Push the difference in chain semantics to the edge.

OpenSSL includes a leaf certificate in a certificate chain when it's a
client, but doesn't when it's a server. This is also reflected in the
serialisation of sessions.

This change makes the internal semantics consistent: the leaf is always
included in the chain in memory, and never duplicated when serialised.
To maintain the same API, SSL_get_peer_cert_chain will construct a copy
of the chain without the leaf if needed.

Since the serialised format of a client session has changed, an
|is_server| boolean is added to the ASN.1 that defaults to true. Thus
any old client sessions will be parsed as server sessions and (silently)
discarded by a client.

Change-Id: Ibcf72bc8a130cedb423bc0fd3417868e0af3ca3e
Reviewed-on: https://boringssl-review.googlesource.com/12704
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/ssl_test.cc b/ssl/ssl_test.cc
index 5e4485f..b74e51e 100644
--- a/ssl/ssl_test.cc
+++ b/ssl/ssl_test.cc
@@ -448,10 +448,9 @@
   return true;
 }
 
-// kOpenSSLSession is a serialized SSL_SESSION generated from openssl
-// s_client -sess_out.
+// kOpenSSLSession is a serialized SSL_SESSION.
 static const char kOpenSSLSession[] =
-    "MIIFpQIBAQICAwMEAsAvBCAG5Q1ndq4Yfmbeo1zwLkNRKmCXGdNgWvGT3cskV0yQ"
+    "MIIFqgIBAQICAwMEAsAvBCAG5Q1ndq4Yfmbeo1zwLkNRKmCXGdNgWvGT3cskV0yQ"
     "kAQwJlrlzkAWBOWiLj/jJ76D7l+UXoizP2KI2C7I2FccqMmIfFmmkUy32nIJ0mZH"
     "IWoJoQYCBFRDO46iBAICASyjggR6MIIEdjCCA16gAwIBAgIIK9dUvsPWSlUwDQYJ"
     "KoZIhvcNAQEFBQAwSTELMAkGA1UEBhMCVVMxEzARBgNVBAoTCkdvb2dsZSBJbmMx"
@@ -481,7 +480,7 @@
     "YTcLEkXqKwOBfF9vE4KX0NxeLwjcDTpsuh3qXEaZ992r1N38VDcyS6P7I6HBYN9B"
     "sNHM362zZnY27GpTw+Kwd751CLoXFPoaMOe57dbBpXoro6Pd3BTbf/Tzr88K06yE"
     "OTDKPNj3+inbMaVigtK4PLyPq+Topyzvx9USFgRvyuoxn0Hgb+R0A3j6SLRuyOdA"
-    "i4gv7Y5oliyn";
+    "i4gv7Y5oliyntgMBAQA=";
 
 // kCustomSession is a custom serialized SSL_SESSION generated by
 // filling in missing fields from |kOpenSSLSession|. This includes