ssh_mcp/

config.rs

//! Configuration and CLI argument parsing for SSH MCP Server

use clap::Parser;
use std::path::PathBuf;

use crate::error::{Result, SshMcpError};
use crate::ssh::HostKeyCheckMode;

/// Default timeout for command execution in milliseconds
pub const DEFAULT_TIMEOUT_MS: u64 = 300_000; // 300 seconds

/// Default max characters for command length (None = unlimited)
pub const DEFAULT_MAX_CHARS: Option<usize> = Some(64_000);

/// Connection timeout in seconds
pub const CONNECTION_TIMEOUT_SECS: u64 = 30;

/// Number of reconnect retries after the initial attempt
pub const DEFAULT_RECONNECT_RETRIES: u64 = 3;

/// Base reconnect backoff in milliseconds
pub const DEFAULT_RECONNECT_BACKOFF_MS: u64 = 250;

/// Health probe timeout in milliseconds
pub const DEFAULT_HEALTH_PROBE_TIMEOUT_MS: u64 = 1500;

/// Maximum reconnect retries allowed by configuration
pub const MAX_RECONNECT_RETRIES: u64 = 10;

/// Minimum reconnect backoff in milliseconds
pub const MIN_RECONNECT_BACKOFF_MS: u64 = 10;

/// Maximum reconnect backoff in milliseconds
pub const MAX_RECONNECT_BACKOFF_MS: u64 = 30_000;

/// Minimum health probe timeout in milliseconds
pub const MIN_HEALTH_PROBE_TIMEOUT_MS: u64 = 100;

/// Maximum health probe timeout in milliseconds
pub const MAX_HEALTH_PROBE_TIMEOUT_MS: u64 = 30_000;

/// SSH MCP Server CLI Arguments
#[derive(Parser, Debug, Clone)]
#[command(name = "ssh-mcp")]
#[command(author = "0FL01")]
#[command(version = env!("CARGO_PKG_VERSION"))]
#[command(about = "MCP server exposing SSH control for Linux systems via Model Context Protocol")]
pub struct Args {
    /// SSH host to connect to
    #[arg(long, env = "SSH_MCP_HOST")]
    pub host: String,

    /// SSH port
    #[arg(long, default_value = "22", env = "SSH_MCP_PORT")]
    pub port: u16,

    /// SSH username
    #[arg(long, env = "SSH_MCP_USER")]
    pub user: String,

    /// SSH password (alternative to key)
    #[arg(long, env = "SSH_MCP_PASSWORD")]
    pub password: Option<String>,

    /// Path to SSH private key file (alternative to password)
    #[arg(long, env = "SSH_MCP_KEY")]
    pub key: Option<PathBuf>,

    /// Password for `su` elevation
    #[arg(long, env = "SSH_MCP_SU_PASSWORD")]
    pub su_password: Option<String>,

    /// Password for `sudo` commands (if different from su_password)
    #[arg(long, env = "SSH_MCP_SUDO_PASSWORD")]
    pub sudo_password: Option<String>,

    /// Command execution timeout in milliseconds
    #[arg(long, default_value = "300000", env = "SSH_MCP_TIMEOUT")]
    pub timeout: u64,

    /// Maximum characters for command length.
    /// Use "none", "0", or negative value to disable limit.
    /// Default: 64000
    #[arg(long = "maxChars", env = "SSH_MCP_MAX_CHARS")]
    pub max_chars: Option<String>,

    /// Disable the sudo_shell and sudo_apply_patch tools
    #[arg(long, default_value = "false", env = "SSH_MCP_DISABLE_SUDO")]
    pub disable_sudo: bool,

    /// Maximum output tokens for command execution.
    /// Use "none" or "0" to disable limit.
    /// Supports "k" suffix (e.g., "16k" for 16000).
    /// Default: 16000 (approximately 64KB)
    #[arg(long = "max-output-tokens", env = "SSH_MCP_MAX_OUTPUT_TOKENS")]
    pub max_output_tokens: Option<String>,

