Avoid retrieving link speed, unused by libpcap

CHANGELOG.md

@@ -7,6 +7,11 @@
   Errors from lower functions are correctly propagated, making diagnosis of failures easier. Fixes
   [#168](http://issues.npcap.org/168), [#61](http://issues.npcap.org/61), and [#586](http://issues.npcap.org/586).
 
+* PacketGetNetType() now always sets the LinkSpeed field to 0. Many adapters did not support the OID
+  that was being used to get the link speed, and libpcap (Npcap's published API) does not pass this
+  information through, so there should be no impact on the majority of software. Software that needs
+  link speed may use `pcap_oid_get_request()` or `GetAdaptersAddresses()` to get the information.
+
 * Npcap is only supported on Windows 7 SP1 and later, and requires KB4474419 to support SHA-2
   signature validation. The installer will now check these specific requirements, rather than
   attempting an installation that will fail anyway.

Common/Packet32.h

@@ -156,12 +156,12 @@ typedef struct _AirpcapHandle* PAirpcapHandle;
 /*!
   \brief Network type structure.
 
-  This structure is used by the PacketGetNetType() function to return information on the current adapter's type and speed.
+  This structure is used by the PacketGetNetType() function to return information on the current adapter's type.
 */
 typedef struct NetType
 {
 	UINT LinkType;	///< The MAC of the current network adapter (see function PacketGetNetType() for more information)
-	ULONGLONG LinkSpeed;	///< The speed of the network in bits per second
+	ULONGLONG LinkSpeed;	/// UNUSED, set to 0
 }NetType;
 
 

packetWin7/Dll/Packet32.cpp

@@ -3439,60 +3439,36 @@ BOOLEAN PacketGetNetType(LPADAPTER AdapterObject, NetType *type)
 					break;
 			}
 		}
-		//
-		// For the moment, we always set the speed to 54Mbps, since the speed is not channel-specific,
-		// but per packet
-		//
-		type->LinkSpeed = 54000000;
 	}
 	else
 #endif // HAVE_AIRPCAP_API
 	{
 		// If this is our loopback adapter, use static values.
 		if (AdapterObject->Flags & INFO_FLAG_NPCAP_LOOPBACK) {
 			type->LinkType = (UINT) NdisMediumNull;
-			type->LinkSpeed = 10 * 1000 * 1000; //we emulate a fake 10MBit Ethernet
 		}
-		// request the media type from the driver
-		else do
-		{
-			// Request the link speed
+		// If this is a WIFI_ adapter, change the link type.
+		else if (AdapterObject->Flags & INFO_FLAG_NPCAP_DOT11) {
+			type->LinkType = (UINT)NdisMediumRadio80211;
+		}
+		else {
+			//get the link-layer type
 			PPACKET_OID_DATA OidData = (PPACKET_OID_DATA) IoCtlBuffer;
-			//get the link-layer speed
-			OidData->Oid = OID_GEN_LINK_SPEED_EX;
-			OidData->Length = sizeof(NDIS_LINK_SPEED);
+
+			OidData->Oid = OID_GEN_MEDIA_IN_USE;
+			OidData->Length = sizeof (ULONG);
 			if (!PacketRequest(AdapterObject, FALSE, OidData)) {
 				err = GetLastError();
-				TRACE_PRINT1("PacketRequest(OID_GEN_LINK_SPEED_EX) error: %d", err);
-				break;
+				TRACE_PRINT1("PacketGetLinkLayerFromRegistry error: %d", err);
 			}
 			else {
-				PNDIS_LINK_SPEED NdisSpeed = (PNDIS_LINK_SPEED)OidData->Data;
-				// Average of Xmit and Rcv speeds is historical. Maybe we should report min instead?
-				type->LinkSpeed = (NdisSpeed->XmitLinkSpeed + NdisSpeed->RcvLinkSpeed) / 2;
+				type->LinkType=*((UINT*)OidData->Data);
 			}
-
-			// If this is a WIFI_ adapter, change the link type.
-			if (AdapterObject->Flags & INFO_FLAG_NPCAP_DOT11) {
-				type->LinkType = (UINT)NdisMediumRadio80211;
-			}
-			else {
-				ZeroMemory(IoCtlBuffer, sizeof(IoCtlBuffer));
-				//get the link-layer type
-				OidData->Oid = OID_GEN_MEDIA_IN_USE;
-				OidData->Length = sizeof (ULONG);
-				if (!PacketRequest(AdapterObject, FALSE, OidData)) {
-					err = GetLastError();
-					TRACE_PRINT1("PacketGetLinkLayerFromRegistry error: %d", err);
-					break;
-				}
-				else {
-					type->LinkType=*((UINT*)OidData->Data);
-				}
-			}
-		} while (FALSE);
+		}
 	}
 
+	// LinkSpeed is not supported
+	type->LinkSpeed = 0;
 	TRACE_EXIT();
 	SetLastError(err);
 	return (err == ERROR_SUCCESS);