web: one line per node pair and RTT/loss on the link board

A pair of nodes now has a single line, dialed by the non-listening side or by the smaller id when both listen, so RTT is measured once. The board draws it undirected and colours it by RTT and loss; a manual setting applies to the pair.

backend/src/MoShiro.Backend.Api/Admin/LinkEndpoints.cs

@@ -9,7 +9,7 @@ using MoShiro.Protocol;
 namespace MoShiro.Backend.Api;
 
 /// <summary>
-/// 线路开关：哪些（拨号方，监听方）要连。自动连接的总开关是设置 <c>fleet.auto_link</c>（不监听的节点自动拨所有监听节点）；
+/// 线路开关：哪些（拨号方，监听方）要连，一对节点一条线路。自动连接的总开关是设置 <c>fleet.auto_link</c>（不监听的节点拨监听节点；两个都监听时 id 较小的一方拨）；
 /// 这里看每一对的结果，并且手动强制开、关或取消手动设置。把一个节点拖到另一个监听节点上建立线路，就是 <c>PUT</c> 一个 <c>enabled: true</c>。
 /// </summary>
 public static class LinkEndpoints
@@ -34,11 +34,21 @@ public static class LinkEndpoints
         LinkSnapshot snapshot = await links.SnapshotAsync(ct);
         AgentView[] nodes = [.. (await agents.ListAsync(ct)).Where(n => n.Agent.Status == NodeStatus.Active).OrderBy(n => n.Agent.Name, StringComparer.Ordinal)];
         var items = new List<LinkDto>();
-        foreach (AgentView dialer in nodes)
+        for (int i = 0; i < nodes.Length; i++)
         {
-            foreach (AgentView listener in nodes.Where(n => n.Agent.Listens && n.Agent.Id != dialer.Agent.Id))
+            for (int j = i + 1; j < nodes.Length; j++)
             {
-                items.Add(ToDto(snapshot, dialer, listener, runtime, time));
+                // 一对节点一条线路：连着的那个方向，没连就是默认方向；两个都不监听的一对没有线路
+                (AgentView Dialer, AgentView Listener)? pair =
+                    snapshot.IsLinked(nodes[i].Agent, nodes[j].Agent) ? (nodes[i], nodes[j])
+                    : snapshot.IsLinked(nodes[j].Agent, nodes[i].Agent) ? (nodes[j], nodes[i])
+                    : LinkSnapshot.IsDefaultDialer(nodes[i].Agent, nodes[j].Agent) ? (nodes[i], nodes[j])
+                    : LinkSnapshot.IsDefaultDialer(nodes[j].Agent, nodes[i].Agent) ? (nodes[j], nodes[i])
+                    : null;
+                if (pair is { } p)
+                {
+                    items.Add(ToDto(snapshot, p.Dialer, p.Listener, runtime, time));
+                }
             }
         }
 
@@ -148,7 +158,7 @@ public static class LinkEndpoints
 
         bool inBackoff = health?.Control.State == ControlState.Backoff;
         return new LinkDto(dialer.Agent.Id.Value, dialer.Agent.Name, listener.Agent.Id.Value, listener.Agent.Name, linked,
-            snapshot.OverrideOf(dialer.Agent.Id.Value, listener.Agent.Id.Value), state == "connected", dialer.RuntimeStatus, listener.RuntimeStatus,
+            snapshot.PairOverride(dialer.Agent.Id.Value, listener.Agent.Id.Value), state == "connected", dialer.RuntimeStatus, listener.RuntimeStatus,
             state, reason, (inBackoff ? health!.Control.LastError : health?.Task.Quic.LastError)?.ToString(),
             health is null ? 0 : inBackoff ? health.Control.RetryAttempt : health.Task.Quic.RetryAttempt,
             health is null ? null : inBackoff ? health.Control.RetryInMs : health.Task.Quic.RetryInMs);