// Copyright 2011 Google Inc. All rights reserved. // Use of this source code is governed by the Apache 2.0 // license that can be found in the LICENSE file. // +build !appengine package internal import ( "bytes" "errors" "fmt" "io/ioutil" "log" "net" "net/http" "net/url" "os" "runtime" "strconv" "strings" "sync" "sync/atomic" "time" "github.com/golang/protobuf/proto" netcontext "golang.org/x/net/context" remotepb "google.golang.org/appengine/internal/remote_api" ) const ( apiPath = "/rpc_http" ) var ( // Incoming headers. ticketHeader = http.CanonicalHeaderKey("X-AppEngine-API-Ticket") dapperHeader = http.CanonicalHeaderKey("X-Google-DapperTraceInfo") traceHeader = http.CanonicalHeaderKey("X-Cloud-Trace-Context") curNamespaceHeader = http.CanonicalHeaderKey("X-AppEngine-Current-Namespace") userIPHeader = http.CanonicalHeaderKey("X-AppEngine-User-IP") remoteAddrHeader = http.CanonicalHeaderKey("X-AppEngine-Remote-Addr") // Outgoing headers. apiEndpointHeader = http.CanonicalHeaderKey("X-Google-RPC-Service-Endpoint") apiEndpointHeaderValue = []string{"app-engine-apis"} apiMethodHeader = http.CanonicalHeaderKey("X-Google-RPC-Service-Method") apiMethodHeaderValue = []string{"/VMRemoteAPI.CallRemoteAPI"} apiDeadlineHeader = http.CanonicalHeaderKey("X-Google-RPC-Service-Deadline") apiContentType = http.CanonicalHeaderKey("Content-Type") apiContentTypeValue = []string{"application/octet-stream"} apiHTTPClient = &http.Client{ Transport: &http.Transport{ Proxy: http.ProxyFromEnvironment, Dial: limitDial, }, } ) func apiURL() *url.URL { host, port := "appengine.googleapis.internal", "10001" if h := os.Getenv("API_HOST"); h != "" { host = h } if p := os.Getenv("API_PORT"); p != "" { port = p } return &url.URL{ Scheme: "http", Host: host + ":" + port, Path: apiPath, } } func handleHTTP(w http.ResponseWriter, r *http.Request) { c := &context{ req: r, outHeader: w.Header(), apiURL: apiURL(), logger: globalLogger(), } ctxs.Lock() ctxs.m[r] = c ctxs.Unlock() defer func() { ctxs.Lock() delete(ctxs.m, r) ctxs.Unlock() }() // Patch up RemoteAddr so it looks reasonable. if addr := r.Header.Get(userIPHeader); addr != "" { r.RemoteAddr = addr } else if addr = r.Header.Get(remoteAddrHeader); addr != "" { r.RemoteAddr = addr } else { // Should not normally reach here, but pick a sensible default anyway. r.RemoteAddr = "127.0.0.1" } // The address in the headers will most likely be of these forms: // 123.123.123.123 // 2001:db8::1 // net/http.Request.RemoteAddr is specified to be in "IP:port" form. if _, _, err := net.SplitHostPort(r.RemoteAddr); err != nil { // Assume the remote address is only a host; add a default port. r.RemoteAddr = net.JoinHostPort(r.RemoteAddr, "80") } executeRequestSafely(c, r) c.outHeader = nil // make sure header changes aren't respected any more // Avoid nil Write call if c.Write is never called. if c.outCode != 0 { w.WriteHeader(c.outCode) } if c.outBody != nil { w.Write(c.outBody) } } func executeRequestSafely(c *context, r *http.Request) { defer func() { if x := recover(); x != nil { logf(c, 4, "%s", renderPanic(x)) // 4 == critical c.outCode = 500 } }() http.DefaultServeMux.ServeHTTP(c, r) } func renderPanic(x interface{}) string { buf := make([]byte, 16<<10) // 16 KB should be plenty buf = buf[:runtime.Stack(buf, false)] // Remove the first few stack frames: // this func // the recover closure in the caller // That will root the stack trace at the site of the panic. const ( skipStart = "internal.renderPanic" skipFrames = 2 ) start := bytes.Index(buf, []byte(skipStart)) p := start for i := 0; i < skipFrames*2 && p+1 < len(buf); i++ { p = bytes.IndexByte(buf[p+1:], '\n') + p + 1 if p < 0 { break } } if p >= 0 { // buf[start:p+1] is the block to remove. // Copy buf[p+1:] over buf[start:] and shrink buf. copy(buf[start:], buf[p+1:]) buf = buf[:len(buf)-(p+1-start)] } // Add panic heading. head := fmt.Sprintf("panic: %v\n\n", x) if len(head) > len(buf) { // Extremely unlikely to happen. return head } copy(buf[len(head):], buf) copy(buf, head) return string(buf) } var ctxs = struct { sync.Mutex m map[*http.Request]*context bg *context // background context, lazily initialized // dec is used by tests to decorate the netcontext.Context returned // for a given request. This allows tests to add overrides (such as // WithAppIDOverride) to the context. The map is nil outside tests. dec map[*http.Request]func(netcontext.Context) netcontext.Context }{ m: make(map[*http.Request]*context), } // context represents the context of an in-flight HTTP request. // It implements the appengine.Context and http.ResponseWriter interfaces. type context struct { req *http.Request logger *jsonLogger outCode int outHeader http.Header outBody []byte apiURL *url.URL } var contextKey = "holds a *context" func fromContext(ctx netcontext.Context) *context { c, _ := ctx.Value(&contextKey).(*context) return c } func withContext(parent netcontext.Context, c *context) netcontext.Context { ctx := netcontext.WithValue(parent, &contextKey, c) if ns := c.req.Header.Get(curNamespaceHeader); ns != "" { ctx = withNamespace(ctx, ns) } return ctx } func toContext(c *context) netcontext.Context { return withContext(netcontext.Background(), c) } func IncomingHeaders(ctx netcontext.Context) http.Header { if c := fromContext(ctx); c != nil { return c.req.Header } return nil } func WithContext(parent netcontext.Context, req *http.Request) netcontext.Context { ctxs.Lock() c := ctxs.m[req] d := ctxs.dec[req] ctxs.Unlock() if d != nil { parent = d(parent) } if c == nil { // Someone passed in an http.Request that is not in-flight. // We panic here rather than panicking at a later point // so that stack traces will be more sensible. log.Panic("appengine: NewContext passed an unknown http.Request") } return withContext(parent, c) } func BackgroundContext() netcontext.Context { ctxs.Lock() defer ctxs.Unlock() if ctxs.bg != nil { return toContext(ctxs.bg) } // Compute background security ticket. appID := partitionlessAppID() escAppID := strings.Replace(strings.Replace(appID, ":", "_", -1), ".", "_", -1) majVersion := VersionID(nil) if i := strings.Index(majVersion, "."); i > 0 { majVersion = majVersion[:i] } ticket := fmt.Sprintf("%s/%s.%s.%s", escAppID, ModuleName(nil), majVersion, InstanceID()) ctxs.bg = &context{ req: &http.Request{ Header: http.Header{ ticketHeader: []string{ticket}, }, }, apiURL: apiURL(), logger: globalLogger(), } return toContext(ctxs.bg) } // RegisterTestRequest registers the HTTP request req for testing, such that // any API calls are sent to the provided URL. It returns a closure to delete // the registration. // It should only be used by aetest package. func RegisterTestRequest(req *http.Request, apiURL *url.URL, decorate func(netcontext.Context) netcontext.Context) func() { c := &context{ req: req, apiURL: apiURL, logger: globalLogger(), } ctxs.Lock() defer ctxs.Unlock() if _, ok := ctxs.m[req]; ok { log.Panic("req already associated with context") } if _, ok := ctxs.dec[req]; ok { log.Panic("req already associated with context") } if ctxs.dec == nil { ctxs.dec = make(map[*http.Request]func(netcontext.Context) netcontext.Context) } ctxs.m[req] = c ctxs.dec[req] = decorate return func() { ctxs.Lock() delete(ctxs.m, req) delete(ctxs.dec, req) ctxs.Unlock() } } var errTimeout = &CallError{ Detail: "Deadline exceeded", Code: int32(remotepb.RpcError_CANCELLED), Timeout: true, } func (c *context) Header() http.Header { return c.outHeader } // Copied from $GOROOT/src/pkg/net/http/transfer.go. Some response status // codes do not permit a response body (nor response entity headers such as // Content-Length, Content-Type, etc). func bodyAllowedForStatus(status int) bool { switch { case status >= 100 && status <= 199: return false case status == 204: return false case status == 304: return false } return true } func (c *context) Write(b []byte) (int, error) { if c.outCode == 0 { c.WriteHeader(http.StatusOK) } if len(b) > 0 && !bodyAllowedForStatus(c.outCode) { return 