Gmail's quoted response confuses BridgeDB's email autoresponder
When replying to a BridgeDB email in Gmail's web interface, one ends up sending an email like this:
On Mon, Apr 6, 2020 at 2:12 PM <bridges@torproject.org> wrote:
>
> [This is an automated email. Please do not reply.]
>
> Here are your bridges:
>
> [redacted]
>
> Add these bridges to your Tor Browser by opening your browser
> preferences, clicking on "Tor", and then adding them to the "Provide a
> bridge" field.
>
> If these bridges are not what you need, reply to this email with one of
> the following commands in the message body:
>
> get bridges (Request unobfuscated Tor bridges.)
> get ipv6 (Request IPv6 bridges.)
> get transport TYPE (Request obfuscated bridges. Replace TYPE with
> 'obfs4'.)
> get key (Get a copy of BridgeDB's public GnuPG key.)
>
>
>
--000000000000dde1a205a2a60f3e
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr">get transport obfs4<br></div><br><div class=3D"gmail_quote=
"><div dir=3D"ltr" class=3D"gmail_attr">On Mon, Apr 6, 2020 at 2:12 PM <=
<a href=3D"mailto:bridges@torproject.org">bridges@torproject.org</a>> wr=
ote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px=
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
[This is an automated email.=C2=A0 Please do not reply.]<br>
<br>
Here are your bridges:<br>
<br>
=C2=A0 [redacted]<br>
<br>
Add these bridges to your Tor Browser by opening your browser<br>
preferences, clicking on "Tor", and then adding them to the "=
;Provide a<br>
bridge" field.<br>
<br>
If these bridges are not what you need, reply to this email with one of<br>
the following commands in the message body:<br>
<br>
=C2=A0 get bridges=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 (Request unobfu=
scated Tor bridges.)<br>
=C2=A0 get ipv6=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0(Requ=
est IPv6 bridges.)<br>
=C2=A0 get transport TYPE=C2=A0 =C2=A0 =C2=A0(Request obfuscated bridges. R=
eplace TYPE with 'obfs4'.)<br>
=C2=A0 get key=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 (Get =
a copy of BridgeDB's public GnuPG key.)<br>
<br>
<br>
</blockquote></div>
--000000000000dde1a205a2a60f3e--BridgeDB correctly ignores the commands that start with > but it doesn't ignore the commands that are encoded in quoted-printable. BridgeDB's email parser ends up interpreting each line as command, ending in "get key", which raises an exception, resulting in BridgeDB sending no response at all.
We should make sure that BridgeDB doesn't get confused by Gmail's quoted-printable response.