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package toolbox
import (
"bytes"
"errors"
"fmt"
"io/ioutil"
"net"
"net/http"
"reflect"
"strings"
"time"
)
const (
jsonContentType = "application/json"
yamlContentTypeSuffix = "/yaml"
textPlainContentType = "text/plain"
contentTypeHeader = "Content-Type"
)
const (
//MethodGet HTTP GET meothd
MethodGet = "GET"
MethodHead = "HEAD"
MethodPost = "POST"
MethodPut = "PUT"
MethodPatch = "PATCH" // RFC 5789
MethodDelete = "DELETE"
MethodOptions = "OPTIONS"
MethodTrace = "TRACE"
)
var httpMethods = map[string]bool{
MethodDelete: true,
MethodGet: true,
MethodPatch: true,
MethodPost: true,
MethodPut: true,
MethodHead: true,
MethodTrace: true,
MethodOptions: true,
}
//HandlerInvoker method is responsible of passing required parameters to router handler.
type HandlerInvoker func(serviceRouting *ServiceRouting, request *http.Request, response http.ResponseWriter, parameters map[string]interface{}) error
//DefaultEncoderFactory - NewJSONEncoderFactory
var DefaultEncoderFactory = NewJSONEncoderFactory()
//DefaultDecoderFactory - NewJSONDecoderFactory
var DefaultDecoderFactory = NewJSONDecoderFactory()
//YamlDefaultEncoderFactory - NewYamlEncoderFactory
var YamlDefaultEncoderFactory = NewYamlEncoderFactory()
//YamlDefaultDecoderFactory - NewYamlDecoderFactory
var YamlDefaultDecoderFactory = NewFlexYamlDecoderFactory()
//ServiceRouting represents a simple web services routing rule, which is matched with http request
type ServiceRouting struct {
URI string //matching uri
Handler interface{} //has to be func
HTTPMethod string
Parameters []string
ContentTypeEncoders map[string]EncoderFactory //content type encoder factory
ContentTypeDecoders map[string]DecoderFactory //content type decoder factory
HandlerInvoker HandlerInvoker //optional function that will be used instead of reflection to invoke a handler.
}
func (sr ServiceRouting) getDecoderFactory(contentType string) DecoderFactory {
if sr.ContentTypeDecoders != nil {
if factory, found := sr.ContentTypeDecoders[contentType]; found {
return factory
}
}
if strings.HasSuffix(contentType, yamlContentTypeSuffix) {
return YamlDefaultDecoderFactory
}
return DefaultDecoderFactory
}
func (sr ServiceRouting) getEncoderFactory(contentType string) EncoderFactory {
if sr.ContentTypeDecoders != nil {
if factory, found := sr.ContentTypeEncoders[contentType]; found {
return factory
}
}
if strings.HasSuffix(contentType, yamlContentTypeSuffix) {
return YamlDefaultEncoderFactory
}
return DefaultEncoderFactory
}
func (sr ServiceRouting) extractParameterFromBody(parameterName string, targetType reflect.Type, request *http.Request) (interface{}, error) {
targetValuePointer := reflect.New(targetType)
contentType := getContentTypeOrJSONContentType(request.Header.Get(contentTypeHeader))
decoderFactory := sr.getDecoderFactory(contentType)
body, err := ioutil.ReadAll(request.Body)
if err != nil {
return nil, err
}
decoder := decoderFactory.Create(bytes.NewReader(body))
if !strings.Contains(parameterName, ":") {
err := decoder.Decode(targetValuePointer.Interface())
if err != nil {
return nil, fmt.Errorf("unable to extract %T due to: %v, body: !%s!", targetValuePointer.Interface(), err, body)
}
} else {
var valueMap = make(map[string]interface{})
pair := strings.SplitN(parameterName, ":", 2)
valueMap[pair[1]] = targetValuePointer.Interface()
err := decoder.Decode(&valueMap)
if err != nil {
return nil, fmt.Errorf("unable to extract %T due to %v", targetValuePointer.Interface(), err)
}
}
return targetValuePointer.Interface(), nil
}
func (sr ServiceRouting) extractParameters(request *http.Request, response http.ResponseWriter) (map[string]interface{}, error) {
var result = make(map[string]interface{})
_ = request.ParseForm()
functionSignature := GetFuncSignature(sr.Handler)
uriParameters, _ := ExtractURIParameters(sr.URI, request.RequestURI)
for _, name := range sr.Parameters {
value, found := uriParameters[name]
if found {
if strings.Contains(value, ",") {
result[name] = strings.Split(value, ",")
} else {
result[name] = value
}
continue
}
value = request.Form.Get(name)
if len(value) > 0 {
result[name] = value
} else {
continue
}
}
if HasSliceAnyElements(sr.Parameters, "@httpRequest") {
result["@httpRequest"] = request
}
