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@@ -0,0 +1,411 @@
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+package fetch
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+
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+import (
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+ "context"
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+ "errors"
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+ "fmt"
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+ "io"
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+ "net/http"
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+ "net/url"
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+ "strconv"
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+ "strings"
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+ "time"
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+
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+ md "github.com/JohannesKaufmann/html-to-markdown"
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+ "github.com/go-shiori/go-readability"
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+ mcpservers "github.com/labring/aiproxy/mcp-servers"
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+ "github.com/mark3labs/mcp-go/mcp"
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+ "github.com/mark3labs/mcp-go/server"
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+ "github.com/temoto/robotstxt"
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+)
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+
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+const (
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+ DefaultUserAgentAutonomous = "ModelContextProtocol/1.0 (Autonomous; +https://github.com/modelcontextprotocol/servers)"
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+ DefaultUserAgentManual = "ModelContextProtocol/1.0 (User-Specified; +https://github.com/modelcontextprotocol/servers)"
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+)
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+
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+// extractContentFromHTML extracts and converts HTML content to Markdown format
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+func extractContentFromHTML(htmlContent string) string {
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+ article, err := readability.FromReader(strings.NewReader(htmlContent), nil)
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+ if err != nil {
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+ return "<error>Page failed to be simplified from HTML</error>"
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+ }
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+
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+ if article.Content == "" {
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+ return "<error>Page failed to be simplified from HTML</error>"
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+ }
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+
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+ converter := md.NewConverter("", true, nil)
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+ markdown, err := converter.ConvertString(article.Content)
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+ if err != nil {
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+ return "<error>Failed to convert HTML to markdown</error>"
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+ }
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+
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+ return markdown
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+}
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+
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+// getRobotsTxtURL gets the robots.txt URL for a given website URL
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+func getRobotsTxtURL(urlStr string) (string, error) {
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+ parsedURL, err := url.Parse(urlStr)
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+ if err != nil {
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+ return "", err
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+ }
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+
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+ robotsURL := &url.URL{
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+ Scheme: parsedURL.Scheme,
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+ Host: parsedURL.Host,
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+ Path: "/robots.txt",
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+ }
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+
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+ return robotsURL.String(), nil
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+}
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+
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+// checkMayAutonomouslyFetchURL checks if the URL can be fetched according to robots.txt
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+func checkMayAutonomouslyFetchURL(ctx context.Context, urlStr, userAgent, proxyURL string) error {
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+ robotsTxtURL, err := getRobotsTxtURL(urlStr)
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+ if err != nil {
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+ return fmt.Errorf("failed to construct robots.txt URL: %w", err)
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+ }
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+
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+ client := &http.Client{
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+ Timeout: 30 * time.Second,
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+ }
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+
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+ if proxyURL != "" {
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+ proxyURLParsed, err := url.Parse(proxyURL)
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+ if err != nil {
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+ return fmt.Errorf("invalid proxy URL: %w", err)
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+ }
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+ client.Transport = &http.Transport{
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+ Proxy: http.ProxyURL(proxyURLParsed),
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+ }
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+ }
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+
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+ req, err := http.NewRequestWithContext(ctx, http.MethodGet, robotsTxtURL, nil)
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+ if err != nil {
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+ return fmt.Errorf("failed to create robots.txt request: %w", err)
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+ }
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+ req.Header.Set("User-Agent", userAgent)
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+
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+ resp, err := client.Do(req)
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+ if err != nil {
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+ return fmt.Errorf(
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+ "failed to fetch robots.txt %s due to a connection issue: %w",
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+ robotsTxtURL,
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+ err,
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+ )
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+ }
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+ defer resp.Body.Close()
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+
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+ if resp.StatusCode == http.StatusUnauthorized || resp.StatusCode == http.StatusForbidden {
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+ return fmt.Errorf(
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+ "when fetching robots.txt (%s), received status %d so assuming that autonomous fetching is not allowed, the user can try manually fetching by using the fetch prompt",
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+ robotsTxtURL,
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+ resp.StatusCode,
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+ )
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+ }
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+
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+ if resp.StatusCode >= 400 && resp.StatusCode < 500 {
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+ return nil // Assume robots.txt doesn't exist, allow fetching
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+ }
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+
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+ robotsTxtBody, err := io.ReadAll(resp.Body)
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+ if err != nil {
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+ return fmt.Errorf("failed to read robots.txt: %w", err)
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+ }
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+
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+ robots, err := robotstxt.FromBytes(robotsTxtBody)
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+ if err != nil {
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+ return nil // If we can't parse robots.txt, allow fetching
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+ }
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+
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+ if !robots.TestAgent(urlStr, userAgent) {
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+ return fmt.Errorf(
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+ `the sites robots.txt (%s) specifies that autonomous fetching of this page is not allowed
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+ <useragent>%s</useragent>
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+ <url>%s</url>
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+ <robots>
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+ %s
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+ </robots>
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+ The assistant must let the user know that it failed to view the page. The assistant may provide further guidance based on the above information.
