Fix cipher property NIDs for SSL_get_current_cipher and add PSK kx mapping

The cipher property helpers (SSL_CIPHER_get_kx_nid / get_auth_nid /
get_cipher_nid / get_digest_nid / is_aead) parse the cipher name looked
up via cipher->offset in GetCipherSegment(). That offset is only
populated when the cipher is obtained through wolfSSL_get_ciphers_compat()
(SSL_get_ciphers()). When the cipher comes from SSL_get_current_cipher(),
offset is left at 0, so these helpers parsed cipher_names[0] (a TLS 1.3
suite) instead of the negotiated cipher - e.g. returning NID_kx_any for a
plain PSK suite while SSL_CIPHER_get_name() (which uses the suite bytes)
reported the correct name.

Resolve the cipher_names entry from the always-populated suite bytes in
GetCipherSegment(), falling back to cipher->offset when no match is found.

Also add the missing plain "PSK" -> NID_kx_psk entry to the kx lookup
table so PSK suites report NID_kx_psk instead of NID_undef.

Add a regression test that drives the SSL_get_current_cipher() path for
TLS_PSK_WITH_AES_128_GCM_SHA256 and checks all five property helpers.

src/internal.c

@@ -28749,6 +28749,29 @@ const char* GetCipherSegment(const WOLFSSL_CIPHER* cipher, char n[][MAX_SEGMENT_
 
     offset = cipher->offset;
 
+    /* The offset field is only populated when the cipher is obtained through
+     * wolfSSL_get_ciphers_compat() (e.g. SSL_get_ciphers()). When the cipher
+     * comes from wolfSSL_get_current_cipher() the offset is left at its default
+     * value of 0, which would make the parsing below operate on
+     * cipher_names[0] (a TLS 1.3 suite) rather than on the actual cipher. The
+     * suite bytes are always populated, so resolve the offset from them. */
+    {
+        int idx;
+        int namesSz = GetCipherNamesSize();
+        for (idx = 0; idx < namesSz; idx++) {
+            if (cipher_names[idx].cipherSuite0 == cipher->cipherSuite0 &&
+                cipher_names[idx].cipherSuite  == cipher->cipherSuite
+            #ifndef NO_CIPHER_SUITE_ALIASES
+                && (!(cipher_names[idx].flags &
+                      WOLFSSL_CIPHER_SUITE_FLAG_NAMEALIAS))
+            #endif
+                ) {
+                offset = (unsigned long)idx;
+                break;
+            }
+        }
+    }
+
     if (offset >= (unsigned long)GetCipherNamesSize())
         return NULL;
 

src/ssl.c

@@ -11321,6 +11321,7 @@ int wolfSSL_CIPHER_get_kx_nid(const WOLFSSL_CIPHER* cipher)
         {"RSAPSK",    WC_NID_kx_rsa_psk},
         {"SRP",       WC_NID_kx_srp},
         {"EDH",       WC_NID_kx_dhe},
+        {"PSK",       WC_NID_kx_psk},
         {"RSA",       WC_NID_kx_rsa},
         {NULL,        WC_NID_undef}
     };

tests/api.c

@@ -28172,6 +28172,52 @@ static int test_SSL_CIPHER_get_xxx(void)
     return EXPECT_RESULT();
 }
 
+/* Regression test: the cipher property helpers (kx/auth/cipher/digest/aead)
+ * must report the actual negotiated cipher when it is obtained through
+ * SSL_get_current_cipher(). That path does not populate cipher->offset, so a
+ * previous bug caused these helpers to parse cipher_names[0] (a TLS 1.3 suite)
+ * instead, e.g. returning NID_kx_any for a plain PSK suite. */
+static int test_SSL_CIPHER_get_current_kx(void)
+{
+    EXPECT_DECLS;
+#if defined(OPENSSL_ALL) && !defined(NO_TLS) && \
+    defined(BUILD_TLS_PSK_WITH_AES_128_GCM_SHA256)
+    SSL_CTX* ctx = NULL;
+    SSL*     ssl = NULL;
+    const SSL_CIPHER* cipher = NULL;
+
+#ifndef NO_WOLFSSL_CLIENT
+    ExpectNotNull(ctx = wolfSSL_CTX_new(wolfSSLv23_client_method()));
+#else
+    ExpectNotNull(ctx = wolfSSL_CTX_new(wolfSSLv23_server_method()));
+#endif
+    ExpectNotNull(ssl = SSL_new(ctx));
+
+    /* Simulate a negotiated plain-PSK cipher suite without doing a full
+     * handshake. SSL_get_current_cipher() reports the suite from these
+     * fields, and leaves cipher->offset at its default value of 0. */
+    if (ssl != NULL) {
+        ssl->options.cipherSuite0 = CIPHER_BYTE; /* 0x00 */
+        ssl->options.cipherSuite  = TLS_PSK_WITH_AES_128_GCM_SHA256;
+    }
+
+    ExpectNotNull(cipher = SSL_get_current_cipher(ssl));
+    /* Name is resolved from the suite bytes and was already correct. */
+    ExpectStrEQ(SSL_CIPHER_get_name(cipher), "TLS_PSK_WITH_AES_128_GCM_SHA256");
+    /* These were wrong before the fix (read cipher_names[0]). */
+    ExpectIntEQ(wolfSSL_CIPHER_get_kx_nid(cipher), NID_kx_psk);
+    ExpectIntEQ(wolfSSL_CIPHER_get_auth_nid(cipher), NID_auth_psk);
+    ExpectIntEQ(wolfSSL_CIPHER_get_cipher_nid(cipher), NID_aes_128_gcm);
+    ExpectIntEQ(wolfSSL_CIPHER_get_digest_nid(cipher), NID_sha256);
+    ExpectIntEQ(wolfSSL_CIPHER_is_aead(cipher), 1);
+
+    SSL_free(ssl);
+    SSL_CTX_free(ctx);
+#endif
+
+    return EXPECT_RESULT();
+}
+
 #if defined(WOLF_CRYPTO_CB) && defined(HAVE_IO_TESTS_DEPENDENCIES) && \
     (!defined(WOLF_CRYPTO_CB_ONLY_SHA256) && !defined(WOLF_CRYPTO_CB_ONLY_AES) && \
      !defined(WOLF_CRYPTO_CB_ONLY_ECC) && !defined(WOLF_CRYPTO_CB_ONLY_RSA))
@@ -34955,6 +35001,7 @@ TEST_CASE testCases[] = {
     TEST_DECL(test_wolfSSL_get_peer_finished_overrun),
 #endif
     TEST_DECL(test_SSL_CIPHER_get_xxx),
+    TEST_DECL(test_SSL_CIPHER_get_current_kx),
     TEST_DECL(test_wolfSSL_ERR_strings),
     TEST_DECL(test_wolfSSL_CTX_set_cipher_list_bytes),
     TEST_DECL(test_wolfSSL_set_cipher_list_tls12_keeps_tls13),