Add support for glob pattern matching in Host directives (#306)

- update parse logic to perform host glob matching (using globset)
- generalise token expansion so it can be used to qualify hosts as well
as localising ProxyCommand
- add proxyjump to the config structure

---------

Co-authored-by: Adam Chappell <Adam.Chappell@gtt.net>

Author: packetsource

russh-config/Cargo.toml

@@ -13,6 +13,7 @@ rust-version = "1.65"
 [dependencies]
 dirs-next = "2.0"
 futures = { workspace = true }
+globset = "0.4.14"
 log = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true, features = ["io-util", "net", "macros", "process"] }

russh-config/src/lib.rs

@@ -8,6 +8,7 @@ use std::io::Read;
 use std::net::ToSocketAddrs;
 use std::path::Path;
 
+use globset::Glob;
 use log::debug;
 use thiserror::*;
 
@@ -34,6 +35,7 @@ pub struct Config {
     pub port: u16,
     pub identity_file: Option<String>,
     pub proxy_command: Option<String>,
+    pub proxy_jump: Option<String>,
     pub add_keys_to_agent: AddKeysToAgent,
 }
 
@@ -45,22 +47,30 @@ impl Config {
             port: 22,
             identity_file: None,
             proxy_command: None,
+            proxy_jump: None,
             add_keys_to_agent: AddKeysToAgent::default(),
         }
     }
 }
 
 impl Config {
-    fn update_proxy_command(&mut self) {
-        if let Some(ref mut prox) = self.proxy_command {
-            *prox = prox.replace("%h", &self.host_name);
-            *prox = prox.replace("%p", &format!("{}", self.port));
-        }
+    // Look for any of the ssh_config(5) percent-style tokens and expand them
+    // based on current data in the struct, returning a new String. This function
+    // can be employed late/lazy eg just before establishing a stream using ProxyCommand
+    // but also can be used to modify Hostname as config parse time
+    fn expand_tokens(&self, original: &str) -> String {
+        let mut string = original.to_string();
+        string = string.replace("%u", &self.user);
+        string = string.replace("%h", &self.host_name); // remote hostname (from context "host")
+        string = string.replace("%H", &self.host_name); // remote hostname (from context "host")
+        string = string.replace("%p", &format!("{}", self.port)); // original typed hostname (from context "host")
+        string = string.replace("%%", "%");
+        string
     }
 
-    pub async fn stream(&mut self) -> Result<Stream, Error> {
-        self.update_proxy_command();
+    pub async fn stream(&self) -> Result<Stream, Error> {
         if let Some(ref proxy_command) = self.proxy_command {
+            let proxy_command = self.expand_tokens(proxy_command);
             let cmd: Vec<&str> = proxy_command.split(' ').collect();
             Stream::proxy_command(cmd.first().unwrap_or(&""), cmd.get(1..).unwrap_or(&[]))
                 .await
@@ -105,9 +115,9 @@ pub enum AddKeysToAgent {
 pub fn parse(file: &str, host: &str) -> Result<Config, Error> {
     let mut config: Option<Config> = None;
     for line in file.lines() {
-        let line = line.trim();
-        if let Some(n) = line.find(' ') {
-            let (key, value) = line.split_at(n);
+        let tokens = line.trim().splitn(2, ' ').collect::<Vec<&str>>();
+        if tokens.len() == 2 {
+            let (key, value) = (tokens.first().unwrap_or(&""), tokens.get(1).unwrap_or(&""));
             let lower = key.to_lowercase();
             if let Some(ref mut config) = config {
                 match lower.as_str() {
@@ -116,10 +126,7 @@ pub fn parse(file: &str, host: &str) -> Result<Config, Error> {
                         config.user.clear();
                         config.user.push_str(value.trim_start());
                     }
-                    "hostname" => {
-                        config.host_name.clear();
-                        config.host_name.push_str(value.trim_start())
-                    }
+                    "hostname" => config.host_name = config.expand_tokens(value.trim_start()),
                     "port" => {
                         if let Ok(port) = value.trim_start().parse() {
                             config.port = port
@@ -148,6 +155,7 @@ pub fn parse(file: &str, host: &str) -> Result<Config, Error> {
                         }
                     }
                     "proxycommand" => config.proxy_command = Some(value.trim_start().to_string()),
+                    "proxyjump" => config.proxy_jump = Some(value.trim_start().to_string()),
                     "addkeystoagent" => match value.to_lowercase().as_str() {
                         "yes" => config.add_keys_to_agent = AddKeysToAgent::Yes,
                         "confirm" => config.add_keys_to_agent = AddKeysToAgent::Confirm,
@@ -158,7 +166,11 @@ pub fn parse(file: &str, host: &str) -> Result<Config, Error> {
                         debug!("{:?}", key);
                     }
                 }
-            } else if lower.as_str() == "host" && value.trim_start() == host {
+            } else if lower.as_str() == "host"
+                && value
+                    .split_whitespace()
+                    .any(|x| check_host_against_glob_pattern(host, x))
+            {
                 let mut c = Config::default(host);
                 c.port = 22;
                 config = Some(c)
@@ -171,3 +183,11 @@ pub fn parse(file: &str, host: &str) -> Result<Config, Error> {
         Err(Error::HostNotFound)
     }
 }
+
+fn check_host_against_glob_pattern(candidate: &str, glob_pattern: &str) -> bool {
+    dbg!(candidate, glob_pattern);
+    match Glob::new(glob_pattern) {
+        Ok(glob) => glob.compile_matcher().is_match(candidate),
+        _ => false,
+    }
+}