<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p.msonormal0, li.msonormal0, div.msonormal0
{mso-style-name:msonormal;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style>
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal">There are TLS control messages which could flow in either direction, spontaneously. Renegotiation (pre TLS 1.3), tickets (TLS 1.3), and so on.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I cannot comment on if your proposal would work or not, sorry.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Alex H <alexhultman@gmail.com><br>
<b>Date: </b>Saturday, May 19, 2018 at 5:03 AM<br>
<b>To: </b>Rich Salz <rsalz@akamai.com>, openssl-users <openssl-users@openssl.org><br>
<b>Subject: </b>Re: [openssl-users] Receive throttling on SSL sockets<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Okay that's a good theoretical answer but practically not very useful.
<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I know for instance Node.js to implement their Streams interface with both TCP and SSL sockets. They both have pause / resume functions for receive-throttling and I've tested it with SSL and it seems to work somehow.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">One solution (I guess?) would be to stop polling for readable until SSL_write demands data then immediately stop polling for readable again once SSL_write is happy. In the case of getting unwanted data while throttling then SSL_peek can
be used instead of SSL_read. That would not guarantee no buildup but would work for the most part, right?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Do you see any flaw with this? Could it still fail due to mass buildup when throttling for long?<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">Den lör 19 maj 2018 04:57Salz, Rich via openssl-users <<a href="mailto:openssl-users@openssl.org">openssl-users@openssl.org</a>> skrev:<o:p></o:p></p>
</div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">TLS is a bidirectional protocol. You can’t throttle only one side.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Alex H <<a href="mailto:alexhultman@gmail.com" target="_blank">alexhultman@gmail.com</a>><br>
<b>Reply-To: </b>openssl-users <<a href="mailto:openssl-users@openssl.org" target="_blank">openssl-users@openssl.org</a>><br>
<b>Date: </b>Friday, May 18, 2018 at 7:21 PM<br>
<b>To: </b>openssl-users <<a href="mailto:openssl-users@openssl.org" target="_blank">openssl-users@openssl.org</a>><br>
<b>Subject: </b>[openssl-users] Receive throttling on SSL sockets</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">How do you properly implement receive throttling on SSL sockets without hindering writing?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">As opposed to raw TCP sockets, an SSL socket cannot be receive-throttled simply by stop polling for readable events on the underlying raw TCP socket. SSL_write still could require
reading of data so simply stop polling for readable would potentially hinder writing of data which is not okay.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Is there any such receive-throttling functionality in the SSL protocol itself? I don't see how SSL_peek would solve the issue since I would still be buffering (potentially uncontrolled
amount of) data in a BIO.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Even if I would _only_ enable readable polling when _absolutely needed_ as per SSL_write error, I still cannot guarantee not reading a chunk of data (which I would then need to
buffer up in a BIO since the application is not expecting it).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">How are we supposed to solve this issue without potentially building up backpressure?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks<o:p></o:p></p>
</div>
</div>
</div>
</div>
<p class="MsoNormal">-- <br>
openssl-users mailing list<br>
To unsubscribe: <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__mta.openssl.org_mailman_listinfo_openssl-2Dusers&d=DwMFaQ&c=96ZbZZcaMF4w0F4jpN6LZg&r=4LM0GbR0h9Fvx86FtsKI-w&m=FtaD7Zbj35pGUXqlS9M4iUkkFSwd55Jyb--utisnk_w&s=RlwtO6T51DUEJML9UBzKu164P3a2abJNnZSSPQIzXQI&e=" target="_blank">
https://mta.openssl.org/mailman/listinfo/openssl-users</a><o:p></o:p></p>
</blockquote>
</div>
</div>
</body>
</html>