fix(security): add SSRF protection to WebFetchTool, warn on plaintext HTTP in provider

Block requests to internal/private networks (loopback, link-local, RFC1918, IPv6 ULA)
in WebFetchTool to prevent SSRF attacks targeting cloud metadata and internal services.
Log a warning when HTTPProvider is configured with plain http:// API base, as API keys
may be transmitted without encryption.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/providers/http_provider.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/sipeed/picoclaw/pkg/auth"
 	"github.com/sipeed/picoclaw/pkg/config"
+	"github.com/sipeed/picoclaw/pkg/logger"
 )
 
 type HTTPProvider struct {
@@ -41,6 +42,14 @@ func NewHTTPProvider(apiKey, apiBase, proxy string) *HTTPProvider {
 		}
 	}
 
+	if strings.HasPrefix(apiBase, "http://") &&
+		!strings.Contains(apiBase, "localhost") &&
+		!strings.Contains(apiBase, "127.0.0.1") {
+		logger.WarnCF("provider", "API base uses plain HTTP — API keys may be transmitted without encryption", map[string]interface{}{
+			"api_base": apiBase,
+		})
+	}
+
 	return &HTTPProvider{
 		apiKey:     apiKey,
 		apiBase:    strings.TrimRight(apiBase, "/"),

pkg/tools/web.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"regexp"
@@ -266,7 +267,8 @@ func (t *WebSearchTool) Execute(ctx context.Context, args map[string]interface{}
 }
 
 type WebFetchTool struct {
-	maxChars int
+	maxChars       int
+	allowLoopback  bool
 }
 
 func NewWebFetchTool(maxChars int) *WebFetchTool {
@@ -304,6 +306,47 @@ func (t *WebFetchTool) Parameters() map[string]interface{} {
 	}
 }
 
+func (t *WebFetchTool) setAllowLoopback(allow bool) {
+	t.allowLoopback = allow
+}
+
+// isBlockedHost returns true if the hostname resolves to a private/internal IP.
+func (t *WebFetchTool) isBlockedHost(hostname string) bool {
+	var ips []net.IP
+
+	if ip := net.ParseIP(hostname); ip != nil {
+		ips = append(ips, ip)
+	} else {
+		addrs, err := net.LookupHost(hostname)
+		if err != nil {
+			// If we can't resolve, block by default for safety
+			return true
+		}
+		for _, addr := range addrs {
+			if ip := net.ParseIP(addr); ip != nil {
+				ips = append(ips, ip)
+			}
+		}
+	}
+
+	for _, ip := range ips {
+		if ip.IsLoopback() && !t.allowLoopback {
+			return true
+		}
+		if ip.Equal(net.IPv4zero) {
+			return true
+		}
+		if ip.IsLinkLocalUnicast() {
+			return true
+		}
+		if ip.IsPrivate() {
+			return true
+		}
+	}
+
+	return false
+}
+
 func (t *WebFetchTool) Execute(ctx context.Context, args map[string]interface{}) *ToolResult {
 	urlStr, ok := args["url"].(string)
 	if !ok {
@@ -323,6 +366,10 @@ func (t *WebFetchTool) Execute(ctx context.Context, args map[string]interface{})
 		return ErrorResult("missing domain in URL")
 	}
 
+	if t.isBlockedHost(parsedURL.Hostname()) {
+		return ErrorResult("URL blocked: requests to internal/private networks are not allowed")
+	}
+
 	maxChars := t.maxChars
 	if mc, ok := args["maxChars"].(float64); ok {
 		if int(mc) > 100 {

pkg/tools/web_test.go

@@ -19,6 +19,7 @@ func TestWebTool_WebFetch_Success(t *testing.T) {
 	defer server.Close()
 
 	tool := NewWebFetchTool(50000)
+	tool.setAllowLoopback(true)
 	ctx := context.Background()
 	args := map[string]interface{}{
 		"url": server.URL,
@@ -55,6 +56,7 @@ func TestWebTool_WebFetch_JSON(t *testing.T) {
 	defer server.Close()
 
 	tool := NewWebFetchTool(50000)
+	tool.setAllowLoopback(true)
 	ctx := context.Background()
 	args := map[string]interface{}{
 		"url": server.URL,
@@ -146,6 +148,7 @@ func TestWebTool_WebFetch_Truncation(t *testing.T) {
 	defer server.Close()
 
 	tool := NewWebFetchTool(1000) // Limit to 1000 chars
+	tool.setAllowLoopback(true)
 	ctx := context.Background()
 	args := map[string]interface{}{
 		"url": server.URL,
@@ -211,6 +214,7 @@ func TestWebTool_WebFetch_HTMLExtraction(t *testing.T) {
 	defer server.Close()
 
 	tool := NewWebFetchTool(50000)
+	tool.setAllowLoopback(true)
 	ctx := context.Background()
 	args := map[string]interface{}{
 		"url": server.URL,
@@ -254,3 +258,37 @@ func TestWebTool_WebFetch_MissingDomain(t *testing.T) {
 		t.Errorf("Expected domain error message, got ForLLM: %s", result.ForLLM)
 	}
 }
+
+// TestWebFetchTool_SSRFBlocking verifies that requests to internal/private networks are blocked
+func TestWebFetchTool_SSRFBlocking(t *testing.T) {
+	tests := []struct {
+		name string
+		url  string
+	}{
+		{"loopback IPv4", "http://127.0.0.1/secret"},
+		{"localhost", "http://localhost/admin"},
+		{"cloud metadata", "http://169.254.169.254/latest/meta-data/"},
+		{"loopback IPv6", "http://[::1]/internal"},
+		{"private 10.x", "http://10.0.0.1/internal"},
+		{"private 192.168.x", "http://192.168.1.1/admin"},
+		{"private 172.16.x", "http://172.16.0.1/internal"},
+	}
+
+	tool := NewWebFetchTool(50000)
+	ctx := context.Background()
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			args := map[string]interface{}{
+				"url": tc.url,
+			}
+			result := tool.Execute(ctx, args)
+			if !result.IsError {
+				t.Errorf("Expected SSRF block for %s, but request was allowed", tc.url)
+			}
+			if !strings.Contains(result.ForLLM, "URL blocked") {
+				t.Errorf("Expected 'URL blocked' message for %s, got: %s", tc.url, result.ForLLM)
+			}
+		})
+	}
+}