Bind functions for dealing with sigalgs

Fixes pyca#7336

src/_cffi_src/openssl/ssl.py

@@ -20,6 +20,7 @@
 static const long Cryptography_HAS_SECURE_RENEGOTIATION;
 static const long Cryptography_HAS_SSL_CTX_CLEAR_OPTIONS;
 static const long Cryptography_HAS_DTLS;
+static const long Cryptography_HAS_SIGALGS;
 static const long Cryptography_HAS_PSK;
 static const long Cryptography_HAS_PSK_TLSv1_3;
 static const long Cryptography_HAS_VERIFIED_CHAIN;
@@ -299,6 +300,8 @@
                                  void (*)(const SSL *, const char *));
 void (*SSL_CTX_get_keylog_callback(SSL_CTX *))(const SSL *, const char *);
 
+long SSL_CTX_set1_sigalgs_list(SSL_CTX *, const char *);
+
 /*  SSL_SESSION */
 void SSL_SESSION_free(SSL_SESSION *);
 
@@ -677,6 +680,13 @@
     return r;
 }
 
+#if CRYPTOGRAPHY_IS_LIBRESSL
+static const long Cryptography_HAS_SIGALGS = 0;
+const long (*SSL_CTX_set1_sigalgs_list)(SSL_CTX *, const char *) = NULL;
+#else
+static const long Cryptography_HAS_SIGALGS = 1;
+#endif
+
 #if CRYPTOGRAPHY_IS_LIBRESSL || defined(OPENSSL_NO_PSK)
 static const long Cryptography_HAS_PSK = 0;
 int (*SSL_CTX_use_psk_identity_hint)(SSL_CTX *, const char *) = NULL;

src/cryptography/hazmat/bindings/openssl/_conditional.py

@@ -119,6 +119,12 @@ def cryptography_has_fips() -> typing.List[str]:
     ]
 
 
+def cryptography_has_ssl_sigalgs() -> typing.List[str]:
+    return [
+        "SSL_CTX_set1_sigalgs_list",
+    ]
+
+
 def cryptography_has_psk() -> typing.List[str]:
     return [
         "SSL_CTX_use_psk_identity_hint",
@@ -345,6 +351,7 @@ def cryptography_has_ssl_op_ignore_unexpected_eof() -> typing.List[str]:
         cryptography_has_evp_pkey_get_set_tls_encodedpoint
     ),
     "Cryptography_HAS_FIPS": cryptography_has_fips,
+    "Cryptography_HAS_SIGALGS": cryptography_has_ssl_sigalgs,
     "Cryptography_HAS_PSK": cryptography_has_psk,
     "Cryptography_HAS_PSK_TLSv1_3": cryptography_has_psk_tlsv13,
     "Cryptography_HAS_CUSTOM_EXT": cryptography_has_custom_ext,