Add example for TLS 1.3 certificate_authorities extension in ClientHello

Author: mattia-moffa

.gitignore

@@ -115,6 +115,8 @@ android/wolfssljni-ndk-sample/proguard-project.txt
 /tls/server-tls-uart
 /tls/server-tls-verifycallback
 /tls/server-tls-writedup
+/tls/client-tls13-certauth-c2s
+/tls/server-tls13-certauth-c2s
 /tls/client-ech
 /tls/client-ech-local
 /tls/server-ech-local

tls/client-tls13-certauth-c2s.c

@@ -0,0 +1,301 @@
+/* client-tls13-certauth-c2s.c
+ *
+ * Copyright (C) 2006-2025 wolfSSL Inc.
+ *
+ * This file is part of wolfSSL. (formerly known as CyaSSL)
+ *
+ * wolfSSL is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfSSL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/* This example showcases the usage of the TLS 1.3 certificate_authorities
+ * extension in the ClientHello message, to indicate to the server which
+ * certificate authorities the client supports, guiding certificate selection.
+ */
+
+/* the usual suspects */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/* socket includes */
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <unistd.h>
+
+/* wolfSSL */
+#ifndef WOLFSSL_USER_SETTINGS
+    #include <wolfssl/options.h>
+#endif
+#include <wolfssl/ssl.h>
+#include <wolfssl/wolfio.h>
+#include <wolfssl/wolfcrypt/error-crypt.h>
+
+#define DEFAULT_PORT 11111
+
+#define CERT_FILE "../certs/client-cert.pem"
+#define KEY_FILE  "../certs/client-key.pem"
+#define CA_FILE   "../certs/ca-cert.pem"
+
+#if defined(WOLFSSL_TLS13) && defined(HAVE_SECRET_CALLBACK)
+
+#ifndef WOLFSSL_SSLKEYLOGFILE_OUTPUT
+    #define WOLFSSL_SSLKEYLOGFILE_OUTPUT "sslkeylog.log"
+#endif
+
+/* Callback function for TLS v1.3 secrets for use with Wireshark */
+static int Tls13SecretCallback(WOLFSSL* ssl, int id, const unsigned char* secret,
+    int secretSz, void* ctx)
+{
+    int i;
+    const char* str = NULL;
+    unsigned char clientRandom[32];
+    int clientRandomSz;
+    XFILE fp = stderr;
+    if (ctx) {
+        fp = XFOPEN((const char*)ctx, "ab");
+        if (fp == XBADFILE) {
+            return BAD_FUNC_ARG;
+        }
+    }
+
+    clientRandomSz = (int)wolfSSL_get_client_random(ssl, clientRandom,
+        sizeof(clientRandom));
+
+    if (clientRandomSz <= 0) {
+        printf("Error getting client random %d\n", clientRandomSz);
+    }
+
+#if 0
+    printf("TLS Client Secret CB: Rand %d, Secret %d\n",
+        clientRandomSz, secretSz);
+#endif
+
+    switch (id) {
+        case CLIENT_EARLY_TRAFFIC_SECRET:
+            str = "CLIENT_EARLY_TRAFFIC_SECRET"; break;
+        case EARLY_EXPORTER_SECRET:
+            str = "EARLY_EXPORTER_SECRET"; break;
+        case CLIENT_HANDSHAKE_TRAFFIC_SECRET:
+            str = "CLIENT_HANDSHAKE_TRAFFIC_SECRET"; break;
+        case SERVER_HANDSHAKE_TRAFFIC_SECRET:
+            str = "SERVER_HANDSHAKE_TRAFFIC_SECRET"; break;
+        case CLIENT_TRAFFIC_SECRET:
+            str = "CLIENT_TRAFFIC_SECRET_0"; break;
+        case SERVER_TRAFFIC_SECRET:
+            str = "SERVER_TRAFFIC_SECRET_0"; break;
+        case EXPORTER_SECRET:
