tests/test-gpg.t

smtp: verify the certificate of the SMTP server for STARTTLS/SMTPS

Before this patch, the certificate of the SMTP server for STARTTLS or
SMTPS isn't verified.

This may cause man-in-the-middle security problem (stealing
authentication information), even though SMTP channel itself is
encrypted by SSL.

When "[smtp] tls" is configured as "smtps" or "starttls", this patch:

  - uses classes introduced by preceding patches instead of "SMTP" or
    "SMTP_SSL" of smtplib, and

  - verifies the certificate of the SMTP server, if "[smtp]
    verifycert" is configured as other than False

"[smtp] verifycert" can be configured in 3 levels:

  - "strict":

    This verifies peer certificate, and aborts if:

      - peer certification is not valid, or
      - no configuration in "[hostfingerprints]" and "[web] cacerts"

    This is default value of "[smtp] verifycert" for security.

  - "loose":

    This verifies peer certificate, and aborts if peer certification is
    not valid.

    This just shows warning message ("certificate not verified"), if
    there is no configuration in "[hostfingerprints]" and "[web]
    cacerts".

    This is as same as verification for HTTPS connection.

  - False(no verification):

    Peer certificate is not verified.

    This is as same as the behavior before this patch series.

"hg email --insecure" uses "loose" level, and ignores "[web] cacerts"
as same as push/pull/etc... with --insecure.

Ignoring "[web] cacerts" configuration for "hg email --insecure" is
already done in "dispatch._dispatch()" by looking "insecure" up in the
table of command options.

Test the GPG extension

  $ "$TESTDIR/hghave" gpg || exit 80
  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > gpg=
  > 
  > [gpg]
  > cmd=gpg --no-permission-warning --no-secmem-warning --no-auto-check-trustdb --homedir "$TESTDIR/gpg"
  > EOF
  $ hg init r
  $ cd r
  $ echo foo > foo
  $ hg ci -Amfoo
  adding foo

  $ hg sigs

  $ hg sign 0
  signing 0:e63c23eaa88a

  $ hg sigs
  hgtest                             0:e63c23eaa88ae77967edcf4ea194d31167c478b0

  $ hg sigcheck 0
  e63c23eaa88a is signed by:
   hgtest

verify that this test has not modified the trustdb.gpg file back in
the main hg working dir
  $ "$TESTDIR/md5sum.py" "$TESTDIR/gpg/trustdb.gpg"
  f6b9c78c65fa9536e7512bb2ceb338ae  */gpg/trustdb.gpg (glob)

  $ cd ..