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| -rw-r--r-- | pkgs/by-name/mp/mpdpopm/src/messages.rs | 409 |
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diff --git a/pkgs/by-name/mp/mpdpopm/src/messages.rs b/pkgs/by-name/mp/mpdpopm/src/messages.rs deleted file mode 100644 index 171a246a..00000000 --- a/pkgs/by-name/mp/mpdpopm/src/messages.rs +++ /dev/null @@ -1,409 +0,0 @@ -// Copyright (C) 2020-2025 Michael herstine <sp1ff@pobox.com> -// -// This file is part of mpdpopm. -// -// mpdpopm is free software: you can redistribute it and/or modify it under the terms of the GNU -// General Public License as published by the Free Software Foundation, either version 3 of the -// License, or (at your option) any later version. -// -// mpdpopm is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even -// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General -// Public License for more details. -// -// You should have received a copy of the GNU General Public License along with mpdpopm. If not, -// see <http://www.gnu.org/licenses/>. - -//! # messages -//! -//! Process incoming messages to the [mpdpopm](https://github.com/sp1ff/mpdpopm) daemon. -//! -//! # Introduction -//! -//! The [mpdpopm](https://github.com/sp1ff/mpdpopm) daemon accepts commands over a dedicated -//! [channel](https://www.musicpd.org/doc/html/protocol.html#client-to-client). It also provides for -//! a generalized framework in which the [mpdpopm](https://github.com/sp1ff/mpdpopm) administrator -//! can define new commands backed by arbitrary command execution server-side. -//! -//! # Commands -//! -//! The following commands are built-in: -//! -//! - set rating: `rate RATING( TRACK)?` -//! - set playcount: `setpc PC( TRACK)?` -//! - set lastplayed: `setlp TIMESTAMP( TRACK)?` -//! -//! There is no need to provide corresponding accessors since this functionality is already provided -//! via "sticker get". Dedicated accessors could provide the same functionality with slightly more -//! convenience since the sticker name would not have to be specified (as with "sticker get") & may -//! be added at a later date. -//! -//! I'm expanding the MPD filter functionality to include attributes tracked by mpdpopm: -//! -//! - findadd replacement: `findadd FILTER [sort TYPE] [window START:END]` -//! (cf. [here](https://www.musicpd.org/doc/html/protocol.html#the-music-database)) -//! -//! - searchadd replacement: `searchadd FILTER [sort TYPE] [window START:END]` -//! (cf. [here](https://www.musicpd.org/doc/html/protocol.html#the-music-database)) -//! -//! Additional commands may be added through the -//! [generalized commands](crate::commands#the-generalized-command-framework) feature. - -use crate::{ - clients::{Client, IdleClient, PlayerStatus}, - filters::ExpressionParser, - filters_ast::{FilterStickerNames, evaluate}, -}; - -use anyhow::{Context, Error, Result, anyhow, bail}; -use boolinator::Boolinator; -use tracing::debug; - -use std::collections::VecDeque; - -/// Break `buf` up into individual tokens while removing MPD-style quoting. -/// -/// When a client sends a command to [mpdpopm](crate), it will look like this on the wire: -/// -/// ```text -/// sendmessage ${CHANNEL} "some-command \"with space\" simple \"'with single' and \\\\\"" -/// ``` -/// -/// In other words, the MPD "sendmessage" command takes two parameters: the channel and the -/// message. The recipient (i.e. us) is responsible for breaking up the message into its constituent -/// parts (a command name & its arguments in our case). -/// -/// The message will perforce be quoted according ot the MPD rules: -/// -/// 1. an un-quoted token may contain any printable ASCII character except space, tab, ' & " -/// -/// 2. to include spaces, tabs, '-s or "-s, the token must be enclosed in "-s, and any "-s or \\-s -/// therein must be backslash escaped -/// -/// When the messages is delivered to us, it has already been un-escaped; i.e. we will see the -/// string: -/// -/// ```text -/// some-command "with space" simple "'with single' and \\" -/// ``` -/// -/// This function will break that string up into individual tokens with one more level -/// of escaping removed; i.e. it will return an iterator that will yield the four tokens: -/// -/// 1. some-command -/// 2. with space -/// 3. simple -/// 4. 