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use crate::error::ParserError;
use crate::parser::{
parse_bgp4mp, parse_table_dump_message, parse_table_dump_v2_message, ParserErrorWithBytes,
ReadUtils,
};
use bgp_models::mrt::{CommonHeader, EntryType, MrtMessage, MrtRecord};
use byteorder::{ReadBytesExt, BE};
use num_traits::FromPrimitive;
use std::io::{ErrorKind, Read};
pub fn parse_common_header<T: Read>(input: &mut T) -> Result<CommonHeader, ParserError> {
let timestamp = match input.read_32b() {
Ok(t) => t,
Err(e) => {
return match e.kind() {
ErrorKind::UnexpectedEof => Err(ParserError::EofExpected),
_ => Err(ParserError::from(e)),
}
}
};
let entry_type_raw = input.read_u16::<BE>()?;
let entry_type = match EntryType::from_u16(entry_type_raw) {
Some(t) => Ok(t),
None => Err(ParserError::ParseError(format!(
"Failed to parse entry type: {}",
entry_type_raw
))),
}?;
let entry_subtype = input.read_u16::<BE>()?;
let mut length = input.read_32b()?;
let microsecond_timestamp = match &entry_type {
EntryType::BGP4MP_ET => {
length -= 4;
Some(input.read_32b()?)
}
_ => None,
};
Ok(CommonHeader {
timestamp,
microsecond_timestamp,
entry_type,
entry_subtype,
length,
})
}
pub fn parse_mrt_record(input: &mut impl Read) -> Result<MrtRecord, ParserErrorWithBytes> {
let common_header = match parse_common_header(input) {
Ok(v) => v,
Err(e) => {
return Err(ParserErrorWithBytes {
error: e,
bytes: None,
})
}
};
let mut buffer = Vec::with_capacity(common_header.length as usize);
match input
.take(common_header.length as u64)
.read_to_end(&mut buffer)
{
Ok(_) => {}
Err(e) => {
return Err(ParserErrorWithBytes {
error: ParserError::IoError(e),
bytes: None,
})
}
}
match parse_raw_bytes(&common_header, buffer.as_slice()) {
Ok(message) => Ok(MrtRecord {
common_header,
message,
}),
Err(e) => {
let mut total_bytes = vec![];
if common_header.write_header(&mut total_bytes).is_err() {
unreachable!("Vec<u8> will never produce errors when used as a std::io::Write")
}
total_bytes.extend(buffer);
Err(ParserErrorWithBytes {
error: e,
bytes: Some(total_bytes),
})
}
}
}
fn parse_raw_bytes(common_header: &CommonHeader, data: &[u8]) -> Result<MrtMessage, ParserError> {
let message: MrtMessage = match &common_header.entry_type {
EntryType::TABLE_DUMP => {
let msg = parse_table_dump_message(common_header.entry_subtype, data);
match msg {
Ok(msg) => MrtMessage::TableDumpMessage(msg),
Err(e) => {
return Err(e);
}
}
}
EntryType::TABLE_DUMP_V2 => {
let msg = parse_table_dump_v2_message(common_header.entry_subtype, data);
match msg {
Ok(msg) => MrtMessage::TableDumpV2Message(msg),
Err(e) => {
return Err(e);
}
}
}
EntryType::BGP4MP | EntryType::BGP4MP_ET => {
let msg = parse_bgp4mp(common_header.entry_subtype, data);
match msg {
Ok(msg) => MrtMessage::Bgp4Mp(msg),
Err(e) => {
return Err(e);
}
}
}
v => {
return Err(ParserError::Unsupported(format!(
"unsupported MRT type: {:?}",
v
)));
}
};
Ok(message)
}