Old pyOpenSSL is missing get_signature_algorithm. Use the default "sha256"

signature algorithm for old pyOpenSSL.

Fixes #7641

src/common/jingle_content.py

@@ -220,7 +220,11 @@ class JingleContent(object):
                 + '.cert'
             cert = load_cert_file(certpath)
             if cert:
-                digest_algo = cert.get_signature_algorithm().split('With')[0]
+                try:
+                    digest_algo = cert.get_signature_algorithm().split('With')[0]
+                except AttributeError, e:
+                    # Old py-OpenSSL is missing get_signature_algorithm
+                    digest_algo = "sha256"
                 security.addChild('fingerprint').addData(cert.digest(
                     digest_algo))
                 for m in ('x509', ): # supported authentication methods

src/common/jingle_xtls.py

@@ -192,7 +192,11 @@ def check_cert(jid, fingerprint):
     if os.path.exists(certpath):
         cert = load_cert_file(certpath)
         if cert:
-            digest_algo = cert.get_signature_algorithm().split('With')[0]
+            try:
+                digest_algo = cert.get_signature_algorithm().split('With')[0]
+            except AttributeError, e: 
+                # Old py-OpenSSL is missing get_signature_algorithm
+                digest_algo = "sha256"
             if cert.digest(digest_algo) == fingerprint:
                 return True
     return False