TLS 1.3 version support

build.rs

@@ -8,6 +8,11 @@ fn main() {
         if version >= 0x1_01_00_00_0 {
             println!("cargo:rustc-cfg=have_min_max_version");
         }
+
+        // TLS 1.3 requires openssl 1.1.1
+        if version >= 0x1_01_01_00_0 {
+            println!("cargo:rustc-cfg=have_tls13_version");
+        }
     }
 
     if let Ok(version) = env::var("DEP_OPENSSL_LIBRESSL_VERSION_NUMBER") {
@@ -16,5 +21,10 @@ fn main() {
         if version >= 0x2_06_01_00_0 {
             println!("cargo:rustc-cfg=have_min_max_version");
         }
+
+        // TLS 1.3 requires libressl 3.2
+        if version >= 0x3_02_01_00_0 {
+            println!("cargo:rustc-cfg=have_tls13_version");
+        }
     }
 }

src/imp/openssl.rs

@@ -32,6 +32,7 @@ fn supported_protocols(
             Protocol::Tlsv10 => SslVersion::TLS1,
             Protocol::Tlsv11 => SslVersion::TLS1_1,
             Protocol::Tlsv12 => SslVersion::TLS1_2,
+            #[cfg(have_tls13_version)]
             Protocol::Tlsv13 => SslVersion::TLS1_3,
         }
     }

src/lib.rs

@@ -323,6 +323,7 @@ pub enum Protocol {
     /// The TLS 1.2 protocol.
     Tlsv12,
     /// The TLS 1.3 protocol.
+    #[cfg(any(target_os = "macos", target_os = "windows", target_os = "ios", have_tls13_version))]
     Tlsv13,
 }