package main
import (
"context"
"log"
"net"
"net/http"
"strings"
)
// Attaches a request's IP address to the request's context.
// If getwtxt is behind a reverse proxy, get the last entry
// in the X-Forwarded-For HTTP header as the user IP.
func newCtxUserIP(ctx context.Context, r *http.Request) context.Context {
base := strings.Split(r.RemoteAddr, ":")
uip := base[0]
if _, ok := r.Header["X-Forwarded-For"]; ok {
proxied := r.Header["X-Forwarded-For"]
base = strings.Split(proxied[len(proxied)-1], ":")
uip = base[0]
}
return context.WithValue(ctx, ctxKey, uip)
}
// Retrieves a request's IP address from the request's context
func getIPFromCtx(ctx context.Context) net.IP {
uip, ok := ctx.Value(ctxKey).(string)
if !ok {
log.Printf("Couldn't retrieve IP from request\n")
}
return net.ParseIP(uip)
}
// Shim function to modify/pass context value to a handler
func ipMiddleware(hop http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ctx := newCtxUserIP(r.Context(), r)
hop.ServeHTTP(w, r.WithContext(ctx))
})
}
// log output for 200s
func log200(r *http.Request) {
uip := getIPFromCtx(r.Context())
log.Printf("*** %v :: 200 :: %v %v\n", uip, r.Method, r.URL)
}
// log output for 400s
func log400(w http.ResponseWriter, r *http.Request, err string) {
uip := getIPFromCtx(r.Context())
log.Printf("*** %v :: 400 :: %v %v :: %v\n", uip, r.Method, r.URL, err)
http.Error(w, "400 Bad Request: "+err, http.StatusBadRequest)
}
// log output for 404s
func log404(w http.ResponseWriter, r *http.Request, err error) {
uip := getIPFromCtx(r.Context())
log.Printf("*** %v :: 404 :: %v %v :: %v\n", uip, r.Method, r.URL, err)
http.Error(w, err.Error(), http.StatusNotFound)
}
// log output for 500s
func log500(w http.ResponseWriter, r *http.Request, err error) {
uip := getIPFromCtx(r.Context())
log.Printf("*** %v :: 500 :: %v %v :: %v\n", uip, r.Method, r.URL, err)
http.Error(w, err.Error(), http.StatusInternalServerError)
}