forgejo/modules/web/handler.go

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// 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/log"
"code.gitea.io/gitea/modules/web/routing"
"code.gitea.io/gitea/modules/web/types"
)
var responseStatusProviders = map[reflect.Type]func(req *http.Request) types.ResponseStatusProvider{}
func RegisterResponseStatusProvider[T any](fn func(req *http.Request) types.ResponseStatusProvider) {
responseStatusProviders[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 _ types.ResponseStatusProvider = (*responseWriter)(nil)
func (r *responseWriter) WrittenStatus() int {
return r.status
}
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().(types.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 := responseStatusProviders[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().(types.ResponseStatusProvider); ok {
if statusProvider.WrittenStatus() != 0 {
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)
})
}
}
[GITEA] Use maintained gziphandler - https://github.com/NYTimes/gziphandler doesn't seems to be maintained anymore and Forgejo already includes https://github.com/klauspost/compress which provides a maintained and faster gzip handler fork. - Enables Jitter to prevent BREACH attacks, as this *seems* to be possible in the context of Forgejo. (cherry picked from commit cc2847241d82001babd8d40c87d03169f21c14cd) (cherry picked from commit 99ba56a8761dd08e08d9499cab2ded1a6b7b970f) Conflicts: go.sum https://codeberg.org/forgejo/forgejo/pulls/1581 (cherry picked from commit 711638193daa2311e2ead6249a47dcec47b4e335) (cherry picked from commit 9c12a37fde6fa84414bf332ff4a066facdb92d38) (cherry picked from commit d13065345431a499f9e0b7a3c2043d7487b8aa5b) (cherry picked from commit 45a16f8c3c6f7d5e4aab8fdde6a621cf36e4801c) (cherry picked from commit a497acb31f76d580c8b0567f9461274bd78080f4) (cherry picked from commit fe87fd828973945192b98310c5c3b2001c6e0f86) (cherry picked from commit 6ac12e6693cf45cb12109028dabd868957c4b74c) (cherry picked from commit 981ec37e1e72ab19c20067ff4d2a7e20a60d3305) (cherry picked from commit 5d6892ec10086f0ba63f26693faa82d0fd4e3f4a) (cherry picked from commit 9df7968f4fc72de9788d84ca3f349e4c98ee630e) (cherry picked from commit 7d588d183329cd760053663ea2e1e82e62958409) Conflicts: routers/web/web.go https://codeberg.org/forgejo/forgejo/pulls/2075 (cherry picked from commit defb101281f5a6ba410abc763674bafa7b63dffd) (cherry picked from commit 5830f204a17767fda3e45d16dbf3af8c32e7f387) (cherry picked from commit 029f4e98636a7776f430684e9d7142d69a444f96) (cherry picked from commit 816fe558126d0ecce969fdf2a196fa6afdcca792) Conflicts: go.sum https://codeberg.org/forgejo/forgejo/pulls/2249 (cherry picked from commit 99866d804560b415b6158371eb0efd17d097cfe0)
2023-10-01 00:09:25 +02:00
if hp, ok := handler.(func(next http.Handler) http.HandlerFunc); 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.(types.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
}