First Commit

mcphttp/client.go

@@ -0,0 +1,578 @@
+// Package mcphttp contains remote Streamable HTTP and legacy SSE MCP clients.
+//
+// The core mcp package only speaks stdio; this adapts an HTTP/JSON-RPC MCP server
+// to the same tool.CoreTool shape (mcp__server__tool) WITHOUT touching the SDK.
+// It implements the MCP "Streamable HTTP" transport: JSON-RPC over HTTP POST, with
+// the server free to answer either as application/json or a text/event-stream (SSE)
+// carrying the response. Custom headers (e.g. Authorization) come from the MCP
+// row's env map, so a bearer token is configured as {"Authorization":"Bearer …"}.
+package mcphttp
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/Autumn-27/norma/llm"
+	"github.com/Autumn-27/norma/permission"
+	actool "github.com/Autumn-27/norma/tool"
+)
+
+const protocolVersion = "2025-06-18"
+const legacySSEProtocolVersion = "2024-11-05"
+
+// ToolName mirrors mcp.ToolName so remote tools share the mcp__server__tool scheme.
+func ToolName(server, name string) string { return "mcp__" + server + "__" + name }
+
+type rpcRequest struct {
+	JSONRPC string `json:"jsonrpc"`
+	ID      int    `json:"id,omitempty"`
+	Method  string `json:"method"`
+	Params  any    `json:"params,omitempty"`
+}
+
+type rpcResponse struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      int             `json:"id"`
+	Result  json.RawMessage `json:"result"`
+	Error   *rpcError       `json:"error"`
+}
+
+type rpcError struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
+
+func (e *rpcError) Error() string { return fmt.Sprintf("mcp rpc error %d: %s", e.Code, e.Message) }
+
+// Client is a connection to one remote MCP server. New uses Streamable HTTP;
+// NewSSE uses the legacy GET /sse + POST /message transport.
+type Client struct {
+	server  string
+	url     string
+	headers map[string]string
+	http    *http.Client
+
+	mu        sync.Mutex
+	nextID    int
+	sessionID string
+
+	// legacySSE is the pre-2025 MCP SSE transport used by servers such as GSL5.
+	legacySSE    bool
+	messageURL   string
+	streamBody   io.ReadCloser
+	streamCancel context.CancelFunc
+	streamDone   chan struct{}
+	legacyMu     sync.Mutex
+	pendingMu    sync.Mutex
+	pending      map[int]chan *rpcResponse
+	streamErr    chan error
+	protocol     string
+}
+
+func normalizeHeaders(headers map[string]string) (map[string]string, error) {
+	out := make(map[string]string, len(headers))
+	for key, value := range headers {
+		clean := strings.TrimSpace(key)
+		if clean == "" || strings.ContainsAny(clean, "\r\n") {
+			return nil, fmt.Errorf("invalid HTTP header name %q", key)
+		}
+		out[clean] = value
+	}
+	return out, nil
+}
+
+// New connects to a remote MCP endpoint and performs the initialize handshake.
+// headers are sent on every request (Authorization, custom API keys, …).
+// When insecure is true, TLS certificate verification is skipped so servers that
+// present a self-signed certificate can still be reached (issue #108).
+func New(ctx context.Context, server, url string, headers map[string]string, insecure bool) (*Client, error) {
+	cleanHeaders, err := normalizeHeaders(headers)
+	if err != nil {
+		return nil, err
+	}
+	hc := &http.Client{Timeout: 120 * time.Second}
+	if insecure {
+		hc.Transport = &http.Transport{TLSClientConfig: &tls.Config{InsecureSkipVerify: true}}
+	}
+	c := &Client{
+		server:   server,
+		url:      url,
+		headers:  cleanHeaders,
+		http:     hc,
+		protocol: protocolVersion,
+	}
+	if err := c.initialize(ctx); err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+// NewSSE connects to the legacy MCP SSE transport: a long-lived GET /sse
+// announces a per-session POST /message endpoint, while JSON-RPC responses are
+// delivered asynchronously as SSE message events.
+func NewSSE(ctx context.Context, server, sseURL string, headers map[string]string, insecure bool) (*Client, error) {
+	cleanHeaders, err := normalizeHeaders(headers)
+	if err != nil {
+		return nil, err
+	}
+	hc := &http.Client{} // the SSE stream is intentionally long-lived.
