mongoose/docs/c-api/mg_net.h/mg_check_ip_acl.md

title	decl_name	symbol_kind	signature
mg_check_ip_acl()	mg_check_ip_acl	func	int mg_check_ip_acl(const char *acl, uint32_t remote_ip);

Verify given IP address against the ACL.

remote_ip - an IPv4 address to check, in host byte order acl - a comma separated list of IP subnets: x.x.x.x/x or x.x.x.x. Each subnet is prepended by either a - or a + sign. A plus sign means allow, where a minus sign means deny. If a subnet mask is omitted, such as -1.2.3.4, it means that only that single IP address is denied. Subnet masks may vary from 0 to 32, inclusive. The default setting is to allow all access. On each request the full list is traversed, and the last match wins. Example:

-0.0.0.0/0,+192.168/16 - deny all accesses, only allow 192.168/16 subnet

To learn more about subnet masks, see this link:https://en.wikipedia.org/wiki/Subnetwork[Wikipedia page on Subnetwork].

Returns -1 if ACL is malformed, 0 if address is disallowed, 1 if allowed.