Attach Response Headers (or middlewares) to redirected requests (CORS issues)

[yashvardhan-kukreja]

Description

When the gin engine's tree is not aware of a path /foo/ , instead of returning a 404, it responds plainly with a 307 Location: /foo (or 301 in case of GET) i.e. telling the client to redirect to /foo

There's no way to tell Gin what to do with such requests through the means any middlewares, like attaching CORS middlewares (a pretty commonly encountered case).

Some solutions I can think of:

• Have a way to define what happens on redirect like we currently do with engine.NoRoute(..,) to explicitly define what happens at NotFound.

	server := gin.New()
	server.OnRedirect(cors.Default())

• Apply the middlewares registered at the routerGroup "/" to all the incoming requests, including redirect request.

	server := gin.New()
	server.Use(cors.Default()) // registered at the "/" routergroup, therefore, redirect requests go through it as well

How to reproduce

package main

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

func main() {
	g := gin.Default()
        g.Use(cors.Default())
	g.GET("/foo", func(c *gin.Context) {
		c.String(200, "Hello, World!"))
	})
	g.Run(":9000")
}

Expectations

Open a new tab in the browser and open dev tools there.
Go to the "Console", and run the following code

let response = await fetch('http://localhost:9000/foo/', {
  method: 'GET'
})

Expectation

response.text() should be "Hello World!"

Actual result

Access to fetch at 'http://localhost:9000/foo/' from origin 'chrome-extension://pejkokffkapolfffcgbmdmhdelanoaih' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

Environment

• go version: 1.22.0
• gin version (or commit ref): 1.9.1
• operating system: MacOS (Darwin ARM64)

[yashvardhan-kukreja]

Raised the above PR #3858 as a resolution if the above issue is deemed worthy of having a solution.