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use super::super::*;
use std::slice::from_raw_parts;
/// IPv6 extension headers present after the ip header.
///
/// Currently supported:
///
/// * Authentication Header
/// * Hop by Hop Options Header
/// * Destination Options Header (before and after routing headers)
/// * Routing Header
/// * Fragment
/// * Authentication Header
///
/// Currently not supported:
////
/// * Encapsulating Security Payload Header (ESP)
/// * Host Identity Protocol (HIP)
/// * IP Mobility
/// * Site Multihoming by IPv6 Intermediation (SHIM6)
#[derive(Clone, Debug, Eq, PartialEq, Default)]
pub struct Ipv6Extensions {
pub hop_by_hop_options: Option<Ipv6RawExtensionHeader>,
pub destination_options: Option<Ipv6RawExtensionHeader>,
pub routing: Option<Ipv6RoutingExtensions>,
pub fragment: Option<Ipv6FragmentHeader>,
pub auth: Option<IpAuthenticationHeader>,
}
impl Ipv6Extensions {
/// Reads as many extension headers as possible from the slice.
///
/// Returns the found ipv6 extension headers, the next header ip number after the read
/// headers and a slice containing the rest of the packet after the read headers.
///
/// Note that this function can only handle ipv6 extensions if each extension header does
/// occur at most once, except for destination options headers which are allowed to
/// exist once in front of a routing header and once after a routing header.
///
/// In case that more extension headers then can fit into a `Ipv6Extensions` struct are
/// encountered, the parsing is stoped at the point where the data would no longer fit into
/// the struct. In such a scenario a struct with the data that could be parsed is returned
/// together with the next header ip number and slice containing the unparsed data.
///
/// It is in the responsibility of the caller to handle a scenario like this.
///
/// The reason that no error is generated, is that even though according to RFC 8200 packets
/// "should" not contain more then one occurence of an extension header the RFC also specifies
/// that "IPv6 nodes must accept and attempt to process extension headers in any order and
/// occurring any number of times in the same packet". So packets with multiple headers "should"
/// not exist, but are still valid IPv6 packets. As such this function does not generate a
/// parsing error, as it is not an invalid packet, but if packets like these are encountered
/// the user of this function has to themself decide how to handle packets like these.
///
/// The only exception is if an hop by hop header is located somewhere else then directly at
/// the start. In this case an `ReadError::Ipv6HopByHopHeaderNotAtStart` error is generated as
/// the hop by hop header is required to be located directly after the IPv6 header according
/// to RFC 8200.
pub fn from_slice(start_ip_number: u8, slice: &[u8]) -> Result<(Ipv6Extensions, u8, &[u8]), ReadError> {
let mut result: Ipv6Extensions = Default::default();
let mut rest = slice;
let mut next_header = start_ip_number;
use ip_number::*;
use ReadError::*;
// the hop by hop header is required to occur directly after the ipv6 header
if IPV6_HOP_BY_HOP == next_header {
let slice = Ipv6RawExtensionHeaderSlice::from_slice(rest)?;
rest = &rest[slice.slice().len()..];
next_header = slice.next_header();
result.hop_by_hop_options = Some(slice.to_header());
}
loop {
match next_header {
IPV6_HOP_BY_HOP => {
return Err(Ipv6HopByHopHeaderNotAtStart);
},
IPV6_DEST_OPTIONS => {
if let Some(ref mut routing) = result.routing {
// if the routing header is already present
// this this a "final destination options" header
if routing.final_destination_options.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_header, rest))
} else {
let slice = Ipv6RawExtensionHeaderSlice::from_slice(rest)?;
rest = &rest[slice.slice().len()..];
next_header = slice.next_header();
routing.final_destination_options = Some(slice.to_header());
}
} else if result.destination_options.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_header, rest));
} else {
let slice = Ipv6RawExtensionHeaderSlice::from_slice(rest)?;
rest = &rest[slice.slice().len()..];
next_header = slice.next_header();
result.destination_options = Some(slice.to_header());
}
},
IPV6_ROUTE => {
if result.routing.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_header, rest))
} else {
let slice = Ipv6RawExtensionHeaderSlice::from_slice(rest)?;
rest = &rest[slice.slice().len()..];
next_header = slice.next_header();
result.routing = Some(
Ipv6RoutingExtensions {
routing: slice.to_header(),
final_destination_options: None,
}
);
}
},
IPV6_FRAG => {
if result.fragment.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_header, rest))
} else {
let slice = Ipv6FragmentHeaderSlice::from_slice(rest)?;
rest = &rest[slice.slice().len()..];
next_header = slice.next_header();
result.fragment = Some(slice.to_header());
}
},
AUTH => {
if result.auth.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_header, rest))
} else {
let slice = IpAuthenticationHeaderSlice::from_slice(rest)?;
rest = &rest[slice.slice().len()..];
next_header = slice.next_header();
result.auth = Some(slice.to_header());
}
},
_ => {
// done parsing, the next header is not a known header extension
return Ok((result, next_header, rest))
}
}
}
//should not be hit
}
/// Reads as many extension headers as possible from the reader and returns the found ipv6
/// extension headers and the next header ip number.
///
/// If no extension headers are present an unfilled struct and the original `first_header`
/// ip number is returned.
///
/// Note that this function can only handle ipv6 extensions if each extension header does
/// occur at most once, except for destination options headers which are allowed to
/// exist once in front of a routing header and once after a routing header.
///
/// In case that more extension headers then can fit into a `Ipv6Extensions` struct are
/// encountered, the parsing is stoped at the point where the data would no longer fit into
/// the struct. In such a scenario a struct with the data that could be parsed is returned
/// together with the next header ip number that identfies which header could be read next.
///
/// It is in the responsibility of the caller to handle a scenario like this.
///
/// The reason that no error is generated, is that even though according to RFC 8200, packets
/// "should" not contain more then one occurence of an extension header, the RFC also specifies
/// that "IPv6 nodes must accept and attempt to process extension headers in any order and
/// occurring any number of times in the same packet". So packets with multiple headers "should"
/// not exist, but are still valid IPv6 packets. As such this function does not generate a
/// parsing error, as it is not an invalid packet, but if packets like these are encountered
/// the user of this function has to themself decide how to handle packets like these.
///
/// The only exception is if an hop by hop header is located somewhere else then directly at
/// the start. In this case an `ReadError::Ipv6HopByHopHeaderNotAtStart` error is generated as
/// the hop by hop header is required to be located directly after the IPv6 header according
/// to RFC 8200.
pub fn read<T: io::Read + io::Seek + Sized>(reader: &mut T, start_ip_number: u8) -> Result<(Ipv6Extensions, u8), ReadError> {
let mut result: Ipv6Extensions = Default::default();
let mut next_protocol = start_ip_number;
use ip_number::*;
use ReadError::*;
// the hop by hop header is required to occur directly after the ipv6 header
if IPV6_HOP_BY_HOP == next_protocol {
let header = Ipv6RawExtensionHeader::read(reader)?;
next_protocol = header.next_header;
result.hop_by_hop_options = Some(header);
}
loop {
match next_protocol {
IPV6_HOP_BY_HOP => {
return Err(Ipv6HopByHopHeaderNotAtStart);
},
IPV6_DEST_OPTIONS => {
if let Some(ref mut routing) = result.routing {
// if the routing header is already present
// asume this is a "final destination options" header
if routing.final_destination_options.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_protocol));
} else {
let header = Ipv6RawExtensionHeader::read(reader)?;
next_protocol = header.next_header;
routing.final_destination_options = Some(header);
}
} else if result.destination_options.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_protocol));
} else {
let header = Ipv6RawExtensionHeader::read(reader)?;
next_protocol = header.next_header;
result.destination_options = Some(header);
}
},
IPV6_ROUTE => {
if result.routing.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_protocol));
} else {
let header = Ipv6RawExtensionHeader::read(reader)?;
next_protocol = header.next_header;
result.routing = Some(
Ipv6RoutingExtensions{
routing: header,
final_destination_options: None,
}
);
}
},
IPV6_FRAG => {
if result.fragment.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_protocol));
} else {
let header = Ipv6FragmentHeader::read(reader)?;
next_protocol = header.next_header;
result.fragment = Some(header);
}
},
AUTH => {
if result.auth.is_some() {
// more then one header of this type found -> abort parsing
return Ok((result, next_protocol));
} else {
let header = IpAuthenticationHeader::read(reader)?;
next_protocol = header.next_header;
result.auth = Some(header);
}
},
_ => {
// done parsing, the next header is not a known header extension
return Ok((result, next_protocol))
}
}
}
//should not be hit
}
/// Writes the given headers to a writer based on the order defined in the next_header fields of
/// the headers and the first header_id passed to this function.
