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use bstr::{BStr, BString, ByteSlice};
#[cfg(any(feature = "blocking-client", feature = "async-client"))]
use crate::client;
use crate::Protocol;
/// The error used in [`Capabilities::from_bytes()`] and [`Capabilities::from_lines()`].
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error("Capabilities were missing entirely as there was no 0 byte")]
MissingDelimitingNullByte,
#[error("there was not a single capability behind the delimiter")]
NoCapabilities,
#[error("a version line was expected, but none was retrieved")]
MissingVersionLine,
#[error("expected 'version X', got {0:?}")]
MalformattedVersionLine(BString),
#[error("Got unsupported version {actual:?}, expected {}", *desired as u8)]
UnsupportedVersion { desired: Protocol, actual: BString },
#[error("An IO error occurred while reading V2 lines")]
Io(#[from] std::io::Error),
}
/// A structure to represent multiple [capabilities][Capability] or features supported by the server.
///
/// ### Deviation
///
/// As a *shortcoming*, we are unable to parse `V1` as emitted from `git-upload-pack` without a `git-daemon` or server,
/// as it will not emit any capabilities for some reason. Only `V2` and `V0` work in that context.
#[derive(Debug, Clone)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Capabilities {
data: BString,
value_sep: u8,
}
/// This implementation yields exactly those minimal capabilities that are required for `gix` to work, nothing more and nothing less.
///
/// This is a bit of a hack just get tests with Protocol V0 to work, which is a good way to enforce stateful transports.
/// Of course, V1 would also do that but when calling `git-upload-pack` directly, it advertises so badly that this is easier to implement.
impl Default for Capabilities {
fn default() -> Self {
Capabilities::from_lines("version 2\nmulti_ack_detailed\nside-band-64k\n".into())
.expect("valid format, known at compile time")
}
}
/// The name of a single capability.
pub struct Capability<'a>(&'a BStr);
impl<'a> Capability<'a> {
/// Returns the name of the capability.
///
/// Most capabilities only consist of a name, making them appear like a feature toggle.
pub fn name(&self) -> &'a BStr {
self.0
.splitn(2, |b| *b == b'=')
.next()
.expect("there is always a single item")
.as_bstr()
}
/// Returns the value associated with the capability.
///
/// Note that the caller must know whether a single or multiple values are expected, in which
/// case [`values()`][Capability::values()] should be called.
pub fn value(&self) -> Option<&'a BStr> {
self.0.splitn(2, |b| *b == b'=').nth(1).map(|s| s.as_bstr())
}
/// Returns the values of a capability if its [`value()`][Capability::value()] is space separated.
pub fn values(&self) -> Option<impl Iterator<Item = &'a BStr>> {
self.value().map(|v| v.split(|b| *b == b' ').map(|s| s.as_bstr()))
}
/// Returns true if its space-separated [`value()`][Capability::value()] contains the given `want`ed capability.
pub fn supports(&self, want: impl Into<&'a BStr>) -> Option<bool> {
let want = want.into();
self.values().map(|mut iter| iter.any(|v| v == want))
}
}
impl Capabilities {
/// Parse capabilities from the given `bytes`.
///
/// Useful in case they are encoded within a `ref` behind a null byte.
pub fn from_bytes(bytes: &[u8]) -> Result<(Capabilities, usize), Error> {
let delimiter_pos = bytes.find_byte(0).ok_or(Error::MissingDelimitingNullByte)?;
if delimiter_pos + 1 == bytes.len() {
return Err(Error::NoCapabilities);
}
let capabilities = &bytes[delimiter_pos + 1..];
Ok((
Capabilities {
data: capabilities.as_bstr().to_owned(),
value_sep: b' ',
},
delimiter_pos,
))
}
/// Parse capabilities from the given a `lines_buf` which is expected to be all newline separated lines
/// from the server.
