I am writing an HTTP proxy and I am having trouble understanding some details of making a CONNECT request over TLS. To get a better picture, I am experimenting with Apache to observe how it interacts with clients. This is from my default virtual host.
NameVirtualHost *:443
<VirtualHost>
ServerName example.com
DocumentRoot htdocs/example.com
ProxyRequests On
AllowConnect 22
SSLEngine on
SSLCertificateFile /root/ssl/example.com-startssl.pem
SSLCertificateKeyFile /root/ssl/example.com-startssl.key
SSLCertificateChainFile /root/ssl/sub.class1.server.ca.pem
SSLStrictSNIVHostCheck off
</VirtualHost>
The conversation between Apache and my client goes like this.
a. client connects to example.com:443 and sends example.com in the TLS handshake.
b. client sends HTTP request.
CONNECT 192.168.1.1:22 HTTP/1.1
Host: example.com
Proxy-Connection: Keep-Alive
c. Apache says HTTP/1.1 400 Bad Request. The Apache error log says
Hostname example.com provided via SNI and hostname 192.168.1.1
provided via HTTP are different.
It appears that Apache does not look at the Host header other than to see that it is there since HTTP/1.1 requires it. I get identical failed behavior if the client sends Host: foo. If I make the HTTP request to example.com:80 without TLS, then Apache will connect me to 192.168.1.1:22.
I don't completely understand this behavior. Is there something wrong with the CONNECT request? I can't seem to locate the relevant parts of the RFCs that explain all this.