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package restful
// Copyright 2013 Ernest Micklei. All rights reserved.
// Use of this source code is governed by a license
// that can be found in the LICENSE file.
import (
"bytes"
"errors"
"fmt"
"net/http"
"os"
"runtime"
"strings"
"sync"
"github.com/emicklei/go-restful/log"
)
// Container holds a collection of WebServices and a http.ServeMux to dispatch http requests.
// The requests are further dispatched to routes of WebServices using a RouteSelector
type Container struct {
webServicesLock sync.RWMutex
webServices []*WebService
ServeMux *http.ServeMux
isRegisteredOnRoot bool
containerFilters []FilterFunction
doNotRecover bool // default is true
recoverHandleFunc RecoverHandleFunction
serviceErrorHandleFunc ServiceErrorHandleFunction
router RouteSelector // default is a CurlyRouter (RouterJSR311 is a slower alternative)
contentEncodingEnabled bool // default is false
}
// NewContainer creates a new Container using a new ServeMux and default router (CurlyRouter)
func NewContainer() *Container {
return &Container{
webServices: []*WebService{},
ServeMux: http.NewServeMux(),
isRegisteredOnRoot: false,
containerFilters: []FilterFunction{},
doNotRecover: true,
recoverHandleFunc: logStackOnRecover,
serviceErrorHandleFunc: writeServiceError,
router: CurlyRouter{},
contentEncodingEnabled: false}
}
// RecoverHandleFunction declares functions that can be used to handle a panic situation.
// The first argument is what recover() returns. The second must be used to communicate an error response.
type RecoverHandleFunction func(interface{}, http.ResponseWriter)
// RecoverHandler changes the default function (logStackOnRecover) to be called
// when a panic is detected. DoNotRecover must be have its default value (=false).
func (c *Container) RecoverHandler(handler RecoverHandleFunction) {
c.recoverHandleFunc = handler
}
// ServiceErrorHandleFunction declares functions that can be used to handle a service error situation.
// The first argument is the service error, the second is the request that resulted in the error and
// the third must be used to communicate an error response.
type ServiceErrorHandleFunction func(ServiceError, *Request, *Response)
// ServiceErrorHandler changes the default function (writeServiceError) to be called
// when a ServiceError is detected.
func (c *Container) ServiceErrorHandler(handler ServiceErrorHandleFunction) {
c.serviceErrorHandleFunc = handler
}
// DoNotRecover controls whether panics will be caught to return HTTP 500.
// If set to true, Route functions are responsible for handling any error situation.
// Default value is true.
func (c *Container) DoNotRecover(doNot bool) {
c.doNotRecover = doNot
}
// Router changes the default Router (currently CurlyRouter)
func (c *Container) Router(aRouter RouteSelector) {
c.router = aRouter
}
// EnableContentEncoding (default=false) allows for GZIP or DEFLATE encoding of responses.
func (c *Container) EnableContentEncoding(enabled bool) {
c.contentEncodingEnabled = enabled
}
// Add a WebService to the Container. It will detect duplicate root paths and exit in that case.
func (c *Container) Add(service *WebService) *Container {
c.webServicesLock.Lock()
defer c.webServicesLock.Unlock()
// if rootPath was not set then lazy initialize it
if len(service.rootPath) == 0 {
service.Path("/")
}
// cannot have duplicate root paths
for _, each := range c.webServices {
if each.RootPath() == service.RootPath() {
log.Printf("WebService with duplicate root path detected:['%v']", each)
os.Exit(1)
}
}
// If not registered on root then add specific mapping
if !c.isRegisteredOnRoot {
c.isRegisteredOnRoot = c.addHandler(service, c.ServeMux)
}
c.webServices = append(c.webServices, service)
return c
}
// addHandler may set a new HandleFunc for the serveMux
// this function must run inside the critical region protected by the webServicesLock.