+	if insecure {
+		hc.Transport = &http.Transport{TLSClientConfig: &tls.Config{InsecureSkipVerify: true}}
+	}
+	streamCtx, cancel := context.WithCancel(context.Background())
+	req, err := http.NewRequestWithContext(streamCtx, http.MethodGet, sseURL, nil)
+	if err != nil {
+		cancel()
+		return nil, err
+	}
+	req.Header.Set("Accept", "text/event-stream")
+	for k, v := range cleanHeaders {
+		req.Header.Set(k, v)
+	}
+	resp, err := hc.Do(req)
+	if err != nil {
+		cancel()
+		return nil, err
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		defer resp.Body.Close()
+		cancel()
+		return nil, fmt.Errorf("mcp sse http %d: %s", resp.StatusCode, readSnippet(resp.Body))
+	}
+	reader := bufio.NewReader(resp.Body)
+	endpoint, err := readSSEEndpoint(reader, sseURL)
+	if err != nil {
+		resp.Body.Close()
+		cancel()
+		return nil, err
+	}
+	c := &Client{
+		server:       server,
+		url:          sseURL,
+		headers:      cleanHeaders,
+		http:         hc,
+		legacySSE:    true,
+		messageURL:   endpoint,
+		streamBody:   resp.Body,
+		streamCancel: cancel,
+		streamDone:   make(chan struct{}),
+		pending:      make(map[int]chan *rpcResponse),
+		streamErr:    make(chan error, 1),
+		protocol:     legacySSEProtocolVersion,
+	}
+	go c.readLegacySSE(reader)
+	if err := c.initialize(ctx); err != nil {
+		_ = c.Close()
+		return nil, err
+	}
+	return c, nil
+}
+
+func readSSEEndpoint(r *bufio.Reader, base string) (string, error) {
+	for {
+		line, err := r.ReadString('\n')
+		if err != nil {
+			return "", fmt.Errorf("mcp sse endpoint: %w", err)
+		}
+		line = strings.TrimRight(line, "\r\n")
+		if !strings.HasPrefix(line, "data:") {
+			continue
+		}
+		candidate := strings.TrimSpace(strings.TrimPrefix(line, "data:"))
+		if candidate == "" {
+			continue
+		}
+		u, err := url.Parse(candidate)
+		if err != nil {
+			return "", fmt.Errorf("mcp sse endpoint URL: %w", err)
+		}
+		if !u.IsAbs() {
+			b, err := url.Parse(base)
+			if err != nil {
+				return "", err
+			}
+			candidate = b.ResolveReference(u).String()
+		}
+		return candidate, nil
+	}
+}
+
+func (c *Client) readLegacySSE(r *bufio.Reader) {
+	defer close(c.streamDone)
+	for {
+		line, err := r.ReadString('\n')
+		if err != nil {
+			if !errors.Is(err, context.Canceled) {
+				select {
+				case c.streamErr <- err:
+				default:
+				}
+			}
+			return
+		}
+		line = strings.TrimRight(line, "\r\n")
+		if !strings.HasPrefix(line, "data:") {
+			continue
+		}
+		var response rpcResponse
+		if err := json.Unmarshal([]byte(strings.TrimSpace(strings.TrimPrefix(line, "data:"))), &response); err != nil || response.ID == 0 {
+			continue
+		}
+		c.pendingMu.Lock()
+		ch := c.pending[response.ID]
+		delete(c.pending, response.ID)
+		c.pendingMu.Unlock()
+		if ch != nil {
+			ch <- &response
+		}
+	}
+}
+
+func (c *Client) initialize(ctx context.Context) error {
+	version := c.protocol
+	if version == "" {
+		version = protocolVersion
+	}
+	if _, err := c.call(ctx, "initialize", map[string]any{
+		"protocolVersion": version,
+		"capabilities":    map[string]any{},
+		"clientInfo":      map[string]any{"name": "artex", "version": "0.2"},
+	}); err != nil {
+		return err
+	}
+	return c.notify(ctx, "notifications/initialized", map[string]any{})
+}
+
+// Tools lists the server's tools and adapts them to CoreTools.
+func (c *Client) Tools(ctx context.Context) ([]actool.CoreTool, error) {
+	raw, err := c.call(ctx, "tools/list", map[string]any{})
+	if err != nil {
+		return nil, err
+	}
+	var res struct {
+		Tools []remoteTool `json:"tools"`
+	}
+	if err := json.Unmarshal(raw, &res); err != nil {
+		return nil, err
+	}
+	out := make([]actool.CoreTool, 0, len(res.Tools))
+	for _, rt := range res.Tools {
+		out = append(out, c.wrap(rt))
+	}
+	return out, nil
+}
+
+type remoteTool struct {
+	Name        string         `json:"name"`
+	Description string         `json:"description"`
+	InputSchema map[string]any `json:"inputSchema"`
+}
+
+func (c *Client) wrap(rt remoteTool) actool.CoreTool {
+	schema := rt.InputSchema
+	if schema == nil {
+		schema = map[string]any{"type": "object"}
+	}
+	full := ToolName(c.server, rt.Name)
+	return actool.Build(actool.Spec{
+		Name:        full,
+		Description: rt.Description,
+		Schema:      schema,
+		Permissions: func(context.Context, json.RawMessage, permission.Context) permission.Decision {
+			return permission.AskUser("call MCP tool " + full + "?")