///
/// It is required that all next header are correctly set in the headers and no other ipv6 header
/// extensions follow this header. If this is not the case a `ValueError::Ipv6ExtensionNotReferenced`
pub fn write<T: io::Write + Sized>(&self, writer: &mut T, first_header: u8) -> Result<(), WriteError> {
use ip_number::*;
use IpNumber::*;
use ValueError::*;
/// Struct flagging if a header needs to be written.
struct NeedsWrite {
pub hop_by_hop_options: bool,
pub destination_options: bool,
pub routing: bool,
pub fragment: bool,
pub auth: bool,
pub final_destination_options: bool
}
let mut needs_write = NeedsWrite {
hop_by_hop_options: self.hop_by_hop_options.is_some(),
destination_options: self.destination_options.is_some(),
routing: self.routing.is_some(),
fragment: self.fragment.is_some(),
auth: self.auth.is_some(),
final_destination_options: if let Some(ref routing) = self.routing {
routing.final_destination_options.is_some()
} else {
false
}
};
let mut next_header = first_header;
let mut route_written = false;
// check if hop by hop header should be written first
if IPV6_HOP_BY_HOP == next_header {
let header = &self.hop_by_hop_options.as_ref().unwrap();
header.write(writer)?;
next_header = header.next_header;
needs_write.hop_by_hop_options = false;
}
loop {
match next_header {
IPV6_HOP_BY_HOP => {
// Only trigger a "hop by hop not at start" error
// if we actually still have to write a hop by hop header.
//
// The ip number for hop by hop is 0, which could be used
// as a placeholder by user and later replaced. So let's
// not be overzealous and allow a next header with hop
// by hop if it is not part of this extensions struct.
if needs_write.hop_by_hop_options {
// the hop by hop header is only allowed at the start
return Err(Ipv6ExtensionHopByHopNotAtStart.into());
} else {
break;
}
},
IPV6_DEST_OPTIONS => {
// the destination options are allowed to be written twice
// once before a routing header and once after.
if route_written {
if needs_write.final_destination_options {
let header = &self.routing.as_ref().unwrap().final_destination_options.as_ref().unwrap();
header.write(writer)?;
next_header = header.next_header;
needs_write.final_destination_options = false;
} else {
break;
}
} else if needs_write.destination_options {
let header = &self.destination_options.as_ref().unwrap();
header.write(writer)?;
next_header = header.next_header;
needs_write.destination_options = false;
} else {
break;
}
},
IPV6_ROUTE => {
if needs_write.routing {
let header = &self.routing.as_ref().unwrap().routing;
header.write(writer)?;
next_header = header.next_header;
needs_write.routing = false;
// for destination options
route_written = true;
} else {
break;
}
},
IPV6_FRAG => {
if needs_write.fragment {
let header = &self.fragment.as_ref().unwrap();
header.write(writer)?;
next_header = header.next_header;
needs_write.fragment = false;
} else {
break;
}
},
AUTH => {
if needs_write.auth {
let header = &self.auth.as_ref().unwrap();
header.write(writer)?;
next_header = header.next_header;
needs_write.auth = false;
} else {
break;
}
},
_ => {
// reached an unknown next_header id, proceed to check if everything was written
break;
}
}
}
// check that all header have been written
if needs_write.hop_by_hop_options {
Err(Ipv6ExtensionNotReferenced(IPv6HeaderHopByHop).into())
} else if needs_write.destination_options {
Err(Ipv6ExtensionNotReferenced(IPv6DestinationOptions).into())
} else if needs_write.routing {
Err(Ipv6ExtensionNotReferenced(IPv6RouteHeader).into())
} else if needs_write.fragment {
Err(Ipv6ExtensionNotReferenced(IPv6FragmentationHeader).into())
} else if needs_write.auth {
Err(Ipv6ExtensionNotReferenced(AuthenticationHeader).into())
} else if needs_write.final_destination_options {
Err(Ipv6ExtensionNotReferenced(IPv6DestinationOptions).into())
} else {
Ok(())
}
}
/// Length of the all present headers in bytes.
pub fn header_len(&self) -> usize {
let mut result = 0;
if let Some(ref header) = self.hop_by_hop_options {
result += header.header_len();
}
if let Some(ref header) = self.destination_options {
result += header.header_len();
}
if let Some(ref header) = self.routing {
result += header.routing.header_len();
if let Some(ref header) = header.final_destination_options {
result += header.header_len();
}
}
if let Some(ref header) = self.fragment {
result += header.header_len();
}
if let Some(ref header) = self.auth {
result += header.header_len();
}
result
}
/// Sets all the next_header fields of the headers based on the adviced default order
/// with the given protocol number as last "next header" value. The return value is the protocol
/// number of the first existing extension header that should be entered in the ipv6 header as
/// next_header.
///
/// If no extension headers are present the value of the argument is returned.
pub fn set_next_headers(&mut self, last_protocol_number: u8) -> u8 {
use ip_number::*;
let mut next = last_protocol_number;
// go through the proposed order of extension headers from
// RFC 8200 backwards. The header order defined in RFC8200 is:
//
// * IPv6 header
// * Hop-by-Hop Options header
// * Destination Options header
// * Routing header
// * Fragment header
// * Authentication header
// * Encapsulating Security Payload header
// * Destination Options header
// * Upper-Layer header
//
if let Some(ref mut routing) = self.routing {
if let Some(ref mut header) = routing.final_destination_options {
header.next_header = next;
next = IPV6_DEST_OPTIONS;
}
}
if let Some(ref mut header) = self.auth {
header.next_header = next;
next = AUTH;
}
if let Some(ref mut header) = self.fragment {
header.next_header = next;
next = IPV6_FRAG;
}
if let Some(ref mut routing) = self.routing {
routing.routing.next_header = next;
next = IPV6_ROUTE;
}
if let Some(ref mut header) = self.destination_options {
header.next_header = next;
next = IPV6_DEST_OPTIONS;
}
if let Some(ref mut header) = self.hop_by_hop_options {
header.next_header = next;
next = IPV6_HOP_BY_HOP;
}
next
}
/// Return next header based on the extension headers and
/// the first ip protocol number.
pub fn next_header(&self, first_next_header: u8) -> Result<u8, ValueError> {
use ValueError::*;
use ip_number::*;
/// Struct flagging if a header needs to be referenced.
struct OutstandingRef {
pub hop_by_hop_options: bool,
pub destination_options: bool,
pub routing: bool,
pub fragment: bool,
pub auth: bool,
pub final_destination_options: bool
}
let mut outstanding_refs = OutstandingRef {
hop_by_hop_options: self.hop_by_hop_options.is_some(),
destination_options: self.destination_options.is_some(),
routing: self.routing.is_some(),
fragment: self.fragment.is_some(),
auth: self.auth.is_some(),
final_destination_options: if let Some(ref routing) = self.routing {
routing.final_destination_options.is_some()
} else {
false
}
};
let mut next = first_next_header;
let mut route_refed = false;
// check if hop by hop header should be written first
if IPV6_HOP_BY_HOP == next {
if let Some(ref header) = self.hop_by_hop_options {
next = header.next_header;
outstanding_refs.hop_by_hop_options = false;
}
}
loop {
match next {
IPV6_HOP_BY_HOP => {
// Only trigger a "hop by hop not at start" error
// if we actually still have to write a hop by hop header.
//
// The ip number for hop by hop is 0, which could be used
// as a placeholder by user and later replaced. So let's
// not be overzealous and allow a next header with hop
// by hop if it is not part of this extensions struct.
if outstanding_refs.hop_by_hop_options {
// the hop by hop header is only allowed at the start
return Err(Ipv6ExtensionHopByHopNotAtStart);
} else {
break;
}
},
IPV6_DEST_OPTIONS => {
// the destination options are allowed to be written twice
// once before a routing header and once after.
if route_refed {
if outstanding_refs.final_destination_options {
let header = &self.routing.as_ref().unwrap().final_destination_options.as_ref().unwrap();
next = header.next_header;
outstanding_refs.final_destination_options = false;
} else {
break;
}
} else if outstanding_refs.destination_options {
let header = &self.destination_options.as_ref().unwrap();
next = header.next_header;
outstanding_refs.destination_options = false;
} else {
break;
}
},
IPV6_ROUTE => {
if outstanding_refs.routing {
let header = &self.routing.as_ref().unwrap().routing;
next = header.next_header;
outstanding_refs.routing = false;
// for destination options
route_refed = true;
} else {
break;
}
},
IPV6_FRAG => {
if outstanding_refs.fragment {
let header = &self.fragment.as_ref().unwrap();
next = header.next_header;
outstanding_refs.fragment = false;
} else {
break;
}
},
AUTH => {
if outstanding_refs.auth {
let header = &self.auth.as_ref().unwrap();
next = header.next_header;
outstanding_refs.auth = false;
} else {
break;
}
},
_ => break,
}
}
// assume all done
if outstanding_refs.hop_by_hop_options {
return Err(
Ipv6ExtensionNotReferenced(IpNumber::IPv6HeaderHopByHop)
);
}
if outstanding_refs.destination_options {
return Err(
Ipv6ExtensionNotReferenced(IpNumber::IPv6DestinationOptions)
);
}
if outstanding_refs.routing {
return Err(
Ipv6ExtensionNotReferenced(IpNumber::IPv6RouteHeader)
);
}
if outstanding_refs.fragment {
return Err(
Ipv6ExtensionNotReferenced(IpNumber::IPv6FragmentationHeader)
);
}
if outstanding_refs.auth {
return Err(
Ipv6ExtensionNotReferenced(IpNumber::AuthenticationHeader)
);
}
if outstanding_refs.final_destination_options {
return Err(
Ipv6ExtensionNotReferenced(IpNumber::IPv6DestinationOptions)
);
}
Ok(next)
}
/// Returns true if a fragmentation header is present in
/// the extensions that fragments the payload.
///
/// Note: A fragmentation header can still be present
/// even if the return value is false in case the fragmentation
/// headers don't fragment the payload. This is the case if
/// the offset of all fragmentation header is 0 and the
/// more fragment bit is not set.
#[inline]
pub fn is_fragmenting_payload(&self) -> bool {
if let Some(frag) = self.fragment.as_ref() {
frag.is_fragmenting_payload()
} else {
false
}
}
/// Returns true if no IPv6 extension header is present (all fields `None`).
#[inline]
pub fn is_empty(&self) -> bool {
self.hop_by_hop_options.is_none() &&
self.destination_options.is_none() &&
self.routing.is_none() &&
self.fragment.is_none() &&
self.auth.is_none()
}
}
/// In case a route header is present it is also possible
/// to attach a "final destination" header.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Ipv6RoutingExtensions {
pub routing: Ipv6RawExtensionHeader,
pub final_destination_options: Option<Ipv6RawExtensionHeader>
}
/// Slice containing the IPv6 extension headers present after the ip header.
///
/// Currently supported:
/// * Authentication Header
/// * Hop by Hop Options Header
/// * Destination Options Header (before and after routing headers)
/// * Routing Header
/// * Fragment
/// * Authentication Header
///
/// Currently not supported:
/// * Encapsulating Security Payload Header (ESP)
/// * Host Identity Protocol (HIP)
/// * IP Mobility
/// * Site Multihoming by IPv6 Intermediation (SHIM6)
#[derive(Clone, Debug, Eq, PartialEq, Default)]
pub struct Ipv6ExtensionsSlice<'a> {
/// IP protocol number of the first header present in the slice.
first_header: Option<u8>,
/// True if a fragment header is present in the ipv6 header extensions that causes the payload to be fragmented.
fragmented: bool,
/// Slice containing ipv6 extension headers.
slice: &'a [u8]
}
impl<'a> Ipv6ExtensionsSlice<'a> {
/// Collects all ipv6 extension headers in a slice & checks if
/// a fragmentation header that fragments the packet is present.
pub fn from_slice(start_ip_number: u8, start_slice: &'a [u8]) -> Result<(Ipv6ExtensionsSlice, u8, &'a[u8]), ReadError> {
let mut rest = start_slice;
let mut next_header = start_ip_number;
let mut fragmented = false;
use ip_number::*;
use ReadError::*;
// the hop by hop header is required to occur directly after the ipv6 header
if IPV6_HOP_BY_HOP == next_header {
let slice = Ipv6RawExtensionHeaderSlice::from_slice(rest)?;
rest = &rest[slice.slice().len()..];
next_header = slice.next_header();
}
loop {
match next_header {
IPV6_HOP_BY_HOP => {
return Err(Ipv6HopByHopHeaderNotAtStart);
},
IPV6_DEST_OPTIONS | IPV6_ROUTE => {
let slice = Ipv6RawExtensionHeaderSlice::from_slice(rest)?;
// SAFETY:
// Ipv6RawExtensionHeaderSlice::from_slice always generates
// a subslice from the given slice rest. Therefor it is guranteed
// that len is always greater or equal the len of rest.
