CDNs found by themselves, and servers followed through time

PrivaPub now finds CDNs three ways, best first: the address ranges the
CDNs publish (Cloudflare, Fastly, Amazon CloudFront, Bunny, Gcore,
Imperva), downloaded daily by CdnUpdater and kept in CdnRangeSet; the
CDN's fingerprint in the responses it already gets from a server
(EdgeHintsHandler on the federation client); and the networks that carry
only a CDN. The fixed ASN list is gone; ASNs shared with plain hosting
(AWS, DataPacket) no longer hide a server. A server's Geo records the
CDN, its domain and how it was found, and weekly snapshots now keep the
city and coordinates too.

Servers through time (ServerPlaces): /instances/:host/history lists a
server's weekly snapshots, a CDN-fronted server's geo names the CDN's
domain and where the server was before it (before_cdn), and
/api/privapub/v1/cdns and /cdns/:domain group servers by CDN with week
by week who joined and who left. Owner decisions recorded in ROADMAP.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

PrivaPub/Infrastructure/Geo/CdnRanges.cs

@@ -0,0 +1,65 @@
+using MongoDB.Entities;
+
+using PrivaPub.Models.Jobs;
+
+using System.Net;
+
+namespace PrivaPub.Infrastructure.Geo
+{
+	public interface ICdnRanges
+	{
+		// the CDN whose published ranges hold the address, or default
+		CdnProvider Of(IPAddress address);
+		void Replace(CdnRangeSet set);
+		Task Load(CancellationToken token);
+		// per CDN key: how many ranges are known and when they were downloaded
+		IReadOnlyDictionary<string, (int Ranges, DateTime FetchedAt)> Status { get; }
+	}
+
+	// The published CDN ranges in memory, rebuilt from the stored CdnRangeSets at start and replaced set by set as
+	// CdnUpdater downloads them. A few thousand networks: a linear scan per describe is cheap, and describes are weekly.
+	public class CdnRanges : ICdnRanges
+	{
+		readonly object _gate = new();
+		Dictionary<string, (CdnProvider Provider, IPNetwork[] Networks, DateTime FetchedAt)> _sets = new(StringComparer.OrdinalIgnoreCase);
+
+		public IReadOnlyDictionary<string, (int Ranges, DateTime FetchedAt)> Status
+		{
+			get
+			{
+				lock (_gate)
+					return _sets.ToDictionary(s => s.Key, s => (s.Value.Networks.Length, s.Value.FetchedAt), StringComparer.OrdinalIgnoreCase);
+			}
+		}
+
+		public CdnProvider Of(IPAddress address)
+		{
+			if (address == default)
+				return default;
+			if (address.IsIPv4MappedToIPv6)
+				address = address.MapToIPv4();
+			Dictionary<string, (CdnProvider Provider, IPNetwork[] Networks, DateTime FetchedAt)> sets;
+			lock (_gate)
+				sets = _sets;
+			foreach (var (provider, networks, _) in sets.Values)
+				foreach (var network in networks)
+					if (network.BaseAddress.AddressFamily == address.AddressFamily && network.Contains(address))
+						return provider;
+			return default;
+		}
+
+		public void Replace(CdnRangeSet set)
+		{
+			var provider = CdnCatalog.ByKey(set.Key) ?? new CdnProvider(set.Name, set.Key, Array.Empty<int>(), Array.Empty<CdnList>(), _ => false);
+			var networks = set.Ranges.Select(r => IPNetwork.TryParse(r, out var n) ? n : (IPNetwork?)null).Where(n => n != default).Select(n => n!.Value).ToArray();
+			lock (_gate)
+				_sets = new(_sets, StringComparer.OrdinalIgnoreCase) { [set.Key] = (provider, networks, set.FetchedAt) };
+		}
+
+		public async Task Load(CancellationToken token)
+		{
+			foreach (var set in await DB.Default.Find<CdnRangeSet>().ExecuteAsync(token))
+				Replace(set);
+		}
+	}
+}