RTCCertificate serialization.

This CL adds the ability to convert RTCCertificate objects to and from
PEM string representations of it (its private key and certificate).
The RTCCertificate being a wrapper of SSLIdentity, this is where the
meat is.

Changes:
- SSLIdentity::PrivateKeyToPEMString() added. It together with the
  already existing SSLCertificate::ToPEMString() yields both private
  key and certificate PEM strings, both of which are required
  parameters to SSLIdentity::FromPEMStrings().
- Its only implementation, OpenSSLIdentity::PrivateKeyToPemString().
- SSLIdentity::PublicKeyToPEMString() added, used by tests.
- sslidentity_unittest.cc updated:
  * FromPEMStringsRSA and FromPEMStringsEC updated.
  * CloneIdentityRSA and CloneIdentityECDSA added.
- RTCCertificate::To/FromPem added, using new class RTCCertificatePem.
- rtccertificate_unittest.cc: New test CloneWithPemSerialization.
- Renamed rtc_unittests.cc to rtccertificate_unittest.cc to match
  convention.

BUG=webrtc:5794, chromium:581354

Review-Url: https://codereview.webrtc.org/1898383003
Cr-Commit-Position: refs/heads/master@{#12546}
diff --git a/webrtc/base/sslidentity_unittest.cc b/webrtc/base/sslidentity_unittest.cc
index e108b7d..399fe9d 100644
--- a/webrtc/base/sslidentity_unittest.cc
+++ b/webrtc/base/sslidentity_unittest.cc
@@ -174,7 +174,38 @@
     EXPECT_EQ(0, memcmp(digest, expected_digest, expected_len));
   }
 
- private:
+  void TestCloningIdentity(const SSLIdentity& identity) {
+    // Convert |identity| to PEM strings and create a new identity by converting
+    // back from the string format.
+    std::string priv_pem = identity.PrivateKeyToPEMString();
+    std::string publ_pem = identity.PublicKeyToPEMString();
+    std::string cert_pem = identity.certificate().ToPEMString();
+    std::unique_ptr<SSLIdentity> clone(
+        SSLIdentity::FromPEMStrings(priv_pem, cert_pem));
+    EXPECT_TRUE(clone);
+
+    // Make sure the clone is identical to the original.
+    EXPECT_TRUE(identity == *clone);
+    ASSERT_EQ(identity.certificate().CertificateExpirationTime(),
+              clone->certificate().CertificateExpirationTime());
+
+    // At this point we are confident that the identities are identical. To be
+    // extra sure, we compare PEM strings of the clone with the original. Note
+    // that the PEM strings of two identities are not strictly guaranteed to be
+    // equal (they describe structs whose members could be listed in a different
+    // order, for example). But because the same function is used to produce
+    // both PEMs, its a good enough bet that this comparison will work. If the
+    // assumption stops holding in the future we can always remove this from the
+    // unittest.
+    std::string clone_priv_pem = clone->PrivateKeyToPEMString();
+    std::string clone_publ_pem = clone->PublicKeyToPEMString();
+    std::string clone_cert_pem = clone->certificate().ToPEMString();
+    ASSERT_EQ(priv_pem, clone_priv_pem);
+    ASSERT_EQ(publ_pem, clone_publ_pem);
+    ASSERT_EQ(cert_pem, clone_cert_pem);
+  }
+
+ protected:
   std::unique_ptr<SSLIdentity> identity_rsa1_;
   std::unique_ptr<SSLIdentity> identity_rsa2_;
   std::unique_ptr<SSLIdentity> identity_ecdsa1_;
@@ -220,71 +251,118 @@
   TestDigestForGeneratedCert(rtc::DIGEST_SHA_512, 64);
 }
 