if HasSliceAnyElements(sr.Parameters, "@httpResponseWriter") {
result["@httpResponseWriter"] = response
}
if request.ContentLength > 0 {
for i, parameter := range sr.Parameters {
if _, found := result[parameter]; !found {
value, err := sr.extractParameterFromBody(parameter, functionSignature[i], request)
if err != nil {
return nil, fmt.Errorf("failed to extract parameters for %v %v due to %v", sr.HTTPMethod, sr.URI, err)
}
result[parameter] = value
break
}
}
}
return result, nil
}
//ServiceRouter represents routing rule
type ServiceRouter struct {
serviceRouting []*ServiceRouting
}
func (r *ServiceRouter) match(request *http.Request) []*ServiceRouting {
var result = make([]*ServiceRouting, 0)
for _, candidate := range r.serviceRouting {
if candidate.HTTPMethod == request.Method {
_, matched := ExtractURIParameters(candidate.URI, request.RequestURI)
if matched {
result = append(result, candidate)
}
}
}
return result
}
func getContentTypeOrJSONContentType(contentType string) string {
if strings.Contains(contentType, textPlainContentType) || strings.Contains(contentType, jsonContentType) || contentType == "" {
return jsonContentType
}
return contentType
}
//Route matches service routing by http method , and number of parameters, then it call routing method, and sent back its response.
func (r *ServiceRouter) Route(response http.ResponseWriter, request *http.Request) error {
candidates := r.match(request)
if len(candidates) == 0 {
var uriTemplates = make([]string, 0)
for _, routing := range r.serviceRouting {
uriTemplates = append(uriTemplates, routing.URI)
}
return fmt.Errorf("failed to route request - unable to match %v with one of %v", request.RequestURI, strings.Join(uriTemplates, ","))
}
var finalError error
for _, serviceRouting := range candidates {
parameterValues, err := serviceRouting.extractParameters(request, response)
if err != nil {
finalError = fmt.Errorf("unable to extract parameters due to %v", err)
continue
}
if serviceRouting.HandlerInvoker != nil {
err := serviceRouting.HandlerInvoker(serviceRouting, request, response, parameterValues)
if err != nil {
finalError = fmt.Errorf("unable to extract parameters due to %v", err)
}
continue
}
functionParameters, err := BuildFunctionParameters(serviceRouting.Handler, serviceRouting.Parameters, parameterValues)
if err != nil {
finalError = fmt.Errorf("unable to build function parameters %T due to %v", serviceRouting.Handler, err)
continue
}
result := CallFunction(serviceRouting.Handler, functionParameters...)
if len(result) > 0 {
err = WriteServiceRoutingResponse(response, request, serviceRouting, result[0])
if err != nil {
return fmt.Errorf("failed to write response response %v, due to %v", result[0], err)
}
return nil
}
response.Header().Set(contentTypeHeader, textPlainContentType)
}
if finalError != nil {
return fmt.Errorf("failed to route request - %v", finalError)
}
return nil
}
//WriteServiceRoutingResponse writes service router response
func WriteServiceRoutingResponse(response http.ResponseWriter, request *http.Request, serviceRouting *ServiceRouting, result interface{}) error {
if result == nil {
result = struct{}{}
}
statusCodeAccessor, ok := result.(StatucCodeAccessor)
if ok {
statusCode := statusCodeAccessor.GetStatusCode()
if statusCode > 0 && statusCode != http.StatusOK {
response.WriteHeader(statusCode)
return nil
}
}
contentTypeAccessor, ok := result.(ContentTypeAccessor)
var responseContentType string
if ok {
responseContentType = contentTypeAccessor.GetContentType()
}
if responseContentType == "" {
requestContentType := request.Header.Get(contentTypeHeader)
responseContentType = getContentTypeOrJSONContentType(requestContentType)
}
encoderFactory := serviceRouting.getEncoderFactory(responseContentType)
encoder := encoderFactory.Create(response)
response.Header().Set(contentTypeHeader, responseContentType)
err := encoder.Encode(result)
if err != nil {
return fmt.Errorf("failed to encode response %v, due to %v", response, err)
}
return nil
if err != nil {
return fmt.Errorf("failed to write response response %v, due to %v", result, err)
}
return nil
}
//WriteResponse writes response to response writer, it used encoder factory to encode passed in response to the writer, it sets back request contenttype to response.
