Some HTTP Issues with Go
1. r.URL.Path vs r.URL.RawPath#
func main() {
u, err := url.Parse("http://example.com/x/xx%20a")
if err != nil {
log.Fatal(err)
}
fmt.Println("Path:", u.Path)
fmt.Println("RawPath:", u.RawPath)
fmt.Println("EscapedPath:", u.EscapedPath())
}
Path: /x/xx a
RawPath:
EscapedPath: /x/xx%20a
If url changes to “http://example.com/x/xx%2Fa", then will print:
Path: /x/xx/a
RawPath: /x/xx%2Fa
EscapedPath: /x/xx%2Fa
In general, code should call EscapedPath() instead of reading u.RawPath directly.
Learn more:
https://pkg.go.dev/net/url#URL.EscapedPath
URL Encoding (Percent Encoding) - David’s Blog
2. Relative path#
You can write relative path directly for the endpoint, because the browser know the Origin, when you make HTTP request, it knows where should go.
<form method="post" action="/login">
...
</form>
And it’s ok to write relative path when redirect in Go code:
// Redirect to login page.
http.Redirect(w, r, "/login", http.StatusFound)
3. Redirection#
3.1. Redirect at front end#
For redirection, you can use js code to redirect based on the status code passed from server:
const response = await fetch("/login", {
method: "POST",
body: data,
})
if (!response.ok) {
...
return
}
// If login successfully, redirect to /home
window.location = "/home"
3.2. Redirect at server with Location header#
Learn more: HTTP Headers - David’s Blog
3.3. Redirect at server with http.Redirect() method#
See above Relative path section.
4. Check the type of the request#
When You are starting a HTTP/s server You use either ListenAndServe or ListenAndServeTLS or both together on different ports. If You are using just one of them, then from Listen.. it’s obvious which scheme request is using and You don’t need a way to check and set it. But if You are serving on both HTTP and HTTP/s then You can use request.TLS state. if its nil it means it’s HTTP.
// TLS allows HTTP servers and other software to record
// information about the TLS connection on which the request
// was received. This field is not filled in by ReadRequest.
// The HTTP server in this package sets the field for
// TLS-enabled connections before invoking a handler;
// otherwise it leaves the field nil.
// This field is ignored by the HTTP client.
TLS *tls.ConnectionState
an example:
func index(w http.ResponseWriter, r *http.Request) {
scheme := "http"
if r.TLS != nil {
scheme = "https"
}
w.Write([]byte(fmt.Sprintf("%v://%v%v", scheme, r.Host, r.RequestURI)))
}