// returns true if the function was registered on root ("/")
func (c *Container) addHandler(service *WebService, serveMux *http.ServeMux) bool {
pattern := fixedPrefixPath(service.RootPath())
// check if root path registration is needed
if "/" == pattern || "" == pattern {
serveMux.HandleFunc("/", c.dispatch)
return true
}
// detect if registration already exists
alreadyMapped := false
for _, each := range c.webServices {
if each.RootPath() == service.RootPath() {
alreadyMapped = true
break
}
}
if !alreadyMapped {
serveMux.HandleFunc(pattern, c.dispatch)
if !strings.HasSuffix(pattern, "/") {
serveMux.HandleFunc(pattern+"/", c.dispatch)
}
}
return false
}
func (c *Container) Remove(ws *WebService) error {
if c.ServeMux == http.DefaultServeMux {
errMsg := fmt.Sprintf("cannot remove a WebService from a Container using the DefaultServeMux: ['%v']", ws)
log.Print(errMsg)
return errors.New(errMsg)
}
c.webServicesLock.Lock()
defer c.webServicesLock.Unlock()
// build a new ServeMux and re-register all WebServices
newServeMux := http.NewServeMux()
newServices := []*WebService{}
newIsRegisteredOnRoot := false
for _, each := range c.webServices {
if each.rootPath != ws.rootPath {
// If not registered on root then add specific mapping
if !newIsRegisteredOnRoot {
newIsRegisteredOnRoot = c.addHandler(each, newServeMux)
}
newServices = append(newServices, each)
}
}
c.webServices, c.ServeMux, c.isRegisteredOnRoot = newServices, newServeMux, newIsRegisteredOnRoot
return nil
}
// logStackOnRecover is the default RecoverHandleFunction and is called
// when DoNotRecover is false and the recoverHandleFunc is not set for the container.
// Default implementation logs the stacktrace and writes the stacktrace on the response.
// This may be a security issue as it exposes sourcecode information.
func logStackOnRecover(panicReason interface{}, httpWriter http.ResponseWriter) {
var buffer bytes.Buffer
buffer.WriteString(fmt.Sprintf("recover from panic situation: - %v\r\n", panicReason))
for i := 2; ; i += 1 {
_, file, line, ok := runtime.Caller(i)
if !ok {
break
}
buffer.WriteString(fmt.Sprintf(" %s:%d\r\n", file, line))
}
log.Print(buffer.String())
httpWriter.WriteHeader(http.StatusInternalServerError)
httpWriter.Write(buffer.Bytes())
}
// writeServiceError is the default ServiceErrorHandleFunction and is called
// when a ServiceError is returned during route selection. Default implementation
// calls resp.WriteErrorString(err.Code, err.Message)
func writeServiceError(err ServiceError, req *Request, resp *Response) {
resp.WriteErrorString(err.Code, err.Message)
}
// Dispatch the incoming Http Request to a matching WebService.
func (c *Container) Dispatch(httpWriter http.ResponseWriter, httpRequest *http.Request) {
if httpWriter == nil {
panic("httpWriter cannot be nil")
}
if httpRequest == nil {
panic("httpRequest cannot be nil")
}
c.dispatch(httpWriter, httpRequest)
}
// Dispatch the incoming Http Request to a matching WebService.
func (c *Container) dispatch(httpWriter http.ResponseWriter, httpRequest *http.Request) {
writer := httpWriter
// CompressingResponseWriter should be closed after all operations are done
defer func() {
if compressWriter, ok := writer.(*CompressingResponseWriter); ok {
compressWriter.Close()
}
}()
// Instal panic recovery unless told otherwise
if !c.doNotRecover { // catch all for 500 response
defer func() {
if r := recover(); r != nil {
c.recoverHandleFunc(r, writer)
return
}
}()
}
// Find best match Route ; err is non nil if no match was found
var webService *WebService
var route *Route
var err error
func() {
c.webServicesLock.RLock()
defer c.webServicesLock.RUnlock()
webService, route, err = c.router.SelectRoute(
c.webServices,
httpRequest)
}()
// Detect if compression is needed
// assume without compression, test for override
contentEncodingEnabled := c.contentEncodingEnabled
if route != nil && route.contentEncodingEnabled != nil {
contentEncodingEnabled = *route.contentEncodingEnabled
}
if contentEncodingEnabled {
doCompress, encoding := wantsCompressedResponse(httpRequest)
if doCompress {
var err error
writer, err = NewCompressingResponseWriter(httpWriter, encoding)
if err != nil {
log.Print("unable to install compressor: ", err)
httpWriter.WriteHeader(http.StatusInternalServerError)
return
}
}
}
if err != nil {
// a non-200 response has already been written
// run container filters anyway ; they should not touch the response...
