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synced 2026-08-15 23:27:47 +00:00
[ip6] use OffsetRange for parsing options in extension headers (#10466)
This commit updates `Ip6` and `Lowpan` to use `OffsetRange` when iterating and parsing options in an HBH extension header. It also simplifies the `RemoveMplOption()` method by adding an `Action` enum, which determines how to remove the MPL option: whether to shrink the HBH header, fully remove the HBH header (if it contains no other options), or replace MPL option with padding.
This commit is contained in:
Abtin Keshavarzian
+73
-52
@@ -309,30 +309,35 @@ exit:
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Error Ip6::RemoveMplOption(Message &aMessage)
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{
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Error error = kErrorNone;
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enum Action : uint8_t
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{
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kNoMplOption,
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kShrinkHbh,
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kRemoveHbh,
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kReplaceMplWithPad,
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};
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Error error = kErrorNone;
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Action action = kNoMplOption;
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Header ip6Header;
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HopByHopHeader hbh;
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Option option;
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uint16_t offset;
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uint16_t endOffset;
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uint16_t mplOffset = 0;
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uint8_t mplLength = 0;
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bool remove = false;
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OffsetRange offsetRange;
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OffsetRange mplOffsetRange;
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PadOption padOption;
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offsetRange.InitFromMessageFullLength(aMessage);
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IgnoreError(aMessage.Read(offsetRange, ip6Header));
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offsetRange.AdvanceOffset(sizeof(ip6Header));
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offset = 0;
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IgnoreError(aMessage.Read(offset, ip6Header));
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offset += sizeof(ip6Header);
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VerifyOrExit(ip6Header.GetNextHeader() == kProtoHopOpts);
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IgnoreError(aMessage.Read(offset, hbh));
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endOffset = offset + hbh.GetSize();
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VerifyOrExit(aMessage.GetLength() >= endOffset, error = kErrorParse);
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SuccessOrExit(error = ReadHopByHopHeader(aMessage, offsetRange, hbh));
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offset += sizeof(hbh);
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for (; offset < endOffset; offset += option.GetSize())
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for (; !offsetRange.IsEmpty(); offsetRange.AdvanceOffset(option.GetSize()))
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{
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IgnoreError(option.ParseFrom(aMessage, offset, endOffset));
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SuccessOrExit(error = option.ParseFrom(aMessage, offsetRange));
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if (option.IsPadding())
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{
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@@ -342,44 +347,49 @@ Error Ip6::RemoveMplOption(Message &aMessage)
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if (option.GetType() == MplOption::kType)
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{
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// If multiple MPL options exist, discard packet
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VerifyOrExit(mplOffset == 0, error = kErrorParse);
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VerifyOrExit(action == kNoMplOption, error = kErrorParse);
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mplOffset = offset;
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mplLength = option.GetLength();
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// `Option::ParseFrom()` already validated that the entire
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// option is present in the `offsetRange`.
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VerifyOrExit(mplLength <= sizeof(MplOption) - sizeof(Option), error = kErrorParse);
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mplOffsetRange = offsetRange;
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mplOffsetRange.ShrinkLength(option.GetSize());
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if (mplOffset == sizeof(ip6Header) + sizeof(hbh) && hbh.GetLength() == 0)
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VerifyOrExit(option.GetSize() <= sizeof(MplOption), error = kErrorParse);
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if (mplOffsetRange.GetOffset() == sizeof(ip6Header) + sizeof(hbh) && hbh.GetLength() == 0)
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{
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// First and only IPv6 Option, remove IPv6 HBH Option header
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remove = true;
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action = kRemoveHbh;
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}
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else if (mplOffset + ExtensionHeader::kLengthUnitSize == endOffset)
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else if (mplOffsetRange.GetOffset() + ExtensionHeader::kLengthUnitSize == offsetRange.GetEndOffset())
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{
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// Last IPv6 Option, remove the last 8 bytes
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remove = true;
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// Last IPv6 Option, shrink the last 8 bytes
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action = kShrinkHbh;
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}
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}
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else
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else if (action != kNoMplOption)
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{
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// Encountered another option, now just replace
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// MPL Option with Pad Option
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remove = false;
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action = kReplaceMplWithPad;
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}
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}
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// verify that IPv6 Options header is properly formed
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VerifyOrExit(offset == endOffset, error = kErrorParse);
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if (remove)
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switch (action)
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{
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case kNoMplOption:
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break;
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case kShrinkHbh:
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case kRemoveHbh:
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// Last IPv6 Option, shrink HBH Option header by
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// 8 bytes (`kLengthUnitSize`)
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aMessage.RemoveHeader(endOffset - ExtensionHeader::kLengthUnitSize, ExtensionHeader::kLengthUnitSize);
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aMessage.RemoveHeader(offsetRange.GetEndOffset() - ExtensionHeader::kLengthUnitSize,
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ExtensionHeader::kLengthUnitSize);
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if (mplOffset == sizeof(ip6Header) + sizeof(hbh))
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if (action == kRemoveHbh)
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{
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// Remove entire HBH header
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ip6Header.SetNextHeader(hbh.GetNextHeader());
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}
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else
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@@ -393,14 +403,12 @@ Error Ip6::RemoveMplOption(Message &aMessage)
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ip6Header.SetPayloadLength(ip6Header.GetPayloadLength() - ExtensionHeader::kLengthUnitSize);
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aMessage.Write(0, ip6Header);
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}
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else if (mplOffset != 0)
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{
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// Replace MPL Option with Pad Option
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PadOption padOption;
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break;
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padOption.InitForPadSize(sizeof(Option) + mplLength);
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aMessage.WriteBytes(mplOffset, &padOption, padOption.GetSize());
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case kReplaceMplWithPad:
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padOption.InitForPadSize(static_cast<uint8_t>(mplOffsetRange.GetLength()));
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aMessage.WriteBytes(mplOffsetRange.GetOffset(), &padOption, padOption.GetSize());
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break;
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}
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exit:
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@@ -501,24 +509,37 @@ void Ip6::HandleSendQueue(void)
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}
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}
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Error Ip6::ReadHopByHopHeader(const Message &aMessage, OffsetRange &aOffsetRange, HopByHopHeader &aHbhHeader) const
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{
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// Reads the HBH header from the message at the given offset range.