'with single' and \\ -/// -/// [MPD](https://github.com/MusicPlayerDaemon/MPD) has a nice -/// [implementation](https://github.com/MusicPlayerDaemon/MPD/blob/master/src/util/Tokenizer.cxx#L170) -/// that modifies the string in place by copying subsequent characters on top of escape characters -/// in the same buffer, inserting nulls in between the resulting tokens,and then working in terms of -/// pointers to the resulting null-terminated strings. -/// -/// Once I realized that I could split slices I saw how to implement an Iterator that do the same -/// thing (an idiomatic interface to the tokenization backed by a zero-copy implementation). I was -/// inspired by [My Favorite Rust Function -/// Signature](<https://www.brandonsmith.ninja/blog/favorite-rust-function>). -/// -/// NB. This method works in terms of a slice of [`u8`] because we can't index into Strings in -/// Rust, and MPD deals only in terms of ASCII at any rate. -pub fn tokenize(buf: &mut [u8]) -> impl Iterator<Item = Result<&[u8]>> { - TokenIterator::new(buf) -} - -struct TokenIterator<'a> { - /// The slice on which we operate; modified in-place as we yield tokens - slice: &'a mut [u8], - /// Index into [`slice`] of the first non-whitespace character - input: usize, -} - -impl<'a> TokenIterator<'a> { - pub fn new(slice: &'a mut [u8]) -> TokenIterator<'a> { - let input = match slice.iter().position(|&x| x > 0x20) { - Some(n) => n, - None => slice.len(), - }; - TokenIterator { slice, input } - } -} - -impl<'a> Iterator for TokenIterator<'a> { - type Item = Result<&'a [u8]>; - - fn next(&mut self) -> Option<Self::Item> { - let nslice = self.slice.len(); - if self.slice.is_empty() || self.input == nslice { - None - } else if '"' == self.slice[self.input] as char { - // This is NextString in MPD: walk self.slice, un-escaping characters, until we find - // a closing ". Note that we un-escape by moving characters forward in the slice. - let mut inp = self.input + 1; - let mut out = self.input; - while self.slice[inp] as char != '"' { - if '\\' == self.slice[inp] as char { - inp += 1; - if inp == nslice { - return Some(Err(anyhow!("Trailing backslash"))); - } - } - self.slice[out] = self.slice[inp]; - out += 1; - inp += 1; - if inp == nslice { - return Some(Err(anyhow!("No closing quote"))); - } - } - // The next token is in self.slice[self.input..out] and self.slice[inp] is " - let tmp = std::mem::take(&mut self.slice); - let (_, tmp) = tmp.split_at_mut(self.input); - let (result, new_slice) = tmp.split_at_mut(out - self.input); - self.slice = new_slice; - // strip any leading whitespace - self.input = inp - out + 1; // +1 to skip the closing " - while self.input < self.slice.len() && self.slice[self.input] as char == ' ' { - self.input += 1; - } - Some(Ok(result)) - } else { - // This is NextUnquoted in MPD; walk self.slice, validating characters until the end - // or the next whitespace - let mut i = self.input; - while i < nslice { - if 0x20 >= self.slice[i] { - break; - } - if self.slice[i] as char == '"' || self.slice[i] as char == '\'' { - return Some(Err(anyhow!("Invalid char: `{}`", self.slice[i]))); - } - i += 1; - } - // The next token is in self.slice[self.input..i] & self.slice[i] is either one- - // past-the end or whitespace. - let tmp = std::mem::take(&mut self.slice); - let (_, tmp) = tmp.split_at_mut(self.input); - let (result, new_slice) = tmp.split_at_mut(i - self.input); - self.slice = new_slice; - // strip any leading whitespace - self.input = match self.slice.iter().position(|&x| x > 0x20) { - Some(n) => n, - None => self.slice.len(), - }; - Some(Ok(result)) - } - } -} - -/// Collective state needed for processing messages, both built-in & generalized -#[derive(Default)] -pub struct MessageProcessor {} - -impl MessageProcessor { - /// Whip up a new instance; other than cloning the iterators, should just hold references in the - /// enclosing scope - pub fn new() -> MessageProcessor { - Self::default() - } - - /// Read messages off the commands channel & dispatch 'em - pub async fn check_messages<'a>( - &self, - client: &mut Client, - idle_client: &mut IdleClient, - state: PlayerStatus, - command_chan: &str, - stickers: &FilterStickerNames<'a>, - ) -> Result<()> { - let m = idle_client - .get_messages() - .await - .context("Failed to `get_messages` from client")?; - - for (chan, msgs) in m { - // Only supporting a single channel, ATM - (chan == command_chan).ok_or_else(|| anyhow!("Unknown chanell: `{}`", chan))?; - for msg in msgs { - self.process(msg, client, &state, stickers).await?; - } - } - - Ok(()) - } - - /// Process a single command - pub async fn process<'a>( - &self, - msg: String, - client: &mut Client, - state: &PlayerStatus, - stickers: &FilterStickerNames<'a>, - ) -> Result<()> { - if let Some(stripped) = msg.strip_prefix("findadd ") { - self.findadd(stripped.to_string(), client, stickers, state) - .await - } else if let Some(stripped) = msg.strip_prefix("searchadd ") { - self.searchadd(stripped.to_string(), client, stickers, state) - .await - } else { - unreachable!("Unkonwn command") - } - } - - /// Handle `findadd': "FILTER [sort TYPE] [window START:END]" - async fn findadd<'a>( - &self, - msg: String, - client: &mut Client, - stickers: &FilterStickerNames<'a>, - _state: &PlayerStatus, - ) -> Result<()> { - let mut buf = msg.into_bytes(); - let args: VecDeque<&str> = tokenize(&mut buf) - .map(|r| match r { - Ok(buf) => Ok(std::str::from_utf8(buf) - .context("Failed to interpete `findadd` string as utf8")?), - Err(err) => Err(err), - }) - .collect::<Result<VecDeque<&str>>>()?; - - debug!("findadd arguments: {:#?}", args); - - // there should be 1, 3 or 5 arguments. `sort' & `window' are not supported, yet. - - // ExpressionParser's not terribly ergonomic: it returns a ParesError<L, T, E>; T is the - // offending token, which has the same lifetime as our input, which makes it tough to - // capture. Nor is there a convenient way in which to treat all variants other than the - // Error Trait. - let ast = match ExpressionParser::new().parse(args[0]) { - Ok(ast) => ast, - Err(err) => { - bail!("Failed to parse filter: `{}`", err) - } - }; - - debug!("ast: {:#?}", ast); - - let mut results = Vec::new(); - for song in evaluate(&ast, true, client, stickers) - .await - .context("Failed to evaluate filter")? - { - results.push(client.add(&song).await); - } - match results - .into_iter() - .collect::<std::result::Result<Vec<()>, Error>>() - { - Ok(_) => Ok(()), - Err(err) => Err(err), - } - } - - /// Handle `searchadd': "FILTER [sort TYPE] [window START:END]" - async fn searchadd<'a>( - &self, - msg: String, - client: &mut Client, - stickers: &FilterStickerNames<'a>, - _state: &PlayerStatus, - ) -> Result<()> { - // Tokenize the message - let mut buf = msg.into_bytes(); - let args: VecDeque<&str> = tokenize(&mut buf) - .map(|r| match r { - Ok(buf) => Ok(std::str::from_utf8(buf) - .context("Failed to interpete `searchadd` string as utf8")?), - Err(err) => Err(err), - }) - .collect::<Result<VecDeque<_>>>()?; - - debug!("searchadd arguments: {:#?}", args); - - // there should be 1, 3 or 5 arguments. `sort' & `window' are not supported, yet. - - // ExpressionParser's not terribly ergonomic: it returns a ParesError<L, T, E>; T is the - // offending token, which has the same lifetime as our input, which makes it tough to - // capture. Nor is there a convenient way in which to treat all variants other than the - // Error Trait. - let ast = match ExpressionParser::new().parse(args[0]) { - Ok(ast) => ast, - Err(err) => { - bail!("Failed to parse filter: `{err}`") - } - }; - - debug!("ast: {:#?}", ast); - - let mut results = Vec::new(); - for song in evaluate(&ast, false, client, stickers) - .await - .context("Failed to evaluate ast")? - { - results.push(client.add(&song).await); - } - match results - .into_iter() - .collect::<std::result::Result<Vec<()>, Error>>() - { - Ok(_) => Ok(()), - Err(err) => Err(err), - } - } -} - -#[cfg(test)] -mod tokenize_tests { - use super::Result; - use super::tokenize; - - #[test] - fn tokenize_smoke() { - let mut buf1 = String::from("some-command").into_bytes(); - let x1: Vec<&[u8]> = tokenize(&mut buf1).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(x1[0], b"some-command"); - - let mut buf2 = String::from("a b").into_bytes(); - let x2: Vec<&[u8]> = tokenize(&mut buf2).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(x2[0], b"a"); - assert_eq!(x2[1], b"b"); - - let mut buf3 = String::from("a \"b c\"").into_bytes(); - let x3: Vec<&[u8]> = tokenize(&mut buf3).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(x3[0], b"a"); - assert_eq!(x3[1], b"b c"); - - let mut buf4 = String::from("a \"b c\" d").into_bytes(); - let x4: Vec<&[u8]> = tokenize(&mut buf4).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(x4[0], b"a"); - assert_eq!(x4[1], b"b c"); - assert_eq!(x4[2], b"d"); - - let mut buf5 = String::from("simple-command \"with space\" \"with '\"").into_bytes(); - let x5: Vec<&[u8]> = tokenize(&mut buf5).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(x5[0], b"simple-command"); - assert_eq!(x5[1], b"with space"); - assert_eq!(x5[2], b"with '"); - - let mut buf6 = String::from("cmd \"with\\\\slash and space\"").into_bytes(); - let x6: Vec<&[u8]> = tokenize(&mut buf6).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(x6[0], b"cmd"); - assert_eq!(x6[1], b"with\\slash and space"); - - let mut buf7 = String::from(" cmd \"with\\\\slash and space\" ").into_bytes(); - let x7: Vec<&[u8]> = tokenize(&mut buf7).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(x7[0], b"cmd"); - assert_eq!(x7[1], b"with\\slash and space"); - } - - #[test] - fn tokenize_filter() { - let mut buf1 = String::from(r#""(artist =~ \"foo\\\\bar\\\"\")""#).into_bytes(); - let x1: Vec<&[u8]> = tokenize(&mut buf1).collect::<Result<Vec<&[u8]>>>().unwrap(); - assert_eq!(1, x1.len()); - eprintln!("x1[0] is ``{}''", std::str::from_utf8(x1[0]).unwrap()); - assert_eq!( - std::str::from_utf8(x1[0]).unwrap(), - r#"(artist =~ "foo\\bar\"")"# - ); - } -} |