    /// Logging level: trace, debug, info, warn, error
    #[arg(long, default_value = "info", env = "SSH_MCP_LOG_LEVEL", value_parser = clap::builder::PossibleValuesParser::new(["trace", "debug", "info", "warn", "error"]))]
    pub log_level: String,

    /// Log file path (default: stdout only)
    #[arg(long, env = "SSH_MCP_LOG_FILE")]
    pub log_file: Option<PathBuf>,

    /// Log format: text or json
    #[arg(long, default_value = "text", env = "SSH_MCP_LOG_FORMAT", value_parser = clap::builder::PossibleValuesParser::new(["text", "json"]))]
    pub log_format: String,

    /// Log rotation strategy: daily, hourly, never
    #[arg(long, default_value = "daily", env = "SSH_MCP_LOG_ROTATION", value_parser = clap::builder::PossibleValuesParser::new(["daily", "hourly", "never"]))]
    pub log_rotation: String,

    /// Keepalive interval in seconds (default: 30)
    /// Sends keepalive packets to maintain connection like a human user
    #[arg(long, default_value = "30", env = "SSH_MCP_KEEPALIVE_INTERVAL")]
    pub keepalive_interval: u64,

    /// Maximum keepalive failures before disconnecting (default: 3)
    /// Total idle timeout = keepalive_interval * keepalive_max
    #[arg(long, default_value = "3", env = "SSH_MCP_KEEPALIVE_MAX")]
    pub keepalive_max: u64,

    /// Number of reconnect retries after the initial attempt (default: 3)
    #[arg(long, default_value = "3", env = "SSH_MCP_RECONNECT_RETRIES")]
    pub reconnect_retries: u64,

    /// Base reconnect backoff in milliseconds (default: 250)
    #[arg(long, default_value = "250", env = "SSH_MCP_RECONNECT_BACKOFF_MS")]
    pub reconnect_backoff_ms: u64,

    /// Health probe timeout in milliseconds for active session checks (default: 1500)
    #[arg(long, default_value = "1500", env = "SSH_MCP_HEALTH_PROBE_TIMEOUT_MS")]
    pub health_probe_timeout_ms: u64,

    /// SSH host key checking mode: yes, accept-new, or no
    #[arg(
        long = "strict-host-key-checking",
        env = "SSH_MCP_STRICT_HOST_KEY_CHECKING",
        value_enum,
        default_value_t = HostKeyCheckMode::AcceptNew
    )]
    pub strict_host_key_checking: HostKeyCheckMode,

    /// Path to known_hosts file (default: OpenSSH user known_hosts)
    #[arg(long = "known-hosts", env = "SSH_MCP_KNOWN_HOSTS")]
    pub known_hosts: Option<PathBuf>,
}

/// Parsed and validated configuration
#[derive(Debug, Clone)]
pub struct Config {
    /// SSH host
    pub host: String,

    /// SSH port
    pub port: u16,

    /// SSH username
    pub user: String,

    /// SSH password
    pub password: Option<String>,

    /// Path to SSH private key
    pub key: Option<PathBuf>,

    /// Password for su elevation
    pub su_password: Option<String>,

    /// Password for sudo commands
    pub sudo_password: Option<String>,

    /// Command timeout in milliseconds
    pub timeout_ms: u64,

    /// Maximum command length (None = unlimited)
    pub max_chars: Option<usize>,

    /// Maximum output tokens for command execution (None = unlimited)
    pub max_output_tokens: Option<usize>,

    /// Whether sudo_shell and sudo_apply_patch tools are disabled
    pub disable_sudo: bool,

    /// Keepalive interval in seconds
    pub keepalive_interval: u64,

    /// Maximum keepalive failures before disconnecting
    pub keepalive_max: u64,

    /// Number of reconnect retries after the initial attempt
    pub reconnect_retries: u64,

