Added parallel DNS resolver.

Cargo.lock

@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "aho-corasick"
@@ -244,6 +244,31 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9dd111b7b7f7d55b72c0a6ae361660ee5853c9af73f70c3c2ef6858b950e2e51"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
+
 [[package]]
 name = "crypto-common"
 version = "0.1.6"
@@ -1029,6 +1054,26 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "rayon"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b418a60154510ca1a002a752ca9714984e21e4241e804d32555251faf8b78ffa"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1465873a3dfdaa8ae7cb14b4383657caab0b3e8a0aa9ae8e04b044854c8dfce2"
+dependencies = [
+ "crossbeam-deque",
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.2.16"
@@ -1079,6 +1124,7 @@ dependencies = [
  "massh",
  "openssl",
  "question",
+ "rayon",
  "regex",
  "whoami",
 ]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rexec"
-version = "1.1.0"
+version = "1.2.0"
 readme = "https://github.com/house-of-vanity/rexec#readme"
 edition = "2021"
 description = "Parallel SSH executor"
@@ -14,6 +14,7 @@ authors = ["AB <gh@hexor.ru>"]
 
 [dependencies]
 dns-lookup = "2.0.2"
+rayon = "1.10"
 log = "0.4.0"
 env_logger = "0.10.0"
 massh = "0.6.3"

src/main.rs

@@ -6,6 +6,7 @@ use std::fs::read_to_string;
 use std::hash::Hash;
 use std::net::IpAddr;
 use std::process;
+use std::sync::{Arc, Mutex};
 
 use clap::Parser;
 use colored::*;
@@ -15,6 +16,7 @@ use itertools::Itertools;
 use log::{error, info};
 use massh::{MasshClient, MasshConfig, MasshHostConfig, SshAuth};
 use question::{Answer, Question};
+use rayon::prelude::*;
 use regex::Regex;
 
 // Define args
@@ -187,8 +189,6 @@ fn main() {
     let matched_hosts: Vec<_> = hosts.into_iter().unique().collect();
 
     // Build MasshHostConfig hostnames list
-    let mut massh_hosts: Vec<MasshHostConfig> = vec![];
-    let mut hosts_and_ips: HashMap<IpAddr, String> = HashMap::new();
     if args.parallel != 100 {
         warn!("Parallelism: {} thread{}", &args.parallel, {
             if args.parallel != 1 {
@@ -200,23 +200,42 @@ fn main() {
     }
 
     info!("Matched hosts:");
-    for host in matched_hosts.iter() {
+    let resolved_ips = Arc::new(Mutex::new(Vec::<(String, IpAddr)>::new()));
-        let ip = match lookup_host(&host.name) {
+
-            Ok(ip) => ip[0],
+    matched_hosts.par_iter().for_each(|host| {
-            Err(_) => {
+        match lookup_host(&host.name) {
-                error!("{} couldn't be resolved.", &host.name.red());
+            Ok(ips) if !ips.is_empty() => {
-                continue;
+                let ip = ips[0];
+
+                info!("{} [{}]", &host.name, ip);
+
+                let mut results = resolved_ips.lock().unwrap();
+                results.push((host.name.clone(), ip));
             }
-        };
+            Ok(_) => {
-        info!("{} [{}]", &host.name, ip);
+                error!("DNS resolved, but IP not found: {}", &host.name.red());
-        hosts_and_ips.insert(ip, host.name.clone());
+            }
-        massh_hosts.push(MasshHostConfig {
+            Err(_) => {
-            addr: ip,
+                error!("DNS resolve failed: {}", &host.name.red());
-            auth: None,
+            }
-            port: None,
+        }
-            user: None,
+    });
-        })
+
+    let mut hosts_and_ips: HashMap<IpAddr, String> = HashMap::new();
+    let mut massh_hosts: Vec<MasshHostConfig> = Vec::new();
+
+    if let Ok(results) = resolved_ips.lock() {
+        for (hostname, ip) in results.iter() {
+            hosts_and_ips.insert(*ip, hostname.clone());
+            massh_hosts.push(MasshHostConfig {
+                addr: *ip,
+                auth: None,
+                port: None,
+                user: None,
+            });
+        }
     }
+
     // Build MasshConfig using massh_hosts vector
     let config = MasshConfig {
         default_auth: SshAuth::Agent,