Support ACME for certificate provisioning (#4384)

1 files changed, 91 insertions, 24 deletions

diff --git a/synapse/config/tls.py b/synapse/config/tls.py
index bb8952c672..a75e233aa0 100644
--- a/synapse/config/tls.py
+++ b/synapse/config/tls.py
@@ -13,60 +13,110 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
 import os
+from datetime import datetime
 from hashlib import sha256
 
 from unpaddedbase64 import encode_base64
 
 from OpenSSL import crypto
 
-from ._base import Config
+from synapse.config._base import Config
+
+logger = logging.getLogger()
 
 
 class TlsConfig(Config):
     def read_config(self, config):
-        self.tls_certificate = self.read_tls_certificate(
-            config.get("tls_certificate_path")
-        )
-        self.tls_certificate_file = config.get("tls_certificate_path")
 
+        acme_config = config.get("acme", {})
+        self.acme_enabled = acme_config.get("enabled", False)
+        self.acme_url = acme_config.get(
+            "url", "https://acme-v01.api.letsencrypt.org/directory"
+        )
+        self.acme_port = acme_config.get("port", 8449)
+        self.acme_bind_addresses = acme_config.get("bind_addresses", ["127.0.0.1"])
+        self.acme_reprovision_threshold = acme_config.get("reprovision_threshold", 30)
+
+        self.tls_certificate_file = os.path.abspath(config.get("tls_certificate_path"))
+        self.tls_private_key_file = os.path.abspath(config.get("tls_private_key_path"))
+        self._original_tls_fingerprints = config["tls_fingerprints"]
+        self.tls_fingerprints = list(self._original_tls_fingerprints)
         self.no_tls = config.get("no_tls", False)
 
-        if self.no_tls:
-            self.tls_private_key = None
-        else:
-            self.tls_private_key = self.read_tls_private_key(
-                config.get("tls_private_key_path")
-            )
+        # This config option applies to non-federation HTTP clients
+        # (e.g. for talking to recaptcha, identity servers, and such)
+        # It should never be used in production, and is intended for
+        # use only when running tests.
+        self.use_insecure_ssl_client_just_for_testing_do_not_use = config.get(
+            "use_insecure_ssl_client_just_for_testing_do_not_use"
+        )
+
+        self.tls_certificate = None
+        self.tls_private_key = None
+
+    def is_disk_cert_valid(self):
+        """
+        Is the certificate we have on disk valid, and if so, for how long?
+
+        Returns:
+            int: Days remaining of certificate validity.
+            None: No certificate exists.
+        """
+        if not os.path.exists(self.tls_certificate_file):
+            return None
+
+        try:
+            with open(self.tls_certificate_file, 'rb') as f:
+                cert_pem = f.read()
+        except Exception:
+            logger.exception("Failed to read existing certificate off disk!")
+            raise
+
+        try:
+            tls_certificate = crypto.load_certificate(crypto.FILETYPE_PEM, cert_pem)
+        except Exception:
+            logger.exception("Failed to parse existing certificate off disk!")
+            raise
+
+        # YYYYMMDDhhmmssZ -- in UTC
+        expires_on = datetime.strptime(
+            tls_certificate.get_notAfter().decode('ascii'), "%Y%m%d%H%M%SZ"
+        )
+        now = datetime.utcnow()
+        days_remaining = (expires_on - now).days
+        return days_remaining
 
-        self.tls_fingerprints = config["tls_fingerprints"]
+    def read_certificate_from_disk(self):
+        """
+        Read the certificates from disk.
+        """
+        self.tls_certificate = self.read_tls_certificate(self.tls_certificate_file)
+
+        if not self.no_tls:
+            self.tls_private_key = self.read_tls_private_key(self.tls_private_key_file)
+
+        self.tls_fingerprints = list(self._original_tls_fingerprints)
 
         # Check that our own certificate is included in the list of fingerprints
         # and include it if it is not.
         x509_certificate_bytes = crypto.dump_certificate(
-            crypto.FILETYPE_ASN1,
-            self.tls_certificate
+            crypto.FILETYPE_ASN1, self.tls_certificate
         )
         sha256_fingerprint = encode_base64(sha256(x509_certificate_bytes).digest())
         sha256_fingerprints = set(f["sha256"] for f in self.tls_fingerprints)
         if sha256_fingerprint not in sha256_fingerprints:
             self.tls_fingerprints.append({u"sha256": sha256_fingerprint})
 
-        # This config option applies to non-federation HTTP clients
-        # (e.g. for talking to recaptcha, identity servers, and such)
-        # It should never be used in production, and is intended for
-        # use only when running tests.
-        self.use_insecure_ssl_client_just_for_testing_do_not_use = config.get(
-            "use_insecure_ssl_client_just_for_testing_do_not_use"
-        )
-
     def default_config(self, config_dir_path, server_name, **kwargs):
         base_key_name = os.path.join(config_dir_path, server_name)
 
         tls_certificate_path = base_key_name + ".tls.crt"
         tls_private_key_path = base_key_name + ".tls.key"
 
-        return """\
+        return (
+            """\
         # PEM encoded X509 certificate for TLS.
         # You can replace the self-signed certificate that synapse
         # autogenerates on launch with your own SSL certificate + key pair
@@ -107,7 +157,24 @@ class TlsConfig(Config):
         #
         tls_fingerprints: []
         # tls_fingerprints: [{"sha256": "<base64_encoded_sha256_fingerprint>"}]
-        """ % locals()
+
+        ## Support for ACME certificate auto-provisioning.
+        # acme:
+        #    enabled: false
+        ##   ACME path.
+        ##   If you only want to test, use the staging url:
+        ##   https://acme-staging.api.letsencrypt.org/directory
+        #    url: 'https://acme-v01.api.letsencrypt.org/directory'
+        ##   Port number (to listen for the HTTP-01 challenge).
+        ##   Using port 80 requires utilising something like authbind, or proxying to it.
+        #    port: 8449
+        ##   Hosts to bind to.
+        #    bind_addresses: ['127.0.0.1']
+        ##   How many days remaining on a certificate before it is renewed.
+        #    reprovision_threshold: 30
+        """
+            % locals()
+        )
 
     def read_tls_certificate(self, cert_path):
         cert_pem = self.read_file(cert_path, "tls_certificate")