asterisk-rs-agi 0.7.1

Async Rust FastAGI server for Asterisk Gateway Interface
Documentation 
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// standard AGI command names
use crate::error::{AgiError, Result};

pub const ANSWER: &str = "ANSWER";
pub const HANGUP: &str = "HANGUP";
pub const STREAM_FILE: &str = "STREAM FILE";
pub const GET_DATA: &str = "GET DATA";
pub const SAY_DIGITS: &str = "SAY DIGITS";
pub const SAY_NUMBER: &str = "SAY NUMBER";
pub const SET_VARIABLE: &str = "SET VARIABLE";
pub const GET_VARIABLE: &str = "GET VARIABLE";
pub const EXEC: &str = "EXEC";
pub const WAIT_FOR_DIGIT: &str = "WAIT FOR DIGIT";
pub const CHANNEL_STATUS: &str = "CHANNEL STATUS";
pub const VERBOSE: &str = "VERBOSE";
pub const SET_CALLERID: &str = "SET CALLERID";
pub const DATABASE_GET: &str = "DATABASE GET";
pub const DATABASE_PUT: &str = "DATABASE PUT";
pub const DATABASE_DEL: &str = "DATABASE DEL";
pub const CONTROL_STREAM_FILE: &str = "CONTROL STREAM FILE";
pub const DATABASE_DELTREE: &str = "DATABASE DELTREE";
pub const GET_FULL_VARIABLE: &str = "GET FULL VARIABLE";
pub const GET_OPTION: &str = "GET OPTION";
pub const GOSUB: &str = "GOSUB";
pub const NOOP: &str = "NOOP";
pub const RECEIVE_CHAR: &str = "RECEIVE CHAR";
pub const RECEIVE_TEXT: &str = "RECEIVE TEXT";
pub const RECORD_FILE: &str = "RECORD FILE";
pub const SAY_ALPHA: &str = "SAY ALPHA";
pub const SAY_DATE: &str = "SAY DATE";
pub const SAY_DATETIME: &str = "SAY DATETIME";
pub const SAY_PHONETIC: &str = "SAY PHONETIC";
pub const SAY_TIME: &str = "SAY TIME";
pub const SEND_IMAGE: &str = "SEND IMAGE";
pub const SEND_TEXT: &str = "SEND TEXT";
pub const SET_AUTOHANGUP: &str = "SET AUTOHANGUP";
pub const SET_CONTEXT: &str = "SET CONTEXT";
pub const SET_EXTENSION: &str = "SET EXTENSION";
pub const SET_MUSIC: &str = "SET MUSIC";
pub const SET_PRIORITY: &str = "SET PRIORITY";
pub const SPEECH_ACTIVATE_GRAMMAR: &str = "SPEECH ACTIVATE GRAMMAR";
pub const SPEECH_CREATE: &str = "SPEECH CREATE";
pub const SPEECH_DEACTIVATE_GRAMMAR: &str = "SPEECH DEACTIVATE GRAMMAR";
pub const SPEECH_DESTROY: &str = "SPEECH DESTROY";
pub const SPEECH_LOAD_GRAMMAR: &str = "SPEECH LOAD GRAMMAR";
pub const SPEECH_RECOGNIZE: &str = "SPEECH RECOGNIZE";
pub const SPEECH_SET: &str = "SPEECH SET";
pub const SPEECH_UNLOAD_GRAMMAR: &str = "SPEECH UNLOAD GRAMMAR";
pub const TDD_MODE: &str = "TDD MODE";
pub const ASYNCAGI_BREAK: &str = "ASYNCAGI BREAK";

/// format an AGI command string with proper quoting
///
/// arguments containing spaces, double quotes, or being empty are wrapped in double
/// quotes, with embedded double quotes escaped as `\"`.
///
/// returns an error if the command name or any argument contains CR (\r) or LF (\n),
/// preventing protocol injection via user-controlled input
pub fn format_command(name: &str, args: &[&str]) -> Result<String> {
    // CR or LF in any token would terminate the AGI command line early,
    // allowing an attacker to inject arbitrary subsequent commands
    let reject_crlf = |s: &str| -> Result<()> {
        if s.contains('\r') || s.contains('\n') {
            return Err(AgiError::InvalidArgument {
                details: "CR or LF in AGI command argument".to_string(),
            });
        }
        Ok(())
    };

    reject_crlf(name)?;
    for arg in args {
        reject_crlf(arg)?;
    }

    let mut cmd = String::from(name);

    for arg in args {
        cmd.push(' ');
        // empty args, args with spaces, or args with quotes are quoted;
        // embedded double quotes are backslash-escaped per AGI spec
        if arg.is_empty() || arg.contains(' ') || arg.contains('"') {
            cmd.push('"');
            for ch in arg.chars() {
                if ch == '\\' {
                    cmd.push('\\');
                }
                if ch == '"' {
                    cmd.push('\\');
                }
                cmd.push(ch);
            }
            cmd.push('"');
        } else {
            cmd.push_str(arg);
        }
    }

    cmd.push('\n');
    Ok(cmd)
}