quoted-string = <"> *(qtext/quoted-pair) <">
* qtext = CHAR except ", \, CR
* quoted-pair = "\" CHAR
*/
for(;;) {
if (word(&x) == 0) return 0;
if (*x == '.') { ++x; continue; }
if (*x == '@') break;
return 0;
}
/* expect "@" */
if (*x != '@') return 0;
++ x;
/* expect domain = sub-domain *("." sub-domain)
* sub-domain = domain-ref/domain-literal
* domain-ref = atom
* domain-literal = "[" *(dtext/quoted-pair) "]" */
for(;;) {
if (subdomain(&x) == 0) return 0;
if (*x == '.') { ++x; continue; }
if (*x == '>') break;
return 0;
}
if (*x != '>') return 0;
return 1;
}
#ifdef TEST
#include <stdio.h>
int main(int argc, char **argv) {
int i;
for (i = 1; i < argc; i++) {
printf("%s: %s\n", argv[i], rfc822_valid_msgid((unsigned char *)argv[i]) ? "OK" : "INVALID");
}
return 0;
}
#endif
