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Reduce the boot time advertisement of addresses.
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MinMDNS advertises once for every IP address, but this makes no
sense as a multicast is per interface not per external IP.

Ensure we only broadcast once per interface.
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@andreilitvin
andreilitvin committed Jun 15, 2023
1 parent 5efdd31 commit 5a8ad4f
Showing 1 changed file with 56 additions and 84 deletions.
140 changes: 56 additions & 84 deletions src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -206,10 +206,6 @@ class AdvertiserMinMdns : public ServiceAdvertiser,
/// removes all records by advertising a 0 TTL)
void AdvertiseRecords(BroadcastAdvertiseType type);

/// Determine if advertisement on the specified interface/address is ok given the
/// interfaces on which the mDNS server is listening
bool ShouldAdvertiseOn(const chip::Inet::InterfaceId id, const chip::Inet::IPAddress & addr);

FullQName GetCommissioningTxtEntries(const CommissionAdvertisingParameters & params);
FullQName GetOperationalTxtEntries(OperationalQueryAllocator::Allocator * allocator,
const OperationalAdvertisingParameters & params);
Expand Down Expand Up @@ -856,35 +852,6 @@ FullQName AdvertiserMinMdns::GetCommissioningTxtEntries(const CommissionAdvertis
return allocator->AllocateQNameFromArray(txtFields, numTxtFields);
}

bool AdvertiserMinMdns::ShouldAdvertiseOn(const chip::Inet::InterfaceId id, const chip::Inet::IPAddress & addr)
{
auto & server = GlobalMinimalMdnsServer::Server();

bool result = false;

server.ForEachEndPoints([&](auto * info) {
if (info->mListenUdp == nullptr)
{
return chip::Loop::Continue;
}

if (info->mInterfaceId != id)
{
return chip::Loop::Continue;
}

if (info->mAddressType != addr.Type())
{
return chip::Loop::Continue;
}

result = true;
return chip::Loop::Break;
});

return result;
}

void AdvertiserMinMdns::AdvertiseRecords(BroadcastAdvertiseType type)
{
ResponseConfiguration responseConfiguration;
Expand All @@ -905,60 +872,65 @@ void AdvertiserMinMdns::AdvertiseRecords(BroadcastAdvertiseType type)
UniquePtr<IpAddressIterator> allIps = GetAddressPolicy()->GetIpAddressesForEndpoint(interfaceId, addressType);
VerifyOrDieWithMsg(allIps != nullptr, Discovery, "Failed to allocate memory for ip addresses.");

Inet::IPAddress ipAddress;
while (allIps->Next(ipAddress))
{
if (!ShouldAdvertiseOn(interfaceId, ipAddress))
{
continue;
}
chip::Inet::IPPacketInfo packetInfo;

chip::Inet::IPPacketInfo packetInfo;
packetInfo.Clear();

packetInfo.Clear();
packetInfo.SrcAddress = ipAddress;
if (ipAddress.IsIPv4())
{
BroadcastIpAddresses::GetIpv4Into(packetInfo.DestAddress);
}
else
{
BroadcastIpAddresses::GetIpv6Into(packetInfo.DestAddress);
}
packetInfo.SrcPort = kMdnsPort;
packetInfo.DestPort = kMdnsPort;
packetInfo.Interface = interfaceId;

// Advertise all records
//
// TODO: Consider advertising delta changes.
//
// Current advertisement does not have a concept of "delta" to only
// advertise changes. Current implementation is to always
// 1. advertise TTL=0 (clear all caches)
// 2. advertise available records (with longer TTL)
//
// It would be nice if we could selectively advertise what changes, like
// send TTL=0 for anything removed/about to be removed (and only those),
// then only advertise new items added.
//
// This optimization likely will take more logic and state storage, so
// for now it is not done.
QueryData queryData(QType::PTR, QClass::IN, false /* unicast */);
queryData.SetIsInternalBroadcast(true);

for (auto & it : mOperationalResponders)
{
it.GetAllocator()->GetQueryResponder()->ClearBroadcastThrottle();
}
mQueryResponderAllocatorCommissionable.GetQueryResponder()->ClearBroadcastThrottle();
mQueryResponderAllocatorCommissioner.GetQueryResponder()->ClearBroadcastThrottle();
// advertising on every interface requires a valid IP address
// since we use "BROADCAST" (unicast is false), we do not actually care about
// the source IP address value, just that it has the right "type"
//
// NOTE: cannot use Boradcast address as the source as they have the type kAny.
//
// TODO: ideally we may want to have a destination that is explicit as "unicast/destIp"
// vs "multicast/addressType". Such a change requires larger code updates.
#if INET_CONFIG_ENABLE_IPV4
if (addressType == chip::Inet::IPAddressType::kIPv4)
{
VerifyOrDie(chip::Inet::IPAddress::FromString("127.0.0.1", packetInfo.SrcAddress));
VerifyOrDie(packetInfo.SrcAddress.Type() == chip::Inet::IPAddressType::kIPv4);
BroadcastIpAddresses::GetIpv4Into(packetInfo.DestAddress);
}
else
#endif
{
VerifyOrDie(chip::Inet::IPAddress::FromString("::1", packetInfo.SrcAddress));
VerifyOrDie(packetInfo.SrcAddress.Type() == chip::Inet::IPAddressType::kIPv6);
BroadcastIpAddresses::GetIpv6Into(packetInfo.DestAddress);
}
packetInfo.SrcPort = kMdnsPort;
packetInfo.DestPort = kMdnsPort;
packetInfo.Interface = interfaceId;

// Advertise all records
//
// TODO: Consider advertising delta changes.
//
// Current advertisement does not have a concept of "delta" to only
// advertise changes. Current implementation is to always
// 1. advertise TTL=0 (clear all caches)
// 2. advertise available records (with longer TTL)
//
// It would be nice if we could selectively advertise what changes, like
// send TTL=0 for anything removed/about to be removed (and only those),
// then only advertise new items added.
//
// This optimization likely will take more logic and state storage, so
// for now it is not done.
QueryData queryData(QType::PTR, QClass::IN, false /* unicast */);
queryData.SetIsInternalBroadcast(true);

for (auto & it : mOperationalResponders)
{
it.GetAllocator()->GetQueryResponder()->ClearBroadcastThrottle();
}
mQueryResponderAllocatorCommissionable.GetQueryResponder()->ClearBroadcastThrottle();
mQueryResponderAllocatorCommissioner.GetQueryResponder()->ClearBroadcastThrottle();

CHIP_ERROR err = mResponseSender.Respond(0, queryData, &packetInfo, responseConfiguration);
if (err != CHIP_NO_ERROR)
{
ChipLogError(Discovery, "Failed to advertise records: %" CHIP_ERROR_FORMAT, err.Format());
}
CHIP_ERROR err = mResponseSender.Respond(0, queryData, &packetInfo, responseConfiguration);
if (err != CHIP_NO_ERROR)
{
ChipLogError(Discovery, "Failed to advertise records: %" CHIP_ERROR_FORMAT, err.Format());
}
}

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