func (r *ServiceRouter) WriteResponse(encoderFactory EncoderFactory, response interface{}, request *http.Request, responseWriter http.ResponseWriter) error {
requestContentType := request.Header.Get(contentTypeHeader)
responseContentType := getContentTypeOrJSONContentType(requestContentType)
encoder := encoderFactory.Create(responseWriter)
responseWriter.Header().Set(contentTypeHeader, responseContentType)
err := encoder.Encode(response)
if err != nil {
return fmt.Errorf("failed to encode response %v, due to %v", response, err)
}
return nil
}
//NewServiceRouter creates a new service router, is takes list of service routing as arguments
func NewServiceRouter(serviceRouting ...ServiceRouting) *ServiceRouter {
var routings = make([]*ServiceRouting, 0)
for i := range serviceRouting {
routings = append(routings, &serviceRouting[i])
}
return &ServiceRouter{routings}
}
//RouteToService calls web service url, with passed in json request, and encodes http json response into passed response
func RouteToService(method, url string, request, response interface{}, options ...*HttpOptions) (err error) {
client, err := NewToolboxHTTPClient(options...)
if err != nil {
return err
}
return client.Request(method, url, request, response, NewJSONEncoderFactory(), NewJSONDecoderFactory())
}
type HttpOptions struct {
Key string
Value interface{}
}
func NewHttpClient(options ...*HttpOptions) (*http.Client, error) {
if len(options) == 0 {
return http.DefaultClient, nil
}
var (
// Default values matching DefaultHttpClient
RequestTimeoutMs = 30 * time.Second
KeepAliveTimeMs = 30 * time.Second
TLSHandshakeTimeoutMs = 10 * time.Second
ExpectContinueTimeout = 1 * time.Second
IdleConnTimeout = 90 * time.Second
DualStack = true
MaxIdleConnsPerHost = http.DefaultMaxIdleConnsPerHost
MaxIdleConns = 100
FollowRedirects = true
ResponseHeaderTimeoutMs time.Duration
TimeoutMs time.Duration
)
for _, option := range options {
switch option.Key {
case "RequestTimeoutMs":
RequestTimeoutMs = time.Duration(AsInt(option.Value)) * time.Millisecond
case "TimeoutMs":
TimeoutMs = time.Duration(AsInt(option.Value)) * time.Millisecond
case "KeepAliveTimeMs":
KeepAliveTimeMs = time.Duration(AsInt(option.Value)) * time.Millisecond
case "TLSHandshakeTimeoutMs":
KeepAliveTimeMs = time.Duration(AsInt(option.Value)) * time.Millisecond
case "ResponseHeaderTimeoutMs":
ResponseHeaderTimeoutMs = time.Duration(AsInt(option.Value)) * time.Millisecond
case "MaxIdleConns":
MaxIdleConns = AsInt(option.Value)
case "MaxIdleConnsPerHost":
MaxIdleConnsPerHost = AsInt(option.Value)
case "DualStack":
DualStack = AsBoolean(option.Value)
case "FollowRedirects":
FollowRedirects = AsBoolean(option.Value)
default:
return nil, fmt.Errorf("Invalid option: %v", option.Key)
}
}
roundTripper := http.Transport{
Proxy: http.ProxyFromEnvironment,
DialContext: (&net.Dialer{
Timeout: RequestTimeoutMs,
KeepAlive: KeepAliveTimeMs,
DualStack: DualStack,
}).DialContext,
MaxIdleConns: MaxIdleConns,
ExpectContinueTimeout: ExpectContinueTimeout,
IdleConnTimeout: IdleConnTimeout,
TLSHandshakeTimeout: TLSHandshakeTimeoutMs,
MaxIdleConnsPerHost: MaxIdleConnsPerHost,
ResponseHeaderTimeout: ResponseHeaderTimeoutMs,
}
client := &http.Client{
Transport: &roundTripper,
Timeout: TimeoutMs,
}
if !FollowRedirects {
client.CheckRedirect = func(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
}
}
return client, nil
}
// ToolboxHTTPClient contains preconfigured http client
type ToolboxHTTPClient struct {
httpClient *http.Client
}
// NewToolboxHTTPClient instantiate new client with provided options
func NewToolboxHTTPClient(options ...*HttpOptions) (*ToolboxHTTPClient, error) {
client, err := NewHttpClient(options...)
