fix ping with TTL on Linux

src/libraries/Common/src/Interop/Unix/System.Native/Interop.IOVector.cs

@@ -2,11 +2,13 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Runtime.InteropServices;
 
 internal static partial class Interop
 {
     internal static partial class Sys
     {
+        [StructLayout(LayoutKind.Sequential)]
         internal unsafe struct IOVector
         {
             public byte* Base;

src/libraries/Common/src/Interop/Unix/System.Native/Interop.ReceiveSocketError.cs

@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Net.Sockets;
+using System.Runtime.InteropServices;
+
+internal static partial class Interop
+{
+    internal static partial class Sys
+    {
+        [LibraryImport(Libraries.SystemNative, EntryPoint = "SystemNative_ReceiveSocketError")]
+        internal static unsafe partial SocketError ReceiveSocketError(SafeHandle socket, MessageHeader* messageHeader);
+    }
+}

src/libraries/System.Net.Ping/src/System.Net.Ping.csproj

@@ -41,15 +41,29 @@
              Link="Common\System\Net\SocketProtocolSupportPal.Unix.cs" />
     <Compile Include="$(CommonPath)System\Net\NetworkInformation\UnixCommandLinePing.cs"
              Link="Common\System\Net\NetworkInformation\UnixCommandLinePing.cs" />
+    <Compile Include="$(CommonPath)System\Net\IPEndPointExtensions.cs"
+             Link="Common\System\Net\IPEndPointExtensions.cs" />
+    <Compile Include="$(CommonPath)System\Net\SocketAddressPal.Unix.cs"
+             Link="Common\System\Net\SocketAddressPal.Unix.cs" />
+    <Compile Include="$(CommonPath)System\Net\IPAddressParserStatics.cs"
+                 Link="Common\System\Net\IPAddressParserStatics.cs" />
+    <Compile Include="$(CommonPath)System\Net\Sockets\SocketErrorPal.Unix.cs"
+                 Link="Common\System\Net\Sockets\SocketErrorPal.Unix" />
     <!-- Interop -->
     <Compile Include="$(CommonPath)Interop\Unix\Interop.DefaultPathBufferSize.cs"
              Link="Common\Interop\Unix\Interop.DefaultPathBufferSize.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Errors.cs"
              Link="Common\Interop\Unix\Interop.Errors.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Libraries.cs"
              Link="Common\Interop\Unix\Interop.Libraries.cs" />
+    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.IOVector.cs"
+             Link="Common\Interop\Unix\System.Native\Interop.IOVector.cs" />
+    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.ReceiveSocketError.cs"
+             Link="Common\Interop\Unix\System.Native\Interop.ReceiveSocketError.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Close.cs"
              Link="Common\Interop\Unix\System.Native\Interop.Close.cs" />
+    <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.MessageHeader.cs"
+             Link="Common\Interop\Unix\System.Native\Interop.MessageHeader.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Socket.cs"
              Link="Common\Interop\Unix\System.Native\Interop.Socket.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.SocketAddress.cs"
@@ -99,6 +113,7 @@
 
   <ItemGroup>
     <Reference Include="Microsoft.Win32.Primitives" />
+    <Reference Include="System.Collections" />
     <Reference Include="System.ComponentModel.EventBasedAsync" />
     <Reference Include="System.ComponentModel.Primitives" />
     <Reference Include="System.Diagnostics.Tracing" />

src/libraries/System.Net.Ping/src/System/Net/NetworkInformation/Ping.RawSocket.cs

@@ -102,6 +102,12 @@ private static Socket GetRawSocket(SocketConfig socketConfig)
             {
                 // If it is not multicast, use Connect to scope responses only to the target address.
                 socket.Connect(socketConfig.EndPoint);
+                unsafe
+                {
+                    int opt = 1;
+                    // setsockopt(fd, IPPROTO_IP, IP_RECVERR, &value, sizeof(int))
+                    socket.SetRawSocketOption(0, 11, new ReadOnlySpan<byte>(&opt, sizeof(int)));
+                }
             }
 #pragma warning restore 618
 
@@ -232,11 +238,12 @@ private static bool TryGetPingReply(
             return true;
         }
 