    /// Base reconnect backoff in milliseconds
    pub reconnect_backoff_ms: u64,

    /// Health probe timeout in milliseconds for active session checks
    pub health_probe_timeout_ms: u64,

    /// SSH host key checking mode
    pub strict_host_key_checking: HostKeyCheckMode,

    /// Optional known_hosts file path
    pub known_hosts: Option<PathBuf>,
}

impl Config {
    /// Create Config from CLI Args
    pub fn from_args(args: Args) -> Result<Self> {
        validate_args(&args)?;

        let max_chars = parse_max_chars(args.max_chars.as_deref());
        let max_output_tokens = parse_max_output_tokens(args.max_output_tokens.as_deref());

        Ok(Config {
            host: args.host,
            port: args.port,
            user: args.user,
            password: sanitize_password(args.password),
            key: args.key,
            su_password: sanitize_password(args.su_password),
            sudo_password: sanitize_password(args.sudo_password),
            timeout_ms: args.timeout,
            max_chars,
            max_output_tokens,
            disable_sudo: args.disable_sudo,
            keepalive_interval: args.keepalive_interval,
            keepalive_max: args.keepalive_max,
            reconnect_retries: args.reconnect_retries,
            reconnect_backoff_ms: args.reconnect_backoff_ms,
            health_probe_timeout_ms: args.health_probe_timeout_ms,
            strict_host_key_checking: args.strict_host_key_checking,
            known_hosts: args.known_hosts,
        })
    }
}

/// Validate CLI arguments
fn validate_args(args: &Args) -> Result<()> {
    let mut errors = Vec::new();

    if args.host.is_empty() {
        errors.push("Missing required --host".to_string());
    }

    if args.user.is_empty() {
        errors.push("Missing required --user".to_string());
    }

    // Must have either password or key
    if args.password.is_none() && args.key.is_none() {
        errors.push("Must provide either --password or --key".to_string());
    }

    // If key is provided, check if file exists
    if let Some(ref key_path) = args.key
        && !key_path.exists()
    {
        errors.push(format!("SSH key file not found: {}", key_path.display()));
    }

    if args.reconnect_retries > MAX_RECONNECT_RETRIES {
        errors.push(format!(
            "--reconnect-retries must be <= {MAX_RECONNECT_RETRIES}"
        ));
    }

    if !(MIN_RECONNECT_BACKOFF_MS..=MAX_RECONNECT_BACKOFF_MS).contains(&args.reconnect_backoff_ms) {
        errors.push(format!(
            "--reconnect-backoff-ms must be between {MIN_RECONNECT_BACKOFF_MS} and {MAX_RECONNECT_BACKOFF_MS}"
        ));
    }

    if !(MIN_HEALTH_PROBE_TIMEOUT_MS..=MAX_HEALTH_PROBE_TIMEOUT_MS)
        .contains(&args.health_probe_timeout_ms)
    {
        errors.push(format!(
            "--health-probe-timeout-ms must be between {MIN_HEALTH_PROBE_TIMEOUT_MS} and {MAX_HEALTH_PROBE_TIMEOUT_MS}"
        ));
    }

    if !errors.is_empty() {
        return Err(SshMcpError::Config(format!(
            "Configuration error:\n{}",
            errors.join("\n")
        )));
    }

    Ok(())
}

/// Default max output tokens (16_000 ≈ 64KB)
pub const DEFAULT_MAX_OUTPUT_TOKENS: Option<usize> = Some(16_000);

/// Parse max_chars argument
///
/// - "none" (case-insensitive) → None (unlimited)
/// - "0" or negative → None (unlimited)
/// - positive integer → Some(value)
/// - None (not provided) → DEFAULT_MAX_CHARS
pub fn parse_max_chars(value: Option<&str>) -> Option<usize> {
    match value {
        None => DEFAULT_MAX_CHARS,
        Some(s) => {
            let lowered = s.to_lowercase();
            if lowered == "none" {
                return None;
            }

            match s.parse::<i64>() {
                Ok(n) if n <= 0 => None,
                Ok(n) => Some(n as usize),
                Err(_) => DEFAULT_MAX_CHARS,
            }
        }
    }
}

