gitea/modules/web/handler.go
wxiaoguang abcf5a7b5e
Fix install page context, make the install page tests really test (#24858)
Fix #24856

Rename "context.contextKey" to "context.WebContextKey", this context is
for web context only. But the Context itself is not renamed, otherwise
it would cause a lot of changes (if we really want to rename it, there
could be a separate PR).

The old test code doesn't really test, the "install page" gets broken
not only one time, so use new test code to make sure the "install page"
could work.
2023-05-23 09:29:15 +08:00

194 lines
6.1 KiB
Go

// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package web
import (
goctx "context"
"fmt"
"net/http"
"reflect"
"code.gitea.io/gitea/modules/context"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/web/routing"
)
// ResponseStatusProvider is an interface to check whether the response has been written by the handler
type ResponseStatusProvider interface {
Written() bool
}
// TODO: decouple this from the context package, let the context package register these providers
var argTypeProvider = map[reflect.Type]func(req *http.Request) ResponseStatusProvider{
reflect.TypeOf(&context.APIContext{}): func(req *http.Request) ResponseStatusProvider { return context.GetAPIContext(req) },
reflect.TypeOf(&context.Context{}): func(req *http.Request) ResponseStatusProvider { return context.GetWebContext(req) },
reflect.TypeOf(&context.PrivateContext{}): func(req *http.Request) ResponseStatusProvider { return context.GetPrivateContext(req) },
}
func RegisterHandleTypeProvider[T any](fn func(req *http.Request) ResponseStatusProvider) {
argTypeProvider[reflect.TypeOf((*T)(nil)).Elem()] = fn
}
// responseWriter is a wrapper of http.ResponseWriter, to check whether the response has been written
type responseWriter struct {
respWriter http.ResponseWriter
status int
}
var _ ResponseStatusProvider = (*responseWriter)(nil)
func (r *responseWriter) Written() bool {
return r.status > 0
}
func (r *responseWriter) Header() http.Header {
return r.respWriter.Header()
}
func (r *responseWriter) Write(bytes []byte) (int, error) {
if r.status == 0 {
r.status = http.StatusOK
}
return r.respWriter.Write(bytes)
}
func (r *responseWriter) WriteHeader(statusCode int) {
r.status = statusCode
r.respWriter.WriteHeader(statusCode)
}
var (
httpReqType = reflect.TypeOf((*http.Request)(nil))
respWriterType = reflect.TypeOf((*http.ResponseWriter)(nil)).Elem()
cancelFuncType = reflect.TypeOf((*goctx.CancelFunc)(nil)).Elem()
)
// preCheckHandler checks whether the handler is valid, developers could get first-time feedback, all mistakes could be found at startup
func preCheckHandler(fn reflect.Value, argsIn []reflect.Value) {
hasStatusProvider := false
for _, argIn := range argsIn {
if _, hasStatusProvider = argIn.Interface().(ResponseStatusProvider); hasStatusProvider {
break
}
}
if !hasStatusProvider {
panic(fmt.Sprintf("handler should have at least one ResponseStatusProvider argument, but got %s", fn.Type()))
}
if fn.Type().NumOut() != 0 && fn.Type().NumIn() != 1 {
panic(fmt.Sprintf("handler should have no return value or only one argument, but got %s", fn.Type()))
}
if fn.Type().NumOut() == 1 && fn.Type().Out(0) != cancelFuncType {
panic(fmt.Sprintf("handler should return a cancel function, but got %s", fn.Type()))
}
}
func prepareHandleArgsIn(resp http.ResponseWriter, req *http.Request, fn reflect.Value, fnInfo *routing.FuncInfo) []reflect.Value {
defer func() {
if err := recover(); err != nil {
log.Error("unable to prepare handler arguments for %s: %v", fnInfo.String(), err)
panic(err)
}
}()
isPreCheck := req == nil
argsIn := make([]reflect.Value, fn.Type().NumIn())
for i := 0; i < fn.Type().NumIn(); i++ {
argTyp := fn.Type().In(i)
switch argTyp {
case respWriterType:
argsIn[i] = reflect.ValueOf(resp)
case httpReqType:
argsIn[i] = reflect.ValueOf(req)
default:
if argFn, ok := argTypeProvider[argTyp]; ok {
if isPreCheck {
argsIn[i] = reflect.ValueOf(&responseWriter{})
} else {
argsIn[i] = reflect.ValueOf(argFn(req))
}
} else {
panic(fmt.Sprintf("unsupported argument type: %s", argTyp))
}
}
}
return argsIn
}
func handleResponse(fn reflect.Value, ret []reflect.Value) goctx.CancelFunc {
if len(ret) == 1 {
if cancelFunc, ok := ret[0].Interface().(goctx.CancelFunc); ok {
return cancelFunc
}
panic(fmt.Sprintf("unsupported return type: %s", ret[0].Type()))
} else if len(ret) > 1 {
panic(fmt.Sprintf("unsupported return values: %s", fn.Type()))
}
return nil
}
func hasResponseBeenWritten(argsIn []reflect.Value) bool {
for _, argIn := range argsIn {
if statusProvider, ok := argIn.Interface().(ResponseStatusProvider); ok {
if statusProvider.Written() {
return true
}
}
}
return false
}
// toHandlerProvider converts a handler to a handler provider
// A handler provider is a function that takes a "next" http.Handler, it can be used as a middleware
func toHandlerProvider(handler any) func(next http.Handler) http.Handler {
funcInfo := routing.GetFuncInfo(handler)
fn := reflect.ValueOf(handler)
if fn.Type().Kind() != reflect.Func {
panic(fmt.Sprintf("handler must be a function, but got %s", fn.Type()))
}
if hp, ok := handler.(func(next http.Handler) http.Handler); ok {
return func(next http.Handler) http.Handler {
h := hp(next) // this handle could be dynamically generated, so we can't use it for debug info
return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
routing.UpdateFuncInfo(req.Context(), funcInfo)
h.ServeHTTP(resp, req)
})
}
}
provider := func(next http.Handler) http.Handler {
return http.HandlerFunc(func(respOrig http.ResponseWriter, req *http.Request) {
// wrap the response writer to check whether the response has been written
resp := respOrig
if _, ok := resp.(ResponseStatusProvider); !ok {
resp = &responseWriter{respWriter: resp}
}
// prepare the arguments for the handler and do pre-check
argsIn := prepareHandleArgsIn(resp, req, fn, funcInfo)
if req == nil {
preCheckHandler(fn, argsIn)
return // it's doing pre-check, just return
}
routing.UpdateFuncInfo(req.Context(), funcInfo)
ret := fn.Call(argsIn)
// handle the return value, and defer the cancel function if there is one
cancelFunc := handleResponse(fn, ret)
if cancelFunc != nil {
defer cancelFunc()
}
// if the response has not been written, call the next handler
if next != nil && !hasResponseBeenWritten(argsIn) {
next.ServeHTTP(resp, req)
}
})
}
provider(nil).ServeHTTP(nil, nil) // do a pre-check to make sure all arguments and return values are supported
return provider
}