APM Irule multiple access profile for one virtual server

What you are asking is quite easy to do. I cannot take full credit for it completely. I took the SNI irule published by Joel Moses a few years back and changed it to simply extract the SNI and put that info into the variable called "tls_servername"

If you look at the very bottom, you will see some generic logic to make a virtual call to the value of tls_servername and if that is unsuccessful, to look up the mapping in a datagroup called "Content_Switch_dg" which is simply a mapping of requested hostname to virtualserver name.

    when CLIENT_ACCEPTED {

                 We have a clientssl profile attached to this VIP but we need
                 to find an SNI record in the client handshake. To do so, we'll
                 disable SSL processing and collect the initial TCP payload.

        set default_tls_pool [LB::server pool]
                set detect_handshake 1
                TCP::collect



}

when CLIENT_DATA {
        set detect_handshake 1  
        TCP::collect  
        if { ($detect_handshake) } {

                 If we're in a handshake detection, look for an SSL/TLS header.

                binary scan [TCP::payload] cSS tls_xacttype tls_version tls_recordlen

                 TLS is the only thing we want to process because it's the only
                 version that allows the servername extension to be present. When we
                 find a supported TLS version, we'll check to make sure we're getting
                 only a Client Hello transaction -- those are the only ones we can pull
                 the servername from prior to connection establishment.

                switch $tls_version {
                        "769" -
                        "770" -
                        "771" {
                                if { ($tls_xacttype == 22) } {
                                        binary scan [TCP::payload] @5c tls_action
                                        if { not (($tls_action == 1) && ([TCP::payload length] > $tls_recordlen)) } {
                                                set detect_handshake 0
                                        }
                                }
                        }
                        default {
                                set detect_handshake 0
                        }
                }

                if { ($detect_handshake) } {

                 If we made it this far, we're still processing a TLS client hello.
                
                 Skip the TLS header (43 bytes in) and process the record body. For TLS/1.0 we
                 expect this to contain only the session ID, cipher list, and compression
                 list. All but the cipher list will be null since we're handling a new transaction
                 (client hello) here. We have to determine how far out to parse the initial record
                 so we can find the TLS extensions if they exist.

                        set record_offset 43
                        binary scan [TCP::payload] @${record_offset}c tls_sessidlen
                        set record_offset [expr {$record_offset + 1 + $tls_sessidlen}]
                        binary scan [TCP::payload] @${record_offset}S tls_ciphlen
                        set record_offset [expr {$record_offset + 2 + $tls_ciphlen}]
                        binary scan [TCP::payload] @${record_offset}c tls_complen
                        set record_offset [expr {$record_offset + 1 + $tls_complen}]

                 If we're in TLS and we've not parsed all the payload in the record
                 at this point, then we have TLS extensions to process. We will detect
                 the TLS extension package and parse each record individually.

                        if { ([TCP::payload length] > $record_offset) } {
                                binary scan [TCP::payload] @${record_offset}S tls_extenlen
                                set record_offset [expr {$record_offset + 2}]
                                binary scan [TCP::payload] @${record_offset}a* tls_extensions

                 Loop through the TLS extension data looking for a type 00 extension
                 record. This is the IANA code for server_name in the TLS transaction.

                                for { set x 0 } { $x < $tls_extenlen } { incr x 4 } {
                                        set start [expr {$x}]
                                        binary scan $tls_extensions @${start}SS etype elen
                                        if { ($etype == "00") } {

                 A servername record is present. Pull this value out of the packet data
                 and save it for later use. We start 9 bytes into the record to bypass
                 type, length, and SNI encoding header (which is itself 5 bytes long), and
                 capture the servername text (minus the header).

                                                set grabstart [expr {$start + 9}]
                                                set grabend [expr {$elen - 5}]
                                                binary scan $tls_extensions @${grabstart}A${grabend} tls_servername
                                                set start [expr {$start + $elen}]
                                        } else {

                 Bypass all other TLS extensions.

                                                set start [expr {$start + $elen}]
                                        }
                                        set x $start
                                }

                 Check to see whether we got a servername indication from TLS. If so,
                 make the appropriate changes.

                                if { ([info exists tls_servername] ) }      {
                                    log local0. "Requested host: $tls_servername"

                                    if { [catch { virtual $tls_servername } ]} {
                                        if { $::DEBUG == 1 } { log local0. "Virtual Server $tls_servername doesn't exist...Searching Datagroup"}
                                        if { [class match $tls_servername equals Content_Switch_dg]} {
                                            if { $::DEBUG == 1 } { log local0. "Server found in Datagroup" }
                                            virtual [class lookup $tls_servername Content_Switch_dg]
                                            TCP::release
                                        }
                                    } else {
                                        if { $::DEBUG == 1 } { log local0. "switching to virtual server $tls_servername" } 
                                           virtual $tls_servername
                                           TCP::release
                                        }
                                    }                        

                                  } else {
                                      Servername not found
                                     log local0. "Servername could not be determined"
                                  }                                  
}
}
}