a433a831d6This PR introduces protection against cross-origin requests by installing `http.CrossOriginProtection`. By default, the zero value is used which does not contain any trusted origins or bypass patterns. The protection can be customized by providing a custom `http.CrossOriginProtection` in `mcp.StreamableHTTPOptions`. Currently, the deny handler set on the protection is ignored. This default has an MCPGODEBUG option (`disableoriginverification`) to disable the default protection. It will be available until `v1.6.0` of the SDK. We also increase the Go version required by the SDK to 1.25, since this is the version that introduced `http.CrossOriginProtection`. This is in line with the SDK's policy of supporting two newest Go versions (1.26 was released in February 2026). Additionally, we start validating if the `Content-Type` header for `POST` requests is set to `application/json` to avoid accepting CORS-safelisted requests.
41 lines
1.7 KiB
Markdown
41 lines
1.7 KiB
Markdown
<!-- Autogenerated by weave; DO NOT EDIT -->
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# Backwards compatibility and MCPGODEBUG
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According to our compatibility promise, we can't break backward compatibility
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of the SDK API. However, sometimes we need to change the behavior of the SDK
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in a backward-incompatible way in order to fix bugs or security issues.
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In those cases we introduce temporary compatibility parameters, that can be
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used to opt-out of the new behavior. They are usually maintained for two
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minor release cycles and then removed.
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The compatibility parameters are provided via the `MCPGODEBUG` environment
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variable. The value of the variable is a comma-separated list of parameter
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value assignments, e.g.:
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```
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MCPGODEBUG=parameter1=value1,parameter2=value2
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```
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## `MCPGODEBUG` history
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### 1.4.1
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Options listed below will be removed in the 1.6.0 version of the SDK.
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- `disablecrossoriginprotection` added. If set to `1`, newly added cross-origin
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protection will be disabled. The default behavior was changed to enable
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cross-origin protection.
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### 1.4.0
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Options listed below will be removed in the 1.6.0 version of the SDK.
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- `jsonescaping` added. If set to `1`, JSON marshaling will preserve the previous
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behavior of escaping HTML characters in JSON strings. The default behavior
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was changed to not escape HTML characters, to be consistent with other SDKs.
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- `disablelocalhostprotection` added. If set to `1`, newly added DNS rebinding
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protection will be disabled. The default behavior was changed to enable DNS rebinding
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protection. The protection can also be disabled by setting the
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`DisableLocalhostProtection` field in the `StreamableHTTPOptions` struct to
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`true`, which is the recommended way to disable the protection long term.
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