331 lines
10 KiB
Go
331 lines
10 KiB
Go
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package fasthttp
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import (
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"fmt"
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"net/http"
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"strconv"
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"strings"
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"git.loafle.net/commons/cors-go"
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"git.loafle.net/commons/cors-go/internal"
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"git.loafle.net/commons/logging-go"
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"github.com/valyala/fasthttp"
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)
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// Cors http handler
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type Cors interface {
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Handle(ctx *fasthttp.RequestCtx) (requestDone bool)
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Handler(h fasthttp.RequestHandler) fasthttp.RequestHandler
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}
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// Cors http handler
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type fasthttpcors struct {
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co cors.Options
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// Set to true when allowed origins contains a "*"
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allowedOriginsAll bool
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// Normalized list of plain allowed origins
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allowedOrigins []string
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// List of allowed origins containing wildcards
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allowedWOrigins []internal.Wildcard
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// Set to true when allowed headers contains a "*"
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allowedHeadersAll bool
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// Normalized list of allowed headers
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allowedHeaders []string
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// Normalized list of allowed methods
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allowedMethods []string
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// Normalized list of exposed headers
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exposedHeaders []string
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}
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// New creates a new Cors handler with the provided options.
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func New(co cors.Options) Cors {
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c := &fasthttpcors{
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co: co,
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exposedHeaders: internal.Convert(co.ExposedHeaders, http.CanonicalHeaderKey),
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}
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// Normalize options
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// Note: for origins and methods matching, the spec requires a case-sensitive matching.
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// As it may error prone, we chose to ignore the spec here.
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// Allowed Origins
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// Allowed Origins
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if len(co.AllowedOrigins) == 0 {
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if co.AllowOriginFunc == nil {
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// Default is all origins
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c.allowedOriginsAll = true
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}
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} else {
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c.allowedOrigins = []string{}
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c.allowedWOrigins = []internal.Wildcard{}
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for _, origin := range co.AllowedOrigins {
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// Normalize
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origin = strings.ToLower(origin)
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if origin == "*" {
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// If "*" is present in the list, turn the whole list into a match all
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c.allowedOriginsAll = true
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c.allowedOrigins = nil
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c.allowedWOrigins = nil
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break
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} else if i := strings.IndexByte(origin, '*'); i >= 0 {
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// Split the origin in two: start and end string without the *
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w := internal.Wildcard{origin[0:i], origin[i+1 : len(origin)]}
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c.allowedWOrigins = append(c.allowedWOrigins, w)
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} else {
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c.allowedOrigins = append(c.allowedOrigins, origin)
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}
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}
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}
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// Allowed Headers
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if len(co.AllowedHeaders) == 0 {
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// Use sensible defaults
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c.allowedHeaders = []string{"Origin", "Accept", "Content-Type"}
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} else {
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// Origin is always appended as some browsers will always request for this header at preflight
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c.allowedHeaders = internal.Convert(append(co.AllowedHeaders, "Origin"), http.CanonicalHeaderKey)
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for _, h := range co.AllowedHeaders {
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if h == "*" {
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c.allowedHeadersAll = true
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c.allowedHeaders = nil
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break
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}
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}
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}
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// Allowed Methods
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if len(co.AllowedMethods) == 0 {
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// Default is spec's "simple" methods
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c.allowedMethods = []string{"GET", "POST", "HEAD"}
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} else {
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c.allowedMethods = internal.Convert(co.AllowedMethods, strings.ToUpper)
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}
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return c
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}
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// Default creates a new Cors handler with default options.
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func Default() Cors {
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return New(cors.Options{})
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}
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// AllowAll create a new Cors handler with permissive configuration allowing all
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// origins with all standard methods with any header and credentials.
