openssl: Use unique_ptr to remove unnecessary goto statements

Bug: None
Change-Id: I377cd17490a009d75545052a9300cfc34869ae85
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/223501
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@nvidia.com>
Cr-Commit-Position: refs/heads/master@{#34383}

rtc_base/openssl_certificate.cc

diff --git a/rtc_base/openssl_certificate.cc b/rtc_base/openssl_certificate.cc
index bd9bb04..802787d 100644
--- a/rtc_base/openssl_certificate.cc
+++ b/rtc_base/openssl_certificate.cc
@@ -59,27 +59,30 @@
   RTC_LOG(LS_INFO) << "Making certificate for " << params.common_name;
 
   ASN1_INTEGER* asn1_serial_number = nullptr;
-  BIGNUM* serial_number = nullptr;
-  X509* x509 = nullptr;
-  X509_NAME* name = nullptr;
+  std::unique_ptr<BIGNUM, decltype(&::BN_free)> serial_number{nullptr,
+                                                              ::BN_free};
+  std::unique_ptr<X509, decltype(&::X509_free)> x509{nullptr, ::X509_free};
+  std::unique_ptr<X509_NAME, decltype(&::X509_NAME_free)> name{
+      nullptr, ::X509_NAME_free};
   time_t epoch_off = 0;  // Time offset since epoch.
-
-  if ((x509 = X509_new()) == nullptr) {
-    goto error;
+  x509.reset(X509_new());
+  if (x509 == nullptr) {
+    return nullptr;
   }
-  if (!X509_set_pubkey(x509, pkey)) {
-    goto error;
+  if (!X509_set_pubkey(x509.get(), pkey)) {
+    return nullptr;
   }
   // serial number - temporary reference to serial number inside x509 struct
-  if ((serial_number = BN_new()) == nullptr ||
-      !BN_pseudo_rand(serial_number, SERIAL_RAND_BITS, 0, 0) ||
-      (asn1_serial_number = X509_get_serialNumber(x509)) == nullptr ||
-      !BN_to_ASN1_INTEGER(serial_number, asn1_serial_number)) {
-    goto error;
+  serial_number.reset(BN_new());
+  if (serial_number == nullptr ||
+      !BN_pseudo_rand(serial_number.get(), SERIAL_RAND_BITS, 0, 0) ||
+      (asn1_serial_number = X509_get_serialNumber(x509.get())) == nullptr ||
+      !BN_to_ASN1_INTEGER(serial_number.get(), asn1_serial_number)) {
+    return nullptr;
   }
   // Set version to X509.V3
-  if (!X509_set_version(x509, 2L)) {
-    goto error;
+  if (!X509_set_version(x509.get(), 2L)) {
+    return nullptr;
   }
 
   // There are a lot of possible components for the name entries. In
@@ -89,31 +92,27 @@
   // arbitrary common_name. Note that this certificate goes out in
   // clear during SSL negotiation, so there may be a privacy issue in
   // putting anything recognizable here.
-  if ((name = X509_NAME_new()) == nullptr ||
-      !X509_NAME_add_entry_by_NID(name, NID_commonName, MBSTRING_UTF8,
+  name.reset(X509_NAME_new());
+  if (name == nullptr ||
+      !X509_NAME_add_entry_by_NID(name.get(), NID_commonName, MBSTRING_UTF8,
                                   (unsigned char*)params.common_name.c_str(),
                                   -1, -1, 0) ||
-      !X509_set_subject_name(x509, name) || !X509_set_issuer_name(x509, name)) {
-    goto error;
+      !X509_set_subject_name(x509.get(), name.get()) ||
+      !X509_set_issuer_name(x509.get(), name.get())) {
+    return nullptr;
   }
-  if (!X509_time_adj(X509_get_notBefore(x509), params.not_before, &epoch_off) ||
-      !X509_time_adj(X509_get_notAfter(x509), params.not_after, &epoch_off)) {
-    goto error;
+  if (!X509_time_adj(X509_get_notBefore(x509.get()), params.not_before,
+                     &epoch_off) ||
+      !X509_time_adj(X509_get_notAfter(x509.get()), params.not_after,
+                     &epoch_off)) {
+    return nullptr;
   }
-  if (!X509_sign(x509, pkey, EVP_sha256())) {
-    goto error;
+  if (!X509_sign(x509.get(), pkey, EVP_sha256())) {
+    return nullptr;
   }
 
-  BN_free(serial_number);
-  X509_NAME_free(name);
   RTC_LOG(LS_INFO) << "Returning certificate";
-  return x509;
-
-error:
-  BN_free(serial_number);
-  X509_NAME_free(name);
-  X509_free(x509);
-  return nullptr;
+  return x509.release();
 }
 
 }  // namespace