feat: add default ips

src/cloudflare.rs

@@ -13,6 +13,39 @@ pub const CF_IPV6_URL: &str = "https://www.cloudflare.com/ips-v6";
 
 const USER_AGENT: &str = "cfopt/0.1";
 
+/// Cloudflare's published IPv4 ranges, baked in as a fallback for when the
+/// live fetch from CF_IPV4_URL is unreachable (offline, censored, etc.).
+/// Source: https://www.cloudflare.com/ips-v4
+const CF_IPV4_DEFAULTS: &str = "\
+173.245.48.0/20
+103.21.244.0/22
+103.22.200.0/22
+103.31.4.0/22
+141.101.64.0/18
+108.162.192.0/18
+190.93.240.0/20
+188.114.96.0/20
+197.234.240.0/22
+198.41.128.0/17
+162.158.0.0/15
+104.16.0.0/13
+104.24.0.0/14
+172.64.0.0/13
+131.0.72.0/22
+";
+
+/// Cloudflare's published IPv6 ranges, baked in as a fallback.
+/// Source: https://www.cloudflare.com/ips-v6
+const CF_IPV6_DEFAULTS: &str = "\
+2400:cb00::/32
+2606:4700::/32
+2803:f800::/32
+2405:b500::/32
+2405:8100::/32
+2a06:98c0::/29
+2c0f:f248::/32
+";
+
 /// Which address families to fetch.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 #[allow(dead_code)] // V4 / V6 reserved for a future --family CLI flag.
@@ -51,11 +84,23 @@ pub async fn fetch_ranges(family: Family) -> Result<CfRanges> {
 
     let mut ranges = CfRanges::default();
     if matches!(family, Family::V4 | Family::Both) {
-        let text = fetch_text(&client, CF_IPV4_URL).await?;
+        let text = match fetch_text(&client, CF_IPV4_URL).await {
+            Ok(text) => text,
+            Err(e) => {
+                eprintln!("warning: fetch {CF_IPV4_URL} failed ({e:#}); using built-in defaults");
+                CF_IPV4_DEFAULTS.to_string()
+            }
+        };
         ranges.v4 = parse_v4_lines(&text);
     }
     if matches!(family, Family::V6 | Family::Both) {
-        let text = fetch_text(&client, CF_IPV6_URL).await?;
+        let text = match fetch_text(&client, CF_IPV6_URL).await {
+            Ok(text) => text,
+            Err(e) => {
+                eprintln!("warning: fetch {CF_IPV6_URL} failed ({e:#}); using built-in defaults");
+                CF_IPV6_DEFAULTS.to_string()
+            }
+        };
         ranges.v6 = parse_v6_lines(&text);
     }
     Ok(ranges)
@@ -115,4 +160,10 @@ mod tests {
         assert_eq!(parse_v6_lines(text).len(), 1);
         assert_eq!(parse_v4_lines(text)[0].to_string(), "173.245.48.0/20");
     }
+
+    #[test]
+    fn builtin_defaults_parse() {
+        assert_eq!(parse_v4_lines(CF_IPV4_DEFAULTS).len(), 15);
+        assert_eq!(parse_v6_lines(CF_IPV6_DEFAULTS).len(), 7);
+    }
 }