feat: add request header

[wlxwlxwlx]

Add the request header to mcp.Request so that users can use the header to handle business logic in the hooks function.

Summary by CodeRabbit

• New Features
  • Added support for passing and accessing HTTP headers in server requests, enabling features like authorization and header-based filtering.
• Tests
  • Updated tests to include header information in server request handling.
  • Added a new test to verify header-based filtering of tools based on authorization tokens.

[coderabbitai[bot]]

Walkthrough

A new Header field was added to the Request struct, and the HandleMessage method in the server was updated to accept and propagate a header map. All relevant server, SSE, stdio, and client code, as well as tests, were updated to accommodate the new header parameter, including a new test for header-based filtering.

Changes

Files/Paths	Change Summary
mcp/types.go	Added Header map[string]string field to the Request struct.
server/request_handler.go	Updated HandleMessage method signature to accept a header map and assign it to request structs.
server/sse.go, server/streamable_http.go	Extracted HTTP headers into a map and passed it to HandleMessage.
server/stdio.go, client/transport/inprocess.go	Updated calls to HandleMessage to include an empty header map argument.
client/client.go	Removed an extraneous blank line in sendRequest; no logic changes.
server/server_test.go	Updated all HandleMessage test calls to include a header map; added TestMCPServer_HandleWithHeader for header-based filtering.
server/resource_test.go, server/session_test.go	Updated all HandleMessage test calls to include an authorization header map.

Suggested reviewers

• robert-jackson-glean
• ezynda3

[!WARNING] There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (1.64.8)

Error: you are using a configuration file for golangci-lint v2 with golangci-lint v1: please use golangci-lint v2 Failed executing command with error: you are using a configuration file for golangci-lint v2 with golangci-lint v1: please use golangci-lint v2

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📥 Commits

Reviewing files that changed from the base of the PR and between d2ea4efc5d32574d10bfbb451782c121d27337e1 and 4386a9e9733e4a71915ffe495f149a40b409f904.

📒 Files selected for processing (1)

• server/request_handler.go (11 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• server/request_handler.go

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• [ ] 📝 Generate Docstrings

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[wlxwlxwlx]

This PR enables the request headers received by the server launched in SSE to be read within the hook function. I have already resolved the conflicts and hope that it can be merged.

[wlxwlxwlx]

I added a testing. I retrieve the token from the header to filter different permissions and allow returning different tools lists.

[0xNF]

Is there any update to this? I'd like to get Auth header to differentiate users for my remote servers, and I'd prefer not to use a fork to do so

[arun11299]

If the only concern is with the naming of the field (i.e Header) then can we close that by renaming it to something like "RequestMetadata" ? I do agree that "Header" is not apt as this is more of a protocol addition rather than transport.

[wlxwlxwlx]

If it can be merged, I think the field name can be changed. I still think this feature is necessary.

[arun11299]

@wlxwlxwlx Thank you. Can you raise review with the suggested changes from @rwjblue-glean ?

[arun11299]

For my use case, I see that in the latest code CallToolRequest has Meta fieds wherein additional information can be passed.

toolCallRequest := mcp.CallToolRequest{}
toolCallRequest.Params.Name = toolCall.Name
toolCallRequest.Params.Arguments = toolCall.Args
toolCallRequest.Params.Meta = &mcp.Meta{
	AdditionalFields: meta,
}

I am pretty sure this is new addition and was not there in the previous code version that I was having.

[leisurelicht]

This is exactly the feature I’ve been looking for. Is there any plan to merge it?