Fix short code on dnssd advertising and chip-tool (#12319)

* Fix short code on dnssd advertising and chip-tool

The short discriminator is the UPPER four bits of the discriminator.

* Update src/controller/SetUpCodePairer.cpp

Co-authored-by: Tennessee Carmel-Veilleux <tennessee.carmelveilleux@gmail.com>

* Update src/app/server/Dnssd.cpp

Co-authored-by: Tennessee Carmel-Veilleux <tennessee.carmelveilleux@gmail.com>

Co-authored-by: Justin Wood <woody@apple.com>
Co-authored-by: Tennessee Carmel-Veilleux <tennessee.carmelveilleux@gmail.com>

Author: 3 people

src/app/server/Dnssd.cpp

@@ -320,7 +320,7 @@ CHIP_ERROR DnssdServer::Advertise(bool commissionableNode, chip::Dnssd::Commissi
         ChipLogError(Discovery, "Setup discriminator not known. Using a default.");
         value = 840;
     }
-    advertiseParameters.SetShortDiscriminator(static_cast<uint8_t>(value & 0xFF)).SetLongDiscriminator(value);
+    advertiseParameters.SetShortDiscriminator(static_cast<uint8_t>((value >> 8) & 0x0F)).SetLongDiscriminator(value);
 
     if (DeviceLayer::ConfigurationMgr().IsCommissionableDeviceTypeEnabled() &&
         DeviceLayer::ConfigurationMgr().GetDeviceTypeId(value) == CHIP_NO_ERROR)

src/controller/SetUpCodePairer.cpp

@@ -64,7 +64,8 @@ CHIP_ERROR SetUpCodePairer::Connect(RendezvousInformationFlag rendezvousInformat
 
     if (searchOverAll || rendezvousInformation == RendezvousInformationFlag::kOnNetwork)
     {
-        if (CHIP_NO_ERROR == (err = StartDiscoverOverIP(discriminator, isShort)))
+        if (CHIP_NO_ERROR ==
+            (err = StartDiscoverOverIP(isShort ? static_cast<uint16_t>((discriminator >> 8) & 0x0F) : discriminator, isShort)))
         {
             isRunning = true;
         }