-        private static PingReply SendIcmpEchoRequestOverRawSocket(IPAddress address, byte[] buffer, int timeout, PingOptions? options)
+        private static unsafe PingReply SendIcmpEchoRequestOverRawSocket(IPAddress address, byte[] buffer, int timeout, PingOptions? options)
         {
             SocketConfig socketConfig = GetSocketConfig(address, buffer, timeout, options);
             using (Socket socket = GetRawSocket(socketConfig))
             {
+                Span<byte> socketAddress = stackalloc byte[SocketAddress.GetMaximumAddressSize(address.AddressFamily)];
                 int ipHeaderLength = socketConfig.IsIpv4 ? MinIpHeaderLengthInBytes : 0;
                 try
                 {
@@ -270,6 +277,29 @@ private static PingReply SendIcmpEchoRequestOverRawSocket(IPAddress address, byt
                 {
                     return CreatePingReply(IPStatus.PacketTooBig);
                 }
+                catch (SocketException ex) when (ex.SocketErrorCode == SocketError.HostUnreachable)
+                {
+                    // This happens on Linux where we explicitly subscribed to error messages
+                    // We should be able to get more info by getting extended socket error from error queue.
+
+                    Interop.Sys.MessageHeader header = default;
+
+                    SocketError result;
+                    fixed (byte* sockAddr = &MemoryMarshal.GetReference(socketAddress))
+                    {
+                        header.SocketAddress = sockAddr;
+                        header.SocketAddressLen = socketAddress.Length;
+                        header.IOVectors = null;
+                        header.IOVectorCount = 0;
+
+                        result = Interop.Sys.ReceiveSocketError(socket.SafeHandle, &header);
+                    }
+
+                    if (result == SocketError.Success && header.SocketAddressLen > 0)
+                    {
+                        return CreatePingReply(IPStatus.TtlExpired, IPEndPointExtensions.GetIPAddress(socketAddress.Slice(0, header.SocketAddressLen)));
+                    }
+                }
 
                 // We have exceeded our timeout duration, and no reply has been received.
                 return CreatePingReply(IPStatus.TimedOut);

src/native/libs/Common/pal_config.h.in

@@ -100,6 +100,7 @@
 #cmakedefine01 HAVE_IOS_NET_IFMEDIA_H
 #cmakedefine01 HAVE_LINUX_RTNETLINK_H
 #cmakedefine01 HAVE_LINUX_CAN_H
+#cmakedefine01 HAVE_LINUX_ERRQUEUE_H
 #cmakedefine01 HAVE_GETDOMAINNAME_SIZET
 #cmakedefine01 HAVE_INOTIFY
 #cmakedefine01 HAVE_CLOCK_MONOTONIC

src/native/libs/System.Native/entrypoints.c

@@ -160,6 +160,7 @@ static const Entry s_sysNative[] =
     DllImportEntry(SystemNative_SetSendTimeout)
     DllImportEntry(SystemNative_Receive)
     DllImportEntry(SystemNative_ReceiveMessage)
+    DllImportEntry(SystemNative_ReceiveSocketError)
     DllImportEntry(SystemNative_Send)
     DllImportEntry(SystemNative_SendMessage)
     DllImportEntry(SystemNative_Accept)

src/native/libs/System.Native/pal_networking.c

@@ -62,6 +62,10 @@
 #if HAVE_SYS_FILIO_H
 #include <sys/filio.h>
 #endif
+#if HAVE_LINUX_ERRQUEUE_H
+#include <linux/errqueue.h>
+#endif
+
 
 #if HAVE_KQUEUE
 #if KEVENT_HAS_VOID_UDATA
@@ -1325,7 +1329,11 @@ int32_t SystemNative_SetSendTimeout(intptr_t socket, int32_t millisecondsTimeout
 
 static int8_t ConvertSocketFlagsPalToPlatform(int32_t palFlags, int* platformFlags)
 {
-    const int32_t SupportedFlagsMask = SocketFlags_MSG_OOB | SocketFlags_MSG_PEEK | SocketFlags_MSG_DONTROUTE | SocketFlags_MSG_TRUNC | SocketFlags_MSG_CTRUNC;
+    const int32_t SupportedFlagsMask =
+#ifdef MSG_ERRQUEUE
+                        SocketFlags_MSG_ERRQUEUE |
+#endif
+                        SocketFlags_MSG_OOB | SocketFlags_MSG_PEEK | SocketFlags_MSG_DONTROUTE | SocketFlags_MSG_TRUNC | SocketFlags_MSG_CTRUNC | SocketFlags_MSG_DONTWAIT;
 
     if ((palFlags & ~SupportedFlagsMask) != 0)
     {
@@ -1335,9 +1343,15 @@ static int8_t ConvertSocketFlagsPalToPlatform(int32_t palFlags, int* platformFla
     *platformFlags = ((palFlags & SocketFlags_MSG_OOB) == 0 ? 0 : MSG_OOB) |
                      ((palFlags & SocketFlags_MSG_PEEK) == 0 ? 0 : MSG_PEEK) |
                      ((palFlags & SocketFlags_MSG_DONTROUTE) == 0 ? 0 : MSG_DONTROUTE) |
+                     ((palFlags & SocketFlags_MSG_DONTWAIT) == 0 ? 0 : MSG_DONTWAIT) |
                      ((palFlags & SocketFlags_MSG_TRUNC) == 0 ? 0 : MSG_TRUNC) |
                      ((palFlags & SocketFlags_MSG_CTRUNC) == 0 ? 0 : MSG_CTRUNC);
-
+#ifdef MSG_ERRQUEUE
+    if ((palFlags & SocketFlags_MSG_ERRQUEUE) != 0)
+    {
+        *platformFlags |= MSG_ERRQUEUE;
+    }
+#endif
     return true;
 }
 
