url: 'ssh known host'-like checking of fingerprints of HTTPS certificates

Known fingerprints of HTTPS servers can now be configured in the
hostfingerprints section. That makes it possible to verify the identify of web
servers without configuring and trusting the CA chain.

Limitations:
* Portnumbers are ignored, just like with ordinary certificates.
* Host name matching is case sensitive.

doc/hgrc.5.txt

@@ -423,6 +423,24 b' Example for ``~/.hgrc``::'
   myfeature = ~/.hgext/myfeature.py
 
 
+``hostfingerprints``
+""""""""""""""""""""
+
+Fingerprints of the certificates of known HTTPS servers.
+A HTTPS connection to a server with a fingerprint configured here will
+only succeed if the servers certificate matches the fingerprint.
+This is very similar to how ssh known hosts works.
+The fingerprint is the SHA-1 hash value of the DER encoded certificate.
+The CA chain and web.cacerts is not used for servers with a fingerprint.
+
+For example::
+
+    [hostfingerprints]
+    hg.intevation.org = 38:76:52:7c:87:26:9a:8f:4a:f8:d3:de:08:45:3b:ea:d6:4b:ee:cc
+
+This feature is only supported when using Python 2.6 or later.
+
+
 ``format``
 """"""""""
 

mercurial/hg.py

@@ -546,7 +546,7 b' def remoteui(src, opts):'
         dst.setconfig('bundle', 'mainreporoot', r)
 
     # copy selected local settings to the remote ui
-    for sect in ('auth', 'http_proxy'):
+    for sect in ('auth', 'hostfingerprints', 'http_proxy'):
         for key, val in src.configitems(sect):
             dst.setconfig(sect, key, val)
     v = src.config('web', 'cacerts')

mercurial/url.py

@@ -533,7 +533,8 b' if has_https:'
             else:
                 cacerts = None
 
-            if cacerts:
+            hostfingerprint = self.ui.config('hostfingerprints', self.host)
+            if cacerts and not hostfingerprint:
                 sock = _create_connection((self.host, self.port))
                 self.sock = _ssl_wrap_socket(sock, self.key_file,
                         self.cert_file, cert_reqs=CERT_REQUIRED,
@@ -545,10 +546,33 b' if has_https:'
                 self.ui.debug('%s certificate successfully verified\n' %
                               self.host)
             else:
-                self.ui.warn(_("warning: %s certificate not verified "
-                               "(check web.cacerts config setting)\n") %
-                             self.host)
                 httplib.HTTPSConnection.connect(self)
+                if hasattr(self.sock, 'getpeercert'):
+                    peercert = self.sock.getpeercert(True)
+                    peerfingerprint = util.sha1(peercert).hexdigest()
+                    nicefingerprint = ":".join([peerfingerprint[x:x + 2]
+                        for x in xrange(0, len(peerfingerprint), 2)])
+                    if hostfingerprint:
+                        if peerfingerprint.lower() != \
+                                hostfingerprint.replace(':', '').lower():
+                            raise util.Abort(_('invalid certificate for %s '
+                                               'with fingerprint %s') %
+                                             (self.host, nicefingerprint))
+                        self.ui.debug('%s certificate matched fingerprint %s\n' %
+                                      (self.host, nicefingerprint))
+                    else:
+                        self.ui.warn(_('warning: %s certificate '
+                                       'with fingerprint %s not verified '
+                                       '(check hostfingerprints or web.cacerts '
+                                       'config setting)\n') %
+                                     (self.host, nicefingerprint))
+                else: # python 2.5 ?
+                    if hostfingerprint:
+                        raise util.Abort(_('no certificate for %s '
+                                           'with fingerprint') % self.host)
+                    self.ui.warn(_('warning: %s certificate not verified '
+                                   '(check web.cacerts config setting)\n') %
+                                 self.host)
 
     class httpsconnection(BetterHTTPS):
         response_class = keepalive.HTTPResponse

tests/test-https.t

@@ -106,7 +106,7 b' Test server address cannot be reused'
 clone via pull
 
   $ hg clone https://localhost:$HGPORT/ copy-pull
-  warning: localhost certificate not verified (check web.cacerts config setting)
+  warning: localhost certificate with fingerprint 91:4f:1a:ff:87:24:9c:09:b6:85:9b:88:b1:90:6d:30:75:64:91:ca not verified (check hostfingerprints or web.cacerts config setting)
   requesting all changes
   adding changesets
   adding manifests
@@ -132,7 +132,7 b' pull without cacert'
   $ echo '[hooks]' >> .hg/hgrc
   $ echo "changegroup = python '$TESTDIR'/printenv.py changegroup" >> .hg/hgrc
   $ hg pull
-  warning: localhost certificate not verified (check web.cacerts config setting)
+  warning: localhost certificate with fingerprint 91:4f:1a:ff:87:24:9c:09:b6:85:9b:88:b1:90:6d:30:75:64:91:ca not verified (check hostfingerprints or web.cacerts config setting)
   changegroup hook: HG_NODE=5fed3813f7f5e1824344fdc9cf8f63bb662c292d HG_SOURCE=pull HG_URL=https://localhost:$HGPORT/ 
   pulling from https://localhost:$HGPORT/
   searching for changes
@@ -188,3 +188,22 b' Test server cert which no longer is vali'
   $ hg -R copy-pull pull --config web.cacerts=pub-expired.pem https://localhost:$HGPORT2/
   abort: error: *:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed (glob)
   [255]
+
+Fingerprints
+
+  $ echo "[hostfingerprints]" >> copy-pull/.hg/hgrc
+  $ echo "localhost = 91:4f:1a:ff:87:24:9c:09:b6:85:9b:88:b1:90:6d:30:75:64:91:ca" >> copy-pull/.hg/hgrc
+  $ echo "127.0.0.1 = 914f1aff87249c09b6859b88b1906d30756491ca" >> copy-pull/.hg/hgrc
+
+- works without cacerts
+  $ hg -R copy-pull id https://localhost:$HGPORT/ --config web.cacerts=
+  5fed3813f7f5
+
+- fails when cert doesn't match hostname (port is ignored)
+  $ hg -R copy-pull id https://localhost:$HGPORT1/
+  abort: invalid certificate for localhost with fingerprint 28:ff:71:bf:65:31:14:23:ad:62:92:b4:0e:31:99:18:fc:83:e3:9b
+  [255]
+
+- ignores that certificate doesn't match hostname
+  $ hg -R copy-pull id https://127.0.0.1:$HGPORT/
+  5fed3813f7f5