OCSP stapling with HAProxy as a server

[vkssv]

This patch allows to load and validate OCSP response file in DER format, when haproxy starts. This file should be kept at the same path as the using server certificate and *.issuer file (set as ssl crt keyword value at haproxy's bind line):

bind *:1443 ssl crt show_ocsp_server.pem

~/haproxy master$ ls -al show_ocsp_server.pem*
-rw-r--r-- 1 root root 6918 mai   16 19:25 show_ocsp_server.pem
-rw-r--r-- 1 root root 1830 mai   16 19:25 show_ocsp_server.pem.issuer
-rw-r--r-- 1 root root 2281 mai   16 19:25 show_ocsp_server.pem.ocsp

Description

Please describe the scope of the fix or feature addition.

Fixes zd#

Testing

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Checklist

• [ ] added tests
• [ ] updated/added doxygen
• [ ] updated appropriate READMEs
• [ ] Updated manual and documentation