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allow API calls without GAE context (#284)
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The ApiHost used to require a security ticket for all API calls, so the
client side code used to be able to assume that  any request without one
was invalid and reject it. The backend now is able to handle requests
without security tickets in many cases, so the client side check is now
just getting in the way. This change removes that check and lets the
backend attempt to handle all requests.

The way the client implementation happened to require a security ticket
was actually by requiring a GAE context. This change removes that
constraint as well and removes the now-unecessary BackgroundContext.
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@zevdg
zevdg committed Jul 18, 2022
1 parent 1f27190 commit 37ff2b8
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Showing 10 changed files with 192 additions and 279 deletions.
14 changes: 1 addition & 13 deletions aetest/instance_vm.go
View file
Expand Up @@ -18,7 +18,6 @@ import (
"regexp"
"time"

"golang.org/x/net/context"
"google.golang.org/appengine/internal"
)

Expand Down Expand Up @@ -61,7 +60,6 @@ type instance struct {
appDir string
appID string
startupTimeout time.Duration
relFuncs []func() // funcs to release any associated contexts
}

// NewRequest returns an *http.Request associated with this instance.
Expand All @@ -72,21 +70,11 @@ func (i *instance) NewRequest(method, urlStr string, body io.Reader) (*http.Requ
}

// Associate this request.
req, release := internal.RegisterTestRequest(req, i.apiURL, func(ctx context.Context) context.Context {
ctx = internal.WithAppIDOverride(ctx, "dev~"+i.appID)
return ctx
})
i.relFuncs = append(i.relFuncs, release)

return req, nil
return internal.RegisterTestRequest(req, i.apiURL, "dev~"+i.appID), nil
}

// Close kills the child api_server.py process, releasing its resources.
func (i *instance) Close() (err error) {
for _, rel := range i.relFuncs {
rel()
}
i.relFuncs = nil
child := i.child
if child == nil {
return nil
Expand Down
9 changes: 5 additions & 4 deletions appengine_vm.go
View file
Expand Up @@ -8,12 +8,13 @@
package appengine

import (
"golang.org/x/net/context"

"google.golang.org/appengine/internal"
"context"
)

// BackgroundContext returns a context not associated with a request.
//
// Deprecated: App Engine no longer has a special background context.
// Just use context.Background().
func BackgroundContext() context.Context {
return internal.BackgroundContext()
return context.Background()
}
127 changes: 39 additions & 88 deletions internal/api.go
View file
Expand Up @@ -24,17 +24,17 @@ import (
"sync/atomic"
"time"

netcontext "context"

"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"
apiPath = "/rpc_http"
)

var (
Expand Down Expand Up @@ -66,21 +66,22 @@ var (
IdleConnTimeout: 90 * time.Second,
},
}

defaultTicketOnce sync.Once
defaultTicket string
backgroundContextOnce sync.Once
backgroundContext netcontext.Context
)

func apiURL() *url.URL {
func apiURL(ctx netcontext.Context) *url.URL {
host, port := "appengine.googleapis.internal", "10001"
if h := os.Getenv("API_HOST"); h != "" {
host = h
}
if hostOverride := ctx.Value(apiHostOverrideKey); hostOverride != nil {
host = hostOverride.(string)
}
if p := os.Getenv("API_PORT"); p != "" {
port = p
}
if portOverride := ctx.Value(apiPortOverrideKey); portOverride != nil {
port = portOverride.(string)
}
return &url.URL{
Scheme: "http",
Host: host + ":" + port,
Expand All @@ -98,7 +99,6 @@ func handleHTTPMiddleware(next http.Handler) http.Handler {
c := &context{
req: r,
outHeader: w.Header(),
apiURL: apiURL(),
}
r = r.WithContext(withContext(r.Context(), c))
c.req = r
Expand Down Expand Up @@ -235,8 +235,6 @@ type context struct {
lines []*logpb.UserAppLogLine
flushes int
}

apiURL *url.URL
}

var contextKey = "holds a *context"
Expand Down Expand Up @@ -304,59 +302,19 @@ func WithContext(parent netcontext.Context, req *http.Request) netcontext.Contex
}
}

// 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 {
backgroundContextOnce.Do(func() {
// Compute background security ticket.
ticket := DefaultTicket()

c := &context{
req: &http.Request{
Header: http.Header{
ticketHeader: []string{ticket},
},
},
apiURL: apiURL(),
}
backgroundContext = toContext(c)