///
/// Useful for parsing capabilities from a data sent from a server, and to avoid having to deal with
/// blocking and async traits for as long as possible. There is no value in parsing a few bytes
/// in a non-blocking fashion.
pub fn from_lines(lines_buf: BString) -> Result<Capabilities, Error> {
let mut lines = <_ as bstr::ByteSlice>::lines(lines_buf.as_slice().trim());
let version_line = lines.next().ok_or(Error::MissingVersionLine)?;
let (name, value) = version_line.split_at(
version_line
.find(b" ")
.ok_or_else(|| Error::MalformattedVersionLine(version_line.to_owned().into()))?,
);
if name != b"version" {
return Err(Error::MalformattedVersionLine(version_line.to_owned().into()));
}
if value != b" 2" {
return Err(Error::UnsupportedVersion {
desired: Protocol::V2,
actual: value.to_owned().into(),
});
}
Ok(Capabilities {
value_sep: b'\n',
data: lines.as_bytes().into(),
})
}
/// Returns true of the given `feature` is mentioned in this list of capabilities.
pub fn contains(&self, feature: &str) -> bool {
self.capability(feature).is_some()
}
/// Returns the capability with `name`.
pub fn capability(&self, name: &str) -> Option<Capability<'_>> {
self.iter().find(|c| c.name() == name.as_bytes().as_bstr())
}
/// Returns an iterator over all capabilities.
pub fn iter(&self) -> impl Iterator<Item = Capability<'_>> {
self.data
.split(move |b| *b == self.value_sep)
.map(|c| Capability(c.as_bstr()))
}
}
/// internal use
#[cfg(any(feature = "blocking-client", feature = "async-client"))]
impl Capabilities {
fn extract_protocol(capabilities_or_version: gix_packetline::TextRef<'_>) -> Result<Protocol, client::Error> {
let line = capabilities_or_version.as_bstr();
let version = if line.starts_with_str("version ") {
if line.len() != "version X".len() {
return Err(client::Error::UnsupportedProtocolVersion(line.as_bstr().into()));
}
match line {
line if line.ends_with_str("1") => Protocol::V1,
line if line.ends_with_str("2") => Protocol::V2,
_ => return Err(client::Error::UnsupportedProtocolVersion(line.as_bstr().into())),
}
} else {
Protocol::V1
};
Ok(version)
}
}
#[cfg(feature = "blocking-client")]
///
pub mod recv {
use std::io;
use bstr::ByteVec;
use crate::{client, client::Capabilities, Protocol};
/// Success outcome of [`Capabilities::from_lines_with_version_detection`].
pub struct Outcome<'a> {
/// The [`Capabilities`] the remote advertised.
pub capabilities: Capabilities,
/// The remote refs as a [`io::BufRead`].
///
/// This is `Some` only when protocol v1 is used. The [`io::BufRead`] must be exhausted by
/// the caller.
pub refs: Option<Box<dyn crate::client::ReadlineBufRead + 'a>>,
/// The [`Protocol`] the remote advertised.
pub protocol: Protocol,
}
impl Capabilities {
/// Read the capabilities and version advertisement from the given packetline reader.
///
/// If [`Protocol::V1`] was requested, or the remote decided to downgrade, the remote refs
/// advertisement will also be included in the [`Outcome`].
pub fn from_lines_with_version_detection<T: io::Read>(
rd: &mut gix_packetline::StreamingPeekableIter<T>,
) -> Result<Outcome<'_>, client::Error> {
// NOTE that this is vitally important - it is turned on and stays on for all following requests so
// we automatically abort if the server sends an ERR line anywhere.
