frameassembly 1.1.0

//! sFlow v5 Layer 7 switched network packet sampling protocol field parser.
//!
//! This module implements the `winnow` parser combinator for sFlow v5 (`SFLOW`) datagrams in
//! FrameAssembly `.fasm` specifications. It recognizes the `SFLOW` protocol keyword, exporter
//! agent IP addresses (`AGENT_IP` and `AGENTIP`), sub-agent identifiers (`SUB_AGENT_ID`), switch
//! uptime values (`UPTIME`), sample counts (`SAMPLES`), and datagram sequence numbers (`SEQ`).

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_u32, tag, ParsedField, Stream};

/// Parses an sFlow protocol declaration or packet sample field.
pub(crate) fn parse_sflow_field<'i, 'a>(input: &mut Stream<'i, 'a>) -> PResult<ParsedField<'a>> {
    alt((
        tag(Token::Sflow)
            .map(|(_, s)| ParsedField::Protocol(Protocol::Sflow, (s.start, s.len()))),
        (tag(Token::AgentIpSflow), cut_err(parse_ip))
            .map(|((_, s), v)| ParsedField::L7IpField("AGENT_IP", v, (s.start, s.end - s.start))),
        (tag(Token::AgentIp), cut_err(parse_ip))
            .map(|((_, s), v)| ParsedField::L7IpField("AGENT_IP", v, (s.start, s.end - s.start))),
        (tag(Token::SubAgentId), cut_err(parse_u32)).map(|((_, s), v)| {
            ParsedField::L7U32Field("SUB_AGENT_ID", v, (s.start, s.end - s.start))
        }),
        (tag(Token::Uptime), cut_err(parse_u32))
            .map(|((_, s), v)| ParsedField::L7U32Field("UPTIME", v, (s.start, s.end - s.start))),
        (tag(Token::Samples), cut_err(parse_u32))
            .map(|((_, s), v)| ParsedField::L7U32Field("SAMPLES", v, (s.start, s.end - s.start))),
    ))
    .parse_next(input)
}