On 29/07/16 20:41, Kyle Rose wrote: > Right, I get that for interoperability with ENO-unaware stacks there is no > way to change data presented in the SYN. In the case where both ends > understand ENO but the server is not negotiating it, we can define TCP SYN > payload semantics differently: essentially, when there is an ENO option in > the SYN, an ENO-aware server will do one of two things: [...] > (2) If it is not negotiating ENO, it will not ACK the data, and will in > fact throw it away and explicitly permit transmission of *different* data > for the same sequence number range.
I don't think so. Whatever the client is, if the server is not showing support for different behaviour then the client must assume a standards TCP-implementing server, meaning that any data sent cannot be altered in a retransmission. That applies whether or not the _initial_ ack for a SYN-with-data acks that data; even if it did not, a later one might. Unless you're dividing signalling of ENO-aware from ENO-negotiating? -- Jeremy _______________________________________________ Tcpinc mailing list [email protected] https://www.ietf.org/mailman/listinfo/tcpinc
