hare

commit ae8018ba6e6544d0b47696a00dfc594ae6c65d6f
parent 4e8aab89270a5bbfa3c3d4e300dee5c798efb2fe
Author: Miccah Castorina <contact@miccah.io>
Date:   Sun, 12 Dec 2021 21:10:37 -0600

net::ip: implement subnet_contains

Signed-off-by: Miccah Castorina <contact@miccah.io>

Diffstat:
M
net/ip/+test.ha
 | 
30
++++++++++++++++++++++++++++++
M
net/ip/ip.ha
 | 
41
+++++++++++++++++++++++++++++++++++++++++

2 files changed, 71 insertions(+), 0 deletions(-)
diff --git a/net/ip/+test.ha b/net/ip/+test.ha
@@ -84,3 +84,33 @@ fn subnet_test_simple(s: str) void = {
 		subnet_test_simple(subnet_tests[i]);
 	};
 };
+
+@test fn test_subnet_contains() void = {
+	let addr_tests: [](str, str, bool) = [
+		// a, b, want
+		("10.10.10.0/24", "10.10.10.0",   true),
+		("10.10.10.0/24", "10.10.10.255", true),
+		("10.10.10.0/24", "10.10.11.0",   false),
+		("127.0.0.1/24",  "::1",          false),
+		("::1/8",         "::1",          true),
+	];
+	let cidr_tests: [](str, str, bool) = [
+		// a, b, want
+		("10.10.10.0/24", "10.10.10.0/24", true),
+		("10.10.10.0/24", "10.10.10.0/25", true),
+		("10.10.10.0/24", "10.10.10.0/23", false),
+		("10.10.10.0/24", "10.10.11.0/24", false),
+	];
+	for (let i = 0z; i < len(addr_tests); i += 1) {
+		const input = addr_tests[i];
+		let a = parsecidr(input.0)!;
+		let b = parse(input.1)!;
+		assert(subnet_contains(a, b) == input.2);
+	};
+	for (let i = 0z; i < len(cidr_tests); i += 1) {
+		const input = cidr_tests[i];
+		let a = parsecidr(input.0)!;
+		let b = parsecidr(input.1)!;
+		assert(subnet_contains(a, b) == input.2);
+	};
+};
diff --git a/net/ip/ip.ha b/net/ip/ip.ha
@@ -350,3 +350,44 @@ fn wanttoken(tok: *strings::tokenizer) (str | invalid) = {
 		return invalid;
 	};
 };
+
+// Returns whether an [[addr]] (or another [[subnet]]) is contained
+// within a [[subnet]].
+export fn subnet_contains(sub: subnet, item: (addr | subnet)) bool = {
+	let addr: subnet = match (item) {
+	case let addr: addr =>
+		yield subnet{
+			addr = addr,
+			mask = sub.mask,
+		};
+	case let sub: subnet =>
+		yield sub;
+	};
+	// Get byte slices for both addresses and masks.
+	let ipa = match (sub.addr) {
+		case let v4: addr4 => yield v4[..];
+		case let v6: addr6 => yield v6[..];
+	};
+	let maska = match (sub.mask) {
+		case let v4: addr4 => yield v4[..];
+		case let v6: addr6 => yield v6[..];
+	};
+	let ipb = match (addr.addr) {
+		case let v4: addr4 => yield v4[..];
+		case let v6: addr6 => yield v6[..];
+	};
+	let maskb = match (addr.mask) {
+		case let v4: addr4 => yield v4[..];
+		case let v6: addr6 => yield v6[..];
+	};
+	if (len(ipa) != len(ipb) || len(maska) != len(maskb) || len(ipa) != len(maska)) {
+		// Mismatched addr4 and addr6 addresses / masks.
+		return false;
+	};
+	for (let i = 0z; i < len(ipa); i += 1) {
+		if (ipa[i] & maska[i] != ipb[i] & maska[i] || maska[i] > maskb[i]) {
+			return false;
+		};
+	};
+	return true;
+};