Cooperative proxy auto-discovery and connection interception
View Patent ↗In a network supporting transactions between clients and servers and proxies that are interposable in a network path between at least one client and at least one server, wherein a pair of proxies can modify a packet stream between a client and a server such that packet data from the client to the server is transformed at a client-side proxy of the proxy pair and untransformed at a server-side proxy of proxy pair and such that packet data from the server to the client is transformed at the server-side proxy and untransformed at the client-side proxy, a method and apparatus for a discovering proxy to transparently discover its position in a proxy pair by using proxy signals to indicate to other proxies that could pair with the discovering proxy. A discovering proxy might determine that it is a client-side proxy by receipt of a packet from client without a proxy signal. A discovering proxy might determine that it is a server-side proxy by receipt of a packet from server without a return proxy signal. Once a proxy pair is discovered, that proxy pair might transform traffic from the server to the client or vice versa, transforming the traffic at one proxy of the proxy pair and untransforming the traffic at the other proxy of the pair.
1. In a network supporting transactions between clients that request transactions and servers that issue responses responsive to client requests, wherein packets between a client and a server travel over a network path comprising one or more hops between network nodes, a method of probing for proxies on a network path comprising:
receiving, at a first probe node in the network path, a first packet from a target client directed at a target server;
modifying the first packet to signal presence of the first probe node in the network path, thus forming a modified first packet;
forwarding the modified first packet toward the target server;
monitoring, at the first probe node, packets for the target client apparently from the target server to detect packets containing return signals, wherein a return signal is a signal from a proxy that detects the signal in the modified first packet and is an indication that the proxy detected the signal as being a proxy probing signal;
acting on a successful probe if a responsive return signal is received corresponding to a signal sent from the first probe node; and
updating a proxy mapping table with results of a successful probe; and
following a current connection, using the updated proxy mapping from the proxy mapping table in a later connection.
2. The method of claim 1 , wherein acting on comprises recording the successful probe or otherwise altering a state of the first probe node.
3. The method of claim 1 , wherein modifying the first packet comprises adding an optional field to the first packet.
4. The method of claim 1 , wherein the return signal is an added optional field in a return packet.
5. The method of claim 1 , further comprising:
following a successful probe, intercepting client-server communications;
instantiating a connection between the proxy that sent the return signal, being a server-side proxy, and a client-side proxy at the first probe node;
terminating client connections at the client-side proxy;
terminating server connections at the server-side proxy; and
transforming client-server traffic according to a protocol conversion.
6. The method of claim 5 , wherein the protocol conversion is a segment cloning conversion.
7. The method of claim 1 , further comprising using the proxy mapping table to transform and untransform data using segment cloning.
8. In a network supporting transactions, a transaction being one or more messages wherein the transaction is initiated by a client and a transaction response is provided by a server, and the network further supporting proxies that are interposable in a network path between at least one client and at least one server, wherein a pair of proxies can modify a packet stream between a client and a server such that packet data from the server to the client is transformed at the server-side proxy and untransformed at the client-side proxy, a method for a discovering proxy to transparently discover its position in a proxy pair, if any, the method comprising:
when receiving a first packet of a first transaction from a client at the discovering proxy, determining whether a proxy signal is present in the first packet;
if the proxy signal is not present in the first packet, storing an indication that the discovering proxy is a client-side proxy for the first transaction;
if the proxy signal is not present in the first packet, forwarding a modified first packet toward the server, wherein the modified first packet contains a proxy signal signaling that the discovering proxy is the client-side proxy for the first transaction;
if the proxy signal is present in the first packet when received by the discovering proxy, evaluating the proxy symbol to determine the client-side proxy for the first transaction from the first packet, thereby discovering at least one proxy pair between that client-side proxy and the discovering proxy; and
using the discovered proxy pairs in subsequent transactions.
9. The method of claim 8 , further comprising using the proxy pair to transform and untransform data using segment cloning.