feat: Add support for default target and implement robust target resolution

Introduces a new `--default-target` argument to allow specifying a default host address.
In case that target isn't defined, as a configuration option.

2 files changed, 30 insertions, 20 deletions

diff --git a/src/args.rs b/src/args.rs
index 7004791..6fdca59 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -37,6 +37,10 @@ pub struct Args {
     #[arg(short = 'r', long = "remainder", action = ArgAction::SetTrue)]
     pub remainder: bool,
 
+    /// Default target, if none is specified
+    #[arg(long = "default-target", value_name = "default_target")]
+    pub default_target: Option<String>,
+
     /// Target IP address
     #[arg(value_name = "target")]
     pub target: Option<String>,
diff --git a/src/main.rs b/src/main.rs
index 99db51b..ee5add6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -17,6 +17,29 @@ use print::{print_legende_line, print_ping_line, print_stats};
 use state::State;
 use stats::compute_stats;
 
+fn parse_target(target_str: &str) -> IpAddr {
+    if let Ok(ip) = parse_ip(target_str) {
+        ip
+    } else {
+        // Try DNS resolution
+        let dns_str = format!("{}:0", target_str);
+        match dns_str.to_socket_addrs() {
+            Ok(mut addrs) => {
+                if let Some(addr) = addrs.next() {
+                    addr.ip()
+                } else {
+                    eprintln!("Error: no DNS addresses found");
+                    std::process::exit(1);
+                }
+            }
+            Err(e) => {
+                eprintln!("Error: DNS resolution failed: {}", e);
+                std::process::exit(1);
+            }
+        }
+    }
+}
+
 fn main_loop(
     args: &Args,
     states: &mut Vec<State>,
@@ -109,26 +132,9 @@ async fn main() {
     let args = Args::parse();
 
     let target: IpAddr = if let Some(target_str) = args.target.clone() {
-        if let Ok(ip) = parse_ip(&target_str) {
-            ip
-        } else {
-            // Try DNS resolution
-            let dns_str = format!("{}:0", target_str);
-            match dns_str.to_socket_addrs() {
-                Ok(mut addrs) => {
-                    if let Some(addr) = addrs.next() {
-                        addr.ip()
-                    } else {
-                        eprintln!("Error: no DNS addresses found");
-                        std::process::exit(1);
-                    }
-                }
-                Err(e) => {
-                    eprintln!("Error: DNS resolution failed: {}", e);
-                    std::process::exit(1);
-                }
-            }
-        }
+        parse_target(&target_str)
+    } else if let Some(default_target_str) = args.default_target.clone() {
+        parse_target(&default_target_str)
     } else {
         eprintln!("Error: target address is required");
         std::process::exit(1);