An implementation of the JA4H hash algorithm in Go.
Note that this is not a perfect implementation of the algorithm.
The JA4H_b section will not be correct because the fingerprint should be the truncated SHA256 hash of the request headers in the order they appear.
Since Go stores the headers in a map, it does not keep the ordering as they appeared in the request.
This implementation of the JA4H_b section sorts the headers before hashing to make the fingerprint consistent.
Below is an example of using the library as a middleware. It calculates the JA4H fingerprint and adds it as a new header.
package main
import (
"fmt"
"net/http"
ja4h "github.com/lum8rjack/go-ja4h"
)
func indexPageHandler(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Index page with a new JA4H header: %s\n", r.Header.Get("JA4H"))
}
func ja4hMiddleware(nextHandler http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
r.Header.Add("JA4H", ja4h.JA4H(r))
nextHandler.ServeHTTP(w, r)
})
}
func main() {
mux := http.NewServeMux()
mux.Handle("/", ja4hMiddleware(http.HandlerFunc(indexPageHandler)))
http.ListenAndServe(":8080", mux)
}After starting the server, you can perform different requests to view the fingerprint.
$ curl http://127.0.0.1:8080
Index page with a new JA4H header: ge11nn020000_a00508f53a24_000000000000_000000000000
$ curl http://127.0.0.1:8080 -H "Accept-Language: en-us"
Index page with a new JA4H header: ge11nn03enus_7cf2b917f4b0_000000000000_000000000000
$ curl http://127.0.0.1:8080 -H "Accept-Language: en-us" -H "Cookie: admin=true" -X POST
Index page with a new JA4H header: po11cn03enus_55e041b6e2b4_8c6976e5b541_8c6976e5b541