fix __ipparse to parse the generic numbers-and-dots IPv4 format correctly

* allow at most 4 parts
* bounds check the parts correctly
* disallow leading whitespace and sign
* check the address family before falling back to IPv6

src/network/__ipparse.c

 #include <string.h>
 #include <stdlib.h>
+#include <ctype.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include "__dns.h"
-#include <stdio.h>
 
 int __ipparse(void *dest, int family, const char *s0)
 {
 	const char *s = s0;
 	unsigned char *d = dest;
 	unsigned long a[16] = { 0 };
-	const char *z;
+	char *z;
 	int i;
 
 	if (family == AF_INET6) goto not_v4;
 
 	for (i=0; i<4; i++) {
-		a[i] = strtoul(s, (char **)&z, 0);
-		if (z==s || (*z && *z != '.')) goto not_v4;
+		a[i] = strtoul(s, &z, 0);
+		if (z==s || (*z && *z != '.') || !isdigit(*s)) {
+			if (family == AF_INET) return -1;
+			goto not_v4;
+		}
 		if (!*z) break;
 		s=z+1;
 	}
+	if (i==4) return -1;
 	switch (i) {
 	case 0:
 		a[1] = a[0] & 0xffffff;
@@ -35,7 +39,10 @@ int __ipparse(void *dest, int family, const char *s0)
 	}
 	((struct sockaddr_in *)d)->sin_family = AF_INET;
 	d = (void *)&((struct sockaddr_in *)d)->sin_addr;
-	for (i=0; i<4; i++) d[i] = a[i];
+	for (i=0; i<4; i++) {
+		if (a[i] > 255) return -1;
+		d[i] = a[i];
+	}
 	return 0;
 
 not_v4: