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[ip6] add operator < overload for 'Ip6::Prefix' comparison (#6274)

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This commit adds an overload of operator `<` in `Ip6::Prefix` class. A
prefix with shorter length is considered smaller than the one with
longer length. If the prefix lengths are equal, then the prefix bytes
are compared directly to determine the smaller prefix. This commit
then changes `RoutingManager` to use the newly added operator `<`
overload.

Unit test `test_ip6_address.cpp` is updated to cover the behavior of
the new operator.
This commit is contained in:
Abtin Keshavarzian
2021-03-17 10:16:05 -07:00
committed by GitHub
parent a79eb0f723
commit 4b2c2e5566
5 changed files with 58 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/core/border_router/routing_manager.cpp
+3 -16
View File
@@ -361,7 +361,7 @@ uint8_t RoutingManager::EvaluateOmrPrefix(Ip6::Prefix *aNewOmrPrefixes, uint8_t
}
aNewOmrPrefixes[newOmrPrefixNum] = onMeshPrefixConfig.GetPrefix();
if (smallestOmrPrefix == nullptr || IsPrefixSmallerThan(onMeshPrefixConfig.GetPrefix(), *smallestOmrPrefix))
if (smallestOmrPrefix == nullptr || (onMeshPrefixConfig.GetPrefix() < *smallestOmrPrefix))
{
smallestOmrPrefix = &aNewOmrPrefixes[newOmrPrefixNum];
}
@@ -523,7 +523,7 @@ const Ip6::Prefix *RoutingManager::EvaluateOnLinkPrefix(void)
continue;
}
if (smallestOnLinkPrefix == nullptr || IsPrefixSmallerThan(prefix.mPrefix, *smallestOnLinkPrefix))
if (smallestOnLinkPrefix == nullptr || (prefix.mPrefix < *smallestOnLinkPrefix))
{
smallestOnLinkPrefix = &prefix.mPrefix;
}
@@ -547,7 +547,7 @@ const Ip6::Prefix *RoutingManager::EvaluateOnLinkPrefix(void)
// the same smallest on-link prefix and the application-specific prefix is not used.
else if (mAdvertisedOnLinkPrefix != nullptr)
{
if (IsPrefixSmallerThan(*mAdvertisedOnLinkPrefix, *smallestOnLinkPrefix))
if (*mAdvertisedOnLinkPrefix < *smallestOnLinkPrefix)
{
newOnLinkPrefix = mAdvertisedOnLinkPrefix;
}
@@ -788,19 +788,6 @@ void RoutingManager::SendRouterAdvertisement(const Ip6::Prefix *aNewOmrPrefixes,
}
}
bool RoutingManager::IsPrefixSmallerThan(const Ip6::Prefix &aFirstPrefix, const Ip6::Prefix &aSecondPrefix)
{
uint8_t matchedLength;
OT_ASSERT(aFirstPrefix.GetLength() == aSecondPrefix.GetLength());
matchedLength =
Ip6::Prefix::MatchLength(aFirstPrefix.GetBytes(), aSecondPrefix.GetBytes(), aFirstPrefix.GetBytesSize());
return matchedLength < aFirstPrefix.GetLength() &&
aFirstPrefix.GetBytes()[matchedLength / CHAR_BIT] < aSecondPrefix.GetBytes()[matchedLength / CHAR_BIT];
}
bool RoutingManager::IsValidOmrPrefix(const NetworkData::OnMeshPrefixConfig &aOnMeshPrefixConfig)
{
return IsValidOmrPrefix(aOnMeshPrefixConfig.GetPrefix()) && aOnMeshPrefixConfig.mSlaac && !aOnMeshPrefixConfig.mDp;
src/core/border_router/routing_manager.hpp
-2
View File
@@ -240,8 +240,6 @@ private:
otRoutePreference aRoutePreference = OT_ROUTE_PREFERENCE_MED);
bool NetworkDataContainsOmrPrefix(const Ip6::Prefix &aPrefix) const;
// Decides the first prefix is numerically smaller than the second one.
static bool IsPrefixSmallerThan(const Ip6::Prefix &aFirstPrefix, const Ip6::Prefix &aSecondPrefix);
static bool IsValidOmrPrefix(const NetworkData::OnMeshPrefixConfig &aOnMeshPrefixConfig);
static bool IsValidOmrPrefix(const Ip6::Prefix &aOmrPrefix);
static bool IsValidOnLinkPrefix(const Ip6::Prefix &aOnLinkPrefix);
src/core/net/ip6_address.cpp
+17
View File
@@ -70,6 +70,23 @@ bool Prefix::IsEqual(const uint8_t *aPrefixBytes, uint8_t aPrefixLength) const
return (mLength == aPrefixLength) && (MatchLength(GetBytes(), aPrefixBytes, GetBytesSize()) >= mLength);
}
bool Prefix::operator<(const Prefix &aOther) const
{
bool isSmaller;
uint8_t matchedLength;
VerifyOrExit(GetLength() == aOther.GetLength(), isSmaller = GetLength() < aOther.GetLength());
matchedLength = MatchLength(GetBytes(), aOther.GetBytes(), GetBytesSize());
VerifyOrExit(matchedLength < GetLength(), isSmaller = false);
isSmaller = GetBytes()[matchedLength / CHAR_BIT] < aOther.GetBytes()[matchedLength / CHAR_BIT];
exit:
return isSmaller;
}
uint8_t Prefix::MatchLength(const uint8_t *aPrefixA, const uint8_t *aPrefixB, uint8_t aMaxSize)
{
uint8_t matchedLength = 0;
src/core/net/ip6_address.hpp
+14
View File
@@ -233,6 +233,20 @@ public:
*/
bool operator!=(const Prefix &aOther) const { return !(*this == aOther); }
/**
* This method overloads operator `<` to compare two prefixes.
*
* A prefix with shorter length is considered smaller than the one with longer length. If the prefix lengths are
* equal, then the prefix bytes are compared directly.
*
* @param[in] aOther The other prefix to compare against.
*
* @retval TRUE If the prefix is smaller than @p aOther.
* @retval FALSE If the prefix is not smaller than @p aOther.
*
*/
bool operator<(const Prefix &aOther) const;
/**
* This static method converts a prefix length (in bits) to size (number of bytes).
*
tests/unit/test_ip6_address.cpp
+24
View File
@@ -252,6 +252,7 @@ void TestIp6Prefix(void)
VerifyOrQuit(!address2.MatchesPrefix(prefix), "Address::MatchedPrefix() failed");
VerifyOrQuit(prefix == prefix, "Prefix::operator==() failed");
VerifyOrQuit(!(prefix < prefix), "Prefix::operator<() failed");
for (uint8_t subPrefixLength = 1; subPrefixLength <= prefixLength; subPrefixLength++)
{
@@ -266,14 +267,37 @@ void TestIp6Prefix(void)
VerifyOrQuit(prefix == subPrefix, "Prefix::operator==() failed");
VerifyOrQuit(prefix.IsEqual(subPrefix.GetBytes(), subPrefix.GetLength()),
"Prefix::IsEqual() failed");
VerifyOrQuit(!(subPrefix < prefix), "Prefix::operator<() failed");
}
else
{
VerifyOrQuit(prefix != subPrefix, "Prefix::operator!= failed");
VerifyOrQuit(!prefix.IsEqual(subPrefix.GetBytes(), subPrefix.GetLength()),
"Prefix::IsEqual() failed");
VerifyOrQuit(subPrefix < prefix, "Prefix::operator<() failed");
}
}
for (uint8_t bitNumber = 0; bitNumber < prefixLength; bitNumber++)
{
ot::Ip6::Prefix prefix2;
uint8_t mask = static_cast<uint8_t>(1U << (7 - (bitNumber & 7)));
uint8_t index = (bitNumber / 8);
bool isPrefixSmaller;
prefix2 = prefix;
VerifyOrQuit(prefix == prefix2, "Prefix::operator==() failed");
// Flip the `bitNumber` bit between `prefix` and `prefix2`
prefix2.mPrefix.mFields.m8[index] ^= mask;
VerifyOrQuit(prefix != prefix2, "Prefix::operator==() failed");
isPrefixSmaller = ((prefix.GetBytes()[index] & mask) == 0);
VerifyOrQuit((prefix < prefix2) == isPrefixSmaller, "Prefix::operator<() failed");
VerifyOrQuit((prefix2 < prefix) == !isPrefixSmaller, "Prefix::operator<() failed");
}
}
}
}