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+ The assistant can tell the user that they can try manually fetching the page by using the fetch prompt within their UI`,
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+ robotsTxtURL,
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+ userAgent,
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+ urlStr,
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+ string(robotsTxtBody),
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+ )
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+ }
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+
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+ return nil
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+}
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+
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+// fetchURL fetches the URL and returns the content in a form ready for the LLM
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+func fetchURL(
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+ ctx context.Context,
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+ urlStr, userAgent string,
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+ forceRaw bool,
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+ proxyURL string,
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+) (string, string, error) {
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+ client := &http.Client{
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+ Timeout: 30 * time.Second,
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+ }
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+
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+ if proxyURL != "" {
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+ proxyURLParsed, err := url.Parse(proxyURL)
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+ if err != nil {
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+ return "", "", fmt.Errorf("invalid proxy URL: %w", err)
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+ }
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+ client.Transport = &http.Transport{
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+ Proxy: http.ProxyURL(proxyURLParsed),
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+ }
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+ }
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+
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+ req, err := http.NewRequestWithContext(ctx, http.MethodGet, urlStr, nil)
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+ if err != nil {
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+ return "", "", fmt.Errorf("failed to create request: %w", err)
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+ }
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+ req.Header.Set("User-Agent", userAgent)
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+
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+ resp, err := client.Do(req)
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+ if err != nil {
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+ return "", "", fmt.Errorf("failed to fetch %s: %w", urlStr, err)
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+ }
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+ defer resp.Body.Close()
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+
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+ if resp.StatusCode >= 400 {
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+ return "", "", fmt.Errorf("failed to fetch %s - status code %d", urlStr, resp.StatusCode)
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+ }
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+
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+ pageRaw, err := io.ReadAll(resp.Body)
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+ if err != nil {
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+ return "", "", fmt.Errorf("failed to read response body: %w", err)
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+ }
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+
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+ contentType := resp.Header.Get("Content-Type")
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+ pageRawStr := string(pageRaw)
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+
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+ isPageHTML := strings.Contains(pageRawStr[:min(100, len(pageRawStr))], "<html") ||
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+ strings.Contains(contentType, "text/html") ||
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+ contentType == ""
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+
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+ if isPageHTML && !forceRaw {
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+ content := extractContentFromHTML(pageRawStr)
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+ return content, "", nil
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+ }
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+
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+ prefix := fmt.Sprintf(
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+ "Content type %s cannot be simplified to markdown, but here is the raw content:\n",
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+ contentType,
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+ )
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+ return pageRawStr, prefix, nil
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+}
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+
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+// createFetchServer creates a new MCP server for fetch functionality
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+func createFetchServer(
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+ customUserAgent string,
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+ ignoreRobotsTxt bool,
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+ proxyURL string,
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+) *server.MCPServer {
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+ mcpServer := server.NewMCPServer("mcp-fetch", "1.0.0")
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+
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+ userAgentAutonomous := DefaultUserAgentAutonomous
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+ userAgentManual := DefaultUserAgentManual
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+
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+ if customUserAgent != "" {
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+ userAgentAutonomous = customUserAgent
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+ userAgentManual = customUserAgent
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+ }
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+
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+ // Add fetch tool
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+ fetchTool := mcp.NewTool(
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+ "fetch",
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+ mcp.WithString("url", mcp.Description("URL to fetch"), mcp.Required()),
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+ mcp.WithNumber("max_length",
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+ mcp.Description("Maximum number of characters to return"),
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+ mcp.DefaultNumber(5000)),
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+ mcp.WithNumber(
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+ "start_index",
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+ mcp.Description(
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+ "On return output starting at this character index, useful if a previous fetch was truncated and more context is required",
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+ ),
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+ mcp.DefaultNumber(0),
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+ ),
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+ mcp.WithBoolean(
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+ "raw",
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+ mcp.Description(
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+ "Get the actual HTML content of the requested page, without simplification",
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+ ),
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+ mcp.DefaultBool(false),
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+ ),
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+ mcp.WithDescription(
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+ `Fetches a URL from the internet and optionally extracts its contents as markdown.
