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/Api/Mastodon/Controllers/CdnsController.cs

@@ -0,0 +1,82 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+
+using PrivaPub.Api.Mastodon.Infrastructure;
+using PrivaPub.Domain.Statistics;
+
+namespace PrivaPub.Api.Mastodon.Controllers
+{
+	// The CDNs in front of the servers this server knows, each named by its own domain (owner decision 2026-10-04): how many
+	// servers are behind it, how it is recognised, and week by week who joined and who left.
+	public class CdnsController : MastodonController
+	{
+		const int MaxWeeks = 260;
+
+		readonly IServerPlaces _places;
+
+		public CdnsController(IServerPlaces places) => _places = places;
+
+		[HttpGet("/api/privapub/v1/cdns"), Scope("read", requiresUser: false), AllowAnonymous]
+		public async Task<IActionResult> List(CancellationToken token) => Json((await _places.Cdns(token)).Select(Summary).ToList());
+
+		[HttpGet("/api/privapub/v1/cdns/{key}"), Scope("read", requiresUser: false), AllowAnonymous]
+		public async Task<IActionResult> Detail(string key, CancellationToken token)
+		{
+			var history = await _places.Cdn(key, Math.Clamp(Params.Int("weeks") ?? 52, 1, MaxWeeks), token);
+			if (history == default)
+				return NotFoundError();
+			var detail = new CdnDetail
+			{
+				Hosts = history.Hosts,
+				HostsTruncated = history.Group.Servers > history.Hosts.Count,
+				Weeks = history.Weeks.Select(w => new CdnWeekEntry { Week = w.Week, Servers = w.Servers, Joined = w.Joined, Left = w.Left }).ToList()
+			};
+			Fill(detail, history.Group);
+			return Json(detail);
+		}
+
+		static CdnSummary Summary(CdnGroup group)
+		{
+			var summary = new CdnSummary();
+			Fill(summary, group);
+			return summary;
+		}
+
+		static void Fill(CdnSummary summary, CdnGroup group)
+		{
+			summary.Key = group.Key;
+			summary.Name = group.Name;
+			summary.Domain = group.Domain;
+			summary.Servers = group.Servers;
+			summary.Ranges = group.Ranges;
+			summary.RangesUpdatedAt = group.RangesUpdatedAt is { } at ? MastodonJson.Time(at) : default;
+			summary.DetectedBy = group.DetectedBy;
+		}
+
+		public class CdnSummary
+		{
+			public string Key { get; set; }
+			public string Name { get; set; }
+			public string Domain { get; set; }
+			public int Servers { get; set; }
+			public int Ranges { get; set; }
+			public string RangesUpdatedAt { get; set; }
+			public List<string> DetectedBy { get; set; } = new();
+		}
+
+		public class CdnDetail : CdnSummary
+		{
+			public List<string> Hosts { get; set; } = new();
+			public bool HostsTruncated { get; set; }
+			public List<CdnWeekEntry> Weeks { get; set; } = new();
+		}
+
+		public class CdnWeekEntry
+		{
+			public string Week { get; set; }
+			public int Servers { get; set; }
+			public List<string> Joined { get; set; } = new();
+			public List<string> Left { get; set; } = new();
+		}
+	}
+}