@@ -1381,6 +1395,51 @@ int32_t SystemNative_Receive(intptr_t socket, void* buffer, int32_t bufferLen, i
     return SystemNative_ConvertErrorPlatformToPal(errno);
 }
 
+int32_t SystemNative_ReceiveSocketError(intptr_t socket, MessageHeader* messageHeader)
+{
+    int fd = ToFileDescriptor(socket);
+    ssize_t res;
+
+#if HAVE_LINUX_ERRQUEUE_H
+    char buffer[sizeof(struct sock_extended_err) + sizeof(struct sockaddr_storage)];
+    messageHeader->ControlBufferLen = sizeof(buffer);
+    messageHeader->ControlBuffer = (void*)buffer;
+
+    struct msghdr header;
+    ConvertMessageHeaderToMsghdr(&header, messageHeader, fd);
+
+    while ((res = recvmsg(fd, &header, SocketFlags_MSG_DONTWAIT | SocketFlags_MSG_ERRQUEUE)) < 0 && errno == EINTR);
+
+    struct cmsghdr *cmsg;
+    for (cmsg = CMSG_FIRSTHDR(&header); cmsg; cmsg = GET_CMSG_NXTHDR(&header, cmsg))
+    {
+        if (cmsg->cmsg_level == SOL_IP && cmsg->cmsg_type == IP_RECVERR)
+        {
+            struct sock_extended_err *e = (struct sock_extended_err *)CMSG_DATA(cmsg);
+            if (e->ee_origin == SO_EE_ORIGIN_ICMP)
+            {
+                int size = (int)(cmsg->cmsg_len - sizeof(struct sock_extended_err));
+                messageHeader->SocketAddressLen = size < messageHeader->SocketAddressLen ? size : messageHeader->SocketAddressLen;
+                memcpy(messageHeader->SocketAddress, (struct sockaddr_in*)(e+1), (size_t)messageHeader->SocketAddressLen);
+                return Error_SUCCESS;
+            }
+        }
+    }
+#else
+    res = -1;
+    errno = ENOTSUP;
+#endif
+
+    messageHeader->SocketAddressLen = 0;
+
+    if (res != -1)
+    {
+        return Error_SUCCESS;
+    }
+
+    return SystemNative_ConvertErrorPlatformToPal(errno);
+}
+
 int32_t SystemNative_ReceiveMessage(intptr_t socket, MessageHeader* messageHeader, int32_t flags, int64_t* received)
 {
     if (messageHeader == NULL || received == NULL || messageHeader->SocketAddressLen < 0 ||

src/native/libs/System.Native/pal_networking.h

@@ -206,6 +206,8 @@ typedef enum
     SocketFlags_MSG_DONTROUTE = 0x0004, // SocketFlags.DontRoute
     SocketFlags_MSG_TRUNC = 0x0100,     // SocketFlags.Truncated
     SocketFlags_MSG_CTRUNC = 0x0200,    // SocketFlags.ControlDataTruncated
+    SocketFlags_MSG_DONTWAIT = 0x1000,  // used privately by Ping
+    SocketFlags_MSG_ERRQUEUE = 0x2000,  // used privately by Ping
 } SocketFlags;
 
 /*
@@ -356,6 +358,8 @@ PALEXPORT int32_t SystemNative_Receive(intptr_t socket, void* buffer, int32_t bu
 
 PALEXPORT int32_t SystemNative_ReceiveMessage(intptr_t socket, MessageHeader* messageHeader, int32_t flags, int64_t* received);
 
+PALEXPORT int32_t SystemNative_ReceiveSocketError(intptr_t socket, MessageHeader* messageHeader);
+
 PALEXPORT int32_t SystemNative_Send(intptr_t socket, void* buffer, int32_t bufferLen, int32_t flags, int32_t* sent);
 
 PALEXPORT int32_t SystemNative_SendMessage(intptr_t socket, MessageHeader* messageHeader, int32_t flags, int64_t* sent);

src/native/libs/configure.cmake

@@ -500,6 +500,10 @@ check_include_files(
      "sys/proc_info.h"
      HAVE_SYS_PROCINFO_H)
 
+check_include_files(
+    "time.h;linux/errqueue.h"
+    HAVE_LINUX_ERRQUEUE_H)
+
 check_symbol_exists(
     epoll_create1
     sys/epoll.h