-TEST_F(SSLIdentityTest, FromPEMStringsRSA) {
-  static const char kRSA_PRIVATE_KEY_PEM[] =
-      "-----BEGIN RSA PRIVATE KEY-----\n"
-      "MIICdwIBADANBgkqhkiG9w0BAQEFAASCAmEwggJdAgEAAoGBAMYRkbhmI7kVA/rM\n"
-      "czsZ+6JDhDvnkF+vn6yCAGuRPV03zuRqZtDy4N4to7PZu9PjqrRl7nDMXrG3YG9y\n"
-      "rlIAZ72KjcKKFAJxQyAKLCIdawKRyp8RdK3LEySWEZb0AV58IadqPZDTNHHRX8dz\n"
-      "5aTSMsbbkZ+C/OzTnbiMqLL/vg6jAgMBAAECgYAvgOs4FJcgvp+TuREx7YtiYVsH\n"
-      "mwQPTum2z/8VzWGwR8BBHBvIpVe1MbD/Y4seyI2aco/7UaisatSgJhsU46/9Y4fq\n"
-      "2TwXH9QANf4at4d9n/R6rzwpAJOpgwZgKvdQjkfrKTtgLV+/dawvpxUYkRH4JZM1\n"
-      "CVGukMfKNrSVH4Ap4QJBAOJmGV1ASPnB4r4nc99at7JuIJmd7fmuVUwUgYi4XgaR\n"
-      "WhScBsgYwZ/JoywdyZJgnbcrTDuVcWG56B3vXbhdpMsCQQDf9zeJrjnPZ3Cqm79y\n"
-      "kdqANep0uwZciiNiWxsQrCHztywOvbFhdp8iYVFG9EK8DMY41Y5TxUwsHD+67zao\n"
-      "ZNqJAkEA1suLUP/GvL8IwuRneQd2tWDqqRQ/Td3qq03hP7e77XtF/buya3Ghclo5\n"
-      "54czUR89QyVfJEC6278nzA7n2h1uVQJAcG6mztNL6ja/dKZjYZye2CY44QjSlLo0\n"
-      "MTgTSjdfg/28fFn2Jjtqf9Pi/X+50LWI/RcYMC2no606wRk9kyOuIQJBAK6VSAim\n"
-      "1pOEjsYQn0X5KEIrz1G3bfCbB848Ime3U2/FWlCHMr6ch8kCZ5d1WUeJD3LbwMNG\n"
-      "UCXiYxSsu20QNVw=\n"
-      "-----END RSA PRIVATE KEY-----\n";
+TEST_F(SSLIdentityTest, IdentityComparison) {
+  EXPECT_TRUE(*identity_rsa1_ == *identity_rsa1_);
+  EXPECT_FALSE(*identity_rsa1_ == *identity_rsa2_);
+  EXPECT_FALSE(*identity_rsa1_ == *identity_ecdsa1_);
+  EXPECT_FALSE(*identity_rsa1_ == *identity_ecdsa2_);
 
