Only genenerate the random fallback MAC address once (#32694)
* Set buf.size() correctly in GetPrimaryMACAddress()
When we fall back to returning the WiFi MAC on a device that supports Thread,
the returned MAC is shorter than kPrimaryMACAddressLength.
* Only genenerate the random fallback MAC address once
This avoids changing our hostname every time we restart advertising, in
scenarios where a real physical MAC is unavailable (e.g. on iOS).
diff --git a/examples/chef/common/clusters/wake-on-lan/WakeOnLanManager.cpp b/examples/chef/common/clusters/wake-on-lan/WakeOnLanManager.cpp
index 5f4e2e1..4b9e0e5 100644
--- a/examples/chef/common/clusters/wake-on-lan/WakeOnLanManager.cpp
+++ b/examples/chef/common/clusters/wake-on-lan/WakeOnLanManager.cpp
@@ -41,7 +41,7 @@
}
char macStr[chip::DeviceLayer::ConfigurationManager::kPrimaryMACAddressLength * 2 + 1] = { 0 }; // added null char
- if (BytesToHex(&macBuffer[0], sizeof(macBuffer), &macStr[0], sizeof(macBuffer) * 2u, chip::Encoding::HexFlags::kUppercase) !=
+ if (BytesToHex(mac.data(), mac.size(), &macStr[0], sizeof(macBuffer) * 2u, chip::Encoding::HexFlags::kUppercase) !=
CHIP_NO_ERROR)
{
ChipLogProgress(Zcl, "WakeOnLanManager::getMacAddress hex conversion failed");
diff --git a/examples/tv-app/tv-common/clusters/wake-on-lan/WakeOnLanManager.cpp b/examples/tv-app/tv-common/clusters/wake-on-lan/WakeOnLanManager.cpp
index 53beede..0d4ebb6 100644
--- a/examples/tv-app/tv-common/clusters/wake-on-lan/WakeOnLanManager.cpp
+++ b/examples/tv-app/tv-common/clusters/wake-on-lan/WakeOnLanManager.cpp
@@ -39,7 +39,7 @@
}
char macStr[chip::DeviceLayer::ConfigurationManager::kPrimaryMACAddressLength * 2 + 1] = { 0 }; // added null char
- if (BytesToHex(&macBuffer[0], sizeof(macBuffer), &macStr[0], sizeof(macBuffer) * 2u, chip::Encoding::HexFlags::kUppercase) !=
+ if (BytesToHex(mac.data(), mac.size(), &macStr[0], sizeof(macBuffer) * 2u, chip::Encoding::HexFlags::kUppercase) !=
CHIP_NO_ERROR)
{
ChipLogProgress(Zcl, "WakeOnLanManager::getMacAddress hex conversion failed");
diff --git a/src/app/server/Dnssd.cpp b/src/app/server/Dnssd.cpp
index 1ec2fa0..3df7964 100644
--- a/src/app/server/Dnssd.cpp
+++ b/src/app/server/Dnssd.cpp
@@ -38,6 +38,11 @@
#include <setup_payload/SetupPayload.h>
#include <system/TimeSource.h>
+#include <algorithm>
+
+using namespace chip;
+using namespace chip::DeviceLayer;
+
namespace chip {
namespace app {
namespace {
@@ -165,6 +170,21 @@
}
#endif
+void DnssdServer::GetPrimaryOrFallbackMACAddress(chip::MutableByteSpan mac)
+{
+ if (ConfigurationMgr().GetPrimaryMACAddress(mac) != CHIP_NO_ERROR)
+ {
+ // Only generate a fallback "MAC" once, so we don't keep constantly changing our host name.
+ if (std::all_of(std::begin(mFallbackMAC), std::end(mFallbackMAC), [](uint8_t v) { return v == 0; }))
+ {
+ ChipLogError(Discovery, "Failed to get primary mac address of device. Generating a random one.");
+ Crypto::DRBG_get_bytes(mFallbackMAC, sizeof(mFallbackMAC));
+ }
+ VerifyOrDie(mac.size() == sizeof(mFallbackMAC)); // kPrimaryMACAddressLength
+ memcpy(mac.data(), mFallbackMAC, sizeof(mFallbackMAC));
+ }
+}
+
/// Set MDNS operational advertisement
CHIP_ERROR DnssdServer::AdvertiseOperational()
{
@@ -179,11 +199,7 @@
uint8_t macBuffer[DeviceLayer::ConfigurationManager::kPrimaryMACAddressLength];
MutableByteSpan mac(macBuffer);
- if (chip::DeviceLayer::ConfigurationMgr().GetPrimaryMACAddress(mac) != CHIP_NO_ERROR)
- {
- ChipLogError(Discovery, "Failed to get primary mac address of device. Generating a random one.");
- Crypto::DRBG_get_bytes(macBuffer, sizeof(macBuffer));
- }
+ GetPrimaryOrFallbackMACAddress(mac);
auto advertiseParameters = chip::Dnssd::OperationalAdvertisingParameters()
.SetPeerId(fabricInfo.GetPeerId())
@@ -224,11 +240,7 @@
uint8_t macBuffer[DeviceLayer::ConfigurationManager::kPrimaryMACAddressLength];
MutableByteSpan mac(macBuffer);
- if (chip::DeviceLayer::ConfigurationMgr().GetPrimaryMACAddress(mac) != CHIP_NO_ERROR)
- {
- ChipLogError(Discovery, "Failed to get primary mac address of device. Generating a random one.");
- Crypto::DRBG_get_bytes(macBuffer, sizeof(macBuffer));
- }
+ GetPrimaryOrFallbackMACAddress(mac);
advertiseParameters.SetMac(mac);
uint16_t value;
diff --git a/src/app/server/Dnssd.h b/src/app/server/Dnssd.h
index 559cac6..e669f4d 100644
--- a/src/app/server/Dnssd.h
+++ b/src/app/server/Dnssd.h
@@ -146,6 +146,11 @@
/// Set MDNS commissionable node advertisement
CHIP_ERROR AdvertiseCommissionableNode(chip::Dnssd::CommissioningMode mode);
+ // Our randomly-generated fallback "MAC address", in case we don't have a real one.
