User-Mode Prototypes in Kernel-Mode Protocol Stacks

• US 20090296685A1
• Filed: 05/29/2008
• Published: 12/03/2009
• Est. Priority Date: 05/29/2008
• Status: Abandoned Application

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Gunawardena, Dinan, O'Shea, Gregory
• Application Number:
  US12/129,119
• Publication Number:
  US 20090296685A1
• Time in Patent Office: Days
• US Class Current: 370/351
• CPC Class Codes: H04L 69/32 Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 69/325 in the network layer [OSI layer 3], e.g. X.25 H04L69/16 takes precedence
• CPC Class Codes: H04L 69/326 in the transport layer [OSI layer 4] H04L69/16 takes precedence

Abstract

Methods of enabling user-mode prototypes in kernel-mode protocol stacks are described. A protocol stack comprises a set of kernel-mode modules. The protocol stack defines a data path for packets. At least one interception point is defined in a kernel-mode module at which a packet can be intercepted and/or inserted. In an embodiment, each packet intercepted at the interception point, or a copy of said packet, is sent to a user-mode module. The user-mode module processes the packet in some way and then returns the packet to the same, or a different, interception point in the data path. In this way, a user-mode module (which is easier to program) can be used to prototype functionality of a kernel-mode module without requiring kernel-mode code to be written.

Claims

1. One or more tangible device-readable media with device-executable instructions for performing steps comprising:

defining at least a first interception point in a kernel-mode module which forms part of a data path for packets;

intercepting a first packet at the first interception point;

sending an intercepted packet to a user-mode module, said intercepted packet comprising one of the first packet and a copy of the first packet;

receiving, at an interception point in the data path, the intercepted packet after processing by the user-mode module;

inserting the received packet into the data path.

2. One or more tangible device-readable media according to claim 1, wherein the device-executable instructions define a first interception point and a second interception point which are at different positions in the data path.

3. One or more tangible device-readable media according to claim 1, wherein the step of inserting the received packet into the data path occurs at the second insertion point.

4. One or more tangible device-readable media according to claim 2 wherein the first interception point and the second interception point are at opposite sides of the same kernel-mode module.

5. One or more tangible device-readable media according to claim 2 wherein at least one of the first interception point and the second interception point is defined as part of a shim module positioned between kernel-mode modules in the data path.

6. One or more tangible device-readable media according to claim 1, further comprising device-executable instructions for performing a step comprising:

removing the first packet from the data path when sending the intercepted packet to a user-mode module.

7. One or more tangible device-readable media according to claim 1, wherein the kernel-mode module forms part of a protocol stack and wherein the steps of sending the intercepted packet to a user-mode module and receiving the intercepted packet from a user-mode module use packet tunneling within the protocol stack.

8. One or more tangible device-readable media according to claim 1, wherein the step of receiving the intercepted packet from the user-mode module comprises receiving the intercepted packet as a payload of an encapsulated packet having overhead information comprising an address of the kernel-mode module hosting the interception point.

9. One or more tangible device-readable media according to claim 8, wherein the data path restricts packets to a maximum size limit and the device-executable instructions further perform a step of:

advertising an increased maximum size limit which is set at a value at least equal to an intercepted packet of an existing maximum size limit plus the overhead information.

10. One or more tangible device-readable media according to claim 1, further comprising device-executable instructions for performing a step comprising:

including control information when sending the intercepted packet to a user-mode module.

11. One or more tangible device-readable media according to claim 10, wherein the control information comprises at least one of:

sequence numbering information;

information identifying an adapter which is the origination of, or destination of, the packet.

12. One or more tangible device-readable media according to claim 1 wherein control information associated with an intercepted packet is encoded using at least one of:

a destination IP address, a source IP address, a port number and a padding byte.

13. One or more tangible device-readable media according to claim 12, wherein sending an intercepted packet to a user-mode module comprises:

selecting a destination address for the intercepted packet, the destination address identifying at least one of;

the first interception point, the data path and a sequence number of the packet.

14. One or more tangible device-readable media according to claim 1 further comprising device-executable instructions for performing steps comprising:

receiving the intercepted packet at a user-mode module;

selecting a form of processing for the intercepted packet, wherein the processing is selected from at least one of;

sending the packet unmodified to the first interception point;

sending the packet unmodified to a different interception point;

modifying the packet and sending the packet to the first interception point; and

modifying the packet and sending the packet to a different interception point.

15. One or more tangible device-readable media according to claim 1 further comprising device-executable instructions for performing steps comprising:

receiving, at an interception point in the data path, a packet which has been newly created by the user-mode module;

inserting the received packet into the data path.

16. One or more tangible device-readable media according to claim 1, wherein the step of sending the intercepted packet to a user-mode module comprises sending the intercepted packet to a socket which has an application programming interface between the socket and the user-mode module.

17. One or more tangible device-readable media according to claim 16, wherein the application programming interface has a restricted set of commands comprising:

registering with an interception point;

creating a packet;

modifying a packet;

deleting a packet.

18. One or more tangible device-readable media with device-executable instructions for implementing a user-mode module in a system also comprising a set of kernel-mode modules which form a data path for packets, the device-executable instructions performing steps comprising:

receiving a packet, the received packet comprising one of a packet which has been intercepted by a first interception point in one of the kernel-mode modules and a copy of said packet;

selecting a form of processing for the received packet, wherein the processing is selected from at least one of;

sending the packet unmodified to the first interception point;

sending the packet unmodified to a different interception point;

modifying the packet and sending the packet to the first interception point; and

modifying the packet and sending the packet to a different interception point.

19. One or more tangible device-readable media according to claim 18, further comprising device-executable instructions for performing steps comprising:

creating a new packet;

sending the new packet to an interception point in the data path for insertion into the data path.

20. A method of prototyping a kernel-mode program module in software comprising a set of kernel-mode program modules and at least one user-mode program module, the set of kernel-mode program modules forming a protocol stack with a data path, the method comprising:

creating a prototype user-mode program module having functionality which is to be prototyped;

adding at least a first interception point and a second interception point at different positions along the data path through the protocol stack;

forwarding, from the first interception point to the prototype user-mode program module, packets intercepted in the data path;

processing forwarded packets at the prototype user-mode program module to form processed packets;

returning processed packets to the second interception point; and

inserting the processed packets into the data path at the second interception point.