diff options
Diffstat (limited to 'pkg/tcpip/header/ipv6_extension_headers.go')
| -rw-r--r-- | pkg/tcpip/header/ipv6_extension_headers.go | 113 |
1 files changed, 83 insertions, 30 deletions
diff --git a/pkg/tcpip/header/ipv6_extension_headers.go b/pkg/tcpip/header/ipv6_extension_headers.go index 3499d8399..583c2c5d3 100644 --- a/pkg/tcpip/header/ipv6_extension_headers.go +++ b/pkg/tcpip/header/ipv6_extension_headers.go @@ -149,6 +149,19 @@ func (b ipv6OptionsExtHdr) Iter() IPv6OptionsExtHdrOptionsIterator { // obtained before modification is no longer used. type IPv6OptionsExtHdrOptionsIterator struct { reader bytes.Reader + + // optionOffset is the number of bytes from the first byte of the + // options field to the beginning of the current option. + optionOffset uint32 + + // nextOptionOffset is the offset of the next option. + nextOptionOffset uint32 +} + +// OptionOffset returns the number of bytes parsed while processing the +// option field of the current Extension Header. +func (i *IPv6OptionsExtHdrOptionsIterator) OptionOffset() uint32 { + return i.optionOffset } // IPv6OptionUnknownAction is the action that must be taken if the processing @@ -226,6 +239,7 @@ func (*IPv6UnknownExtHdrOption) isIPv6ExtHdrOption() {} // the options data, or an error occured. func (i *IPv6OptionsExtHdrOptionsIterator) Next() (IPv6ExtHdrOption, bool, error) { for { + i.optionOffset = i.nextOptionOffset temp, err := i.reader.ReadByte() if err != nil { // If we can't read the first byte of a new option, then we know the @@ -238,6 +252,7 @@ func (i *IPv6OptionsExtHdrOptionsIterator) Next() (IPv6ExtHdrOption, bool, error // know the option does not have Length and Data fields. End processing of // the Pad1 option and continue processing the buffer as a new option. if id == ipv6Pad1ExtHdrOptionIdentifier { + i.nextOptionOffset = i.optionOffset + 1 continue } @@ -254,41 +269,40 @@ func (i *IPv6OptionsExtHdrOptionsIterator) Next() (IPv6ExtHdrOption, bool, error return nil, true, fmt.Errorf("error when reading the option's Length field for option with id = %d: %w", id, io.ErrUnexpectedEOF) } - // Special-case the variable length padding option to avoid a copy. - if id == ipv6PadNExtHdrOptionIdentifier { - // Do we have enough bytes in the reader for the PadN option? - if n := i.reader.Len(); n < int(length) { - // Reset the reader to effectively consume the remaining buffer. - i.reader.Reset(nil) - - // We return the same error as if we failed to read a non-padding option - // so consumers of this iterator don't need to differentiate between - // padding and non-padding options. - return nil, true, fmt.Errorf("read %d out of %d option data bytes for option with id = %d: %w", n, length, id, io.ErrUnexpectedEOF) - } + // Do we have enough bytes in the reader for the next option? + if n := i.reader.Len(); n < int(length) { + // Reset the reader to effectively consume the remaining buffer. + i.reader.Reset(nil) + + // We return the same error as if we failed to read a non-padding option + // so consumers of this iterator don't need to differentiate between + // padding and non-padding options. + return nil, true, fmt.Errorf("read %d out of %d option data bytes for option with id = %d: %w", n, length, id, io.ErrUnexpectedEOF) + } + + i.nextOptionOffset = i.optionOffset + uint32(length) + 1 /* option ID */ + 1 /* length byte */ + switch id { + case ipv6PadNExtHdrOptionIdentifier: + // Special-case the variable length padding option to avoid a copy. if _, err := i.reader.Seek(int64(length), io.SeekCurrent); err != nil { panic(fmt.Sprintf("error when skipping PadN (N = %d) option's data bytes: %s", length, err)) } - - // End processing of the PadN option and continue processing the buffer as - // a new option. continue - } - - bytes := make([]byte, length) - if n, err := io.ReadFull(&i.reader, bytes); err != nil { - // io.ReadFull may return io.EOF if i.reader has been exhausted. We use - // io.ErrUnexpectedEOF instead as the io.EOF is unexpected given the - // Length field found in the option. - if err == io.EOF { - err = io.ErrUnexpectedEOF + default: + bytes := make([]byte, length) + if n, err := io.ReadFull(&i.reader, bytes); err != nil { + // io.ReadFull may return io.EOF if i.reader has been exhausted. We use + // io.ErrUnexpectedEOF