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func AllowAll() Cors {
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return New(cors.Options{
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AllowedOrigins: []string{"*"},
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AllowedMethods: []string{"HEAD", "GET", "POST", "PUT", "PATCH", "DELETE"},
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AllowedHeaders: []string{"*"},
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AllowCredentials: true,
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})
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}
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func (c *fasthttpcors) Handle(ctx *fasthttp.RequestCtx) (requestDone bool) {
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if string(ctx.Method()) == "OPTIONS" && ctx.Request.Header.Peek("Access-Control-Request-Method") != nil {
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logging.Logger().Info("Handler: Preflight request")
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c.handlePreflight(ctx)
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// Preflight requests are standalone and should stop the chain as some other
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// middleware may not handle OPTIONS requests correctly. One typical example
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// is authentication middleware ; OPTIONS requests won't carry authentication
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// headers (see #1)
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if c.co.OptionsPassthrough {
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return false
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}
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ctx.SetStatusCode(fasthttp.StatusOK)
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return true
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}
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logging.Logger().Info("Handler: Actual request")
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c.handleActualRequest(ctx)
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return false
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}
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// Handler apply the CORS specification on the request, and add relevant CORS headers
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// as necessary.
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func (c *fasthttpcors) Handler(h fasthttp.RequestHandler) fasthttp.RequestHandler {
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return fasthttp.RequestHandler(func(ctx *fasthttp.RequestCtx) {
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if string(ctx.Method()) == "OPTIONS" && ctx.Request.Header.Peek("Access-Control-Request-Method") != nil {
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logging.Logger().Info("Handler: Preflight request")
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c.handlePreflight(ctx)
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// Preflight requests are standalone and should stop the chain as some other
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// middleware may not handle OPTIONS requests correctly. One typical example
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// is authentication middleware ; OPTIONS requests won't carry authentication
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// headers (see #1)
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if c.co.OptionsPassthrough {
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h(ctx)
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} else {
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ctx.SetStatusCode(fasthttp.StatusOK)
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}
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} else {
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logging.Logger().Info("Handler: Actual request")
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c.handleActualRequest(ctx)
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h(ctx)
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}
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})
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}
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// handlePreflight handles pre-flight CORS requests
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func (c *fasthttpcors) handlePreflight(ctx *fasthttp.RequestCtx) {
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origin := string(ctx.Request.Header.Peek("Origin"))
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if string(ctx.Method()) != "OPTIONS" {
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logging.Logger().Info(fmt.Sprintf(" Preflight aborted: %s!=OPTIONS", string(ctx.Method())))
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return
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}
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// Always set Vary headers
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// see https://github.com/rs/fasthttpcors/issues/10,
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// https://github.com/rs/fasthttpcors/commit/dbdca4d95feaa7511a46e6f1efb3b3aa505bc43f#commitcomment-12352001
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ctx.Response.Header.Add("Vary", "Origin")
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ctx.Response.Header.Add("Vary", "Access-Control-Request-Method")
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ctx.Response.Header.Add("Vary", "Access-Control-Request-Headers")
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if origin == "" {
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logging.Logger().Info(" Preflight aborted: empty origin")
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return
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}
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if !c.isOriginAllowed(origin) {
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logging.Logger().Info(fmt.Sprintf(" Preflight aborted: origin '%s' not allowed", origin))
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return
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}
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reqMethod := string(ctx.Request.Header.Peek("Access-Control-Request-Method"))
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if !c.isMethodAllowed(reqMethod) {
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logging.Logger().Info(fmt.Sprintf(" Preflight aborted: method '%s' not allowed", reqMethod))
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return
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}
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reqHeaders := internal.ParseHeaderList(string(ctx.Request.Header.Peek("Access-Control-Request-Headers")))
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if !c.areHeadersAllowed(reqHeaders) {
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logging.Logger().Info(fmt.Sprintf(" Preflight aborted: headers '%v' not allowed", reqHeaders))
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return
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}
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if c.allowedOriginsAll && !c.co.AllowCredentials {
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ctx.Response.Header.Set("Access-Control-Allow-Origin", "*")
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} else {
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ctx.Response.Header.Set("Access-Control-Allow-Origin", origin)
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}
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// Spec says: Since the list of methods can be unbounded, simply returning the method indicated
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// by Access-Control-Request-Method (if supported) can be enough
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ctx.Response.Header.Set("Access-Control-Allow-Methods", strings.ToUpper(reqMethod))
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if len(reqHeaders) > 0 {
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// Spec says: Since the list of headers can be unbounded, simply returning supported headers
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// from Access-Control-Request-Headers can be enough
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ctx.Response.Header.Set("Access-Control-Allow-Headers", strings.Join(reqHeaders, ", "))
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}
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if c.co.AllowCredentials {
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ctx.Response.Header.Set("Access-Control-Allow-Credentials", "true")
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}
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if c.co.MaxAge > 0 {
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ctx.Response.Header.Set("Access-Control-Max-Age", strconv.Itoa(c.co.MaxAge))
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}
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// logging.Logger().Info(fmt.Sprintf(" Preflight response headers: %v", ctx.Response.Header.))
