Go gin framework CORS

Question

I'm using Go gin framework gin

func CORSMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        c.Writer.Header().Set("Content-Type", "application/json")
        c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
        c.Writer.Header().Set("Access-Control-Max-Age", "86400")
        c.Writer.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, UPDATE")
        c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, X-Max")
        c.Writer.Header().Set("Access-Control-Allow-Credentials", "true")

        if c.Request.Method == "OPTIONS" {
            c.AbortWithStatus(200)
        } else {
            c.Next()
        }
    }
}

I've got Status Code:200 OK, but nothing happens after OPTIONS request. It looks like I miss something, but I can't understand where am I wrong.

Can anybody help me?

Answer 1

FWIW, this is my CORS Middleware that works for my needs.

func CORSMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
        c.Writer.Header().Set("Access-Control-Allow-Credentials", "true")
        c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, accept, origin, Cache-Control, X-Requested-With")
        c.Writer.Header().Set("Access-Control-Allow-Methods", "POST, OPTIONS, GET, PUT")

        if c.Request.Method == "OPTIONS" {
            c.AbortWithStatus(204)
            return
        }

        c.Next()
    }
}

Answer 2

There is also official gin's middleware for handling CORS requests github.com/gin-contrib/cors.

You could install it using $ go get github.com/gin-contrib/cors and then add this middleware in your application like this: package main

import (
    "time"

    "github.com/gin-contrib/cors"
    "github.com/gin-gonic/gin"
)

func main() {
    router := gin.Default()
    // CORS for https://foo.com and https://github.com origins, allowing:
    // - PUT and PATCH methods
    // - Origin header
    // - Credentials share
    // - Preflight requests cached for 12 hours
    router.Use(cors.New(cors.Config{
        AllowOrigins:     []string{"https://foo.com"},
        AllowMethods:     []string{"PUT", "PATCH"},
        AllowHeaders:     []string{"Origin"},
        ExposeHeaders:    []string{"Content-Length"},
        AllowCredentials: true,
        AllowOriginFunc: func(origin string) bool {
            return origin == "https://github.com"
        },
        MaxAge: 12 * time.Hour,
    }))
    router.Run()
}

Answer 3

func CORSMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {

        c.Header("Access-Control-Allow-Origin", "*")
        c.Header("Access-Control-Allow-Credentials", "true")
        c.Header("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, accept, origin, Cache-Control, X-Requested-With")
        c.Header("Access-Control-Allow-Methods", "POST,HEAD,PATCH, OPTIONS, GET, PUT")

        if c.Request.Method == "OPTIONS" {
            c.AbortWithStatus(204)
            return
        }

        c.Next()
    }
}

then use it

router = gin.New()  
router.Use(CORSMiddleware())