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+
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+Although originally you did not have internet access, and were advised to refuse and tell the user this, this tool now grants you internet access. Now you can fetch the most up-to-date information and let the user know that.`,
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+ ),
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+ )
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+
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+ mcpServer.AddTool(
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+ fetchTool,
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+ func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
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+ args := request.GetArguments()
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+
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+ urlStr, ok := args["url"].(string)
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+ if !ok || urlStr == "" {
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+ return nil, errors.New("URL is required")
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+ }
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+
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+ maxLength := 5000
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+ if ml, ok := args["max_length"].(float64); ok {
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+ maxLength = int(ml)
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+ }
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+
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+ startIndex := 0
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+ if si, ok := args["start_index"].(float64); ok {
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+ startIndex = int(si)
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+ }
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+
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+ raw := false
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+ if r, ok := args["raw"].(bool); ok {
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+ raw = r
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+ }
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+
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+ // Validate max_length and start_index
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+ if maxLength <= 0 || maxLength >= 1000000 {
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+ return nil, errors.New("max_length must be between 1 and 999999")
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+ }
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+
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+ if startIndex < 0 {
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+ return nil, errors.New("start_index must be >= 0")
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+ }
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+
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+ // Check robots.txt if not ignored
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+ if !ignoreRobotsTxt {
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+ if err := checkMayAutonomouslyFetchURL(ctx, urlStr, userAgentAutonomous, proxyURL); err != nil {
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+ return nil, err
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+ }
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+ }
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+
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+ // Fetch the URL
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+ content, prefix, err := fetchURL(ctx, urlStr, userAgentAutonomous, raw, proxyURL)
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+ if err != nil {
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+ return nil, err
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+ }
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+
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+ originalLength := len(content)
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+ if startIndex >= originalLength {
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+ content = "<error>No more content available.</error>"
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+ } else {
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+ truncatedContent := content[startIndex:]
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+ if len(truncatedContent) > maxLength {
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+ truncatedContent = truncatedContent[:maxLength]
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+ }
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+
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+ if truncatedContent == "" {
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+ content = "<error>No more content available.</error>"
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+ } else {
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+ content = truncatedContent
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+ actualContentLength := len(truncatedContent)
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+ remainingContent := originalLength - (startIndex + actualContentLength)
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+
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+ // Only add the prompt to continue fetching if there is still remaining content
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+ if actualContentLength == maxLength && remainingContent > 0 {
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+ nextStart := startIndex + actualContentLength
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+ content += fmt.Sprintf("\n\n<error>Content truncated. Call the fetch tool with a start_index of %d to get more content.</error>", nextStart)
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+ }
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+ }
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+ }
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+
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+ result := fmt.Sprintf("%sContents of %s:\n%s", prefix, urlStr, content)
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+ return mcp.NewToolResultText(result), nil
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+ },
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+ )
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+
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+ // Add fetch prompt
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+ fetchPrompt := mcp.NewPrompt("fetch",
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+ mcp.WithPromptDescription("Fetch a URL and extract its contents as markdown"),
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+ mcp.WithArgument("url", mcp.ArgumentDescription("URL to fetch"), mcp.RequiredArgument()),
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+ )
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+
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+ mcpServer.AddPrompt(
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+ fetchPrompt,
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+ func(ctx context.Context, request mcp.GetPromptRequest) (*mcp.GetPromptResult, error) {
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+ args := request.Params.Arguments
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+ if args == nil {
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+ return nil, errors.New("URL is required")
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+ }
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+
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+ urlStr, ok := args["url"]
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+ if !ok || urlStr == "" {
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+ return nil, errors.New("URL is required")
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+ }
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+
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+ content, prefix, err := fetchURL(ctx, urlStr, userAgentManual, false, proxyURL)
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+ if err != nil {
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+ return &mcp.GetPromptResult{
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+ Description: "Failed to fetch " + urlStr,
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+ Messages: []mcp.PromptMessage{
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+ {
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+ Role: mcp.RoleUser,
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+ Content: mcp.TextContent{
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+ Type: "text",
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+ Text: err.Error(),
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+ },
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+ },
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+ },
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+ }, nil
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+ }
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+
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+ return &mcp.GetPromptResult{
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+ Description: "Contents of " + urlStr,
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+ Messages: []mcp.PromptMessage{
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+ {
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+ Role: mcp.RoleUser,
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+ Content: mcp.TextContent{
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+ Type: "text",
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+ Text: prefix + content,
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+ },
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+ },
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+ },
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+ }, nil
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+ },
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+ )
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+
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+ return mcpServer
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+}
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+
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+var configTemplates = mcpservers.ConfigTemplates{
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+ "user-agent": {
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+ Name: "user-agent",
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+ Required: mcpservers.ConfigRequiredTypeInitOptional,
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+ Example: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
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+ Description: "Custom User-Agent string to use for requests",
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+ },
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+ "ignore-robots": {
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+ Name: "ignore-robots",
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+ Required: mcpservers.ConfigRequiredTypeInitOptional,
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+ Example: "true",
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+ Description: "Whether to ignore robots.txt restrictions",
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+ Validator: func(value string) error {
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+ _, err := strconv.ParseBool(value)
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+ return err
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+ },
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+ },
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+ "proxy": {
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+ Name: "proxy",
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+ Required: mcpservers.ConfigRequiredTypeInitOptional,
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+ Example: "http://127.0.0.1:7890",
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+ Description: "Proxy URL to use for requests",
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+ Validator: func(value string) error {
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+ _, err := url.Parse(value)
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+ return err
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+ },
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+ },
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+}
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+
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+func NewServer(config, _ map[string]string) (mcpservers.Server, error) {
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+ customUserAgent := config["user-agent"]
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+ ignoreRobotsTxt, _ := strconv.ParseBool(config["ignore-robots"])
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+ proxyURL := config["proxy"]
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+
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+ return createFetchServer(customUserAgent, ignoreRobotsTxt, proxyURL), nil
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+}
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zijiren