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}
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// handleActualRequest handles simple cross-origin requests, actual request or redirects
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func (c *fasthttpcors) handleActualRequest(ctx *fasthttp.RequestCtx) {
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origin := string(ctx.Request.Header.Peek("Origin"))
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method := string(ctx.Method())
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if method == "OPTIONS" {
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logging.Logger().Info(fmt.Sprintf(" Actual request no headers added: method == %s", method))
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return
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}
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// Always set Vary, see https://github.com/rs/fasthttpcors/issues/10
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ctx.Response.Header.Add("Vary", "Origin")
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if origin == "" {
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logging.Logger().Info(" Actual request no headers added: missing origin")
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return
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}
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if !c.isOriginAllowed(origin) {
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logging.Logger().Info(fmt.Sprintf(" Actual request no headers added: origin '%s' not allowed", origin))
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return
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}
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// Note that spec does define a way to specifically disallow a simple method like GET or
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// POST. Access-Control-Allow-Methods is only used for pre-flight requests and the
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// spec doesn't instruct to check the allowed methods for simple cross-origin requests.
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// We think it's a nice feature to be able to have control on those methods though.
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if !c.isMethodAllowed(method) {
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logging.Logger().Info(fmt.Sprintf(" Actual request no headers added: method '%s' not allowed", method))
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return
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}
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if c.allowedOriginsAll && !c.co.AllowCredentials {
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ctx.Response.Header.Set("Access-Control-Allow-Origin", "*")
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} else {
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ctx.Response.Header.Set("Access-Control-Allow-Origin", origin)
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}
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if len(c.exposedHeaders) > 0 {
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ctx.Response.Header.Set("Access-Control-Expose-Headers", strings.Join(c.exposedHeaders, ", "))
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}
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if c.co.AllowCredentials {
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ctx.Response.Header.Set("Access-Control-Allow-Credentials", "true")
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}
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// c.logf(" Actual response added headers: %v", headers)
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}
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// isOriginAllowed checks if a given origin is allowed to perform cross-domain requests
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// on the endpoint
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func (c *fasthttpcors) isOriginAllowed(origin string) bool {
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if c.co.AllowOriginFunc != nil {
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return c.co.AllowOriginFunc(origin)
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}
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if c.allowedOriginsAll {
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return true
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}
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origin = strings.ToLower(origin)
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for _, o := range c.allowedOrigins {
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if o == origin {
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return true
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}
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}
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for _, w := range c.allowedWOrigins {
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if w.Match(origin) {
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return true
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}
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}
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return false
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}
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// isMethodAllowed checks if a given method can be used as part of a cross-domain request
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// on the endpoing
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func (c *fasthttpcors) isMethodAllowed(method string) bool {
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if len(c.allowedMethods) == 0 {
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// If no method allowed, always return false, even for preflight request
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return false
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}
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method = strings.ToUpper(method)
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if method == "OPTIONS" {
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// Always allow preflight requests
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return true
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}
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for _, m := range c.allowedMethods {
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if m == method {
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return true
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}
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}
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return false
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}
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// areHeadersAllowed checks if a given list of headers are allowed to used within
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// a cross-domain request.
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func (c *fasthttpcors) areHeadersAllowed(requestedHeaders []string) bool {
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if c.allowedHeadersAll || len(requestedHeaders) == 0 {
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return true
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}
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for _, header := range requestedHeaders {
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header = http.CanonicalHeaderKey(header)
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found := false
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for _, h := range c.allowedHeaders {
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if h == header {
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found = true
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}
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}
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if !found {
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return false
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}
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}
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return true
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}
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