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Avoid reading time stamp counter #1074

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Sep 7, 2023
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9 changes: 9 additions & 0 deletions src/NetMQ/Core/Utils/OpCode.cs
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,15 @@ internal static class Opcode

public static bool Open()
{
// Look for an environment variable: "NETQM_SUPPRESS_RDTSC" with any value.
// The application can set this environment variable when this code is running in a system where
// it is not desirable to read the processor's time stamp counter.
// While this is supported in modern CPUs, the technique used for allocating executable memory, copying OP Code
// for the read of the time stamp and invoking the OP Code can be detected as Malware by some anti-virus vendors.
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Please include a link to the original issue here so that we can more easily see the motivation for this feature in future:

Suggested change
// for the read of the time stamp and invoking the OP Code can be detected as Malware by some anti-virus vendors.
// for the read of the time stamp and invoking the OP Code can be detected as Malware by some anti-virus vendors.
// https://github.com/zeromq/netmq/issues/1071

// https://github.com/zeromq/netmq/issues/1071
string val = Environment.GetEnvironmentVariable("NETQM_SUPPRESS_RDTSC");
if (!string.IsNullOrEmpty(val))
return false;
#if NETSTANDARD1_1_OR_GREATER || NET471_OR_GREATER
if (RuntimeInformation.ProcessArchitecture != Architecture.X86 &&
RuntimeInformation.ProcessArchitecture != Architecture.X64)
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