Add support for the Binary Content extension [RFC3516].

Unfortunately as of Debian Wheezy it doesn't work for Dovecot with
COMPRESS=DEFLATE [RFC4978] and non-synchronizing literals.

    perl -e 'use Compress::Raw::Zlib;
             print "a COMPRESS DEFLATE\r\n";
             sleep 1;
             my $d = new Compress::Raw::Zlib::Deflate( -WindowBits => -15 );
             $d->deflate("b APPEND TRASH ~{1+}\r\nx\r\n", my $buf);
             print $buf;
             $d->flush($buf, Z_SYNC_FLUSH);
             print $buf;
             sleep 1;
    ' | /usr/lib/dovecot/imap
    imap(guilhem): Panic: stream doesn't support seeking backwards

Interestingly, it works just fine for non-binary literals:

    perl -e 'use Compress::Raw::Zlib;
             print "a COMPRESS DEFLATE\r\n";
             sleep 1;
             my $d = new Compress::Raw::Zlib::Deflate( -WindowBits => -15 );
             $d->deflate("b APPEND TRASH {1+}\r\nx\r\n", my $buf);
             print $buf;
             $d->flush($buf, Z_SYNC_FLUSH);
             print $buf;
             sleep 1;
    ' | /usr/lib/dovecot/imap

However I can't reproduce the problem Dovecot 2.2.18 and Debian Sid (but
it doesn't help to install Dovecot from testing to my Wheezy box.)

1 files changed, 4 insertions, 0 deletions

diff --git a/Changelog b/Changelog
index 23d2a17..5b010d2 100644
--- a/Changelog
+++ b/Changelog
@@ -6,6 +6,10 @@ interimap (0.2) upstream
     server.
   * Add a configuration option 'null-stderr=YES' to send STDERR to
     /dev/null for type=tunnel.
+  * Add support for the Binary Content extension [RFC3516].  Enabled by
+    default if both the local and remote servers advertize "BINARY".
+	Can be disabled by adding 'use-binary=NO' to the default section in
+	the configuration file.
 
  -- Guilhem Moulin <guilhem@guilhem.org>  Wed, 09 Sep 2015 00:44:35 +0200