if err != nil {
return nil, err
}
return &ToolboxHTTPClient{client}, nil
}
// Request sends http request using the existing client
func (c *ToolboxHTTPClient) Request(method, url string, request, response interface{}, encoderFactory EncoderFactory, decoderFactory DecoderFactory) (err error) {
if _, found := httpMethods[strings.ToUpper(method)]; !found {
return errors.New("unsupported method:" + method)
}
var buffer *bytes.Buffer
if request != nil {
buffer = new(bytes.Buffer)
if IsString(request) {
buffer.Write([]byte(AsString(request)))
} else {
err := encoderFactory.Create(buffer).Encode(&request)
if err != nil {
return fmt.Errorf("failed to encode request: %v due to ", err)
}
}
}
var serverResponse *http.Response
var httpRequest *http.Request
httpMethod := strings.ToUpper(method)
if request != nil {
httpRequest, err = http.NewRequest(httpMethod, url, buffer)
if err != nil {
return err
}
httpRequest.Header.Set(contentTypeHeader, jsonContentType)
} else {
httpRequest, err = http.NewRequest(httpMethod, url, nil)
if err != nil {
return err
}
}
serverResponse, err = c.httpClient.Do(httpRequest)
if serverResponse != nil {
// must close we have serverResponse to avoid fd leak
defer serverResponse.Body.Close()
}
if err != nil && serverResponse != nil {
return fmt.Errorf("failed to get response %v %v", err, serverResponse.Header.Get("error"))
}
if response != nil {
updateResponse(serverResponse, response)
if serverResponse == nil {
return fmt.Errorf("failed to receive response %v", err)
}
var errorPrefix = fmt.Sprintf("failed to process response: %v, ", serverResponse.StatusCode)
body, err := ioutil.ReadAll(serverResponse.Body)
if err != nil {
return fmt.Errorf("%v unable read body %v", errorPrefix, err)
}
if len(body) == 0 {
return fmt.Errorf("%v response body was empty", errorPrefix)
}
if serverResponse.StatusCode == http.StatusNotFound {
updateResponse(serverResponse, response)
return nil
}
if int(serverResponse.StatusCode/100)*100 == http.StatusInternalServerError {
return errors.New(string(body))
}
err = decoderFactory.Create(strings.NewReader(string(body))).Decode(response)
if err != nil {
return fmt.Errorf("%v. unable decode response as %T: body: %v: %v", errorPrefix, response, string(body), err)
}
updateResponse(serverResponse, response)
}
return nil
}
//StatucCodeMutator client side reponse optional interface
type StatucCodeMutator interface {
SetStatusCode(code int)
}
//StatucCodeAccessor server side response accessor
type StatucCodeAccessor interface {
GetStatusCode() int
}
//ContentTypeMutator client side reponse optional interface
type ContentTypeMutator interface {
SetContentType(contentType string)
}
//ContentTypeAccessor server side response accessor
type ContentTypeAccessor interface {
GetContentType() string
}
//updateResponse update response with content type and status code if applicable
func updateResponse(httpResponse *http.Response, response interface{}) {
if response == nil {
return
}
statusCodeMutator, ok := response.(StatucCodeMutator)
if ok {
statusCodeMutator.SetStatusCode(httpResponse.StatusCode)
}
contentTypeMutator, ok := response.(ContentTypeMutator)
if ok {
contentTypeMutator.SetContentType(httpResponse.Header.Get(contentTypeHeader))
}
}
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