0, http.ErrBodyNotAllowed } c.outBody = append(c.outBody, b...) return len(b), nil } func (c *context) WriteHeader(code int) { if c.outCode != 0 { logf(c, 3, "WriteHeader called multiple times on request.") // error level return } c.outCode = code } func (c *context) post(body []byte, timeout time.Duration) (b []byte, err error) { hreq := &http.Request{ Method: "POST", URL: c.apiURL, Header: http.Header{ apiEndpointHeader: apiEndpointHeaderValue, apiMethodHeader: apiMethodHeaderValue, apiContentType: apiContentTypeValue, apiDeadlineHeader: []string{strconv.FormatFloat(timeout.Seconds(), 'f', -1, 64)}, }, Body: ioutil.NopCloser(bytes.NewReader(body)), ContentLength: int64(len(body)), Host: c.apiURL.Host, } if info := c.req.Header.Get(dapperHeader); info != "" { hreq.Header.Set(dapperHeader, info) } if info := c.req.Header.Get(traceHeader); info != "" { hreq.Header.Set(traceHeader, info) } tr := apiHTTPClient.Transport.(*http.Transport) var timedOut int32 // atomic; set to 1 if timed out t := time.AfterFunc(timeout, func() { atomic.StoreInt32(&timedOut, 1) tr.CancelRequest(hreq) }) defer t.Stop() defer func() { // Check if timeout was exceeded. if atomic.LoadInt32(&timedOut) != 0 { err = errTimeout } }() hresp, err := apiHTTPClient.Do(hreq) if err != nil { return nil, &CallError{ Detail: fmt.Sprintf("service bridge HTTP failed: %v", err), Code: int32(remotepb.RpcError_UNKNOWN), } } defer hresp.Body.Close() hrespBody, err := ioutil.ReadAll(hresp.Body) if hresp.StatusCode != 200 { return nil, &CallError{ Detail: fmt.Sprintf("service bridge returned HTTP %d (%q)", hresp.StatusCode, hrespBody), Code: int32(remotepb.RpcError_UNKNOWN), } } if err != nil { return nil, &CallError{ Detail: fmt.Sprintf("service bridge response bad: %v", err), Code: int32(remotepb.RpcError_UNKNOWN), } } return hrespBody, nil } func Call(ctx netcontext.Context, service, method string, in, out proto.Message) error { if ns := NamespaceFromContext(ctx); ns != "" { if fn, ok := NamespaceMods[service]; ok { fn(in, ns) } } if f, ctx, ok := callOverrideFromContext(ctx); ok { return f(ctx, service, method, in, out) } // Handle already-done contexts quickly. select { case <-ctx.Done(): return ctx.Err() default: } c := fromContext(ctx) if c == nil { // Give a good error message rather than a panic lower down. return errors.New("not an App Engine context") } // Apply transaction modifications if we're in a transaction. if t := transactionFromContext(ctx); t != nil { if t.finished { return errors.New("transaction context has expired") } applyTransaction(in, &t.transaction) } // Default RPC timeout is 60s. timeout := 60 * time.Second if deadline, ok := ctx.Deadline(); ok { timeout = deadline.Sub(time.Now()) } data, err := proto.Marshal(in) if err != nil { return err } ticket := c.req.Header.Get(ticketHeader) req := &remotepb.Request{ ServiceName: &service, Method: &method, Request: data, RequestId: &ticket, } hreqBody, err := proto.Marshal(req) if err != nil { return err } hrespBody, err := c.post(hreqBody, timeout) if err != nil { return err } res := &remotepb.Response{} if err := proto.Unmarshal(hrespBody, res); err != nil { return err } if res.RpcError != nil { ce := &CallError{ Detail: res.RpcError.GetDetail(), Code: *res.RpcError.Code, } switch remotepb.RpcError_ErrorCode(ce.Code) { case remotepb.RpcError_CANCELLED, remotepb.RpcError_DEADLINE_EXCEEDED: ce.Timeout = true } return ce } if res.ApplicationError != nil { return &APIError{ Service: *req.ServiceName, Detail: res.ApplicationError.GetDetail(), Code: *res.ApplicationError.Code, } } if res.Exception != nil || res.JavaException != nil { // This shouldn't happen, but let's be defensive. return &CallError{ Detail: "service bridge returned exception", Code: int32(remotepb.RpcError_UNKNOWN), } } return proto.Unmarshal(res.Response, out) } func (c *context) Request() *http.Request { return c.req } func ContextForTesting(req *http.Request) netcontext.Context { return toContext(&context{ req: req, logger: testLogger, }) }