Support binding to a local IP address or interface

Cargo.toml

@@ -34,6 +34,7 @@ memchr = "2.4.1"
 mime = "0.3.16"
 mime2ext = "0.1.0"
 mime_guess = "2.0"
+network-interface = "1.0.0"
 once_cell = "1.8.0"
 os_display = "0.1.3"
 pem = "0.8.2"

src/cli.rs

@@ -148,14 +148,6 @@ Example: --print=Hb"
     #[clap(short = 'P', long, value_name = "FORMAT")]
     pub history_print: Option<Print>,
 
-    /// Resolve hostname to ipv4 addresses only.
-    #[clap(short = '4', long)]
-    pub ipv4: bool,
-
-    /// Resolve hostname to ipv6 addresses only.
-    #[clap(short = '6', long)]
-    pub ipv6: bool,
-
     /// Do not print to stdout or stderr.
     #[clap(short = 'q', long)]
     pub quiet: bool,
@@ -318,6 +310,20 @@ Example: --print=Hb"
     )]
     pub http_version: Option<HttpVersion>,
 
+    /// Bind to a network interface or local IP address.
+    ///
+    /// Example: --interface=eth0 --interface=192.168.0.2
+    #[clap(long, value_name = "NAME")]
+    pub interface: Option<String>,
+
+    /// Resolve hostname to ipv4 addresses only.
+    #[clap(short = '4', long)]
+    pub ipv4: bool,
+
+    /// Resolve hostname to ipv6 addresses only.
+    #[clap(short = '6', long)]
+    pub ipv6: bool,
+
     /// Do not attempt to read stdin.
     ///
     /// This disables the default behaviour of reading the request body from stdin

src/main.rs

@@ -27,6 +27,7 @@ use std::sync::Arc;
 
 use anyhow::{anyhow, Context, Result};
 use atty::Stream;
+use network_interface::{NetworkInterface, NetworkInterfaceConfig};
 use redirect::RedirectFollower;
 use reqwest::blocking::Client;
 use reqwest::header::{
@@ -318,6 +319,30 @@ fn run(args: Cli) -> Result<i32> {
         _ => client,
     };
 
+    if let Some(name_or_ip) = &args.interface {
+        let ip_addr = if let Ok(ip_addr) = IpAddr::from_str(name_or_ip) {
+            Some(ip_addr)
+        } else {
+            // TODO: Directly bind to interface name once hyper/reqwest adds support for it.
+            // See https://github.com/seanmonstar/reqwest/issues/1336 and https://github.com/hyperium/hyper/pull/3076
+            let network_interfaces = NetworkInterface::show()?;
+            network_interfaces.iter().find_map(|interface| {
+                if &interface.name == name_or_ip {
+                    if let Some(addr) = interface.addr.first() {
+                        return Some(addr.ip());
+                    }
+                }
+                None
+            })
+        };
+
+        if let Some(ip_addr) = ip_addr {
+            client = client.local_address(ip_addr);
+        } else {
+            return Err(anyhow!("Couldn't bind to {:?}", name_or_ip));
+        }
+    }
+
     let client = client.build()?;
 
     let mut session = match &args.session {

src/to_curl.rs

@@ -279,6 +279,11 @@ pub fn translate(args: Cli) -> Result<Command> {
         _ => (),
     };
 
+    if let Some(interface) = args.interface {
+        cmd.arg("--interface");
+        cmd.arg(interface);
+    };
+
     // Payload
     for (header, value) in headers.iter() {
         cmd.opt("-H", "--header");