I am unsure about how extensions are handled in TLS v1.2.
During the handshake, the client is able to add some extensions during ClientHello. As far I understood, the server can pick arbitrary subsets from this list in ServerHello similar to picking the cipher suite, which the client provided during ClientHello. Is this correct?
If not, is it that the server can either take all those extensions into account, or must abort the handshake? I am not sure which is true.
I was looking for an adequate answer here in RFC5246, but didn't really find the one statement I am looking for.