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// On success, updates `aOffsetRange` to indicate the location of
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// options within the HBH header.
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Error error;
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SuccessOrExit(error = aMessage.Read(aOffsetRange, aHbhHeader));
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VerifyOrExit(aOffsetRange.Contains(aHbhHeader.GetSize()), error = kErrorParse);
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aOffsetRange.ShrinkLength(aHbhHeader.GetSize());
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aOffsetRange.AdvanceOffset(sizeof(HopByHopHeader));
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exit:
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return error;
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}
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Error Ip6::HandleOptions(Message &aMessage, Header &aHeader, bool &aReceive)
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{
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Error error = kErrorNone;
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HopByHopHeader hbhHeader;
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Option option;
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uint16_t offset = aMessage.GetOffset();
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uint16_t endOffset;
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OffsetRange offsetRange;
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SuccessOrExit(error = aMessage.Read(offset, hbhHeader));
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offsetRange.InitFromMessageOffsetToEnd(aMessage);
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endOffset = offset + hbhHeader.GetSize();
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VerifyOrExit(endOffset <= aMessage.GetLength(), error = kErrorParse);
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SuccessOrExit(error = ReadHopByHopHeader(aMessage, offsetRange, hbhHeader));
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offset += sizeof(HopByHopHeader);
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for (; offset < endOffset; offset += option.GetSize())
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for (; !offsetRange.IsEmpty(); offsetRange.AdvanceOffset(option.GetSize()))
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{
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SuccessOrExit(error = option.ParseFrom(aMessage, offset, endOffset));
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SuccessOrExit(error = option.ParseFrom(aMessage, offsetRange));
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if (option.IsPadding())
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{
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@@ -527,14 +548,14 @@ Error Ip6::HandleOptions(Message &aMessage, Header &aHeader, bool &aReceive)
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if (option.GetType() == MplOption::kType)
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{
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SuccessOrExit(error = mMpl.ProcessOption(aMessage, offset, aHeader.GetSource(), aReceive));
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SuccessOrExit(error = mMpl.ProcessOption(aMessage, offsetRange, aHeader.GetSource(), aReceive));
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continue;
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}
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VerifyOrExit(option.GetAction() == Option::kActionSkip, error = kErrorDrop);
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}
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aMessage.SetOffset(offset);
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aMessage.SetOffset(offsetRange.GetEndOffset());
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exit:
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return error;
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@@ -402,6 +402,7 @@ private:
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void UpdateReassemblyList(void);
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void SendIcmpError(Message &aMessage, Icmp::Header::Type aIcmpType, Icmp::Header::Code aIcmpCode);
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#endif
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Error ReadHopByHopHeader(const Message &aMessage, OffsetRange &aOffsetRange, HopByHopHeader &aHbhHeader) const;
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Error AddMplOption(Message &aMessage, Header &aHeader);
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Error PrepareMulticastToLargerThanRealmLocal(Message &aMessage, const Header &aHeader);
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Error InsertMplOption(Message &aMessage, Header &aHeader);
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@@ -69,14 +69,14 @@ bool Header::IsValid(void) const
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//---------------------------------------------------------------------------------------------------------------------
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// Option
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Error Option::ParseFrom(const Message &aMessage, uint16_t aOffset, uint16_t aEndOffset)
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Error Option::ParseFrom(const Message &aMessage, const OffsetRange &aOffsetRange)
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{
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Error error;
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// Read the Type first to check for the Pad1 Option.
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// If it is not, then we read the full `Option` header.
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SuccessOrExit(error = aMessage.Read(aOffset, this, sizeof(mType)));
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SuccessOrExit(error = aMessage.Read(aOffsetRange, this, sizeof(mType)));
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if (mType == kTypePad1)
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{
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@@ -84,9 +84,8 @@ Error Option::ParseFrom(const Message &aMessage, uint16_t aOffset, uint16_t aEnd
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ExitNow();
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}
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SuccessOrExit(error = aMessage.Read(aOffset, *this));
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VerifyOrExit(aOffset + GetSize() <= aEndOffset, error = kErrorParse);
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SuccessOrExit(error = aMessage.Read(aOffsetRange, *this));
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VerifyOrExit(aOffsetRange.Contains(GetSize()), error = kErrorParse);
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exit:
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return error;
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@@ -517,17 +517,16 @@ public:
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* Parses and validates the IPv6 Option from a given message.
