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Wrap GetHostAddresses/Async calls to catch SocketException #5664

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Merged
NinoFloris merged 3 commits into from
Oct 29, 2025
Merged

Wrap GetHostAddresses/Async calls to catch SocketException #5664

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a82886c
ref: wrapped GetHostAddresses/Async calls to catch SocketException
pedrowindisch Apr 8, 2024
c2d1d5d
Make mostly some formatting changes
NinoFloris Oct 29, 2025
ffd29b0
Change test
NinoFloris Oct 29, 2025
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52 changes: 39 additions & 13 deletions src/Npgsql/Internal/NpgsqlConnector.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1232,10 +1232,24 @@ internal async Task NegotiateEncryption(SslMode sslMode, NpgsqlTimeout timeout,

void Connect(NpgsqlTimeout timeout)
{
// Note that there aren't any timeout-able or cancellable DNS methods
var endpoints = NpgsqlConnectionStringBuilder.IsUnixSocket(Host, Port, out var socketPath)
? new EndPoint[] { new UnixDomainSocketEndPoint(socketPath) }
: IPAddressesToEndpoints(Dns.GetHostAddresses(Host), Port);
EndPoint[]? endpoints;
if (NpgsqlConnectionStringBuilder.IsUnixSocket(Host, Port, out var socketPath))
{
endpoints = [new UnixDomainSocketEndPoint(socketPath!)];
}
else
{
// Note that there aren't any timeout-able or cancellable DNS methods
try
{
endpoints = IPAddressesToEndpoints(Dns.GetHostAddresses(Host), Port);
}
catch (SocketException ex)
{
throw new NpgsqlException(ex.Message, ex);
}
}

timeout.Check();

// Give each endpoint an equal share of the remaining time
Expand Down Expand Up @@ -1302,16 +1316,28 @@ void Connect(NpgsqlTimeout timeout)

async Task ConnectAsync(NpgsqlTimeout timeout, CancellationToken cancellationToken)
{
Task<IPAddress[]> GetHostAddressesAsync(CancellationToken ct) =>
Dns.GetHostAddressesAsync(Host, ct);

// Whether the framework and/or the OS platform support Dns.GetHostAddressesAsync cancellation API or they do not,
// we always fake-cancel the operation with the help of TaskTimeoutAndCancellation.ExecuteAsync. It stops waiting
// and raises the exception, while the actual task may be left running.
var endpoints = NpgsqlConnectionStringBuilder.IsUnixSocket(Host, Port, out var socketPath)
? new EndPoint[] { new UnixDomainSocketEndPoint(socketPath) }
: IPAddressesToEndpoints(await TaskTimeoutAndCancellation.ExecuteAsync(GetHostAddressesAsync, timeout, cancellationToken).ConfigureAwait(false),
Port);
EndPoint[] endpoints;
if (NpgsqlConnectionStringBuilder.IsUnixSocket(Host, Port, out var socketPath))
{
endpoints = [new UnixDomainSocketEndPoint(socketPath)];
}
else
{
IPAddress[] ipAddresses;
try
{
ipAddresses = await Dns.GetHostAddressesAsync(Host, cancellationToken)
.WaitAsync(timeout.CheckAndGetTimeLeft(), cancellationToken).ConfigureAwait(false);
Comment on lines +1332 to +1333

@vonzshik vonzshik Nov 5, 2025

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@NinoFloris I'm pretty sure before it was calling TaskTimeoutAndCancellation.ExecuteAsync instead of Dns.GetHostAddressesAsync directly

@NinoFloris NinoFloris Nov 5, 2025

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IMO this became obsolete after we removed the ifdefs for <= 6.0

See https://github.com/npgsql/npgsql/pull/4173/files#diff-b45ed9d534512c2b95cd6aafbdceff63d87439bf00b57a605d637cc64785e438R942-R955

@NinoFloris NinoFloris Nov 5, 2025

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Let me put up a PR to pull it out entirely and fix the timeout flowing into the token.

}
catch (SocketException ex)
{
throw new NpgsqlException(ex.Message, ex);
}
endpoints = IPAddressesToEndpoints(ipAddresses, Port);
}

// Give each endpoint an equal share of the remaining time
var perEndpointTimeout = default(TimeSpan);
Expand Down Expand Up @@ -1376,9 +1402,9 @@ Task ConnectAsync(CancellationToken ct) =>
}
}

IPEndPoint[] IPAddressesToEndpoints(IPAddress[] ipAddresses, int port)
EndPoint[] IPAddressesToEndpoints(IPAddress[] ipAddresses, int port)
{
var result = new IPEndPoint[ipAddresses.Length];
var result = new EndPoint[ipAddresses.Length];
for (var i = 0; i < ipAddresses.Length; i++)
result[i] = new IPEndPoint(ipAddresses[i], port);
return result;
Expand Down
33 changes: 33 additions & 0 deletions test/Npgsql.Tests/ConnectionTests.cs
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Expand Up @@ -6,6 +6,7 @@
using System.Linq;
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Security.Cryptography.X509Certificates;
using System.Text;
Expand Down Expand Up @@ -313,6 +314,38 @@ public void Connect_timeout_cancel()
Assert.That(conn.State, Is.EqualTo(ConnectionState.Closed));
}

[Test]
public void Bad_hostname()
{
using var dataSource = CreateDataSource(csb => csb.Host = "hostname.that.does.not.exist");
using var conn = dataSource.CreateConnection();

Assert.That(
() => conn.Open(),
Throws.Exception
.TypeOf<NpgsqlException>()
.With
.Property(nameof(NpgsqlException.InnerException))
.TypeOf<SocketException>()
);
}

[Test]
public void Bad_hostname_async()
{
using var dataSource = CreateDataSource(csb => csb.Host = "hostname.that.does.not.exist");
using var conn = dataSource.CreateConnection();

Assert.That(
async () => await conn.OpenAsync(),
Throws.Exception
.TypeOf<NpgsqlException>()
.With
.Property(nameof(NpgsqlException.InnerException))
.TypeOf<SocketException>()
);
}

#endregion

#region Client Encoding
Expand Down
2 changes: 1 addition & 1 deletion test/Npgsql.Tests/TracingTests.cs
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Expand Up @@ -158,7 +158,7 @@ public async Task Error_open([Values] bool async)
ActivitySource.AddActivityListener(activityListener);

await using var dataSource = CreateDataSource(x => x.Host = "not-existing-host");
var ex = Assert.ThrowsAsync<SocketException>(async () =>
var ex = Assert.ThrowsAsync<NpgsqlException>(async () =>
{
await using var conn = async
? await dataSource.OpenConnectionAsync()
Expand Down