instead as the io.EOF is unexpected given the + // Length field found in the option. + if err == io.EOF { + err = io.ErrUnexpectedEOF + } + + return nil, true, fmt.Errorf("read %d out of %d option data bytes for option with id = %d: %w", n, length, id, err) } - - return nil, true, fmt.Errorf("read %d out of %d option data bytes for option with id = %d: %w", n, length, id, err) + return &IPv6UnknownExtHdrOption{Identifier: id, Data: bytes}, false, nil } - - return &IPv6UnknownExtHdrOption{Identifier: id, Data: bytes}, false, nil } } @@ -382,6 +396,29 @@ type IPv6PayloadIterator struct { // Indicates to the iterator that it should return the remaining payload as a // raw payload on the next call to Next. forceRaw bool + + // headerOffset is the offset of the beginning of the current extension + // header starting from the beginning of the fixed header. + headerOffset uint32 + + // parseOffset is the byte offset into the current extension header of the + // field we are currently examining. It can be added to the header offset + // if the absolute offset within the packet is required. + parseOffset uint32 + + // nextOffset is the offset of the next header. + nextOffset uint32 +} + +// HeaderOffset returns the offset to the start of the extension +// header most recently processed. +func (i IPv6PayloadIterator) HeaderOffset() uint32 { + return i.headerOffset +} + +// ParseOffset returns the number of bytes successfully parsed. +func (i IPv6PayloadIterator) ParseOffset() uint32 { + return i.headerOffset + i.parseOffset } // MakeIPv6PayloadIterator returns an iterator over the IPv6 payload containing @@ -397,7 +434,8 @@ func MakeIPv6PayloadIterator(nextHdrIdentifier IPv6ExtensionHeaderIdentifier, pa nextHdrIdentifier: nextHdrIdentifier, payload: payload.Clone(nil), // We need a buffer of size 1 for calls to bufio.Reader.ReadByte. - reader: *bufio.NewReaderSize(io.MultiReader(readerPs...), 1), + reader: *bufio.NewReaderSize(io.MultiReader(readerPs...), 1), + nextOffset: IPv6FixedHeaderSize, } } @@ -434,6 +472,8 @@ func (i *IPv6PayloadIterator) AsRawHeader(consume bool) IPv6RawPayloadHeader { // Next is unable to return anything because the iterator has reached the end of // the payload, or an error occured. func (i *IPv6PayloadIterator) Next() (IPv6PayloadHeader, bool, error) { + i.headerOffset = i.nextOffset + i.parseOffset = 0 // We could be forced to return i as a raw header when the previous header was // a fragment extension header as the data following the fragment extension // header may not be complete. @@ -461,7 +501,7 @@ func (i *IPv6PayloadIterator) Next() (IPv6PayloadHeader, bool, error) { return IPv6RoutingExtHdr(bytes), false, nil case IPv6FragmentExtHdrIdentifier: var data [6]byte - // We ignore the returned bytes becauase we know the fragment extension + // We ignore the returned bytes because we know the fragment extension // header specific data will fit in data. nextHdrIdentifier, _, err := i.nextHeaderData(true /* fragmentHdr */, data[:]) if err != nil { @@ -519,10 +559,12 @@ func (i *IPv6PayloadIterator) nextHeaderData(fragmentHdr bool, bytes []byte) (IP if err != nil { return 0, nil, fmt.Errorf("error when reading the Next Header field for extension header with id = %d: %w", i.nextHdrIdentifier, err) } + i.parseOffset++ var length uint8 length, err = i.reader.ReadByte() i.payload.TrimFront(1) + if err != nil { if fragmentHdr { return 0, nil, fmt.Errorf("error when reading the Length field for extension header with id = %d: %w", i.nextHdrIdentifier, err) @@ -534,6 +576,17 @@ func (i *IPv6PayloadIterator) nextHeaderData(fragmentHdr bool, bytes []byte) (IP length = 0 } + // Make parseOffset point to the first byte of the Extension Header + // specific data. + i.parseOffset++ + + // length is in 8 byte chunks but doesn't include the first one. + // See RFC 8200 for each header type, sections 4.3-4.6 and the requirement + // in section 4.8 for new extension headers at the top of page 24. + // [ Hdr Ext Len ] ... Length of the Destination Options header in 8-octet + // units, not including the first 8 octets. + i.nextOffset += uint32((length + 1) * ipv6ExtHdrLenBytesPerUnit) + bytesLen := int(length)*ipv6ExtHdrLenBytesPerUnit + ipv6ExtHdrLenBytesExcluded if bytes == nil { bytes = make([]byte, bytesLen) |