urls to check must be prefixed with http(s)

main.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"html/template"
 	"net/http"
+	"strings"
 
 	"codeberg.org/meadowingc/fido/linkchecker"
 )
@@ -31,6 +32,12 @@ func main() {
 			return
 		}
 
+		// Check if the submitted link starts with http:// or https://
+		if !strings.HasPrefix(submittedLink, "http://") && !strings.HasPrefix(submittedLink, "https://") {
+			http.Error(w, "Invalid link. Link must start with http:// or https://", http.StatusBadRequest)
+			return
+		}
+
 		resultUUID := linkchecker.SubmitLinkForCheck(submittedLink)
 
 		// redirect to results page