diff --git a/ylong_http_client/src/async_impl/ssl_stream/c_ssl_stream.rs b/ylong_http_client/src/async_impl/ssl_stream/c_ssl_stream.rs
index 8ee6dca6318a8ea1c2947b394cc611598175eb79..75aa3ce0928f2d70a19589ec39dad5a4f87ba45c 100644
--- a/ylong_http_client/src/async_impl/ssl_stream/c_ssl_stream.rs
+++ b/ylong_http_client/src/async_impl/ssl_stream/c_ssl_stream.rs
@@ -46,6 +46,10 @@ impl<S> AsyncSslStream<S> {
         // SAFETY:
         unsafe { Pin::new_unchecked(&mut self.get_unchecked_mut().0.get_mut().stream) }
     }
+
+    pub(crate) fn negotiated_alpn_protocol(&self) -> Option<&[u8]> {
+        self.0.ssl().negotiated_alpn_protocol()
+    }
 }
 
 impl<S> AsyncSslStream<S>
diff --git a/ylong_http_client/src/util/c_openssl/ffi/ssl.rs b/ylong_http_client/src/util/c_openssl/ffi/ssl.rs
index 3af302050d38a020f7e56abcdb9919b743933caf..c02eafe28824e1cfee52eb865eaef5a5cb83f4db 100644
--- a/ylong_http_client/src/util/c_openssl/ffi/ssl.rs
+++ b/ylong_http_client/src/util/c_openssl/ffi/ssl.rs
@@ -79,11 +79,18 @@ extern "C" {
 
     /// Client sets the list of protocols available to be negotiated.
     pub(crate) fn SSL_CTX_set_alpn_protos(
-        s: *mut SSL_CTX,
+        ctx: *mut SSL_CTX,
         data: *const c_uchar,
         len: c_uint,
     ) -> c_int;
 
+    /// returns the selected protocol. It is not NUL-terminated.
+    pub(crate) fn SSL_get0_alpn_selected(
+        ssl: *const SSL,
+        data: *mut *const c_uchar,
+        len: *mut c_uint,
+    );
+
     /// Sets/replaces the certificate verification storage of ctx to/with store.
     /// If another X509_STORE object is currently set in ctx, it will be
     /// X509_STORE_free()ed.
diff --git a/ylong_http_client/src/util/c_openssl/ssl/ssl_base.rs b/ylong_http_client/src/util/c_openssl/ssl/ssl_base.rs
index 1f65d12706a979c03214e4ee1b95a7470b4777c2..ad2f58b9647226ba2ffd934aeaae6569430d648d 100644
--- a/ylong_http_client/src/util/c_openssl/ssl/ssl_base.rs
+++ b/ylong_http_client/src/util/c_openssl/ssl/ssl_base.rs
@@ -12,9 +12,11 @@
 // limitations under the License.
 
 use core::{cmp, ffi, fmt, str};
-use std::ffi::CString;
+use std::ffi::{c_uchar, CString};
 #[cfg(feature = "sync")]
 use std::io::{Read, Write};
+use std::ptr::null;
+use std::slice::from_raw_parts;
 
 use libc::{c_char, c_int, c_long, c_void};
 
@@ -35,7 +37,7 @@ use crate::c_openssl::x509::{
 };
 use crate::util::c_openssl::check_ptr;
 use crate::util::c_openssl::error::ErrorStack;
-use crate::util::c_openssl::ffi::ssl::{SSL_free, SSL_new, SSL};
+use crate::util::c_openssl::ffi::ssl::{SSL_free, SSL_new, SSL, SSL_get0_alpn_selected};
 use crate::util::c_openssl::foreign::Foreign;
 
 foreign_type!(
@@ -140,6 +142,19 @@ impl SslRef {
             Err(_) => param.set_host(host_name),
         }
     }
+
+    pub(crate) fn negotiated_alpn_protocol(&self) -> Option<&[u8]> {
+        let mut data = null() as *const c_uchar;
+        let mut len = 0_u32;
+        unsafe {
+            SSL_get0_alpn_selected(self.as_ptr(), &mut data, &mut len);
+            if data.is_null() {
+                None
+            } else {
+                Some(from_raw_parts(data, len as usize))
+            }
+        }
+    }
 }
 
 impl fmt::Debug for SslRef {