+  EXPECT_TRUE(*identity_rsa2_ == *identity_rsa2_);
+  EXPECT_FALSE(*identity_rsa2_ == *identity_ecdsa1_);
+  EXPECT_FALSE(*identity_rsa2_ == *identity_ecdsa2_);
+
+  EXPECT_TRUE(*identity_ecdsa1_ == *identity_ecdsa1_);
+  EXPECT_FALSE(*identity_ecdsa1_ == *identity_ecdsa2_);
+}
+
+TEST_F(SSLIdentityTest, FromPEMStringsRSA) {
+  // These PEM strings were created by generating an identity with
+  // |SSLIdentity::Generate| and invoking |identity->PrivateKeyToPEMString()|,
+  // |identity->PublicKeyToPEMString()| and
+  // |identity->certificate().ToPEMString()|. If the crypto library is updated,
+  // and the update changes the string form of the keys, these will have to be
+  // updated too.
+  static const char kRSA_PRIVATE_KEY_PEM[] =
+      "-----BEGIN PRIVATE KEY-----\n"
+      "MIICdQIBADANBgkqhkiG9w0BAQEFAASCAl8wggJbAgEAAoGBAMQPqDStRlYeDpkX\n"
+      "erRmv+a1naM8vSVSY0gG2plnrnofViWRW3MRqWC+020MsIj3hPZeSAnt/y/FL/nr\n"
+      "4Ea7NXcwdRo1/1xEK7U/f/cjSg1aunyvHCHwcFcMr31HLFvHr0ZgcFwbgIuFLNEl\n"
+      "7kK5HMO9APz1ntUjek8BmBj8yMl9AgMBAAECgYA8FWBC5GcNtSBcIinkZyigF0A7\n"
+      "6j081sa+J/uNz4xUuI257ZXM6biygUhhvuXK06/XoIULJfhyN0fAm1yb0HtNhiUs\n"
+      "kMOYeon6b8FqFaPjrQf7Gr9FMiIHXNK19uegTMKztXyPZoUWlX84X0iawY95x0Y3\n"
+      "73f6P2rN2UOjlVVjAQJBAOKy3l2w3Zj2w0oAJox0eMwl+RxBNt1C42SHrob2mFUT\n"
+      "rytpVVYOasr8CoDI0kjacjI94sLum+buJoXXX6YTGO0CQQDdZwlYIEkoS3ftfxPa\n"
+      "Ai0YTBzAWvHJg0r8Gk/TkHo6IM+LSsZ9ZYUv/vBe4BKLw1I4hZ+bQvBiq+f8ROtk\n"
+      "+TDRAkAPL3ghwoU1h+IRBO2QHwUwd6K2N9AbBi4BP+168O3HVSg4ujeTKigRLMzv\n"
+      "T4R2iNt5bhfQgvdCgtVlxcWMdF8JAkBwDCg3eEdt5BuyjwBt8XH+/O4ED0KUWCTH\n"
+      "x00k5dZlupsuhE5Fwe4QpzXg3gekwdnHjyCCQ/NCDHvgOMTkmhQxAkA9V03KRX9b\n"
+      "bhvEzY/fu8gEp+EzsER96/D79az5z1BaMGL5OPM2xHBPJATKlswnAa7Lp3QKGZGk\n"
+      "TxslfL18J71s\n"
+      "-----END PRIVATE KEY-----\n";
