[PATCH 1 of 2] sslutil: issue warning when unable to load certificates on OS X

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1467863165 25200
#      Wed Jul 06 20:46:05 2016 -0700
# Node ID 93723841473c4aa7bb794144e00a8377198c79f3
# Parent  54ad81b0665f8b7191e6f049594db06b06d34e50
sslutil: issue warning when unable to load certificates on OS X

Previously, failure to load system certificates on OS X would lead
to a certificate verify failure and that's it. We now print a warning
message with a URL that will contain information on how to configure
certificates on OS X.

As the inline comment states, there is room to improve here. I think
we could try harder to detect Homebrew and MacPorts installed
certificate files, for example. It's worth noting that Homebrew's
openssl package uses `security find-certificate -a -p` during package
installation to export the system keychain root CAs to
etc/openssl/cert.pem. This is something we could consider adding
to setup.py. We could also encourage packagers to do this. For now,
I'd just like to get this warning (which matches Windows behavior)
landed. We should have time to improve things before release.

diff --git a/mercurial/sslutil.py b/mercurial/sslutil.py
--- a/mercurial/sslutil.py
+++ b/mercurial/sslutil.py
@@ -463,16 +463,28 @@ def _defaultcacerts(ui):
     # Apple's OpenSSL has patches that allow a specially constructed certificate
     # to load the system CA store. If we're running on Apple Python, use this
     # trick.
     if _plainapplepython():
         dummycert = os.path.join(os.path.dirname(__file__), 'dummycert.pem')
         if os.path.exists(dummycert):
             return dummycert
 
+    # The Apple OpenSSL trick isn't available to us. If Python isn't able to
+    # load system certs, we're out of luck.
+    if sys.platform == 'darwin':
+        # FUTURE Consider looking for Homebrew or MacPorts installed certs
+        # files. Also consider exporting the keychain certs to a file during
+        # Mercurial install.
+        if not _canloaddefaultcerts:
+            ui.warn(_('(unable to load CA certificates; see '
+                      'https://mercurial-scm.org/wiki/SecureConnections for '
+                      'how to configure Mercurial to avoid this message)\n'))
+        return None
+
     return None
 
 def validatesocket(sock):
     """Validate a socket meets security requiremnets.
 
     The passed socket must have been created with ``wrapsocket()``.
     """
     host = sock._hgstate['hostname']
diff --git a/tests/test-https.t b/tests/test-https.t
--- a/tests/test-https.t
+++ b/tests/test-https.t
@@ -62,24 +62,33 @@ we are able to load CA certs.
 
 #if no-sslcontext windows
   $ hg clone https://localhost:$HGPORT/ copy-pull
   (unable to load Windows CA certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message)
   abort: error: *certificate verify failed* (glob)
   [255]
 #endif
 
+#if no-sslcontext osx
+  $ hg clone https://localhost:$HGPORT/ copy-pull
+  (unable to load CA certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message)
+  abort: localhost certificate error: no certificate received
+  (set hostsecurity.localhost:certfingerprints=sha256:62:09:97:2f:97:60:e3:65:8f:12:5d:78:9e:35:a1:36:7a:65:4b:0e:9f:ac:db:c3:bc:6e:b6:a3:c0:16:e0:30 config setting or use --insecure to connect insecurely)
+  [255]
+#endif
+
 #if defaultcacertsloaded
   $ hg clone https://localhost:$HGPORT/ copy-pull
   abort: error: *certificate verify failed* (glob)
   [255]
 #endif
 
 #if no-defaultcacerts
   $ hg clone https://localhost:$HGPORT/ copy-pull
+  (unable to load * certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
   abort: localhost certificate error: no certificate received
   (set hostsecurity.localhost:certfingerprints=sha256:62:09:97:2f:97:60:e3:65:8f:12:5d:78:9e:35:a1:36:7a:65:4b:0e:9f:ac:db:c3:bc:6e:b6:a3:c0:16:e0:30 config setting or use --insecure to connect insecurely)
   [255]
 #endif
 
 Specifying a per-host certificate file that doesn't exist will abort
 
   $ hg --config hostsecurity.localhost:verifycertsfile=/does/not/exist clone https://localhost:$HGPORT/
diff --git a/tests/test-patchbomb-tls.t b/tests/test-patchbomb-tls.t
--- a/tests/test-patchbomb-tls.t
+++ b/tests/test-patchbomb-tls.t
@@ -72,16 +72,17 @@ we are able to load CA certs:
 
 #endif
 
 #if no-defaultcacerts
   $ try
   this patch series consists of 1 patches.
   
   
+  (unable to load * certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
   abort: localhost certificate error: no certificate received
   (set hostsecurity.localhost:certfingerprints=sha256:62:09:97:2f:97:60:e3:65:8f:12:5d:78:9e:35:a1:36:7a:65:4b:0e:9f:ac:db:c3:bc:6e:b6:a3:c0:16:e0:30 config setting or use --insecure to connect insecurely)
   [255]
 #endif
 
   $ DISABLECACERTS="--config devel.disableloaddefaultcerts=true"
 
 Without certificates: