[SM-PLUGINS] Updated S/MIME Verification plugin (now correct mail)

[Walter H. <wal...@ma...>]

Hello anybody,

This plugin v1.0 has a few critical bugs, which made the apache logs
endless growing;

$fd = fopen( ... )
while (!feof($fd))    // <-- there is the problem in downloadcert.php, {  
                  //    no error check, if the fopen failed or not ... ...
}

I fixed them and also did some error handling: now it is possible to see
the difference between the following:
- an unmodified mail
- an unmodified mail, but the signer's certificate can't be verified
    (self-signed or CA not in trusted certificate store)
- an modified mail
- an modifoed mail, and the signer's certificate can't be verified
    (self-signed or CA not in trusted certificate store)
- a mail with an invalid signature:
    in this case there is no difference if the mail itself is altered or not

the case when the signer's certificate gots invalid is handled the same as
when unable to be verified (self-signed or CA not in trusted certificate
store);

moved any call to openssl into one shell script: openssl-cmds.sh
(solved an "incompatiblity" issue with some linux distributions:
                                            trusted certificate store)

added a complete certificate view (certview-complete.php):
 displays 'openssl x509 -in certfile -noout -text';

the certificate fingerprint is not only MD5, also SHA1; I added/fixed this
to the certificate view page (certview.php)

I didn't add the possibility that the fingerprint could also be SHA256;
(this would be 1 line in openssl-cmds.sh and two lines in viewcert.php
each similar to the lines for the SHA1 fingerprint)
if wished I'll add this;

could anybody please test it with squirrelmail 1.5.0+ - just to sse if
everything works there as expected, too?

I'm using squirrelmail from a rpm from fedora epel-7 (1.4.22-15.el7) (I'm
running CentOS 6.x with PHP5.4 from remi repository)

would be great to publish my update as release 1.1 ...

my work is stored here
https://vhost01.mathemainzel.info/sqmailplugin/smime-1.1-1.1.1.tar.gz

Thanks.

Greetings from Austria,
Walter