don't return any forwarded hops if the header is invalid

src/headers.rs

@@ -1,8 +1,9 @@
 use comma_separated::CommaSeparatedIterator;
+use either::Either;
 use rfc7239::{parse, Forwarded, NodeIdentifier, NodeName};
 use std::borrow::Cow;
-use std::iter::IntoIterator;
-use std::net::IpAddr;
+use std::iter::{empty, IntoIterator};
+use std::net::{AddrParseError, IpAddr};
 use std::str::FromStr;
 
 /// Get the list of ip addresses from an `forwarded` header
@@ -22,17 +23,29 @@ use std::str::FromStr;
 pub fn extract_forwarded_header(
     header_value: &str,
 ) -> impl DoubleEndedIterator<Item = IpAddr> + '_ {
-    parse(header_value).filter_map(|forward| match forward {
-        Ok(Forwarded {
-            forwarded_for:
-                Some(NodeIdentifier {
-                    name: NodeName::Ip(ip),
-                    ..
-                }),
-            ..
-        }) => Some(ip),
-        _ => None,
-    })
+    if parse(header_value).all(|result| result.is_ok()) {
+        Either::Left(parse(header_value).filter_map(|forward| match forward {
+            Ok(Forwarded {
+                forwarded_for:
+                    Some(NodeIdentifier {
+                        name: NodeName::Ip(ip),
+                        ..
+                    }),
+                ..
+            }) => Some(ip),
+            _ => None,
+        }))
+    } else {
+        Either::Right(empty())
+    }
+}
+
+fn extract_x_forwarded_for_header_raw(
+    header_value: &str,
+) -> impl DoubleEndedIterator<Item = Result<IpAddr, AddrParseError>> + '_ {
+    CommaSeparatedIterator::new(header_value)
+        .map(str::trim)
+        .map(|x| IpAddr::from_str(maybe_bracketed(&maybe_quoted(x))))
 }
 
 /// Get the list of ip addresses from an `x-forwarded-for` header
@@ -50,9 +63,11 @@ pub fn extract_forwarded_header(
 pub fn extract_x_forwarded_for_header(
     header_value: &str,
 ) -> impl DoubleEndedIterator<Item = IpAddr> + '_ {
-    CommaSeparatedIterator::new(header_value)
-        .map(str::trim)
-        .flat_map(|x| IpAddr::from_str(maybe_bracketed(&maybe_quoted(x))))
+    if extract_x_forwarded_for_header_raw(header_value).all(|result| result.is_ok()) {
+        Either::Left(extract_x_forwarded_for_header_raw(header_value).flatten())
+    } else {
+        Either::Right(empty())
+    }
 }
 
 /// Get the list of ip addresses from an `x-real-ip` header

src/lib.rs

@@ -74,6 +74,7 @@ pub fn real_ip(headers: &HeaderMap, remote: IpAddr, trusted_proxies: &[IpNet]) -
 
     'outer: for hop in hops.rev() {
         for proxy in trusted_proxies {
+            dbg!(proxy);
             if proxy.contains(&hop) {
                 continue 'outer;
             }
@@ -110,3 +111,25 @@ pub fn get_forwarded_for(headers: &HeaderMap) -> impl DoubleEndedIterator<Item =
 #[allow(dead_code)]
 #[doc = include_str!("../README.md")]
 fn test_readme_examples() {}
+
+#[test]
+fn test_malformed() {
+    use http::header::HeaderValue;
+    let mut headers = HeaderMap::new();
+    headers.insert(
+        "forwarded",
+        HeaderValue::from_static(
+            "by=203.0.111.42;for=1.2.3.4:8888,for=5.6.7.8;proto=https;nonsense",
+        ),
+    );
+    let trusted_proxies = [
+        IpAddr::from([2, 3, 4, 5]).into(),
+        IpAddr::from([5, 6, 7, 8]).into(),
+    ];
+    let remote = IpAddr::from([2, 3, 4, 5]);
+    assert!(get_forwarded_for(&headers).next().is_none());
+    assert_eq!(
+        Some(IpAddr::from([2, 3, 4, 5])),
+        real_ip(&headers, remote, &trusted_proxies)
+    );
+}