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context.go
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context.go
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/*
* Copyright 2023 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package web
import (
"context"
"fmt"
"io"
"mime/multipart"
"net"
"net/http"
"net/textproto"
"net/url"
"strings"
"unicode"
"go-spring.dev/web/binding"
"go-spring.dev/web/render"
)
type contextKey struct{}
func WithContext(parent context.Context, ctx *Context) context.Context {
return context.WithValue(parent, contextKey{}, ctx)
}
func FromContext(ctx context.Context) *Context {
if v := ctx.Value(contextKey{}); v != nil {
return v.(*Context)
}
return nil
}
type Context struct {
// A ResponseWriter interface is used by an HTTP handler to
// construct an HTTP response.
Writer http.ResponseWriter
// A Request represents an HTTP request received by a server
// or to be sent by a client.
Request *http.Request
// SameSite allows a server to define a cookie attribute making it impossible for
// the browser to send this cookie along with cross-site requests.
sameSite http.SameSite
}
// Context returns the request's context.
func (c *Context) Context() context.Context {
return c.Request.Context()
}
// ContentType returns the request header `Content-Type`.
func (c *Context) ContentType() string {
contentType := c.Request.Header.Get("Content-Type")
return contentType
}
// Header returns the named header in the request.
func (c *Context) Header(key string) (string, bool) {
if values, ok := c.Request.Header[textproto.CanonicalMIMEHeaderKey(key)]; ok && len(values) > 0 {
return values[0], true
}
return "", false
}
// Cookie returns the named cookie provided in the request.
func (c *Context) Cookie(name string) (string, bool) {
cookie, err := c.Request.Cookie(name)
if err != nil {
return "", false
}
if val, err := url.QueryUnescape(cookie.Value); nil == err {
return val, true
}
return cookie.Value, true
}
// PathParam returns the named variables in the request.
func (c *Context) PathParam(name string) (string, bool) {
if ctx := FromRouteContext(c.Request.Context()); nil != ctx {
return ctx.URLParams.Get(name)
}
return "", false
}
// QueryParam returns the named query in the request.
func (c *Context) QueryParam(name string) (string, bool) {
if values := c.Request.URL.Query(); nil != values {
if value, ok := values[name]; ok && len(value) > 0 {
return value[0], true
}
}
return "", false
}
// FormParams returns the form in the request.
func (c *Context) FormParams() (url.Values, error) {
if err := c.Request.ParseForm(); nil != err {
return nil, err
}
return c.Request.Form, nil
}
// MultipartParams returns a request body as multipart/form-data.
// The whole request body is parsed and up to a total of maxMemory bytes of its file parts are stored in memory, with the remainder stored on disk in temporary files.
func (c *Context) MultipartParams(maxMemory int64) (*multipart.Form, error) {
if !strings.Contains(c.ContentType(), binding.MIMEMultipartForm) {
return nil, fmt.Errorf("require `multipart/form-data` request")
}
if nil == c.Request.MultipartForm {
if err := c.Request.ParseMultipartForm(maxMemory); nil != err {
return nil, err
}
}
return c.Request.MultipartForm, nil
}
// RequestBody returns the request body.
func (c *Context) RequestBody() io.Reader {
return c.Request.Body
}
// IsWebsocket returns true if the request headers indicate that a websocket
// handshake is being initiated by the client.
func (c *Context) IsWebsocket() bool {
if strings.Contains(strings.ToLower(c.Request.Header.Get("Connection")), "upgrade") &&
strings.EqualFold(c.Request.Header.Get("Upgrade"), "websocket") {
return true
}
return false
}
// SetSameSite with cookie
func (c *Context) SetSameSite(samesite http.SameSite) {
c.sameSite = samesite
}
// Status sets the HTTP response code.
func (c *Context) Status(code int) {
c.Writer.WriteHeader(code)
}
// SetHeader is an intelligent shortcut for c.Writer.Header().Set(key, value).
// It writes a header in the response.
// If value == "", this method removes the header `c.Writer.Header().Del(key)`
func (c *Context) SetHeader(key, value string) {
if value == "" {
c.Writer.Header().Del(key)
return
}
c.Writer.Header().Set(key, value)
}
// SetCookie adds a Set-Cookie header to the ResponseWriter's headers.
