add: obtain original peer ip from headers

4 years ago · 989ab443b9
parent 302a84f4b4
commit 989ab443b9
3 changed files with 58 additions and 11 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 3

+[[package]]
+name = "httparse"
+version = "1.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "acd94fdbe1d4ff688b67b04eee2e17bd50995534a61539e45adfefb45e5e5503"
+
 [[package]]
 name = "myip"
 version = "0.1.0"
+dependencies = [
+ "httparse",
+]
--- a/Cargo.toml
+++ b/Cargo.toml
@ -6,3 +6,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

 [dependencies]
+httparse = "1.5.1"
--- a/src/main.rs
+++ b/src/main.rs
@ -1,7 +1,9 @@
+use httparse;
 use std::io::prelude::*;
 use std::net::{TcpListener, TcpStream};

 fn main() {
+    println!("Replying with most probable peer's ip on port 7878");
    let listener = TcpListener::bind("127.0.0.1:7878").unwrap();

    for stream in listener.incoming() {
@ -11,6 +13,8 @@ fn main() {
    }
 }

+// Reply to TCP streem with peer's IP
+// if anyhting goes wrong, just slap 404 on it
 fn handle_connection(mut stream: TcpStream) {
    // make it 8k?
    // https://stackoverflow.com/questions/686217/maximum-on-http-header-values
@ -18,20 +22,33 @@ fn handle_connection(mut stream: TcpStream) {
    stream.read(&mut buffer).unwrap();

    let get = b"GET / HTTP";
-
-    let (status_line, contents) = if buffer.starts_with(get) {
-        (
-            "HTTP/1.1 200 OK",
-            stream.peer_addr().unwrap().ip().to_string(),
-        )
-    } else {
-        (
+    let err404 = (
        "HTTP/1.1 404 NOT FOUND",
        "<html>\n<head><title>404 Not Found</title></head>\n\
        <body bgcolor=\"white\">\n<center><h1>404 Not Found</h1></center>\n\
        <hr>\n</body>\n</html>"
            .to_string(),
-        )
+    );
+
+    // println!("Request: {}", String::from_utf8_lossy(&buffer[..]));
+
+    let (status_line, contents) = if buffer.starts_with(get) {
+        let mut headers = [httparse::EMPTY_HEADER; 30];
+        let mut req = httparse::Request::new(&mut headers);
+
+        match req.parse(&buffer) {
+            Ok(_) => {
+                let peer_ip =
+                    pick_ip(req).unwrap_or_else(|| stream.peer_addr().unwrap().ip().to_string());
+                ("HTTP/1.1 200 OK", peer_ip)
+            }
+            Err(e) => {
+                eprintln!("{:?}", e);
+                err404
+            }
+        }
+    } else {
+        err404
    };

    // add date header formatted to rfc2822?
@ -49,3 +66,23 @@ fn handle_connection(mut stream: TcpStream) {
    stream.write(response.as_bytes()).unwrap();
    stream.flush().unwrap();
 }
+
+/// Pick most likely peer ip from request headers
+fn pick_ip(req: httparse::Request) -> Option<String> {
+    // https://support.cloudflare.com/hc/en-us/articles/200170986-How-does-Cloudflare-handle-HTTP-Request-headers-
+    // CF-Connecting-IP
+    // X-Forwarded-For
+    let mut ip = None;
+
+    for header in req.headers {
+        let name = header.name.to_lowercase();
+
+        if name == "CF-Connecting-IP".to_lowercase() {
+            ip = Some(String::from_utf8_lossy(header.value).to_string());
+            break;
+        } else if name == "X-Forwarded-For".to_lowercase() {
+            ip = Some(String::from_utf8_lossy(header.value).to_string());
+        }
+    }
+    ip
+}