It is quite possible that the SNI option is used to select an appropriate certificate (usually web servers do this), when a plugin try to do this then the existence of more than one callback to do this could be confusing. SNI is a TLS option but there are others like ALPN so all of them could potential be in one callback.
Regards, Roland -----Original Message----- From: Susan Hinrichs [mailto:shinr...@network-geographics.com] Sent: Tuesday, January 27, 2015 5:34 PM To: dev@trafficserver.apache.org Subject: Re: Certificate process in openssl 1.0.2 On 1/27/2015 10:30 AM, James Peach wrote: >> On Jan 27, 2015, at 8:18 AM, Susan Hinrichs >> <shinr...@network-geographics.com> wrote: >> >> Originally, I was planning on leaving in plugin support for both the SNI >> callback and the cert callback. But as I reflect, I question that decision. >> I think it adds complexity without giving more power to the plugin writer. >> >> Both callbacks take place at the same point in the handshake. From both >> callbacks you can set the certificate. Depending on the version and patch >> level, only one of the callbacks will let you pause processing. >> >> Perhaps it is better to support only point for the plugin to callback after >> the client hello during the handshake processing? If we did that, ATS could >> adapt depending on the linked version of openssl and the plugin would not >> change. I'd still add a TS_SSL_CERT_HOOK for clarity, but I'd make it the >> same value as TS_SSL_SNI_HOOK. > Why do you need to make this change? What is the compatibility impact? Well we do need to support the certificate callbacks in openssl 1.0.2, so we have a means to pause handshake processing to load certificates, etc in a stock version of openssl. >> If openssl 1.0.1 is linked, it would execute the plugin's callback during >> the SNI callback. If openssl 1.0.2 is linked, it would execute the plugin's >> callback during the certificate callback. > Did openssl 1.0.1 contain your patch? If there is no released version of > openssl that contains the original callback you added, what is is that we > need to support? My patch was not rolled into open ssl. The only reason to continue to support it is that we had previously supported it. If you are unable to move to openssl 1.0.2, then at least you can patch up openssl 1.0.1 (though if you can run with a patched version you can likely upgrade too). My second idea, would have the least impact upon people who have already invested effort in writing plugins on the SNI callback. Judging from your questions, you don't see a reason to support both a SNI callback and a certificate callback either. Is that right? >> What are people's thoughts? >> >> Thanks, >> Susan >> >> On 1/27/2015 10:08 AM, Susan Hinrichs wrote: >>> Hi All, >>> >>> With 1.0.2 openssl expanded their support of the certificate callback to >>> handle pausing processing during the SSL handshake negotiation. This >>> replaces the functionality I added to the SNI callback in my patch for >>> openssl 1.0.1. >>> >>> With TS-3319, I'm updating the ATS callback logic to support the >>> certificate callback if you are compiling against openssl 1.0.2. >>> >>> There is a new hook constant, TS_SSL_CERT_HOOK. If you had a SNI callback >>> that was pausing the handshake to make decisions about the certificate, you >>> can move it from the TS_SSL_SNI_HOOK to the TS_SSL_CERT_HOOK. >>> >>> I'm finishing tidying up TS-3319. It should be ready later today or >>> tomorrow. >>> >>> Susan
