Expand description
Low-level packet access and construction.
The wire module deals with the packet representation. It provides two levels
of functionality.
- First, it provides functions to extract fields from sequences of octets,
and to insert fields into sequences of octets. This happens
Packetfamily of structures, e.g. EthernetFrame or Ipv4Packet. - Second, in cases where the space of valid field values is much smaller than the space
of possible field values, it provides a compact, high-level representation
of packet data that can be parsed from and emitted into a sequence of octets.
This happens through the
Reprfamily of structs and enums, e.g. ArpRepr or Ipv4Repr.
The functions in the wire module are designed for use together with -Cpanic=abort.
The Packet family of data structures guarantees that, if the Packet::check_len() method
returned Ok(()), then no accessor or setter method will panic; however, the guarantee
provided by Packet::check_len() may no longer hold after changing certain fields,
which are listed in the documentation for the specific packet.
The Packet::new_checked method is a shorthand for a combination of Packet::new_unchecked
and Packet::check_len.
When parsing untrusted input, it is necessary to use Packet::new_checked();
so long as the buffer is not modified, no accessor will fail.
When emitting output, though, it is incorrect to use Packet::new_checked();
the length check is likely to succeed on a zeroed buffer, but fail on a buffer
filled with data from a previous packet, such as when reusing buffers, resulting
in nondeterministic panics with some network devices but not others.
The buffer length for emission is not calculated by the Packet layer.
In the Repr family of data structures, the Repr::parse() method never panics
as long as Packet::new_checked() (or Packet::check_len()) has succeeded, and
the Repr::emit() method never panics as long as the underlying buffer is exactly
Repr::buffer_len() octets long.
Examples
To emit an IP packet header into an octet buffer, and then parse it back:
use smoltcp::phy::ChecksumCapabilities;
use smoltcp::wire::*;
let repr = Ipv4Repr {
src_addr: Ipv4Address::new(10, 0, 0, 1),
dst_addr: Ipv4Address::new(10, 0, 0, 2),
protocol: IpProtocol::Tcp,
payload_len: 10,
hop_limit: 64
};
let mut buffer = vec![0; repr.buffer_len() + repr.payload_len];
{ // emission
let mut packet = Ipv4Packet::new_unchecked(&mut buffer);
repr.emit(&mut packet, &ChecksumCapabilities::default());
}
{ // parsing
let packet = Ipv4Packet::new_checked(&buffer)
.expect("truncated packet");
let parsed = Ipv4Repr::parse(&packet, &ChecksumCapabilities::default())
.expect("malformed packet");
assert_eq!(repr, parsed);
}Re-exports
pub use self::pretty_print::PrettyPrinter;pub use self::ieee802154::Address as Ieee802154Address;pub use self::ieee802154::AddressingMode as Ieee802154AddressingMode;pub use self::ieee802154::Frame as Ieee802154Frame;pub use self::ieee802154::FrameType as Ieee802154FrameType;pub use self::ieee802154::FrameVersion as Ieee802154FrameVersion;pub use self::ieee802154::Pan as Ieee802154Pan;pub use self::ieee802154::Repr as Ieee802154Repr;Modules
Pretty-printing of packet representation.
Structs
A read/write wrapper around an Address Resolution Protocol packet buffer.
A read/write wrapper around a Dynamic Host Configuration Protocol packet buffer.
A high-level representation of a Dynamic Host Configuration Protocol packet.
A six-octet Ethernet II address.
A read/write wrapper around an Ethernet II frame buffer.
A high-level representation of an Internet Protocol version 4 packet header.
A read/write wrapper around an Internet Control Message Protocol version 4 packet buffer.
A read/write wrapper around an Internet Control Message Protocol version 6 packet buffer.
A read/write wrapper around an Internet Group Management Protocol v1/v2 packet buffer.
An internet endpoint address.
A four-octet IPv4 address.
A specification of an IPv4 CIDR block, containing an address and a variable-length subnet masking prefix length.
A read/write wrapper around an Internet Protocol version 4 packet buffer.
A high-level representation of an Internet Protocol version 4 packet header.
A sixteen-octet IPv6 address.
A specification of an IPv6 CIDR block, containing an address and a variable-length subnet masking prefix length.
A read/write wrapper around an IPv6 Fragment Header.
A high-level representation of an IPv6 Fragment header.
A read/write wrapper around an IPv6 Hop-by-Hop Options Header.
A high-level representation of an IPv6 Hop-by-Hop Options header.
A read/write wrapper around an IPv6 Extension Header Option.
A read/write wrapper around an Internet Protocol version 6 packet buffer.
A high-level representation of an Internet Protocol version 6 packet header.
A read/write wrapper around an IPv6 Routing Header buffer.
A read/write wrapper around an MLDv2 Listener Report Message Address Record.
A read/write wrapper around an NDISC Option.
Unparsed hardware address.
A read/write wrapper around a LOWPAN_NHC Next Header frame buffer.
A high-level representation of an LOWPAN_NHC Extension Header header.
A read/write wrapper around a LOWPAN_IPHC frame buffer.
A high-level representation of a LOWPAN_IPHC header.
A read/write wrapper around a 6LoWPAN_NHC_UDP frame buffer.
A high-level representation of a LOWPAN_NHC UDP header.
A read/write wrapper around a Transmission Control Protocol packet buffer.
A high-level representation of a Transmission Control Protocol packet.
A TCP sequence number.
A read/write wrapper around an User Datagram Protocol packet buffer.
A high-level representation of an User Datagram Protocol packet.
Enums
ARP hardware type.
ARP operation type.
A high-level representation of an Address Resolution Protocol packet.
The possible message types of a DHCP packet.
Ethernet protocol type.
Representation of an hardware address, such as an Ethernet address or an IEEE802.15.4 address.
Internet protocol control message subtype for type “Destination Unreachable”.
Internet protocol control message type.
Internet protocol control message subtype for type “Parameter Problem”.
Internet protocol control message subtype for type “Redirect Message”.
A high-level representation of an Internet Control Message Protocol version 4 packet header.
Internet protocol control message subtype for type “Time Exceeded”.
Internet protocol control message subtype for type “Destination Unreachable”.
Internet protocol control message type.
Internet protocol control message subtype for the type “Parameter Problem”.
A high-level representation of an Internet Control Message Protocol version 6 packet header.
Internet protocol control message subtype for the type “Time Exceeded”.
A high-level representation of an Internet Group Management Protocol v1/v2 header.
Type of IGMP membership report version
An internetworking address.
A specification of a CIDR block, containing an address and a variable-length subnet masking prefix length.
IP datagram encapsulated protocol.
An IP packet representation.
Internet protocol version.
Action required when parsing the given IPv6 Extension Header Option Type fails
A high-level representation of an IPv6 Extension Header Option.
IPv6 Extension Header Option Type
A high-level representation of an IPv6 Routing Header.
A high-level representation of an MLDv2 packet header.
A high-level representation of an NDISC Option.
NDISC Option Type
A high-level representation of an Neighbor Discovery packet header.
A read/write wrapper around a LOWPAN_NHC frame buffer.
The possible control flags of a Transmission Control Protocol packet.
A representation of a single TCP option.
Constants
The Ethernet header length
Minimum MTU required of all links supporting IPv4. See RFC 791 § 3.1.
Length of an IPv6 header.
Minimum MTU required of all links supporting IPv6. See RFC 8200 § 5.