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use std::iter::Peekable;
use log::debug;
use crate::armor::BlockType;
use crate::composed::message::Message;
use crate::composed::Deserializable;
use crate::errors::{Error, Result};
use crate::packet::Packet;
use crate::types::{PkeskVersion, SkeskVersion, Tag};
use crate::{Edata, Esk};
pub struct MessageParser<I: Sized + Iterator<Item = Result<Packet>>> {
source: Peekable<I>,
}
fn next<I: Iterator<Item = Result<Packet>>>(packets: &mut Peekable<I>) -> Option<Result<Message>> {
while let Some(res) = packets.by_ref().next() {
let packet = match res {
Ok(packet) => packet,
Err(err) => return Some(Err(err)),
};
debug!("{:?}: ", packet);
let tag = packet.tag();
match tag {
Tag::LiteralData => {
return match packet.try_into() {
Ok(data) => Some(Ok(Message::Literal(data))),
Err(err) => Some(Err(err)),
};
}
Tag::CompressedData => {
return match packet.try_into() {
Ok(data) => Some(Ok(Message::Compressed(data))),
Err(err) => Some(Err(err)),
};
}
// ESK :- Public-Key Encrypted Session Key Packet |
// Symmetric-Key Encrypted Session Key Packet.
Tag::PublicKeyEncryptedSessionKey | Tag::SymKeyEncryptedSessionKey => {
return match packet.try_into() {
Ok(p) => {
let mut esk: Vec<Esk> = vec![p];
// while ESK take em
while let Some(res) = packets.next_if(|res| {
res.as_ref().is_ok_and(|p| {
p.tag() == Tag::PublicKeyEncryptedSessionKey
|| p.tag() == Tag::SymKeyEncryptedSessionKey
})
}) {
match res {
Ok(packet) => esk.push(packet.try_into().expect("peeked")),
Err(e) => return Some(Err(e)),
}
}
// we expect exactly one edata after the ESKs
let edata = match packets.next() {
Some(Ok(p))
if p.tag() == Tag::SymEncryptedData
|| p.tag() == Tag::SymEncryptedProtectedData =>
{
Edata::try_from(p).expect("peeked")
}
Some(Ok(p)) => {
return Some(Err(Error::Message(format!(
"Expected encrypted data packet, but found {:?}",
p
))));
}
None => {
return Some(Err(Error::Message(
"Missing encrypted data packet".to_string(),
)))
}
Some(Err(e)) => return Some(Err(e)),
};
// Drop PKESK and SKESK with versions that are not aligned with the encryption container
fn esk_filter(
esk: Vec<Esk>,
pkesk_allowed: PkeskVersion,
skesk_allowed: SkeskVersion,
) -> Vec<Esk> {
esk.into_iter()
.filter(|esk| match esk {
Esk::PublicKeyEncryptedSessionKey(pkesk) => {
pkesk.version() == pkesk_allowed
}
Esk::SymKeyEncryptedSessionKey(skesk) => {
skesk.version() == skesk_allowed
}
})
.collect()
}
// An implementation processing an Encrypted Message MUST discard any
// preceding ESK packet with a version that does not align with the
// version of the payload.
// (See https://www.rfc-editor.org/rfc/rfc9580.html#section-10.3.2.1-7)
let esk = match edata {
Edata::SymEncryptedData(_) => {
esk_filter(esk, PkeskVersion::V3, SkeskVersion::V4)
}
Edata::SymEncryptedProtectedData(ref p) if p.version() == 1 => {
esk_filter(esk, PkeskVersion::V3, SkeskVersion::V4)
}
Edata::SymEncryptedProtectedData(ref p) if p.version() == 2 => {
esk_filter(esk, PkeskVersion::V6, SkeskVersion::V6)
}
_ => {
return Some(Err(format_err!("Unsupported Edata variant")));
}
};
Some(Ok(Message::Encrypted { esk, edata }))
}
Err(err) => Some(Err(err)),
};
}
Tag::Signature => {
return match packet.try_into() {
Ok(signature) => {
let message = match next(packets.by_ref()) {
Some(Ok(m)) => Some(Box::new(m)),
Some(Err(err)) => return Some(Err(err)),
None => None,
};
Some(Ok(Message::Signed {
message,
one_pass_signature: None,
signature,
}))
}
Err(err) => Some(Err(err)),
};
}
Tag::OnePassSignature => {
return match packet.try_into() {
Ok(p) => {
let one_pass_signature = Some(p);
let message = match next(packets.by_ref()) {
Some(Ok(m)) => Some(Box::new(m)),
Some(Err(err)) => return Some(Err(err)),
None => None,
};
let signature = if let Some(res) = packets
.next_if(|res| res.as_ref().is_ok_and(|p| p.tag() == Tag::Signature))
{
match res {
Ok(packet) => packet.try_into().expect("peeked"),
Err(e) => return Some(Err(e)),
}
} else {
return Some(Err(format_err!(
"missing signature for, one pass signature"
)));
};
Some(Ok(Message::Signed {
message,
one_pass_signature,
signature,
}))
}
Err(err) => Some(Err(err)),
};
}
Tag::Marker => {
// Marker Packets are ignored
// see https://www.rfc-editor.org/rfc/rfc9580.html#marker-packet
}
Tag::Padding => {
// Padding Packets are ignored
//
// "Such a packet MUST be ignored when received."
// (See https://www.rfc-editor.org/rfc/rfc9580.html#section-5.14-2)
}
_ => {
return Some(Err(format_err!("unexpected packet {:?}", packet.tag())));
}
}
}
None
}
impl<I: Sized + Iterator<Item = Result<Packet>>> Iterator for MessageParser<I> {
type Item = Result<Message>;
fn next(&mut self) -> Option<Self::Item> {
next(self.source.by_ref())
}
}
impl Deserializable for Message {
/// Parse a composed message.
/// Ref: <https://www.rfc-editor.org/rfc/rfc9580.html#name-openpgp-messages>
fn from_packets<'a, I: Iterator<Item = Result<Packet>> + 'a>(
packets: std::iter::Peekable<I>,
) -> Box<dyn Iterator<Item = Result<Self>> + 'a> {
Box::new(MessageParser {
source: packets.peekable(),
})
}
fn matches_block_type(typ: BlockType) -> bool {
matches!(
typ,
BlockType::Message | BlockType::MultiPartMessage(_, _) | BlockType::File
)
}
}