Merge pull request 'SFTP: stop waiting for ever on a host whose login prints text, and draw the file panes' icons whole' (#25) from claude/sftp-connection-icons-5ad752 into main

Reviewed-on: #25

tests/DodoSSH.Client.Ssh.Tests/SftpSessionTests.cs

@@ -211,6 +211,31 @@ public sealed class SftpSessionTests(SshServerFixture fixture)
         refusal.Presentation.Fingerprint.ShouldStartWith("SHA256:");
     }
 
+    [Fact]
+    public async Task AHostWhoseLoginPrintsText_FailsWithinTheConnectTimeout_AndSaysWhy()
+    {
+        var knownHosts = new InMemoryKnownHostStore();
+        var factory = new SshNetConnectionFactory(knownHosts);
+
+        var request = Request() with { Port = fixture.ChattyPort, ConnectTimeout = TimeSpan.FromSeconds(3) };
+
+        var unknown = await Should.ThrowAsync<SshHostKeyUnknownException>(async () =>
+            await factory.OpenSftpAsync(request, Token));
+        await knownHosts.TrustAsync(unknown.Presentation, Token);
+
+        // The banner's first four bytes read as the length of a packet about a gigabyte long, and SSH.NET's
+        // own default is to wait for the rest of it for ever — which the file browser drew as "Connecting…"
+        // with no end. The outer bound is only there so that regression fails this test rather than hangs it,
+        // and it is a cancellation rather than a timeout so that it cannot be mistaken for the answer.
+        using var bound = CancellationTokenSource.CreateLinkedTokenSource(Token);
+        bound.CancelAfter(TimeSpan.FromSeconds(30));
+
+        var failure = await Should.ThrowAsync<TimeoutException>(async () =>
+            await factory.OpenSftpAsync(request, Token).WaitAsync(bound.Token));
+
+        failure.Message.ShouldContain("SFTP service did not answer within 3 seconds");
+    }
+
     private SshConnectionRequest Request() => new(
         fixture.Host,
         fixture.Port,

tests/DodoSSH.Client.Ssh.Tests/SshServerFixture.cs

@@ -42,6 +42,17 @@ public sealed class SshServerFixture : IAsyncLifetime
 
     private const int SshPort = 2222;
 
+    /// <summary>
+    /// A second port on the same sshd, where every session starts with a line of text before SFTP.
+    /// </summary>
+    /// <remarks>
+    /// What a host with an <c>echo</c> in its login script looks like to a file-transfer client: the text
+    /// arrives where the server's first SFTP packet should be. A port rather than an account because this
+    /// image's sshd runs unprivileged and cannot log in as anybody but <see cref="Username"/>, and a port
+    /// rather than a change to the main one so the shell and SFTP suites keep a server that behaves.
+    /// </remarks>
+    private const int ChattySshPort = 2223;
+
     /// <summary>
     /// How many connections in a row the server has to answer before this fixture calls it ready.
     /// </summary>
@@ -65,6 +76,9 @@ public sealed class SshServerFixture : IAsyncLifetime
     /// <summary>Host port the container's sshd is published on.</summary>
     public ushort Port => container!.GetMappedPublicPort(SshPort);
 
+    /// <summary>Host port of the same sshd whose sessions print a banner first; see <see cref="ChattySshPort"/>.</summary>
+    public ushort ChattyPort => container!.GetMappedPublicPort(ChattySshPort);
+
     /// <summary>Host the container is reachable at.</summary>
     public string Host => container!.Hostname;
 
@@ -83,6 +97,7 @@ public sealed class SshServerFixture : IAsyncLifetime
             .WithEnvironment("SUDO_ACCESS", "false")
             .WithEnvironment("PUBLIC_KEY", ExportOpenSshPublicKey(ClientKey))
             .WithPortBinding(SshPort, assignRandomHostPort: true)
+            .WithPortBinding(ChattySshPort, assignRandomHostPort: true)
 
             // The entrypoint generates host keys, rewrites sshd_config and installs the authorized
             // key before sshd is usable, so a published port is not readiness. Both conditions are
@@ -176,6 +191,10 @@ public sealed class SshServerFixture : IAsyncLifetime
     /// been touched — the same trap as the wrong file, one layer up. Measured from the log, after a version
     /// of this fixture did exactly that and failed twenty-eight tests.
     /// </para>
+    /// <para>
+    /// The <see cref="ChattySshPort"/> block goes last because a <c>Match</c> runs to the end of the file:
+    /// anything appended after it would apply only to that port.
+    /// </para>
     /// </remarks>
     private async Task ReconfigureAsync()
     {
@@ -185,6 +204,10 @@ public sealed class SshServerFixture : IAsyncLifetime
             "sed -i 's/^AllowTcpForwarding no/AllowTcpForwarding yes/' /config/sshd/sshd_config"
                 + " && sed -i 's/^#*MaxStartups .*/MaxStartups 200/' /config/sshd/sshd_config"
                 + " && printf '\\nPerSourcePenalties no\\n' >> /config/sshd/sshd_config"
+                + $" && sed -i 's/^Port {SshPort}$/Port {SshPort}\\nPort {ChattySshPort}/' /config/sshd/sshd_config"
+                + $" && printf '\\nMatch LocalPort {ChattySshPort}\\n"
+                + "    ForceCommand /bin/sh -c \"echo Welcome to the test server; exec /usr/lib/ssh/sftp-server\"\\n'"
+                + " >> /config/sshd/sshd_config"
                 + " && pkill -HUP sshd",
         ]);