Carlos Florêncio
78 lines
1.9 KiB
Go
78 lines
1.9 KiB
Go
package backendapp
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import (
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"net"
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"net/http"
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"net/url"
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"strings"
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"github.com/gin-gonic/gin"
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)
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// corsMiddleware returns a CORS middleware for HTTP and WebSocket connections.
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func corsMiddleware() gin.HandlerFunc {
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return func(c *gin.Context) {
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if origin := c.Request.Header.Get("Origin"); origin != "" {
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if !isAllowedCORSOrigin(origin, c.Request.Host) {
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if c.Request.Method == http.MethodOptions {
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c.AbortWithStatus(http.StatusForbidden)
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return
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}
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c.Next()
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return
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}
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c.Header("Access-Control-Allow-Origin", origin)
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c.Header("Vary", "Origin")
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c.Header("Access-Control-Allow-Credentials", "true")
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} else {
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c.Header("Access-Control-Allow-Origin", "*")
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}
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c.Header("Access-Control-Allow-Methods", "GET, POST, PATCH, PUT, DELETE, OPTIONS")
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c.Header("Access-Control-Allow-Headers", "Origin, Content-Type, Authorization, Upgrade, Connection, Sec-WebSocket-Key, Sec-WebSocket-Version, Sec-WebSocket-Protocol")
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if c.Request.Method == "OPTIONS" {
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c.AbortWithStatus(http.StatusNoContent)
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return
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}
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c.Next()
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}
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}
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func isAllowedCORSOrigin(origin string, requestHost string) bool {
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parsed, err := url.Parse(origin)
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if err != nil || parsed.Scheme == "" || parsed.Host == "" {
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return false
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}
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if parsed.Scheme != "http" && parsed.Scheme != "https" {
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return false
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}
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originHost := normalizeCORSHost(parsed.Hostname())
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host := normalizeCORSHost(requestHost)
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if originHost == "" || host == "" {
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return false
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}
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return originHost == host || (isLoopbackCORSHost(originHost) && isLoopbackCORSHost(host))
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}
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func normalizeCORSHost(host string) string {
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if parsedHost, _, err := net.SplitHostPort(host); err == nil {
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host = parsedHost
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}
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return strings.ToLower(strings.Trim(host, "[]"))
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}
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func isLoopbackCORSHost(host string) bool {
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if host == "localhost" {
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return true
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}
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ip := net.ParseIP(host)
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return ip != nil && ip.IsLoopback()
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}
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