--api-allow special case 0/0 means all

api.c

@@ -1234,7 +1234,10 @@ static void tidyup()
 
 /*
  * Interpret IP[/Prefix][,IP2[/Prefix2][,...]] --api-allow option
- *
+ *	special case of 0/0 allows /0 (means all IP addresses)
+ */
+#define ALLIP4 "0/0"
+/*
  * N.B. IP4 addresses are by Definition 32bit big endian on all platforms
  */
 static void setup_ipaccess()
@@ -1274,6 +1277,9 @@ static void setup_ipaccess()
 		if (comma)
 			*(comma++) = '\0';
 
+		if (strcmp(ptr, ALLIP4) == 0)
+			ipaccess[ips].ip = ipaccess[ips].mask = 0;
+		else {
 			slash = strchr(ptr, '/');
 			if (!slash)
 				ipaccess[ips].mask = 0xffffffff;
@@ -1306,6 +1312,7 @@ static void setup_ipaccess()
 			}
 
 			ipaccess[ips].ip &= ipaccess[ips].mask;
+		}
 
 		ips++;
 popipo: