frameassembly 1.4.3

Compile .fasm code into deterministic .pcap/.pcapng captures across 81 L2-L7 protocols to test firewalls, IDS rules, SNMPv3 traps, Wireshark & Rust.
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//! Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Layer 7 field parser.
//!
//! This module implements the `winnow` parser combinator for RFC 2131 DHCPv4 and RFC 8415 DHCPv6
//! (`DHCP`) frames in FrameAssembly `.fasm` specifications. It recognizes the `DHCP` protocol
//! keyword, message type flags (`DISCOVER`, `SOLICIT`, `OFFER`, `ADVERTISE`, `REQUEST`, `ACK`,
//! `REPLY`, `RELEASE`), transaction IDs (`XID`), client/your/server IP addresses (`CIADDR`,
//! `YIADDR`, `SIADDR`), client hardware MACs (`CHADDR`), and DHCP options (`HOSTNAME`,
//! `DNS_SERVER`, `ROUTER`, `SUBNET_MASK`, `LEASE_TIME`).

use winnow::ModalResult as PResult;
use winnow::combinator::{alt, cut_err};
use winnow::prelude::*;

use crate::ast::*;
use crate::lexer::Token;
use crate::parser::{parse_ip, parse_mac, parse_str_val, parse_u32, tag, ParsedField, Stream};

/// Parses a DHCP protocol declaration or configuration option field.
pub(crate) fn parse_dhcp_field<'i, 'a>(input: &mut Stream<'i, 'a>) -> PResult<ParsedField<'a>> {
    alt((
        alt((
            tag(Token::Dhcp)
                .map(|(_, s)| ParsedField::Protocol(Protocol::Dhcp, (s.start, s.len()))),
            tag(Token::Discover).map(|(_, s)| ParsedField::L7Flag("DISCOVER", (s.start, s.len()))),
            tag(Token::Solicit).map(|(_, s)| ParsedField::L7Flag("SOLICIT", (s.start, s.len()))),
            tag(Token::Offer).map(|(_, s)| ParsedField::L7Flag("OFFER", (s.start, s.len()))),
            tag(Token::Advertise)
                .map(|(_, s)| ParsedField::L7Flag("ADVERTISE", (s.start, s.len()))),
            tag(Token::Request).map(|(_, s)| ParsedField::L7Flag("REQUEST", (s.start, s.len()))),
            tag(Token::Ack).map(|(_, s)| ParsedField::L7Flag("ACK", (s.start, s.len()))),
            tag(Token::Reply).map(|(_, s)| ParsedField::L7Flag("REPLY", (s.start, s.len()))),
        )),
        alt((
            tag(Token::Release).map(|(_, s)| ParsedField::L7Flag("RELEASE", (s.start, s.len()))),
            (tag(Token::Xid), cut_err(parse_u32))
                .map(|((_, s), v)| ParsedField::Xid(v, (s.start, s.end - s.start))),
            (tag(Token::Ciaddr), cut_err(parse_ip))
                .map(|((_, s), v)| ParsedField::L7IpField("CIADDR", v, (s.start, s.end - s.start))),
            (tag(Token::Yiaddr), cut_err(parse_ip))
                .map(|((_, s), v)| ParsedField::L7IpField("YIADDR", v, (s.start, s.end - s.start))),
            (tag(Token::Siaddr), cut_err(parse_ip))
                .map(|((_, s), v)| ParsedField::L7IpField("SIADDR", v, (s.start, s.end - s.start))),
            (tag(Token::Chaddr), cut_err(parse_mac)).map(|((_, s), v)| {
                ParsedField::L7MacField("CHADDR", v, (s.start, s.end - s.start))
            }),
            (tag(Token::Hostname), cut_err(parse_str_val)).map(|((_, s), v)| {
                ParsedField::L7StringField("HOSTNAME", v, (s.start, s.end - s.start))
            }),
        )),
        alt((
            (tag(Token::DnsServer), cut_err(parse_ip)).map(|((_, s), v)| {
                ParsedField::L7IpField("DNS_SERVER", v, (s.start, s.end - s.start))
            }),
            (tag(Token::Router), cut_err(parse_ip))
                .map(|((_, s), v)| ParsedField::L7IpField("ROUTER", v, (s.start, s.end - s.start))),
            (tag(Token::SubnetMask), cut_err(parse_ip)).map(|((_, s), v)| {
                ParsedField::L7IpField("SUBNET_MASK", v, (s.start, s.end - s.start))
            }),
            (tag(Token::LeaseTime), cut_err(parse_u32)).map(|((_, s), v)| {
                ParsedField::L7U32Field("LEASE_TIME", v, (s.start, s.end - s.start))
            }),
        )),
    ))
    .parse_next(input)
}