+		},
+		Run: func(ctx context.Context, in json.RawMessage, tc *actool.ToolContext) (actool.Result, error) {
+			var args any
+			if len(in) > 0 {
+				_ = json.Unmarshal(in, &args)
+			}
+			raw, err := c.call(ctx, "tools/call", map[string]any{"name": rt.Name, "arguments": args})
+			if err != nil {
+				return actool.Errorf("Error: " + err.Error()), nil
+			}
+			var res struct {
+				Content []struct {
+					Type string `json:"type"`
+					Text string `json:"text"`
+				} `json:"content"`
+				IsError bool `json:"isError"`
+			}
+			if err := json.Unmarshal(raw, &res); err != nil {
+				return actool.Errorf("Error: bad MCP response: " + err.Error()), nil
+			}
+			var text string
+			for _, blk := range res.Content {
+				text += blk.Text
+			}
+			// 与内置/自定义工具一致：超长输出走 Capture——按会话 MaxOutputChars（默认
+			// 30000）截断，配了 ToolOutputDir 时全量溢写到磁盘只留 head + 指针，避免大
+			// MCP 结果整段灌爆上下文。
+			return actool.Result{Content: []llm.ContentBlock{llm.TextBlock(actool.Capture(tc, text))}, IsError: res.IsError}, nil
+		},
+	})
+}
+
+// Call invokes one tool and returns the concatenated text of its content blocks
+// (ScopeSentry answers with a single JSON text block). Unlike the CoreTool wrapper
+// from Tools(), this bypasses the agent permission (AskUser) layer — it is meant
+// for backend batch jobs (e.g. asset sync) that call MCP tools programmatically.
+func (c *Client) Call(ctx context.Context, tool string, args any) (string, error) {
+	raw, err := c.call(ctx, "tools/call", map[string]any{"name": tool, "arguments": args})
+	if err != nil {
+		return "", err
+	}
+	var res struct {
+		Content []struct {
+			Type string `json:"type"`
+			Text string `json:"text"`
+		} `json:"content"`
+		IsError bool `json:"isError"`
+	}
+	if err := json.Unmarshal(raw, &res); err != nil {
+		return "", fmt.Errorf("bad MCP response: %w", err)
+	}
+	var text strings.Builder
+	for _, blk := range res.Content {
+		text.WriteString(blk.Text)
+	}
+	if res.IsError {
+		return text.String(), fmt.Errorf("mcp tool %q error: %s", tool, text.String())
+	}
+	return text.String(), nil
+}
+
+// Close terminates the MCP session best-effort (DELETE with the session id, per the
+// Streamable HTTP spec). Servers that don't track sessions simply ignore it.
+func (c *Client) Close() error {
+	if c.legacySSE {
+		if c.streamCancel != nil {
+			c.streamCancel()
+		}
+		if c.streamBody != nil {
+			_ = c.streamBody.Close()
+		}
+		select {
+		case <-c.streamDone:
+		case <-time.After(time.Second):
+		}
+		return nil
+	}
+	c.mu.Lock()
+	sid := c.sessionID
+	c.mu.Unlock()
+	if sid == "" {
+		return nil
+	}
+	req, err := http.NewRequest(http.MethodDelete, c.url, nil)
+	if err != nil {
+		return nil
+	}
+	req.Header.Set("Mcp-Session-Id", sid)
+	for k, v := range c.headers {
+		req.Header.Set(k, v)
+	}
+	if resp, err := c.http.Do(req); err == nil {
+		resp.Body.Close()
+	}
+	return nil
+}
+
+// --- JSON-RPC over Streamable HTTP ---
+
+func (c *Client) call(ctx context.Context, method string, params any) (json.RawMessage, error) {
+	c.mu.Lock()
+	c.nextID++
+	id := c.nextID
+	c.mu.Unlock()
+	resp, err := c.roundTrip(ctx, rpcRequest{JSONRPC: "2.0", ID: id, Method: method, Params: params}, true)
+	if err != nil {
+		return nil, err
+	}
+	if resp == nil {
+		return nil, fmt.Errorf("mcp: empty response for %s", method)
+	}
+	if resp.Error != nil {
+		return nil, resp.Error
+	}
+	return resp.Result, nil
+}
+
+func (c *Client) notify(ctx context.Context, method string, params any) error {
+	_, err := c.roundTrip(ctx, rpcRequest{JSONRPC: "2.0", Method: method, Params: params}, false)
+	return err
+}
+
+// roundTrip POSTs one JSON-RPC frame. When expectResp is false (a notification) the
+// server replies 202 Accepted with no body. Otherwise the reply is parsed from JSON
+// or from an SSE stream, whichever the server chose.
