Crisscross cancellation protocol
Technologies, systems, and methods for ordered message delivery that avoid message races or crisscrosses between communicating nodes. For example, if Node A sends message 3 towards Node B and, shortly thereafter, Node B sends message X to Node A, Node A would like to know whether or not message X reflects Node B's state after receiving message 3. If Node B received message 3 prior to sending message X, then proper state may be maintained between the nodes. But if messages 3 and X crisscrossed, or if message 3 was never properly received by Node B, then the state between the nodes may be corrupt. Technologies, systems, and methods are provided to avoid such corruption.
1. A method performed on an electronic device that includes memory, the method comprising:
receiving, from a remote device by the electronic device while a state of a protocol is set to a race fix state, an incoming message that conforms to the protocol and that includes a first set of state variables that corresponds to the remote device and that comprises a nonce value and a remote nonce value and a counter value and a remote counter value, where the remote nonce value uniquely identifies a last known session of the electronic device as known by the remote device as different from other sessions of the electronic device, and where the memory comprises a second set of state variables of the protocol that corresponds to the electronic device;
validating, based on comparing the second set of state variables to the first set of state variables of the received incoming message, the received incoming message;
updating, in response to the received incoming message being valid, the second set of state variables based on the first set of state variables; and
setting, in response to the updating, the state to a normal state.
2. The method of claim 1 where the received incoming message is buffered in a single-message receive buffer in the memory.
3. The method of claim 1 where the comparing comprises determining that the nonce value of the first set of state variables matches a remote nonce value of the second set of state variables.
4. The method of claim 1 where the comparing comprises determining that the counter value of the first set of state variables is strictly greater than a remote counter value of the second set of state variables.
5. The method of claim 1 where the comparing comprises determining that the remote counter value of the first set of state variables matches a counter value of the second set of state variables.
6. The method of claim 1 where the comparing comprises determining that the remote nonce value of the first set of state variables is either zero or matches a nonce value of the second set of state variables.
7. The method of claim 1 further comprising dropping, in response to the received incoming message being invalid, the received incoming message.
8. An electronic device comprising:
a processor;
memory coupled to the processor;
a network adapter coupled to the processor and memory and via which the electronic device is configured to receive, from a remote device while a state of a protocol is set to a race fix state, an incoming message that conforms to the protocol and that includes a first set of state variables that corresponds to the remote device and that comprises a nonce value and a remote nonce value and a counter value and a remote counter value, where the remote nonce value uniquely identifies a last known session of the electronic device as known by the remote device as different from other sessions of the electronic device, and where the memory comprises a second set of state variables of the protocol that corresponds to the electronic device; and
the processor via which the electronic device:
validates, based on comparing the second set of state variables to the first set of state variables of the received incoming message, the received incoming message;
updates, in response to the received incoming message being valid, the second set of state variables based on the first set of state variables; and
sets, in response to the updating, the state to a normal state.
9. The electronic device of claim 8 where the received incoming message is buffered in a single-message receive buffer in the memory.
10. The electronic device of claim 8 where the comparing comprises determining that the nonce value of the first set of state variables matches a remote nonce value of the second set of state variables.
11. The electronic device of claim 8 where the comparing comprises determining that the counter value of the first set of state variables is strictly greater than a remote counter value of the second set of state variables.
12. The electronic device of claim 8 where the comparing comprises determining that the remote counter value of the first set of state variables matches a counter value of the second set of state variables.
13. The electronic device of claim 8 where the comparing comprises determining that the remote nonce value of the first set of state variables is either zero or matches a nonce value of the second set of state variables.
14. The electronic device of claim 8 configured to drop, in response to the received incoming message being invalid, the received incoming message.
15. At least one computer storage device comprising:
memory that includes computer-executable instructions that, based on execution by an electronic device, configure the electronic device to perform actions comprising:
receiving, from a remote device by the electronic device while a state of a protocol is set to a race fix state, an incoming message that conforms to the protocol and that includes a first set of state variables that corresponds to the remote device and that comprises a nonce value and a remote nonce value and a counter value and a remote counter value, where the remote nonce value uniquely identifies a last known session of the electronic device as known by the remote device as different from other sessions of the electronic device, and where the memory comprises a second set of state variables of the protocol that corresponds to the electronic device;
validating, based on comparing the second set of state variables to the first set of state variables of the received incoming message, the received incoming message;
updating, in response to the received incoming message being valid, the second set of state variables based on the first set of state variables; and
setting, in response to the updating, the state to a normal state.
16. The at least one computer storage device of claim 15 where the received incoming message is buffered in a single-message receive buffer in the memory.
17. The at least one computer storage device of claim 15 where the comparing comprises determining that the nonce value of the first set of state variables matches a remote nonce value of the second set of state variables.
18. The at least one computer storage device of claim 15 where the comparing comprises determining that the counter value of the first set of state variables is strictly greater than a remote counter value of the second set of state variables.
19. The at least one computer storage device of claim 15 where the comparing comprises determining that the remote counter value of the first set of state variables matches a counter value of the second set of state variables.
20. The at least one computer storage device of claim 15 where the comparing comprises determining that the remote nonce value of the first set of state variables is either zero or matches a nonce value of the second set of state variables.