[master] Add a better warning about multiple key definitions

RELNOTES

@@ -69,6 +69,11 @@ by Eric Young (eay@cryptsoft.com).
 - Remove an extra set of the msg_controllen variable.
   [ISC-Bugs #21035]
 
+- Add a more understandable error message if a configuration attempts
+  to add multiple keys for a single zone.  Thanks to a patch from Jiri
+  Popelka at Red Hat.
+  [ISC-Bugs #31892]
+
 			Changes since 4.3.0rc1
 
 - None

common/parse.c

@@ -2872,27 +2872,31 @@ int parse_zone (struct dns_zone *zone, struct parse *cfile)
 		    break;
 
 		  case KEY:
-		    skip_token(&val, (unsigned *)0, cfile);
+		    skip_token(&val, NULL, cfile);
-		    token = peek_token (&val, (unsigned *)0, cfile);
+		    token = peek_token(&val, NULL, cfile);
 		    if (token == STRING) {
-			    skip_token(&val, (unsigned *)0, cfile);
+			    skip_token(&val, NULL, cfile);
-			    key_name = (char *)0;
+			    key_name = NULL;
 		    } else {
 			    key_name = parse_host_name(cfile);
 			    if (!key_name) {
 				    parse_warn(cfile, "expecting key name.");
 				    skip_to_semi(cfile);
-				    return 0;
+				    return (0);
 			    }
 			    val = key_name;
 		    }
+		    if (zone->key) {
+			    log_fatal("Multiple key definitions for zone %s.",
+				      zone->name);
+		    }
 		    if (omapi_auth_key_lookup_name(&zone->key, val) !=
 			ISC_R_SUCCESS)
 			    parse_warn(cfile, "unknown key %s", val);
 		    if (key_name)
 			    dfree(key_name, MDL);
 		    if (!parse_semi(cfile))
-			    return 0;
+			    return (0);
 		    break;
 		    
 		  default:
@@ -2901,12 +2905,12 @@ int parse_zone (struct dns_zone *zone, struct parse *cfile)
 	    }
 	} while (!done);
 
-	token = next_token (&val, (unsigned *)0, cfile);
+	token = next_token(&val, NULL, cfile);
 	if (token != RBRACE) {
 		parse_warn(cfile, "expecting right brace.");
-		return 0;
+		return (0);
 	}
-	return 1;
+	return (1);
 }
 
 /* key-statements :== key-statement |