rest = unsafe {
let len = slice.slice().len();
from_raw_parts(
rest.as_ptr().add(len),
rest.len() - len
)
};
next_header = slice.next_header();
},
IPV6_FRAG => {
let slice = Ipv6FragmentHeaderSlice::from_slice(rest)?;
// SAFETY:
// Ipv6FragmentHeaderSlice::from_slice always generates
// a subslice from the given slice rest. Therefor it is guranteed
// that len is always greater or equal the len of rest.
rest = unsafe {
let len = slice.slice().len();
from_raw_parts(
rest.as_ptr().add(len),
rest.len() - len
)
};
next_header = slice.next_header();
// check if the fragment header actually causes fragmentation
fragmented = fragmented || slice.is_fragmenting_payload();
},
AUTH => {
let slice = IpAuthenticationHeaderSlice::from_slice(rest)?;
// SAFETY:
// IpAuthenticationHeaderSlice::from_slice always generates
// a subslice from the given slice rest. Therefor it is guranteed
// that len is always greater or equal the len of rest.
rest = unsafe {
let len = slice.slice().len();
from_raw_parts(
rest.as_ptr().add(len),
rest.len() - len
)
};
next_header = slice.next_header();
},
// done parsing, the next header is not a known/supported header extension
_ => break,
}
}
Ok((Ipv6ExtensionsSlice{
first_header: if rest.len() != start_slice.len() {
Some(start_ip_number)
} else {
None
},
fragmented,
slice: &start_slice[..start_slice.len() - rest.len()],
}, next_header, rest))
}
/// Returns true if a fragmentation header is present in
/// the extensions that fragments the payload.
///
/// Note: A fragmentation header can still be present
/// even if the return value is false in case the fragmentation
/// headers don't fragment the payload. This is the case if
/// the offset of all fragmentation header is 0 and the
/// more fragment bit is not set.
#[inline]
pub fn is_fragmenting_payload(&self) -> bool {
self.fragmented
}
/// Returns the ip protocol number of the first header in the slice
/// if the slice contains an ipv6 extension header. If no ipv6 header
/// is present None is returned.
///
/// None is only returned if the slice length of this struct is 0.
#[inline]
pub fn first_header(&self) -> Option<u8> {
self.first_header
}
/// Slice containing the ipv6 extension headers.
#[inline]
pub fn slice(&self) -> &'a[u8] {
self.slice
}
/// Returns true if no IPv6 extension header is present (slice is empty).
#[inline]
pub fn is_empty(&self) -> bool {
self.slice.is_empty()
}
}
/// Enum containing a slice of a supported ipv6 extension header.
///
/// This enum is used as item type when iterating over a list of extension headers
/// with an [Ipv6ExtensionSliceIter].
///
/// Note the following extension headers are missing from
/// this enum and currently not supported (list taken on 2021-07-17
/// from <https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml>):
///
/// * Encapsulating Security Payload \[[RFC4303](https://datatracker.ietf.org/doc/html/rfc4303)\]
/// * Mobility Header \[[RFC6275](https://datatracker.ietf.org/doc/html/rfc6275)\]
/// * Host Identity Protocol \[[RFC7401](https://datatracker.ietf.org/doc/html/rfc7401)\]
/// * Shim6 Protocol \[[RFC5533](https://datatracker.ietf.org/doc/html/rfc5533)\]
/// * 253 Use for experimentation and testing \[[RFC3692](https://datatracker.ietf.org/doc/html/rfc3692)\]\[[RFC4727](https://datatracker.ietf.org/doc/html/rfc4727)\]
/// * 254 Use for experimentation and testing \[[RFC3692](https://datatracker.ietf.org/doc/html/rfc3692)\]\[[RFC4727](https://datatracker.ietf.org/doc/html/rfc4727)\]
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum Ipv6ExtensionSlice<'a> {
/// IPv6 Hop-by-Hop Option \[[RFC8200](https://datatracker.ietf.org/doc/html/rfc8200)\]
HopByHop(Ipv6RawExtensionHeaderSlice<'a>),
/// Routing Header for IPv6 \[[RFC8200](https://datatracker.ietf.org/doc/html/rfc8200)\] \[[RFC5095](https://datatracker.ietf.org/doc/html/rfc5095)\]
Routing(Ipv6RawExtensionHeaderSlice<'a>),
/// Fragment Header for IPv6 \[[RFC8200](https://datatracker.ietf.org/doc/html/rfc8200)\]
Fragment(Ipv6FragmentHeaderSlice<'a>),
/// Destination Options for IPv6 \[[RFC8200](https://datatracker.ietf.org/doc/html/rfc8200)\]
DestinationOptions(Ipv6RawExtensionHeaderSlice<'a>),
/// Authentication Header \[[RFC4302](https://datatracker.ietf.org/doc/html/rfc4302)\]
Authentication(IpAuthenticationHeaderSlice<'a>),
}
impl<'a> IntoIterator for Ipv6ExtensionsSlice<'a> {
type Item = Ipv6ExtensionSlice<'a>;
type IntoIter = Ipv6ExtensionSliceIter<'a>;
fn into_iter(self) -> Self::IntoIter {
Ipv6ExtensionSliceIter {
// map the next header None value to some non ipv6 ext header
// value.
next_header: self.first_header.unwrap_or(ip_number::UDP),
rest: self.slice,
}
}
}
/// Allows iterating over the IPv6 extension headers present in an [Ipv6ExtensionsSlice].
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Ipv6ExtensionSliceIter<'a> {
next_header: u8,
rest: &'a [u8],
}
impl<'a> Default for Ipv6ExtensionSliceIter<'a> {
fn default() -> Self {
Ipv6ExtensionSliceIter {
// don't use 0 as this is the reserved value
// for the hop by hop header
next_header: IpNumber::IPv6NoNextHeader as u8,
rest: &[],
}
}
}
impl<'a> Iterator for Ipv6ExtensionSliceIter<'a> {
type Item = Ipv6ExtensionSlice<'a>;
fn next(&mut self) -> Option<Ipv6ExtensionSlice<'a>> {
use ip_number::*;
use Ipv6ExtensionSlice::*;
match self.next_header {
// Note on the unsafe calls:
//
// As the slice contents & length were previously checked by
// Ipv6ExtensionsSlice::from_slice the content does not have to be
// rechecked.
IPV6_HOP_BY_HOP => unsafe {
let slice = Ipv6RawExtensionHeaderSlice::from_slice_unchecked(self.rest);
let len = slice.slice().len();
self.rest = from_raw_parts(
self.rest.as_ptr().add(len),
self.rest.len() - len
);
self.next_header = slice.next_header();
Some(HopByHop(slice))
},
IPV6_ROUTE => unsafe {
let slice = Ipv6RawExtensionHeaderSlice::from_slice_unchecked(self.rest);
let len = slice.slice().len();
self.rest = from_raw_parts(
self.rest.as_ptr().add(len),
self.rest.len() - len
);
self.next_header = slice.next_header();
Some(Routing(slice))
},
IPV6_DEST_OPTIONS => unsafe {
let slice = Ipv6RawExtensionHeaderSlice::from_slice_unchecked(self.rest);
let len = slice.slice().len();
self.rest = from_raw_parts(
self.rest.as_ptr().add(len),
self.rest.len() - len
);
self.next_header = slice.next_header();
Some(DestinationOptions(slice))
},
IPV6_FRAG => unsafe {
let slice = Ipv6FragmentHeaderSlice::from_slice_unchecked(self.rest);
let len = slice.slice().len();
self.rest = from_raw_parts(
self.rest.as_ptr().add(len),
self.rest.len() - len
);
self.next_header = slice.next_header();
Some(Fragment(slice))
},
AUTH => unsafe {
let slice = IpAuthenticationHeaderSlice::from_slice_unchecked(self.rest);
let len = slice.slice().len();
self.rest = from_raw_parts(
self.rest.as_ptr().add(len),
self.rest.len() - len
);
self.next_header = slice.next_header();
Some(Authentication(slice))
},
// done parsing, the next header is not a known/supported header extension
_ => None,
}
}
}