From aa503c46c384c13fb02bf0cc98438336a161fcd4 Mon Sep 17 00:00:00 2001
From: Isaac Parker <parrotmac@gmail.com>
Date: Sun, 28 Jun 2020 14:03:31 -0600
Subject: Bind to random port when port 0 specified

---
 Cargo.lock             |  1 +
 Cargo.toml             |  2 ++
 src/args.rs            |  8 +++++++-
 tests/serve_request.rs | 26 ++++++++++++++++++++++++++
 4 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index ddcdb74..96fe95f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1753,6 +1753,7 @@ dependencies = [
  "percent-encoding 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "port_check 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "pretty_assertions 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "reqwest 0.10.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rstest 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "select 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/Cargo.toml b/Cargo.toml
index 909ec59..a975fa8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -27,6 +27,7 @@ actix-web = "0.7"
 simplelog = "0.8"
 base64 = "0.12"
 percent-encoding = "2.1"
+port_check = "0.1"
 htmlescape = "0.3.1"
 bytesize = "1.0.0"
 nanoid = "0.3"
@@ -55,5 +56,6 @@ assert_fs = "1.0"
 select = "0.4"
 port_check = "0.1"
 rstest = "0.6"
+regex = "1.3.9"
 pretty_assertions = "0.6"
 url = "2.1"
diff --git a/src/args.rs b/src/args.rs
index 7e30ee1..a5bcfea 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -1,6 +1,7 @@
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 use std::path::PathBuf;
 use structopt::StructOpt;
+use port_check::free_local_port;
 
 use crate::auth;
 use crate::errors::ContextualError;
@@ -170,10 +171,15 @@ pub fn parse_args() -> crate::MiniserveConfig {
 
     let path_explicitly_chosen = args.path.is_some();
 
+    let port = match args.port {
+        0 => free_local_port().expect("no free ports available"),
+        _ => args.port,
+    };
+
     crate::MiniserveConfig {
         verbose: args.verbose,
         path: args.path.unwrap_or_else(|| PathBuf::from(".")),
-        port: args.port,
+        port,
         interfaces,
         auth: args.auth,
         path_explicitly_chosen,
diff --git a/tests/serve_request.rs b/tests/serve_request.rs
index 5761a65..918bb98 100644
--- a/tests/serve_request.rs
+++ b/tests/serve_request.rs
@@ -9,6 +9,7 @@ use select::node::Node;
 use std::process::{Command, Stdio};
 use std::thread::sleep;
 use std::time::Duration;
+use regex::{Regex};
 
 #[rstest]
 fn serves_requests_with_no_options(tmpdir: TempDir) -> Result<(), Error> {
@@ -69,6 +70,31 @@ fn serves_requests_with_non_default_port(tmpdir: TempDir, port: u16) -> Result<(
     Ok(())
 }
 
+#[rstest]
+fn serves_requests_with_randomly_assigned_port(tmpdir: TempDir) -> Result<(), Error> {
+    let mut child = Command::cargo_bin("miniserve")?
+        .arg(tmpdir.path())
+        .arg("-p")
+        .arg("0".to_string())
+        .stdout(Stdio::piped())
+        .spawn()?;
+
+    sleep(Duration::from_secs(1));
+    child.kill()?;
+
+    let output = child.wait_with_output().expect("Failed to read stdout");
+    let all_text = String::from_utf8(output.stdout)?;
+
+    let re = Regex::new(r"http://127.0.0.1:(\d+)").unwrap();
+    let caps = re.captures(all_text.as_str()).unwrap();
+    let port_num = caps.get(1).unwrap().as_str().parse::<u32>().unwrap();
+
+    assert!(port_num > 0);
+    assert!(port_num <= 65535);
+
+    Ok(())
+}
+
 #[rstest]
 fn serves_requests_custom_index_notice(tmpdir: TempDir, port: u16) -> Result<(), Error> {
     let mut child = Command::cargo_bin("miniserve")?
-- 
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