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// 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"
basepb "google.golang.org/appengine/internal/base"
logpb "google.golang.org/appengine/internal/log"
remotepb "google.golang.org/appengine/internal/remote_api"
)
const (
apiPath = "/rpc_http"
defaultTicketSuffix = "/default.20150612t184001.0"
)
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"}
logFlushHeader = http.CanonicalHeaderKey("X-AppEngine-Log-Flush-Count")
apiHTTPClient = &http.Client{
Transport: &http.Transport{
Proxy: http.ProxyFromEnvironment,
Dial: limitDial,
},
}
defaultTicketOnce sync.Once
defaultTicket string
)
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{
outHeader: w.Header(),
apiURL: apiURL(),
req: r,
}
r = r.WithContext(withContext(r.Context(), c))
c.req = r
stopFlushing := make(chan int)
// 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")
}
// Start goroutine responsible for flushing app logs.
// This is done after adding c to ctx.m (and stopped before removing it)
// because flushing logs requires making an API call.
go c.logFlusher(stopFlushing)
executeRequestSafely(c, r)
c.outHeader = nil // make sure header changes aren't respected any more
stopFlushing <- 1 // any logging beyond this point will be dropped
// Flush any pending logs asynchronously.
c.pendingLogs.Lock()
flushes := c.pendingLogs.flushes
if len(c.pendingLogs.lines) > 0 {
flushes++
}
c.pendingLogs.Unlock()
go c.flushLog(false)
w.Header().Set(logFlushHeader, strconv.Itoa(flushes))
// 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
bg *context // background context, lazily initialized
}{}
// 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
outCode int
outHeader http.Header
outBody []byte
pendingLogs struct {
sync.Mutex
lines []*logpb.UserAppLogLine
flushes int
}
apiURL *url.URL
}
var contextKey = "holds a *context"
// fromContext returns the App Engine context or nil if ctx is not
// derived from an App Engine 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 {
return withContext(parent, fromContext(req.Context()))
}
// DefaultTicket returns a ticket used for background context or dev_appserver.
func DefaultTicket() string {
defaultTicketOnce.Do(func() {
if IsDevAppServer() {
defaultTicket = "testapp" + defaultTicketSuffix
return
}
appID := partitionlessAppID()
escAppID := strings.Replace(strings.Replace(appID, ":", "_", -1), ".", "_", -1)
majVersion := VersionID(nil)
if i := strings.Index(majVersion, "."); i > 0 {
majVersion = majVersion[:i]
}
defaultTicket = fmt.Sprintf("%s/%s.%s.%s", escAppID, ModuleName(nil), majVersion, InstanceID())
})
return defaultTicket
}
func BackgroundContext() netcontext.Context {
ctxs.Lock()
defer ctxs.Unlock()
if ctxs.bg != nil {
return toContext(ctxs.bg)
}
// Compute background security ticket.
ticket := DefaultTicket()
ctxs.bg = &context{
req: &http.Request{
Header: http.Header{
ticketHeader: []string{ticket},
},
},
apiURL: apiURL(),
}
// TODO(dsymonds): Wire up the shutdown handler to do a final flush.
go ctxs.bg.logFlusher(make(chan int))
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) *http.Request {
c := &context{
apiURL: apiURL,
req: req,
}
req = req.WithContext(withContext(req.Context(), c))
c.req = req
return req
}
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 errNotAppEngineContext
}
// 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)
// Use a test ticket under test environment.
if ticket == "" {
if appid := ctx.Value(&appIDOverrideKey); appid != nil {
ticket = appid.(string) + defaultTicketSuffix
}
}
// Fall back to use background ticket when the request ticket is not available in Flex or dev_appserver.
if ticket == "" {
ticket = DefaultTicket()
}
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 (c *context) addLogLine(ll *logpb.UserAppLogLine) {
// Truncate long log lines.
// TODO(dsymonds): Check if this is still necessary.
const lim = 8 << 10
if len(*ll.Message) > lim {
suffix := fmt.Sprintf("...(length %d)", len(*ll.Message))
ll.Message = proto.String((*ll.Message)[:lim-len(suffix)] + suffix)
}
c.pendingLogs.Lock()
c.pendingLogs.lines = append(c.pendingLogs.lines, ll)
c.pendingLogs.Unlock()
}
var logLevelName = map[int64]string{
0: "DEBUG",
1: "INFO",
2: "WARNING",
3: "ERROR",
4: "CRITICAL",
}
func logf(c *context, level int64, format string, args ...interface{}) {
if c == nil {
panic("not an App Engine context")
}
s := fmt.Sprintf(format, args...)
s = strings.TrimRight(s, "\n") // Remove any trailing newline characters.
c.addLogLine(&logpb.UserAppLogLine{
TimestampUsec: proto.Int64(time.Now().UnixNano() / 1e3),
Level: &level,
Message: &s,
})
log.Print(logLevelName[level] + ": " + s)
}
// flushLog attempts to flush any pending logs to the appserver.
// It should not be called concurrently.
func (c *context) flushLog(force bool) (flushed bool) {
c.pendingLogs.Lock()
// Grab up to 30 MB. We can get away with up to 32 MB, but let's be cautious.
n, rem := 0, 30<<20
for ; n < len(c.pendingLogs.lines); n++ {
ll := c.pendingLogs.lines[n]
// Each log line will require about 3 bytes of overhead.
nb := proto.Size(ll) + 3
if nb > rem {
break
}
rem -= nb
}
lines := c.pendingLogs.lines[:n]
c.pendingLogs.lines = c.pendingLogs.lines[n:]
c.pendingLogs.Unlock()
if len(lines) == 0 && !force {
// Nothing to flush.
return false
}
rescueLogs := false
defer func() {
if rescueLogs {
c.pendingLogs.Lock()
c.pendingLogs.lines = append(lines, c.pendingLogs.lines...)
c.pendingLogs.Unlock()
}
}()
buf, err := proto.Marshal(&logpb.UserAppLogGroup{
LogLine: lines,
})
if err != nil {
log.Printf("internal.flushLog: marshaling UserAppLogGroup: %v", err)
rescueLogs = true
return false
}
req := &logpb.FlushRequest{
Logs: buf,
}
res := &basepb.VoidProto{}
c.pendingLogs.Lock()
c.pendingLogs.flushes++
c.pendingLogs.Unlock()
if err := Call(toContext(c), "logservice", "Flush", req, res); err != nil {
log.Printf("internal.flushLog: Flush RPC: %v", err)
rescueLogs = true
return false
}
return true
}
const (
// Log flushing parameters.
flushInterval = 1 * time.Second
forceFlushInterval = 60 * time.Second
)
func (c *context) logFlusher(stop <-chan int) {
lastFlush := time.Now()
tick := time.NewTicker(flushInterval)
for {
select {
case <-stop:
// Request finished.
tick.Stop()
return
case <-tick.C:
force := time.Now().Sub(lastFlush) > forceFlushInterval
if c.flushLog(force) {
lastFlush = time.Now()
}
}
}
}
func ContextForTesting(req *http.Request) netcontext.Context {
return toContext(&context{req: req})
}