97 lines
2.2 KiB
Go
97 lines
2.2 KiB
Go
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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// Package oauthex implements extensions to OAuth2.
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//go:build mcp_go_client_oauth
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package oauthex
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import (
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"context"
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"encoding/json"
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"fmt"
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"io"
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"mime"
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"net/http"
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"net/url"
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"strings"
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"github.com/modelcontextprotocol/go-sdk/internal/util"
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)
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type httpStatusError struct {
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StatusCode int
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}
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func (e *httpStatusError) Error() string {
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return fmt.Sprintf("bad status %d", e.StatusCode)
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}
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// getJSON retrieves JSON and unmarshals JSON from the URL, as specified in both
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// RFC 9728 and RFC 8414.
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// It will not read more than limit bytes from the body.
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func getJSON[T any](ctx context.Context, c *http.Client, url string, limit int64) (*T, error) {
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
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if err != nil {
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return nil, err
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}
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if c == nil {
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c = http.DefaultClient
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}
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res, err := c.Do(req)
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if err != nil {
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return nil, err
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}
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defer res.Body.Close()
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if res.StatusCode != http.StatusOK {
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return nil, &httpStatusError{StatusCode: res.StatusCode}
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}
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ct := res.Header.Get("Content-Type")
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mediaType, _, err := mime.ParseMediaType(ct)
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if err != nil || mediaType != "application/json" {
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return nil, fmt.Errorf("bad content type %q", ct)
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}
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var t T
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dec := json.NewDecoder(io.LimitReader(res.Body, limit))
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if err := dec.Decode(&t); err != nil {
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return nil, err
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}
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return &t, nil
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}
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// checkURLScheme ensures that its argument is a valid URL with a scheme
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// that prevents XSS attacks.
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// See #526.
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func checkURLScheme(u string) error {
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if u == "" {
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return nil
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}
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uu, err := url.Parse(u)
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if err != nil {
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return err
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}
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scheme := strings.ToLower(uu.Scheme)
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if scheme == "javascript" || scheme == "data" || scheme == "vbscript" {
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return fmt.Errorf("URL has disallowed scheme %q", scheme)
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}
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return nil
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}
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func checkHTTPSOrLoopback(addr string) error {
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if addr == "" {
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return nil
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}
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u, err := url.Parse(addr)
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if err != nil {
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return err
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}
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if !util.IsLoopback(u.Host) && u.Scheme != "https" {
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return fmt.Errorf("URL %q does not use HTTPS or is not a loopback address", addr)
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}
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return nil
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}
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