Add support for NETSCAPE_SPKI_print (#1624)

Ruby consumes NETSCAPE_SPKI_print for debugging purposes.
This adds support for the symbol for easier integration.

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license and the ISC license.

crypto/x509/x509_test.cc

@@ -7583,3 +7583,43 @@ TEST(X509Test, PublicKeyCache) {
   key2.reset(X509_PUBKEY_get(pub));
   EXPECT_FALSE(key2);
 }
+
+TEST(X509Test, SPKIPrint) {
+  bssl::UniquePtr<BIO> bio(BIO_new(BIO_s_mem()));
+  ASSERT_TRUE(bio);
+  bssl::UniquePtr<NETSCAPE_SPKI> spki(NETSCAPE_SPKI_new());
+  ASSERT_TRUE(spki);
+
+  bssl::UniquePtr<EVP_PKEY> key = PrivateKeyFromPEM(kP256Key);
+  EXPECT_TRUE(NETSCAPE_SPKI_set_pubkey(spki.get(), key.get()));
+  EXPECT_TRUE(NETSCAPE_SPKI_sign(spki.get(), key.get(), EVP_sha256()));
+
+  std::string challenge = "challenge string";
+  ASSERT_TRUE(ASN1_STRING_set(spki.get()->spkac->challenge, challenge.data(),
+                              challenge.size()));
+
+  EXPECT_TRUE(NETSCAPE_SPKI_print(bio.get(), spki.get()));
+
+  // The contents of the signature is printed last but it's randomized,
+  // so we only check the expected output before that.
+  static const char expected_certificate_string[] = R"(Netscape SPKI:
+  Public Key Algorithm: id-ecPublicKey
+    Public-Key: (P-256)
+    pub:
+        04:e6:2b:69:e2:bf:65:9f:97:be:2f:1e:0d:94:8a:
+        4c:d5:97:6b:b7:a9:1e:0d:46:fb:dd:a9:a9:1e:9d:
+        dc:ba:5a:01:e7:d6:97:a8:0a:18:f9:c3:c4:a3:1e:
+        56:e2:7c:83:48:db:16:1a:1c:f5:1d:7e:f1:94:2d:
+        4b:cf:72:22:c1
+  Challenge String: challenge string
+  Signature Algorithm: ecdsa-with-SHA256
+  )";
+
+  const uint8_t *data;
+  size_t data_len;
+  ASSERT_TRUE(BIO_mem_contents(bio.get(), &data, &data_len));
+  ASSERT_GT(data_len, strlen(expected_certificate_string));
+  std::string print(reinterpret_cast<const char *>(data),
+                    strlen(expected_certificate_string));
+  EXPECT_EQ(print, expected_certificate_string);
+}

crypto/x509/x509spki.c

@@ -60,6 +60,7 @@
 #include <openssl/err.h>
 #include <openssl/mem.h>
 #include <openssl/x509.h>
+#include "internal.h"
 
 int NETSCAPE_SPKI_set_pubkey(NETSCAPE_SPKI *x, EVP_PKEY *pkey) {
   if ((x == NULL) || (x->spkac == NULL)) {
@@ -131,3 +132,47 @@ char *NETSCAPE_SPKI_b64_encode(NETSCAPE_SPKI *spki) {
   OPENSSL_free(der_spki);
   return b64_str;
 }
+
+int NETSCAPE_SPKI_print(BIO *out, NETSCAPE_SPKI *spki) {
+  if (out == NULL || spki == NULL || spki->spkac == NULL ||
+      spki->spkac->pubkey == NULL || spki->sig_algor == NULL ||
+      spki->sig_algor->algorithm == NULL || spki->signature == NULL ||
+      spki->signature->data == NULL) {
+    OPENSSL_PUT_ERROR(X509, ERR_R_PASSED_NULL_PARAMETER);
+    return 0;
+  }
+  BIO_printf(out, "Netscape SPKI:\n");
+
+  // Print out public key algorithm and contents.
+  ASN1_OBJECT *spkioid;
+  X509_PUBKEY_get0_param(&spkioid, NULL, NULL, NULL, spki->spkac->pubkey);
+  int spkioid_nid = OBJ_obj2nid(spkioid);
+  BIO_printf(out, "  Public Key Algorithm: %s\n",
+             (spkioid_nid == NID_undef) ? "UNKNOWN" : OBJ_nid2ln(spkioid_nid));
+  EVP_PKEY *pkey = X509_PUBKEY_get0(spki->spkac->pubkey);
+  if (pkey == NULL) {
+    BIO_printf(out, "  Unable to load public key\n");
+  } else {
+    EVP_PKEY_print_public(out, pkey, 4, NULL);
+  }
+
+  ASN1_IA5STRING *chal = spki->spkac->challenge;
+  if (chal != NULL && chal->length != 0) {
+    BIO_printf(out, "  Challenge String: %.*s\n", chal->length, chal->data);
+  }
+
+  // Print out signature algorithm and contents.
+  BIO_printf(out, "  Signature Algorithm: %s",
+             (OBJ_obj2nid(spki->sig_algor->algorithm) == NID_undef)
+                 ? "UNKNOWN"
+                 : OBJ_nid2ln(OBJ_obj2nid(spki->sig_algor->algorithm)));
+  for (int i = 0; i < spki->signature->length; i++) {
+    if ((i % 18) == 0) {
+      BIO_printf(out, "\n      ");
+    }
+    BIO_printf(out, "%02x%s", (unsigned char)spki->signature->data[i],
+               ((i + 1) == spki->signature->length) ? "" : ":");
+  }
+  BIO_write(out, "\n", 1);
+  return 1;
+}

include/openssl/x509.h

@@ -2345,6 +2345,9 @@ OPENSSL_EXPORT NETSCAPE_SPKAC *d2i_NETSCAPE_SPKAC(NETSCAPE_SPKAC **out,
 OPENSSL_EXPORT int i2d_NETSCAPE_SPKAC(const NETSCAPE_SPKAC *spkac,
                                       uint8_t **outp);
 
+// NETSCAPE_SPKI_print prints out the contents of |spki| to |out|.
+OPENSSL_EXPORT int NETSCAPE_SPKI_print(BIO *out, NETSCAPE_SPKI *spki);
+
 
 // RSASSA-PSS Parameters.
 //