/// Parse max_output_tokens argument
///
/// - "none" (case-insensitive) → None (unlimited)
/// - "0" or negative → None (unlimited)
/// - positive integer with optional "k" suffix (e.g., "12k") → Some(value)
/// - None (not provided) → DEFAULT_MAX_OUTPUT_TOKENS
pub fn parse_max_output_tokens(value: Option<&str>) -> Option<usize> {
    match value {
        None => DEFAULT_MAX_OUTPUT_TOKENS,
        Some(s) => {
            let lowered = s.to_lowercase().replace(" ", "");
            if lowered == "none" {
                return None;
            }

            // Try to parse with k suffix
            if lowered.ends_with('k') {
                let num_part = &lowered[..lowered.len() - 1];
                match num_part.parse::<i64>() {
                    Ok(n) if n <= 0 => None,
                    Ok(n) => Some((n as usize).saturating_mul(1_000)),
                    Err(_) => DEFAULT_MAX_OUTPUT_TOKENS,
                }
            } else {
                match lowered.parse::<i64>() {
                    Ok(n) if n <= 0 => None,
                    Ok(n) => Some(n as usize),
                    Err(_) => DEFAULT_MAX_OUTPUT_TOKENS,
                }
            }
        }
    }
}

/// Sanitize password: return None if empty
fn sanitize_password(password: Option<String>) -> Option<String> {
    password.filter(|p| !p.is_empty())
}

#[cfg(test)]
mod tests {
    use super::*;

    fn base_args() -> Args {
        Args {
            host: "localhost".to_string(),
            port: 22,
            user: "test".to_string(),
            password: Some("secret".to_string()),
            key: None,
            su_password: None,
            sudo_password: None,
            timeout: DEFAULT_TIMEOUT_MS,
            max_chars: None,
            disable_sudo: false,
            max_output_tokens: None,
            log_level: "info".to_string(),
            log_file: None,
            log_format: "text".to_string(),
            log_rotation: "daily".to_string(),
            keepalive_interval: 30,
            keepalive_max: 3,
            reconnect_retries: DEFAULT_RECONNECT_RETRIES,
            reconnect_backoff_ms: DEFAULT_RECONNECT_BACKOFF_MS,
            health_probe_timeout_ms: DEFAULT_HEALTH_PROBE_TIMEOUT_MS,
            strict_host_key_checking: HostKeyCheckMode::AcceptNew,
            known_hosts: None,
        }
    }

    #[test]
    fn test_parse_max_chars_none_string() {
        assert_eq!(parse_max_chars(Some("none")), None);
        assert_eq!(parse_max_chars(Some("None")), None);
        assert_eq!(parse_max_chars(Some("NONE")), None);
    }

    #[test]
    fn test_parse_max_chars_zero_or_negative() {
        assert_eq!(parse_max_chars(Some("0")), None);
        assert_eq!(parse_max_chars(Some("-1")), None);
        assert_eq!(parse_max_chars(Some("-100")), None);
    }

    #[test]
    fn test_parse_max_chars_positive() {
        assert_eq!(parse_max_chars(Some("500")), Some(500));
        assert_eq!(parse_max_chars(Some("2000")), Some(2000));
    }

    #[test]
    fn test_parse_max_chars_invalid() {
        // Invalid strings should return default
        assert_eq!(parse_max_chars(Some("abc")), DEFAULT_MAX_CHARS);
        assert_eq!(parse_max_chars(Some("")), DEFAULT_MAX_CHARS);
    }

    #[test]
    fn test_parse_max_chars_not_provided() {
        assert_eq!(parse_max_chars(None), DEFAULT_MAX_CHARS);
    }

