Implement certificate lifetime parameter as required by WebRTC RFC.

webrtc/base/sslidentity.h

Index: webrtc/base/sslidentity.h
diff --git a/webrtc/base/sslidentity.h b/webrtc/base/sslidentity.h
index a143ee4108bc4585174e2a19838133273751a5d9..8acee01dfc9f5cb24c39058325a598a5b4745a18 100644
--- a/webrtc/base/sslidentity.h
+++ b/webrtc/base/sslidentity.h
@@ -125,6 +125,12 @@ static const int kRsaDefaultExponent = 0x10001;  // = 2^16+1 = 65537
 static const int kRsaMinModSize = 1024;
 static const int kRsaMaxModSize = 8192;
 
+// Certificate default validity lifetime.
+static const int CERTIFICATE_LIFETIME = 60*60*24*30;  // 30 days, arbitrarily

[tommi, 2016/02/11 16:59:30]

spaces around operators.
Also, this should be kCertificateLifetime

[torbjorng (webrtc), 2016/02/12 10:54:32]

Done.

+// Certificate validity window.
+// This is to compensate for slightly incorrect system clocks.
+static const int CERTIFICATE_WINDOW = -60*60*24;

[tommi, 2016/02/11 16:59:30]

same thing here

[torbjorng (webrtc), 2016/02/12 10:54:32]

Done.

+
 struct RSAParams {
   unsigned int mod_size;
   unsigned int pub_exp;
@@ -189,13 +195,20 @@ class SSLIdentity {
   // Returns NULL on failure.
   // Caller is responsible for freeing the returned object.
   static SSLIdentity* Generate(const std::string& common_name,

[hbos, 2016/02/11 16:37:04]

Add a comment about |certificate_lifetime| and say that it should be >= 0.
(Technically it would still work if it was >= CERTIFICATE_WINDOW but that's an
implementation detail that I don't think should be documented in the API)

[tommi, 2016/02/11 16:59:30]

having dchecks for the expected valid values, helps

[torbjorng (webrtc), 2016/02/12 10:54:32]

Done.

-                               const KeyParams& key_param);
+                               const KeyParams& key_param,
+                               time_t certificate_lifetime);
+  static SSLIdentity* Generate(const std::string& common_name,
+                               const KeyParams& key_param) {
+    return Generate(common_name, key_param, CERTIFICATE_LIFETIME);
+  }
   static SSLIdentity* Generate(const std::string& common_name,
                                KeyType key_type) {
     return Generate(common_name, KeyParams(key_type));
   }
 
   // Generates an identity with the specified validity period.
+  // TODO(torbjorng): Now that Generate() accepts relevant params, make tests
+  // use that instead of this function.
   static SSLIdentity* GenerateForTest(const SSLIdentityParams& params);
 
   // Construct an identity from a private key and a certificate.