// We are sure this can't clash with binary data when sent due to the way the PACK
// format looks like, thus there is no binary blob that could ever look like an ERR line by accident.
rd.fail_on_err_lines(true);
Ok(match rd.peek_line() {
Some(line) => {
let line = line??.as_text().ok_or(client::Error::ExpectedLine("text"))?;
let version = Capabilities::extract_protocol(line)?;
match version {
Protocol::V0 => unreachable!("already handled in `None` case"),
Protocol::V1 => {
let (capabilities, delimiter_position) = Capabilities::from_bytes(line.0)?;
rd.peek_buffer_replace_and_truncate(delimiter_position, b'\n');
Outcome {
capabilities,
refs: Some(Box::new(rd.as_read())),
protocol: Protocol::V1,
}
}
Protocol::V2 => Outcome {
capabilities: {
let mut rd = rd.as_read();
let mut buf = Vec::new();
while let Some(line) = rd.read_data_line() {
let line = line??;
match line.as_bstr() {
Some(line) => {
buf.push_str(line);
if buf.last() != Some(&b'\n') {
buf.push(b'\n');
}
}
None => break,
}
}
Capabilities::from_lines(buf.into())?
},
refs: None,
protocol: Protocol::V2,
},
}
}
None => Outcome {
capabilities: Capabilities::default(),
refs: Some(Box::new(rd.as_read())),
protocol: Protocol::V0,
},
})
}
}
}
#[cfg(feature = "async-client")]
#[allow(missing_docs)]
///
pub mod recv {
use bstr::ByteVec;
use futures_io::AsyncRead;
use crate::{client, client::Capabilities, Protocol};
/// Success outcome of [`Capabilities::from_lines_with_version_detection`].
pub struct Outcome<'a> {
/// The [`Capabilities`] the remote advertised.
pub capabilities: Capabilities,
/// The remote refs as an [`AsyncBufRead`].
///
/// This is `Some` only when protocol v1 is used. The [`AsyncBufRead`] must be exhausted by
/// the caller.
pub refs: Option<Box<dyn crate::client::ReadlineBufRead + Unpin + 'a>>,
/// The [`Protocol`] the remote advertised.
pub protocol: Protocol,
}
impl Capabilities {
/// Read the capabilities and version advertisement from the given packetline reader.
///
/// If [`Protocol::V1`] was requested, or the remote decided to downgrade, the remote refs
/// advertisement will also be included in the [`Outcome`].
pub async fn from_lines_with_version_detection<T: AsyncRead + Unpin>(
rd: &mut gix_packetline::StreamingPeekableIter<T>,
) -> Result<Outcome<'_>, client::Error> {
// NOTE that this is vitally important - it is turned on and stays on for all following requests so
// we automatically abort if the server sends an ERR line anywhere.
// We are sure this can't clash with binary data when sent due to the way the PACK
// format looks like, thus there is no binary blob that could ever look like an ERR line by accident.
rd.fail_on_err_lines(true);
Ok(match rd.peek_line().await {
Some(line) => {
let line = line??.as_text().ok_or(client::Error::ExpectedLine("text"))?;
let version = Capabilities::extract_protocol(line)?;
match version {
Protocol::V0 => unreachable!("already handled in `None` case"),
Protocol::V1 => {
let (capabilities, delimiter_position) = Capabilities::from_bytes(line.0)?;
rd.peek_buffer_replace_and_truncate(delimiter_position, b'\n');
Outcome {
capabilities,
refs: Some(Box::new(rd.as_read())),
protocol: Protocol::V1,
}
}
Protocol::V2 => Outcome {
capabilities: {
let mut rd = rd.as_read();
let mut buf = Vec::new();
while let Some(line) = rd.read_data_line().await {
let line = line??;
match line.as_bstr() {
Some(line) => {
buf.push_str(line);
if buf.last() != Some(&b'\n') {
buf.push(b'\n');
}
}
None => break,
}
}
Capabilities::from_lines(buf.into())?
},
refs: None,
protocol: Protocol::V2,
},
}
}
None => Outcome {
capabilities: Capabilities::default(),
refs: Some(Box::new(rd.as_read())),
protocol: Protocol::V0,
},
})
}
}
}
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