    #[test]
    fn test_config_from_args_uses_default_max_chars() {
        let config = Config::from_args(base_args()).unwrap();

        assert_eq!(config.max_chars, Some(64_000));
        assert_eq!(config.strict_host_key_checking, HostKeyCheckMode::AcceptNew);
        assert!(config.known_hosts.is_none());
    }

    #[test]
    fn test_args_parse_host_key_options() {
        let args = Args::try_parse_from([
            "ssh-mcp",
            "--host",
            "example.com",
            "--user",
            "alice",
            "--password",
            "secret",
            "--strict-host-key-checking",
            "yes",
            "--known-hosts",
            "/tmp/known_hosts",
        ])
        .unwrap();

        assert_eq!(args.strict_host_key_checking, HostKeyCheckMode::Yes);
        assert_eq!(args.known_hosts, Some(PathBuf::from("/tmp/known_hosts")));
    }

    #[test]
    fn test_sanitize_password() {
        assert_eq!(
            sanitize_password(Some("secret".to_string())),
            Some("secret".to_string())
        );
        assert_eq!(sanitize_password(Some(String::new())), None);
        assert_eq!(sanitize_password(None), None);
    }

    #[test]
    fn test_parse_max_output_tokens_none_string() {
        assert_eq!(parse_max_output_tokens(Some("none")), None);
        assert_eq!(parse_max_output_tokens(Some("None")), None);
        assert_eq!(parse_max_output_tokens(Some("NONE")), None);
    }

    #[test]
    fn test_parse_max_output_tokens_zero_or_negative() {
        assert_eq!(parse_max_output_tokens(Some("0")), None);
        assert_eq!(parse_max_output_tokens(Some("-1")), None);
        assert_eq!(parse_max_output_tokens(Some("-100")), None);
    }

    #[test]
    fn test_parse_max_output_tokens_positive() {
        assert_eq!(parse_max_output_tokens(Some("500")), Some(500));
        assert_eq!(parse_max_output_tokens(Some("12000")), Some(12_000));
    }

    #[test]
    fn test_parse_max_output_tokens_with_k_suffix() {
        assert_eq!(parse_max_output_tokens(Some("12k")), Some(12_000));
        assert_eq!(parse_max_output_tokens(Some("5K")), Some(5_000));
        assert_eq!(parse_max_output_tokens(Some("100k")), Some(100_000));
    }

    #[test]
    fn test_parse_max_output_tokens_invalid() {
        // Invalid strings should return default
        assert_eq!(
            parse_max_output_tokens(Some("abc")),
            DEFAULT_MAX_OUTPUT_TOKENS
        );
        assert_eq!(parse_max_output_tokens(Some("")), DEFAULT_MAX_OUTPUT_TOKENS);
    }

    #[test]
    fn test_parse_max_output_tokens_not_provided() {
        assert_eq!(parse_max_output_tokens(None), DEFAULT_MAX_OUTPUT_TOKENS);
    }

    #[test]
    fn test_validate_args_rejects_reconnect_retries_out_of_range() {
        let mut args = base_args();
        args.reconnect_retries = MAX_RECONNECT_RETRIES.saturating_add(1);

        let result = validate_args(&args);
        assert!(result.is_err());
    }

    #[test]
    fn test_validate_args_rejects_reconnect_backoff_out_of_range() {
        let mut args = base_args();
        args.reconnect_backoff_ms = MIN_RECONNECT_BACKOFF_MS.saturating_sub(1);

        let result = validate_args(&args);
        assert!(result.is_err());
    }

    #[test]
    fn test_validate_args_rejects_health_probe_timeout_out_of_range() {
        let mut args = base_args();
        args.health_probe_timeout_ms = MAX_HEALTH_PROBE_TIMEOUT_MS.saturating_add(1);

        let result = validate_args(&args);
        assert!(result.is_err());
    }
}