support spoofing the host address

src/request.rs

@@ -1,5 +1,6 @@
 use std::io::Read;
 use std::{fmt, time};
+use std::borrow::Cow;
 
 use url::{form_urlencoded, ParseError, Url};
 
@@ -32,6 +33,7 @@ pub struct Request {
     url: String,
     pub(crate) headers: Vec<Header>,
     timeout: Option<time::Duration>,
+    spoofed_host: Option<Cow<'static, str>>,
 }
 
 impl fmt::Debug for Request {
@@ -52,6 +54,7 @@ impl Request {
             url,
             headers: vec![],
             timeout: None,
+            spoofed_host: None,
         }
     }
 
@@ -62,6 +65,13 @@ impl Request {
         self
     }
 
+    #[inline(always)]
+    /// Sets overall timeout for the request, overriding agent's configuration if any.
+    pub fn connection_host(mut self, dns_host: Cow<'static, str>) -> Self {
+        self.spoofed_host = Some(dns_host);
+        self
+    }
+
     /// Sends the request with no body and blocks the caller until done.
     ///
     /// Use this with GET, HEAD, OPTIONS or TRACE. It sends neither
@@ -138,7 +148,7 @@ impl Request {
 
         let request_fn = |req: Request| {
             let reader = payload.into_read();
-            let unit = Unit::new(
+            let mut unit = Unit::new(
                 &req.agent,
                 &req.method,
                 &url,
@@ -147,6 +157,9 @@ impl Request {
                 deadline,
             );
 
+            // forward the spoofed host address
+            unit.spoofed_host = req.spoofed_host;
+
             unit::connect(unit, true, reader).map_err(|e| e.url(url.clone()))
         };
 

src/unit.rs

@@ -1,3 +1,4 @@
+use std::borrow::Cow;
 use std::fmt::{self, Display};
 use std::io::{self, Write};
 use std::ops::Range;
@@ -32,6 +33,7 @@ pub(crate) struct Unit {
     is_chunked: bool,
     headers: Vec<Header>,
     pub deadline: Option<time::Instant>,
+    pub spoofed_host: Option<Cow<'static, str>>,
 }
 
 impl Unit {
@@ -252,8 +254,13 @@ fn connect_inner(
         .unwrap();
     let url = &unit.url;
     let method = &unit.method;
+
+    let socket_host = unit.spoofed_host
+        .map(|r|r.as_ref())
+        .unwrap_or(host);
+
     // open socket
-    let (mut stream, is_recycled) = connect_socket(unit, host, use_pooled)?;
+    let (mut stream, is_recycled) = connect_socket(unit, socket_host, use_pooled)?;
 
     if is_recycled {
         debug!("sending request (reused connection) {} {}", method, url);