// The provided cookie must have a valid Name. Invalid cookies may be
// silently dropped.
func (c *Context) SetCookie(name, value string, maxAge int, path, domain string, secure, httpOnly bool) {
if path == "" {
path = "/"
}
http.SetCookie(c.Writer, &http.Cookie{
Name: name,
Value: url.QueryEscape(value),
MaxAge: maxAge,
Path: path,
Domain: domain,
SameSite: c.sameSite,
Secure: secure,
HttpOnly: httpOnly,
})
}
// Bind checks the Method and Content-Type to select a binding engine automatically,
// Depending on the "Content-Type" header different bindings are used, for example:
//
// "application/json" --> JSON binding
// "application/xml" --> XML binding
func (c *Context) Bind(r interface{}) error {
return binding.Bind(r, c)
}
// Render writes the response headers and calls render.Render to render data.
func (c *Context) Render(code int, render render.Renderer) error {
if code > 0 {
if len(c.Writer.Header().Get("Content-Type")) <= 0 {
if contentType := render.ContentType(); len(contentType) > 0 {
c.Writer.Header().Set("Content-Type", contentType)
}
}
c.Writer.WriteHeader(code)
}
if !bodyAllowedForStatus(code) {
return nil
}
return render.Render(c.Writer)
}
// Redirect returns an HTTP redirect to the specific location.
func (c *Context) Redirect(code int, location string) error {
return c.Render(-1, render.RedirectRenderer{Code: code, Request: c.Request, Location: location})
}
// String writes the given string into the response body.
func (c *Context) String(code int, format string, args ...interface{}) error {
return c.Render(code, render.TextRenderer{Format: format, Args: args})
}
// Data writes some data into the body stream and updates the HTTP code.
func (c *Context) Data(code int, contentType string, data []byte) error {
return c.Render(code, render.BinaryRenderer{DataType: contentType, Data: data})
}
// JSON serializes the given struct as JSON into the response body.
// It also sets the Content-Type as "application/json".
func (c *Context) JSON(code int, obj interface{}) error {
return c.Render(code, render.JsonRenderer{Data: obj})
}
// IndentedJSON serializes the given struct as pretty JSON (indented + endlines) into the response body.
// It also sets the Content-Type as "application/json".
func (c *Context) IndentedJSON(code int, obj interface{}) error {
return c.Render(code, render.JsonRenderer{Data: obj, Indent: " "})
}
// XML serializes the given struct as XML into the response body.
// It also sets the Content-Type as "application/xml".
func (c *Context) XML(code int, obj interface{}) error {
return c.Render(code, render.XmlRenderer{Data: obj})
}
// IndentedXML serializes the given struct as pretty XML (indented + endlines) into the response body.
// It also sets the Content-Type as "application/xml".
func (c *Context) IndentedXML(code int, obj interface{}) error {
return c.Render(code, render.XmlRenderer{Data: obj, Indent: " "})
}
// File writes the specified file into the body stream in an efficient way.
func (c *Context) File(filepath string) {
http.ServeFile(c.Writer, c.Request, filepath)
}
// FileAttachment writes the specified file into the body stream in an efficient way
// On the client side, the file will typically be downloaded with the given filename
func (c *Context) FileAttachment(filepath, filename string) {
if isASCII(filename) {
c.Writer.Header().Set("Content-Disposition", `attachment; filename="`+escapeQuotes(filename)+`"`)
} else {
c.Writer.Header().Set("Content-Disposition", `attachment; filename*=UTF-8''`+url.QueryEscape(filename))
}
http.ServeFile(c.Writer, c.Request, filepath)
}
// RemoteIP parses the IP from Request.RemoteAddr, normalizes and returns the IP (without the port).
func (c *Context) RemoteIP() string {
ip, _, err := net.SplitHostPort(strings.TrimSpace(c.Request.RemoteAddr))
if err != nil {
return ""
}
return ip
}
// ClientIP implements one best effort algorithm to return the real client IP.
// It calls c.RemoteIP() under the hood, to check if the remote IP is a trusted proxy or not.
