fix: connectStandaloneSSE checking Content-Type header#736
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findleyr merged 3 commits intomodelcontextprotocol:mainfrom Jan 4, 2026
Merged
fix: connectStandaloneSSE checking Content-Type header#736findleyr merged 3 commits intomodelcontextprotocol:mainfrom
findleyr merged 3 commits intomodelcontextprotocol:mainfrom
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Thanks for this CL. We're on break now, but I'll review next week. |
findleyr
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Dec 29, 2025
findleyr
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Dec 31, 2025
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Thanks for adding the test! One more minor comment.
mcp/streamable.go
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| // | ||
| // [§2.2.3]: https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#listening-for-messages-from-the-server | ||
| if resp.StatusCode == http.StatusMethodNotAllowed { | ||
| if resp.StatusCode == http.StatusMethodNotAllowed || resp.Header.Get("Content-Type") != "text/event-stream" { |
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Sorry for not catching this before: I think this is a non-conformant server implementation, so we should at the very least log.
Let's pull this out into a separate if block, and similar to the block on line 1558 below, we should log a warning.
findleyr
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Dec 31, 2025
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Issue encountered: the MCP server request was unexpectedly redirected to an HTML page. Because the client didn’t validate the response Content-Type, it still entered handleSSE, which then kept treating the HTML as an SSE stream and repeatedly re-requesting the same page—creating an infinite request loop.