+func (c *Client) roundTrip(ctx context.Context, body rpcRequest, expectResp bool) (*rpcResponse, error) {
+	if c.legacySSE {
+		return c.legacyRoundTrip(ctx, body, expectResp)
+	}
+	data, err := json.Marshal(body)
+	if err != nil {
+		return nil, err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.url, bytes.NewReader(data))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Accept", "application/json, text/event-stream")
+	version := c.protocol
+	if version == "" {
+		version = protocolVersion
+	}
+	req.Header.Set("MCP-Protocol-Version", version)
+	for k, v := range c.headers {
+		req.Header.Set(k, v)
+	}
+	c.mu.Lock()
+	sid := c.sessionID
+	c.mu.Unlock()
+	if sid != "" {
+		req.Header.Set("Mcp-Session-Id", sid)
+	}
+
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	// Capture the session id the server assigns on initialize.
+	if sid == "" {
+		if got := resp.Header.Get("Mcp-Session-Id"); got != "" {
+			c.mu.Lock()
+			c.sessionID = got
+			c.mu.Unlock()
+		}
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return nil, fmt.Errorf("mcp http %d: %s", resp.StatusCode, readSnippet(resp.Body))
+	}
+	if !expectResp {
+		return nil, nil // notification — no JSON-RPC body to parse
+	}
+	if strings.HasPrefix(resp.Header.Get("Content-Type"), "text/event-stream") {
+		return parseSSE(resp.Body, body.ID)
+	}
+	var out rpcResponse
+	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
+		return nil, fmt.Errorf("mcp: decode json response: %w", err)
+	}
+	return &out, nil
+}
+
+// legacyRoundTrip posts to the endpoint announced by GET /sse. The HTTP POST
+// only acknowledges receipt; the JSON-RPC response arrives on the SSE stream.
+func (c *Client) legacyRoundTrip(ctx context.Context, body rpcRequest, expectResp bool) (*rpcResponse, error) {
+	// Serializing calls keeps the first implementation deterministic while the
+	// shared SSE reader still handles asynchronous delivery.
+	c.legacyMu.Lock()
+	defer c.legacyMu.Unlock()
+
+	data, err := json.Marshal(body)
+	if err != nil {
+		return nil, err
+	}
+	var responseCh chan *rpcResponse
+	if expectResp {
+		responseCh = make(chan *rpcResponse, 1)
+		c.pendingMu.Lock()
+		c.pending[body.ID] = responseCh
+		c.pendingMu.Unlock()
+		defer func() {
+			c.pendingMu.Lock()
+			delete(c.pending, body.ID)
+			c.pendingMu.Unlock()
+		}()
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.messageURL, bytes.NewReader(data))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Accept", "application/json")
+	for k, v := range c.headers {
+		req.Header.Set(k, v)
+	}
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return nil, fmt.Errorf("mcp sse http %d: %s", resp.StatusCode, readSnippet(resp.Body))
+	}
+	if !expectResp {
+		return nil, nil
+	}
+	select {
+	case response := <-responseCh:
+		return response, nil
+	case err := <-c.streamErr:
+		return nil, fmt.Errorf("mcp sse stream: %w", err)
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
+
+// parseSSE reads an SSE stream and returns the first data frame that is a JSON-RPC
+// response matching wantID (server-to-client requests/notifications are skipped).
+func parseSSE(r io.Reader, wantID int) (*rpcResponse, error) {
+	sc := bufio.NewScanner(r)
+	sc.Buffer(make([]byte, 0, 64*1024), 8*1024*1024)
+	var dataBuf strings.Builder
+	flush := func() (*rpcResponse, bool) {
+		if dataBuf.Len() == 0 {
+			return nil, false
+		}
+		payload := dataBuf.String()
+		dataBuf.Reset()
+		var out rpcResponse
+		if err := json.Unmarshal([]byte(payload), &out); err != nil {
+			return nil, false
+		}
+		if out.ID != wantID {
+			return nil, false
+		}
+		return &out, true
+	}
+	for sc.Scan() {
+		line := sc.Text()
+		if line == "" { // event boundary
+			if resp, ok := flush(); ok {
+				return resp, nil
+			}
+			continue
+		}
+		if strings.HasPrefix(line, "data:") {
+			dataBuf.WriteString(strings.TrimSpace(line[len("data:"):]))
+		}
+	}
+	if resp, ok := flush(); ok {
+		return resp, nil
+	}
+	if err := sc.Err(); err != nil {
+		return nil, err
+	}
+	return nil, fmt.Errorf("mcp: no matching response in event stream")
+}
+
+func readSnippet(r io.Reader) string {
+	b, _ := io.ReadAll(io.LimitReader(r, 2048))
+	return strings.TrimSpace(string(b))
+}