// If it is it will then try to parse the headers defined in RemoteIPHeaders (defaulting to [X-Forwarded-For, X-Real-Ip]).
// If the headers are not syntactically valid OR the remote IP does not correspond to a trusted proxy,
// the remote IP (coming from Request.RemoteAddr) is returned.
func (c *Context) ClientIP() string {
// It also checks if the remoteIP is a trusted proxy or not.
// In order to perform this validation, it will see if the IP is contained within at least one of the CIDR blocks
// defined by Engine.SetTrustedProxies()
remoteIP := net.ParseIP(c.RemoteIP())
if remoteIP == nil {
return ""
}
for _, headerName := range []string{"X-Forwarded-For", "X-Real-Ip"} {
if ns := strings.Split(c.Request.Header.Get(headerName), ","); len(ns) > 0 && len(ns[0]) > 0 {
return ns[0]
}
}
return remoteIP.String()
}
type routeContextKey struct{}
func WithRouteContext(parent context.Context, ctx *RouteContext) context.Context {
return context.WithValue(parent, routeContextKey{}, ctx)
}
func FromRouteContext(ctx context.Context) *RouteContext {
if v := ctx.Value(routeContextKey{}); v != nil {
return v.(*RouteContext)
}
return nil
}
type RouteContext struct {
Routes Routes
// URLParams are the stack of routeParams captured during the
// routing lifecycle across a stack of sub-routers.
URLParams RouteParams
// routeParams matched for the current sub-router. It is
// intentionally unexported so it can't be tampered.
routeParams RouteParams
// Routing path/method override used during the route search.
RoutePath string
RouteMethod string
// The endpoint routing pattern that matched the request URI path
// or `RoutePath` of the current sub-router. This value will update
// during the lifecycle of a request passing through a stack of
// sub-routers.
RoutePattern string
routePatterns []string
methodsAllowed []methodTyp
methodNotAllowed bool
}
// AllowedMethods report allowed http methods.
func (c *RouteContext) AllowedMethods() (methods []string) {
for _, m := range c.methodsAllowed {
methods = append(methods, methodTypString(m))
}
return
}
// Reset context to initial state
func (c *RouteContext) Reset() {
c.Routes = nil
c.RoutePath = ""
c.RouteMethod = ""
c.RoutePattern = ""
c.routePatterns = c.routePatterns[:0]
c.URLParams.Keys = c.URLParams.Keys[:0]
c.URLParams.Values = c.URLParams.Values[:0]
c.routeParams.Keys = c.routeParams.Keys[:0]
c.routeParams.Values = c.routeParams.Values[:0]
c.methodNotAllowed = false
c.methodsAllowed = c.methodsAllowed[:0]
}
// RouteParams is a structure to track URL routing parameters efficiently.
type RouteParams struct {
Keys, Values []string
}
// Add will append a URL parameter to the end of the route param
func (s *RouteParams) Add(key, value string) {
s.Keys = append(s.Keys, key)
s.Values = append(s.Values, value)
}
func (s *RouteParams) Get(key string) (value string, ok bool) {
for i := len(s.Keys) - 1; i >= 0; i-- {
if s.Keys[i] == key {
return s.Values[i], true
}
}
return "", false
}
// https://stackoverflow.com/questions/53069040/checking-a-string-contains-only-ascii-characters
func isASCII(s string) bool {
for i := 0; i < len(s); i++ {
if s[i] > unicode.MaxASCII {
return false
}
}
return true
}
var quoteEscaper = strings.NewReplacer("\\", "\\\\", `"`, "\\\"")
func escapeQuotes(s string) string {
return quoteEscaper.Replace(s)
}
// bodyAllowedForStatus is a copy of http.bodyAllowedForStatus non-exported function.
func bodyAllowedForStatus(status int) bool {
switch {
case status >= 100 && status <= 199:
return false
case status == http.StatusNoContent:
return false
case status == http.StatusNotModified:
return false
}
return true
}
func notFound() http.Handler {
return http.NotFoundHandler()
}
func notAllowed() http.Handler {
return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
http.Error(writer, "405 method not allowed", http.StatusMethodNotAllowed)
})
}