// TODO(dsymonds): Wire up the shutdown handler to do a final flush.
go c.logFlusher(make(chan int))
})

return backgroundContext
}

// 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.
// any API calls are sent to the provided URL.
// It should only be used by aetest package.
func RegisterTestRequest(req *http.Request, apiURL *url.URL, decorate func(netcontext.Context) netcontext.Context) (*http.Request, func()) {
c := &context{
req: req,
apiURL: apiURL,
}
ctx := withContext(decorate(req.Context()), c)
req = req.WithContext(ctx)
c.req = req
return req, func() {}
func RegisterTestRequest(req *http.Request, apiURL *url.URL, appID string) *http.Request {
ctx := req.Context()
ctx = withAPIHostOverride(ctx, apiURL.Hostname())
ctx = withAPIPortOverride(ctx, apiURL.Port())
ctx = WithAppIDOverride(ctx, appID)

// use the unregistered request as a placeholder so that withContext can read the headers
c := &context{req: req}
c.req = req.WithContext(withContext(ctx, c))
return c.req
}

var errTimeout = &CallError{
Expand Down Expand Up @@ -401,10 +359,11 @@ func (c *context) WriteHeader(code int) {
c.outCode = code
}

func (c *context) post(body []byte, timeout time.Duration) (b []byte, err error) {
func post(ctx netcontext.Context, body []byte, timeout time.Duration) (b []byte, err error) {
apiURL := apiURL(ctx)
hreq := &http.Request{
Method: "POST",
URL: c.apiURL,
URL: apiURL,
Header: http.Header{
apiEndpointHeader: apiEndpointHeaderValue,
apiMethodHeader: apiMethodHeaderValue,
Expand All @@ -413,13 +372,16 @@ func (c *context) post(body []byte, timeout time.Duration) (b []byte, err error)
},
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)
Host: apiURL.Host,
}
if info := c.req.Header.Get(traceHeader); info != "" {
hreq.Header.Set(traceHeader, info)
c := fromContext(ctx)
if c != nil {
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)
Expand Down Expand Up @@ -480,10 +442,6 @@ func Call(ctx netcontext.Context, service, method string, in, out proto.Message)
}

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 {
Expand All @@ -504,20 +462,13 @@ func Call(ctx netcontext.Context, service, method string, in, out proto.Message)
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
ticket := ""
if c != nil {
ticket = c.req.Header.Get(ticketHeader)
if dri := c.req.Header.Get(devRequestIdHeader); IsDevAppServer() && dri != "" {
ticket = dri
}
}
// Fall back to use background ticket when the request ticket is not available in Flex or dev_appserver.
if ticket == "" {
ticket = DefaultTicket()
}
if dri := c.req.Header.Get(devRequestIdHeader); IsDevAppServer() && dri != "" {
ticket = dri
}
req := &remotepb.Request{
ServiceName: &service,
Method: &method,
Expand All @@ -529,7 +480,7 @@ func Call(ctx netcontext.Context, service, method string, in, out proto.Message)
return err
}

hrespBody, err := c.post(hreqBody, timeout)
hrespBody, err := post(ctx, hreqBody, timeout)
if err != nil {
return err
}
Expand Down
20 changes: 19 additions & 1 deletion internal/api_common.go
View file
Expand Up @@ -5,13 +5,19 @@
package internal

import (
netcontext "context"
"errors"
"os"

"github.com/golang/protobuf/proto"
netcontext "golang.org/x/net/context"
)

type ctxKey string

func (c ctxKey) String() string {
return "appengine context key: " + string(c)
}

var errNotAppEngineContext = errors.New("not an App Engine context")

type CallOverrideFunc func(ctx netcontext.Context, service, method string, in, out proto.Message) error
Expand Down Expand Up @@ -55,6 +61,18 @@ func WithAppIDOverride(ctx netcontext.Context, appID string) netcontext.Context
return netcontext.WithValue(ctx, &appIDOverrideKey, appID)
}

var apiHostOverrideKey = ctxKey("holds a string, being the alternate API_HOST")

func withAPIHostOverride(ctx netcontext.Context, apiHost string) netcontext.Context {
return netcontext.WithValue(ctx, apiHostOverrideKey, apiHost)
}

var apiPortOverrideKey = ctxKey("holds a string, being the alternate API_PORT")

func withAPIPortOverride(ctx netcontext.Context, apiPort string) netcontext.Context {
return netcontext.WithValue(ctx, apiPortOverrideKey, apiPort)
}

var namespaceKey = "holds the namespace string"

func withNamespace(ctx netcontext.Context, ns string) netcontext.Context {
Expand Down

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