+ uint8_t mFallbackMAC[chip::DeviceLayer::ConfigurationManager::kPrimaryMACAddressLength] = { 0 };
+
+ void GetPrimaryOrFallbackMACAddress(chip::MutableByteSpan mac);
+
//
// Check if we have any valid operational credentials present in the fabric table and return true
// if we do.
diff --git a/src/include/platform/ConfigurationManager.h b/src/include/platform/ConfigurationManager.h
index 4ebf2c6..c7158d2 100644
--- a/src/include/platform/ConfigurationManager.h
+++ b/src/include/platform/ConfigurationManager.h
@@ -80,17 +80,26 @@
kMinRotatingDeviceIDUniqueIDLength = 16,
kRotatingDeviceIDUniqueIDLength = CHIP_DEVICE_CONFIG_ROTATING_DEVICE_ID_UNIQUE_ID_LENGTH,
#endif
+ kEthernetMACAddressLength = 6,
+ kThreadMACAddressLength = 8,
#if CHIP_DEVICE_CONFIG_ENABLE_THREAD
- kPrimaryMACAddressLength = 8,
+ kPrimaryMACAddressLength = kThreadMACAddressLength,
#else
- kPrimaryMACAddressLength = 6,
+ kPrimaryMACAddressLength = kEthernetMACAddressLength,
#endif
kMaxMACAddressLength = 8,
kMaxLanguageTagLength = 5 // ISO 639-1 standard language codes
};
- virtual CHIP_ERROR GetPrimaryMACAddress(MutableByteSpan buf) = 0;
- virtual CHIP_ERROR GetPrimaryWiFiMACAddress(uint8_t * buf) = 0;
+ // Copies the primary MAC into a mutable span, which must be of size kPrimaryMACAddressLength.
+ // Upon success, the span will be reduced to the size of the MAC address being returned, which
+ // can be less than kPrimaryMACAddressLength on a device that supports Thread.
+ virtual CHIP_ERROR GetPrimaryMACAddress(MutableByteSpan buf) = 0;
+
+ // Copies the primary WiFi MAC into a buffer of size kEthernetMACAddressLength
+ virtual CHIP_ERROR GetPrimaryWiFiMACAddress(uint8_t * buf) = 0;
+
+ // Copies the primary Thread (802.15.4) MAC into a buffer of size kThreadMACAddressLength
virtual CHIP_ERROR GetPrimary802154MACAddress(uint8_t * buf) = 0;
virtual CHIP_ERROR GetSoftwareVersionString(char * buf, size_t bufSize) = 0;
virtual CHIP_ERROR GetSoftwareVersion(uint32_t & softwareVer) = 0;
diff --git a/src/include/platform/internal/GenericConfigurationManagerImpl.ipp b/src/include/platform/internal/GenericConfigurationManagerImpl.ipp
index 24c6a28..955b782 100644
--- a/src/include/platform/internal/GenericConfigurationManagerImpl.ipp
+++ b/src/include/platform/internal/GenericConfigurationManagerImpl.ipp
@@ -374,19 +374,21 @@
if (buf.size() != ConfigurationManager::kPrimaryMACAddressLength)
return CHIP_ERROR_INVALID_ARGUMENT;
- memset(buf.data(), 0, buf.size());
+ memset(buf.data(), 0, buf.size()); // zero the whole buffer, in case the caller ignores buf.size()
#if CHIP_DEVICE_CONFIG_ENABLE_THREAD
if (chip::DeviceLayer::ThreadStackMgr().GetPrimary802154MACAddress(buf.data()) == CHIP_NO_ERROR)
{
ChipLogDetail(DeviceLayer, "Using Thread extended MAC for hostname.");
+ buf.reduce_size(kThreadMACAddressLength);
return CHIP_NO_ERROR;
}
#endif
if (chip::DeviceLayer::ConfigurationMgr().GetPrimaryWiFiMACAddress(buf.data()) == CHIP_NO_ERROR)
{
- ChipLogDetail(DeviceLayer, "Using wifi MAC for hostname");
+ ChipLogDetail(DeviceLayer, "Using WiFi MAC for hostname");
+ buf.reduce_size(kEthernetMACAddressLength);
return CHIP_NO_ERROR;
}