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*
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* The Option is read from @p aOffset in @p aMessage. This method then checks that the entire Option is present
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* in @p aMessage before the @p aEndOffset.
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* within @p aOffsetRange.
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*
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* @param[in] aMessage The IPv6 message.
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* @param[in] aOffset The offset in @p aMessage to read the IPv6 Option.
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* @param[in] aEndOffset The end offset in @p aMessage.
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* @param[in] aMessage The IPv6 message.
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* @param[in] aOffsetRange The offset range in @p aMessage to read the IPv6 Option.
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*
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* @retval kErrorNone Successfully parsed the IPv6 option from @p aMessage.
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* @retval kErrorParse Malformed IPv6 Option or Option is not contained within @p aMessage by @p aEndOffset.
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* @retval kErrorParse Malformed IPv6 Option or Option is not contained within @p aMessage and @p aOffsetRange.
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*
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*/
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Error ParseFrom(const Message &aMessage, uint16_t aOffset, uint16_t aEndOffset);
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Error ParseFrom(const Message &aMessage, const OffsetRange &aOffsetRange);
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protected:
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static constexpr uint8_t kTypePad1 = 0x00; ///< Pad1 Option Type.
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@@ -90,14 +90,14 @@ void Mpl::InitOption(MplOption &aOption, const Address &aAddress)
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aOption.SetSequence(mSequence++);
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}
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Error Mpl::ProcessOption(Message &aMessage, uint16_t aOffset, const Address &aAddress, bool &aReceive)
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Error Mpl::ProcessOption(Message &aMessage, const OffsetRange &aOffsetRange, const Address &aAddress, bool &aReceive)
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{
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Error error;
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MplOption option;
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// Read the min size bytes first, then check the expected
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// `SeedIdLength` and read the full `MplOption` if needed.
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SuccessOrExit(error = aMessage.Read(aOffset, &option, MplOption::kMinSize));
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SuccessOrExit(error = aMessage.Read(aOffsetRange, &option, MplOption::kMinSize));
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switch (option.GetSeedIdLength())
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{
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@@ -108,7 +108,7 @@ Error Mpl::ProcessOption(Message &aMessage, uint16_t aOffset, const Address &aAd
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break;
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case MplOption::kSeedIdLength2:
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SuccessOrExit(error = aMessage.Read(aOffset, option));
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SuccessOrExit(error = aMessage.Read(aOffsetRange, option));
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break;
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case MplOption::kSeedIdLength8:
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@@ -191,17 +191,17 @@ public:
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* MPL Seed it allows to send the first MPL Data Message directly, then sets up Trickle
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* timer expirations for subsequent retransmissions.
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*
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* @param[in] aMessage A reference to the message.
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* @param[in] aOffset The offset in @p aMessage to read the MPL option.
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* @param[in] aAddress A reference to the IPv6 Source Address.
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* @param[out] aReceive Set to FALSE if the MPL message is a duplicate and must not
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* go through the receiving process again, untouched otherwise.
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* @param[in] aMessage A reference to the message.
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* @param[in] aOffsetRange The offset range in @p aMessage to read the MPL option.
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* @param[in] aAddress A reference to the IPv6 Source Address.
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* @param[out] aReceive Set to FALSE if the MPL message is a duplicate and must not
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* go through the receiving process again, untouched otherwise.
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*
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* @retval kErrorNone Successfully processed the MPL option.
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* @retval kErrorDrop The MPL message is a duplicate and should be dropped.
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*
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*/
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Error ProcessOption(Message &aMessage, uint16_t aOffset, const Address &aAddress, bool &aReceive);
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Error ProcessOption(Message &aMessage, const OffsetRange &aOffsetRange, const Address &aAddress, bool &aReceive);
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#if OPENTHREAD_FTD
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/**
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@@ -470,14 +470,15 @@ Error Lowpan::CompressExtensionHeader(Message &aMessage, FrameBuilder &aFrameBui
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// Pad1 or PadN option MAY be elided by the compressor."
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if (aNextHeader == Ip6::kProtoHopOpts || aNextHeader == Ip6::kProtoDstOpts)
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{
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uint16_t offset = aMessage.GetOffset();
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uint16_t endOffset = offset + len;
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OffsetRange offsetRange;
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bool hasOption = false;
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Ip6::Option option;
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for (; offset < endOffset; offset += option.GetSize())
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offsetRange.Init(aMessage.GetOffset(), len);
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for (; !offsetRange.IsEmpty(); offsetRange.AdvanceOffset(option.GetSize()))
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{
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SuccessOrExit(error = option.ParseFrom(aMessage, offset, endOffset));
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SuccessOrExit(error = option.ParseFrom(aMessage, offsetRange));
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hasOption = true;
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}
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