+  static const char kRSA_PUBLIC_KEY_PEM[] =
+      "-----BEGIN PUBLIC KEY-----\n"
+      "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDED6g0rUZWHg6ZF3q0Zr/mtZ2j\n"
+      "PL0lUmNIBtqZZ656H1YlkVtzEalgvtNtDLCI94T2XkgJ7f8vxS/56+BGuzV3MHUa\n"
+      "Nf9cRCu1P3/3I0oNWrp8rxwh8HBXDK99Ryxbx69GYHBcG4CLhSzRJe5CuRzDvQD8\n"
+      "9Z7VI3pPAZgY/MjJfQIDAQAB\n"
+      "-----END PUBLIC KEY-----\n";
   static const char kCERT_PEM[] =
       "-----BEGIN CERTIFICATE-----\n"
-      "MIIBmTCCAQKgAwIBAgIEbzBSAjANBgkqhkiG9w0BAQsFADARMQ8wDQYDVQQDEwZX\n"
-      "ZWJSVEMwHhcNMTQwMTAyMTgyNDQ3WhcNMTQwMjAxMTgyNDQ3WjARMQ8wDQYDVQQD\n"
-      "EwZXZWJSVEMwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMYRkbhmI7kVA/rM\n"
-      "czsZ+6JDhDvnkF+vn6yCAGuRPV03zuRqZtDy4N4to7PZu9PjqrRl7nDMXrG3YG9y\n"
-      "rlIAZ72KjcKKFAJxQyAKLCIdawKRyp8RdK3LEySWEZb0AV58IadqPZDTNHHRX8dz\n"
-      "5aTSMsbbkZ+C/OzTnbiMqLL/vg6jAgMBAAEwDQYJKoZIhvcNAQELBQADgYEAUflI\n"
-      "VUe5Krqf5RVa5C3u/UTAOAUJBiDS3VANTCLBxjuMsvqOG0WvaYWP3HYPgrz0jXK2\n"
-      "LJE/mGw3MyFHEqi81jh95J+ypl6xKW6Rm8jKLR87gUvCaVYn/Z4/P3AqcQTB7wOv\n"
-      "UD0A8qfhfDM+LK6rPAnCsVN0NRDY3jvd6rzix9M=\n"
+      "MIIBnDCCAQWgAwIBAgIJAOEHLgeWYwrpMA0GCSqGSIb3DQEBCwUAMBAxDjAMBgNV\n"
+      "BAMMBXRlc3QxMB4XDTE2MDQyNDE4MTAyMloXDTE2MDUyNTE4MTAyMlowEDEOMAwG\n"
+      "A1UEAwwFdGVzdDEwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMQPqDStRlYe\n"
+      "DpkXerRmv+a1naM8vSVSY0gG2plnrnofViWRW3MRqWC+020MsIj3hPZeSAnt/y/F\n"
+      "L/nr4Ea7NXcwdRo1/1xEK7U/f/cjSg1aunyvHCHwcFcMr31HLFvHr0ZgcFwbgIuF\n"
+      "LNEl7kK5HMO9APz1ntUjek8BmBj8yMl9AgMBAAEwDQYJKoZIhvcNAQELBQADgYEA\n"
+      "C3ehaZFl+oEYN069C2ht/gMzuC77L854RF/x7xRtNZzkcg9TVgXXdM3auUvJi8dx\n"
+      "yTpU3ixErjQvoZew5ngXTEvTY8BSQUijJEaLWh8n6NDKRbEGTdAk8nPAmq9hdCFq\n"
+      "e3UkexqNHm3g/VxG4NUC1Y+w29ai0/Rgh+VvgbDwK+Q=\n"
       "-----END CERTIFICATE-----\n";
 
   std::unique_ptr<SSLIdentity> identity(
       SSLIdentity::FromPEMStrings(kRSA_PRIVATE_KEY_PEM, kCERT_PEM));
   EXPECT_TRUE(identity);
+  EXPECT_EQ(kRSA_PRIVATE_KEY_PEM, identity->PrivateKeyToPEMString());
+  EXPECT_EQ(kRSA_PUBLIC_KEY_PEM, identity->PublicKeyToPEMString());
   EXPECT_EQ(kCERT_PEM, identity->certificate().ToPEMString());
 }
 
 TEST_F(SSLIdentityTest, FromPEMStringsEC) {
-  static const char kRSA_PRIVATE_KEY_PEM[] =
-      "-----BEGIN EC PRIVATE KEY-----\n"
-      "MHcCAQEEIKkIztWLPbs4Y2zWv7VW2Ov4is2ifleCuPgRB8fRv3IkoAoGCCqGSM49\n"
-      "AwEHoUQDQgAEDPV33NrhSdhg9cBRkUWUXnVMXc3h17i9ARbSmNgminKcBXb8/y8L\n"
-      "A76cMWQPPM0ybHO8OS7ZVg2U/m+TwE1M2g==\n"
-      "-----END EC PRIVATE KEY-----\n";
+  // These PEM strings were created by generating an identity with
+  // |SSLIdentity::Generate| and invoking |identity->PrivateKeyToPEMString()|,
+  // |identity->PublicKeyToPEMString()| and
+  // |identity->certificate().ToPEMString()|. If the crypto library is updated,
+  // and the update changes the string form of the keys, these will have to be
+  // updated too.
+  static const char kECDSA_PRIVATE_KEY_PEM[] =
+      "-----BEGIN PRIVATE KEY-----\n"
+      "MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg/AkEA2hklq7dQ2rN\n"
+      "ZxYL6hOUACL4pn7P4FYlA3ZQhIChRANCAAR7YgdO3utP/8IqVRq8G4VZKreMAxeN\n"
+      "rUa12twthv4uFjuHAHa9D9oyAjncmn+xvZZRyVmKrA56jRzENcEEHoAg\n"
+      "-----END PRIVATE KEY-----\n";
+  static const char kECDSA_PUBLIC_KEY_PEM[] =
+      "-----BEGIN PUBLIC KEY-----\n"
+      "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEe2IHTt7rT//CKlUavBuFWSq3jAMX\n"
+      "ja1GtdrcLYb+LhY7hwB2vQ/aMgI53Jp/sb2WUclZiqwOeo0cxDXBBB6AIA==\n"
+      "-----END PUBLIC KEY-----\n";
   static const char kCERT_PEM[] =
       "-----BEGIN CERTIFICATE-----\n"
-      "MIIB0jCCAXmgAwIBAgIJAMCjpFt9t6LMMAoGCCqGSM49BAMCMEUxCzAJBgNVBAYT\n"
-      "AkFVMRMwEQYDVQQIDApTb21lLVN0YXRlMSEwHwYDVQQKDBhJbnRlcm5ldCBXaWRn\n"
-      "aXRzIFB0eSBMdGQwIBcNMTUwNjMwMTMwMTIyWhgPMjI4OTA0MTMxMzAxMjJaMEUx\n"
-      "CzAJBgNVBAYTAkFVMRMwEQYDVQQIDApTb21lLVN0YXRlMSEwHwYDVQQKDBhJbnRl\n"
-      "cm5ldCBXaWRnaXRzIFB0eSBMdGQwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAAQM\n"
-      "9Xfc2uFJ2GD1wFGRRZRedUxdzeHXuL0BFtKY2CaKcpwFdvz/LwsDvpwxZA88zTJs\n"
-      "c7w5LtlWDZT+b5PATUzao1AwTjAdBgNVHQ4EFgQUYHq6nxNNIE832ZmaHc/noODO\n"
-      "rtAwHwYDVR0jBBgwFoAUYHq6nxNNIE832ZmaHc/noODOrtAwDAYDVR0TBAUwAwEB\n"
-      "/zAKBggqhkjOPQQDAgNHADBEAiAQRojsTyZG0BlKoU7gOt5h+yAMLl2cxmDtOIQr\n"
-      "GWP/PwIgJynB4AUDsPT0DWmethOXYijB5sY5UPd9DvgmiS/Mr6s=\n"
+      "MIIBFDCBu6ADAgECAgkArpkxjw62sW4wCgYIKoZIzj0EAwIwEDEOMAwGA1UEAwwF\n"
+      "dGVzdDMwHhcNMTYwNDI0MTgxNDM4WhcNMTYwNTI1MTgxNDM4WjAQMQ4wDAYDVQQD\n"
+      "DAV0ZXN0MzBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABHtiB07e60//wipVGrwb\n"
+      "hVkqt4wDF42tRrXa3C2G/i4WO4cAdr0P2jICOdyaf7G9llHJWYqsDnqNHMQ1wQQe\n"
+      "gCAwCgYIKoZIzj0EAwIDSAAwRQIhANyreQ/K5yuPPpirsd0e/4WGLHou6bIOSQks\n"
+      "DYzo56NmAiAKOr3u8ol3LmygbUCwEvtWrS8QcJDygxHPACo99hkekw==\n"
       "-----END CERTIFICATE-----\n";
 
   std::unique_ptr<SSLIdentity> identity(
-      SSLIdentity::FromPEMStrings(kRSA_PRIVATE_KEY_PEM, kCERT_PEM));
+      SSLIdentity::FromPEMStrings(kECDSA_PRIVATE_KEY_PEM, kCERT_PEM));
   EXPECT_TRUE(identity);
+  EXPECT_EQ(kECDSA_PRIVATE_KEY_PEM, identity->PrivateKeyToPEMString());
+  EXPECT_EQ(kECDSA_PUBLIC_KEY_PEM, identity->PublicKeyToPEMString());
   EXPECT_EQ(kCERT_PEM, identity->certificate().ToPEMString());
 }
 
+TEST_F(SSLIdentityTest, CloneIdentityRSA) {
+  TestCloningIdentity(*identity_rsa1_);
+  TestCloningIdentity(*identity_rsa2_);
+}
+
+TEST_F(SSLIdentityTest, CloneIdentityECDSA) {
+  TestCloningIdentity(*identity_ecdsa1_);
+  TestCloningIdentity(*identity_ecdsa2_);
+}
+
 TEST_F(SSLIdentityTest, PemDerConversion) {
   std::string der;
   EXPECT_TRUE(SSLIdentity::PemToDer("CERTIFICATE", kTestCertificate, &der));