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Fix marshalling of StringBuilder errors #533

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merged 7 commits into from
Oct 8, 2024
Merged

Fix marshalling of StringBuilder errors #533

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a3b097e
Fix marshalling of StringBuilder errors
kayoub5 Sep 15, 2024
a7db60e
Move StringBuilder logic to PcapStringBuilderMarshaler
kayoub5 Sep 15, 2024
0464f05
Drop ICustomMarshaler for error string, use ErrorBuffer class instead.ss
kayoub5 Oct 1, 2024
5df8f1d
Revert csproj changes
kayoub5 Oct 1, 2024
b2acced
Fix build
kayoub5 Oct 1, 2024
ace732f
Merge remote-tracking branch 'origin/master' into hotfix/stringbuilde…
kayoub5 Oct 4, 2024
3b1b506
Cleanup
kayoub5 Oct 7, 2024
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85 changes: 66 additions & 19 deletions SharpPcap/LibPcap/LibPcapSafeNativeMethods.Encoding.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,66 @@
return Encoding.GetEncoding(0);
}

/// <summary>
/// Helper class to marshall StringBuilder depending on encoding used by Libpcap
/// </summary>
private class PcapStringBuilderMarshaler : ICustomMarshaler
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{

public static ICustomMarshaler GetInstance(string cookie)
{
return new PcapStringBuilderMarshaler();
}

public void CleanUpManagedData(object managedObj)
{

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SharpPcap/LibPcap/LibPcapSafeNativeMethods.Encoding.cs#L63 

Added line #L63 was not covered by tests
// Nothing to clean
}

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public void CleanUpNativeData(IntPtr nativeData)
{
// Nothing to clean
}

public int GetNativeDataSize()
{
return -1;
}

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SharpPcap/LibPcap/LibPcapSafeNativeMethods.Encoding.cs#L73-L75 

Added lines #L73 - L75 were not covered by tests

public IntPtr MarshalManagedToNative(object managedObj)
{
var builder = (StringBuilder)managedObj;
var byteCount = builder.Capacity + 1;
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var gcHandle = GCHandle.ToIntPtr(GCHandle.Alloc(managedObj));

// The problem is that we need a reference to the StringBuilder in MarshalNativeToManaged
// So we get a pointer to it with GCHandle, and put it as prefix of the pointer we return
var ptr = Marshal.AllocHGlobal(byteCount + IntPtr.Size);
Marshal.WriteIntPtr(ptr, gcHandle);
ptr += IntPtr.Size;
return ptr;
}

public unsafe object MarshalNativeToManaged(IntPtr nativeData)
{
var gcHandlePtr = Marshal.ReadIntPtr(nativeData - IntPtr.Size);
var bytes = (byte*)nativeData;
var nbBytes = 0;
while (*(bytes + nbBytes) != 0)
{
nbBytes++;
}
var stringData = StringEncoding.GetString(bytes, nbBytes);

var gcHandle = GCHandle.FromIntPtr(gcHandlePtr);
var stringBuilder = (StringBuilder)gcHandle.Target;
gcHandle.Free();
stringBuilder.Append(stringData);

return null;
}
}

/// <summary>
/// Helper class to marshall string depending on encoding used by Libpcap
/// </summary>
Expand Down Expand Up @@ -90,25 +150,11 @@
{
return IntPtr.Zero;
}
byte[] bytes = null;
var byteCount = 0;
if (managedObj is string str)
{
bytes = StringEncoding.GetBytes(str);
byteCount = bytes.Length + 1;
}

if (managedObj is StringBuilder builder)
{
bytes = StringEncoding.GetBytes(builder.ToString());
byteCount = StringEncoding.GetMaxByteCount(builder.Capacity) + 1;
}

if (bytes is null)
{
throw new ArgumentException("The input argument is not a supported type.");
}
var ptr = Marshal.AllocHGlobal(byteCount);
var str = (string)managedObj;
var bytes = StringEncoding.GetBytes(str);
// The problem is that we need a reference to the StringBuilder in MarshalNativeToManaged
// So we get a pointer to it with GCHandle, and put it as prefix of the pointer we return
var ptr = Marshal.AllocHGlobal(bytes.Length + 1);
Marshal.Copy(bytes, 0, ptr, bytes.Length);
// Put zero string termination
Marshal.WriteByte(ptr + bytes.Length, 0);
Expand All @@ -121,6 +167,7 @@
{
return null;
}
var gcHandlePtr = Marshal.ReadIntPtr(nativeData);
var bytes = (byte*)nativeData;
var nbBytes = 0;
while (*(bytes + nbBytes) != 0)
Expand Down
22 changes: 11 additions & 11 deletions SharpPcap/LibPcap/LibPcapSafeNativeMethods.Interop.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -30,21 +30,21 @@ internal static partial class LibPcapSafeNativeMethods
[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
internal extern static int pcap_init(
uint opts,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /* char* */ errbuf
);

[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
internal extern static int pcap_findalldevs(
ref IntPtr /* pcap_if_t** */ alldevs,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /* char* */ errbuf
);

[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
internal extern static int pcap_findalldevs_ex(
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] string /*char **/source,
ref pcap_rmtauth /*pcap_rmtauth **/auth,
ref IntPtr /*pcap_if_t ** */alldevs,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /*char * */errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /*char * */errbuf
);

[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
Expand All @@ -57,19 +57,19 @@ internal extern static int pcap_findalldevs_ex(
int flags,
int read_timeout,
ref pcap_rmtauth rmtauth,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder errbuf
);

[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
internal extern static PcapHandle /* pcap_t* */ pcap_create(
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] string dev,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder errbuf
);

[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
internal extern static PcapHandle /* pcap_t* */ pcap_open_offline(
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] string/*const char* */ fname,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder/* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder/* char* */ errbuf
);

[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
Expand Down Expand Up @@ -187,7 +187,7 @@ internal extern static int pcap_compile(
internal extern static int pcap_setnonblock(
PcapHandle /* pcap_if_t** */ adaptHandle,
int nonblock,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /* char* */ errbuf
);

/// <summary>
Expand All @@ -196,7 +196,7 @@ internal extern static int pcap_setnonblock(
[DllImport(PCAP_DLL, CallingConvention = CallingConvention.Cdecl)]
internal extern static int pcap_getnonblock(
PcapHandle /* pcap_if_t** */ adaptHandle,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /* char* */ errbuf
);

/// <summary>
Expand Down Expand Up @@ -422,7 +422,7 @@ internal extern static int pcap_tstamp_type_name_to_val(
internal extern static PcapHandle /* pcap_t* */ pcap_open_offline_with_tstamp_precision(
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] string /* const char* */ fname,
uint precision,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /* char* */ errbuf
);

/// <summary>
Expand Down Expand Up @@ -488,7 +488,7 @@ internal extern static int pcap_tstamp_type_name_to_val(
internal extern static IntPtr /* pcap_t* */ _pcap_hopen_offline_with_tstamp_precision(
SafeHandle handle,
uint precision,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /* char* */ errbuf
);

/// <summary>
Expand All @@ -503,7 +503,7 @@ internal extern static int pcap_tstamp_type_name_to_val(
internal extern static IntPtr /* pcap_t* */ _pcap_fopen_offline_with_tstamp_precision(
SafeHandle fileObject,
uint precision,
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringMarshaler))] StringBuilder /* char* */ errbuf
[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(PcapStringBuilderMarshaler))] StringBuilder /* char* */ errbuf
);
}
}
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