chain := FilterChain{Filters: c.containerFilters, Target: func(req *Request, resp *Response) {
switch err.(type) {
case ServiceError:
ser := err.(ServiceError)
c.serviceErrorHandleFunc(ser, req, resp)
}
// TODO
}}
chain.ProcessFilter(NewRequest(httpRequest), NewResponse(writer))
return
}
pathProcessor, routerProcessesPath := c.router.(PathProcessor)
if !routerProcessesPath {
pathProcessor = defaultPathProcessor{}
}
pathParams := pathProcessor.ExtractParameters(route, webService, httpRequest.URL.Path)
wrappedRequest, wrappedResponse := route.wrapRequestResponse(writer, httpRequest, pathParams)
// pass through filters (if any)
if len(c.containerFilters)+len(webService.filters)+len(route.Filters) > 0 {
// compose filter chain
allFilters := []FilterFunction{}
allFilters = append(allFilters, c.containerFilters...)
allFilters = append(allFilters, webService.filters...)
allFilters = append(allFilters, route.Filters...)
chain := FilterChain{Filters: allFilters, Target: func(req *Request, resp *Response) {
// handle request by route after passing all filters
route.Function(wrappedRequest, wrappedResponse)
}}
chain.ProcessFilter(wrappedRequest, wrappedResponse)
} else {
// no filters, handle request by route
route.Function(wrappedRequest, wrappedResponse)
}
}
// fixedPrefixPath returns the fixed part of the partspec ; it may include template vars {}
func fixedPrefixPath(pathspec string) string {
varBegin := strings.Index(pathspec, "{")
if -1 == varBegin {
return pathspec
}
return pathspec[:varBegin]
}
// ServeHTTP implements net/http.Handler therefore a Container can be a Handler in a http.Server
func (c *Container) ServeHTTP(httpwriter http.ResponseWriter, httpRequest *http.Request) {
c.ServeMux.ServeHTTP(httpwriter, httpRequest)
}
// Handle registers the handler for the given pattern. If a handler already exists for pattern, Handle panics.
func (c *Container) Handle(pattern string, handler http.Handler) {
c.ServeMux.Handle(pattern, handler)
}
// HandleWithFilter registers the handler for the given pattern.
// Container's filter chain is applied for handler.
// If a handler already exists for pattern, HandleWithFilter panics.
func (c *Container) HandleWithFilter(pattern string, handler http.Handler) {
f := func(httpResponse http.ResponseWriter, httpRequest *http.Request) {
if len(c.containerFilters) == 0 {
handler.ServeHTTP(httpResponse, httpRequest)
return
}
chain := FilterChain{Filters: c.containerFilters, Target: func(req *Request, resp *Response) {
handler.ServeHTTP(httpResponse, httpRequest)
}}
chain.ProcessFilter(NewRequest(httpRequest), NewResponse(httpResponse))
}
c.Handle(pattern, http.HandlerFunc(f))
}
// Filter appends a container FilterFunction. These are called before dispatching
// a http.Request to a WebService from the container
func (c *Container) Filter(filter FilterFunction) {
c.containerFilters = append(c.containerFilters, filter)
}
// RegisteredWebServices returns the collections of added WebServices
func (c *Container) RegisteredWebServices() []*WebService {
c.webServicesLock.RLock()
defer c.webServicesLock.RUnlock()
result := make([]*WebService, len(c.webServices))
for ix := range c.webServices {
result[ix] = c.webServices[ix]
}
return result
}
// computeAllowedMethods returns a list of HTTP methods that are valid for a Request
func (c *Container) computeAllowedMethods(req *Request) []string {
// Go through all RegisteredWebServices() and all its Routes to collect the options
methods := []string{}
requestPath := req.Request.URL.Path
for _, ws := range c.RegisteredWebServices() {
matches := ws.pathExpr.Matcher.FindStringSubmatch(requestPath)
if matches != nil {
finalMatch := matches[len(matches)-1]
for _, rt := range ws.Routes() {
matches := rt.pathExpr.Matcher.FindStringSubmatch(finalMatch)
if matches != nil {
lastMatch := matches[len(matches)-1]
if lastMatch == "" || lastMatch == "/" { // do not include if value is neither empty nor ‘/’.
methods = append(methods, rt.Method)
}
}
}
}
}
// methods = append(methods, "OPTIONS") not sure about this
return methods
}
// newBasicRequestResponse creates a pair of Request,Response from its http versions.
// It is basic because no parameter or (produces) content-type information is given.
func newBasicRequestResponse(httpWriter http.ResponseWriter, httpRequest *http.Request) (*Request, *Response) {
resp := NewResponse(httpWriter)
resp.requestAccept = httpRequest.Header.Get(HEADER_Accept)
return NewRequest(httpRequest), resp
}
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