1  package web
 2  
 3  import (
 4  	"encoding/json"
 5  	"fmt"
 6  	"log"
 7  	"net/http"
 8  	"strings"
 9  )
10  
11  func sendResponse(w http.ResponseWriter, payload any) {
12  	// note: w.Header after this, so we can call sendError
13  	b, err := json.Marshal(payload)
14  	if err != nil {
15  		sendErrorResponse(w, http.StatusInternalServerError, fmt.Sprintf("in json.Marshal: %s", err.Error()))
16  		return
17  	}
18  	w.Header().Set("Content-Type", "application/json")
19  	w.Header().Set("Cache-Control", "no-store") // do not cache (Browsers cache GET forever by default)
20  	w.Write(b)
21  }
22  
23  func sendErrorResponse(w http.ResponseWriter, code int, message string) {
24  	log.Printf("[!] %d: %s\n", code, message)
25  	// would prefer to use json.Marshal, but this avoids the need
26  	// to handle encoding errors arising from json.Marshal itself!
27  	payload := fmt.Sprintf("{\"error\":{\"code\":%q,\"message\":%q}}", code, message)
28  	w.Header().Set("Content-Type", "application/json")
29  	w.Header().Set("Cache-Control", "no-store") // do not cache (Browsers cache GET forever by default)
30  	w.WriteHeader(code)
31  	w.Write([]byte(payload))
32  }
33  
34  func getOriginIP(r *http.Request) string {
35  	var originIP string
36  
37  	// handle proxies
38  	if r.Header.Get("X-Forwarded-For") != "" {
39  		// If there are multiple IPs in X-Forwarded-For, take the first one
40  		originIP = strings.Split(r.Header.Get("X-Forwarded-For"), ",")[0]
41  	} else {
42  		// otherwise just use the remote address
43  		originIP = strings.Split(r.RemoteAddr, ":")[0]
44  	}
45  
46  	return originIP
47  }