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<p class="MsoNormal">Hello team,<o:p></o:p></p>
<p class="MsoNormal">We use nginx as reverse proxy to a upstream endpoint which requires a client cert authentication. The proxy is configured to request a certificate from the browser and then to set a header in the proxy location block like:<o:p></o:p></p>
<p class="MsoNormal"><b>proxy_set_header SSL_CLIENT_CERT $ssl_client_escaped_cert;<o:p></o:p></b></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The upstream server supports PEM with some restrictions:<o:p></o:p></p>
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<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Newlines should be replaced by space (or any whitespace)<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Or alternatively only the base64 content in one row (no blanks) without BEGIN.. END CERTIFICATE sections<o:p></o:p></li></ol>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Manipulating the upstream server is not an option. It is not another nginx instance. Is it possible to rewrite the header before it is sent by replacing all %0d and %0a with space and URL decoding a few other characters like %2f?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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