+            str = "EXPORTER_SECRET"; break;
+    }
+
+    fprintf(fp, "%s ", str);
+    for (i = 0; i < clientRandomSz; i++) {
+        fprintf(fp, "%02x", clientRandom[i]);
+    }
+    fprintf(fp, " ");
+    for (i = 0; i < secretSz; i++) {
+        fprintf(fp, "%02x", secret[i]);
+    }
+    fprintf(fp, "\n");
+
+    if (fp != stderr) {
+        XFCLOSE(fp);
+    }
+
+    return 0;
+}
+#endif /* WOLFSSL_TLS13 && HAVE_SECRET_CALLBACK */
+
+int main(int argc, char** argv)
+{
+    int ret = 0;
+#ifdef WOLFSSL_TLS13
+    int                sockfd = SOCKET_INVALID;
+    struct sockaddr_in servAddr;
+    char               buff[256];
+    size_t             len;
+
+    /* declare wolfSSL objects */
+    WOLFSSL_CTX* ctx = NULL;
+    WOLFSSL*     ssl = NULL;
+
+    /* Declare CA name object */
+    WOLF_STACK_OF(WOLFSSL_X509_NAME)* caName = NULL;
+
+    /* Check for proper calling convention */
+    if (argc != 2) {
+        printf("usage: %s <IPv4 address>\n", argv[0]);
+        return 0;
+    }
+
+    /* Create a socket that uses an internet IPv4 address,
+     * Sets the socket to be stream based (TCP),
+     * 0 means choose the default protocol. */
+    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
+        fprintf(stderr, "ERROR: failed to create the socket\n");
+        ret = -1; goto exit;
+    }
+
+    /* Initialize the server address struct with zeros */
+    memset(&servAddr, 0, sizeof(servAddr));
+
+    /* Fill in the server address */
+    servAddr.sin_family = AF_INET;             /* using IPv4      */
+    servAddr.sin_port   = htons(DEFAULT_PORT); /* on DEFAULT_PORT */
+
+    /* Get the server IPv4 address from the command line call */
+    if (inet_pton(AF_INET, argv[1], &servAddr.sin_addr) != 1) {
+        fprintf(stderr, "ERROR: invalid address\n");
+        ret = -1; goto exit;
+    }
+
+    /* Connect to the server */
+    if ((ret = connect(sockfd, (struct sockaddr*) &servAddr, sizeof(servAddr)))
+         == -1) {
+        fprintf(stderr, "ERROR: failed to connect\n");
+        goto exit;
+    }
+
+    /*---------------------------------*/
+    /* Start of wolfSSL initialization and configuration */
+    /*---------------------------------*/
+#if 0
+    wolfSSL_Debugging_ON();
+#endif
+
+    /* Initialize wolfSSL */
+    if ((ret = wolfSSL_Init()) != WOLFSSL_SUCCESS) {
+        fprintf(stderr, "ERROR: Failed to initialize the library\n");
+        goto exit;
+    }
+
+    /* Create and initialize WOLFSSL_CTX */
+    if ((ctx = wolfSSL_CTX_new(wolfTLSv1_3_client_method())) == NULL) {
+        fprintf(stderr, "ERROR: failed to create WOLFSSL_CTX\n");
+        ret = -1; goto exit;
+    }
+
+    /* Load client certificate into WOLFSSL_CTX */
+    if ((ret = wolfSSL_CTX_use_certificate_file(ctx, CERT_FILE, WOLFSSL_FILETYPE_PEM))
+        != WOLFSSL_SUCCESS) {
+        fprintf(stderr, "ERROR: failed to load %s, please check the file.\n",
+                CERT_FILE);
+        goto exit;
+    }
+
+    /* Load client key into WOLFSSL_CTX */
+    if ((ret = wolfSSL_CTX_use_PrivateKey_file(ctx, KEY_FILE, WOLFSSL_FILETYPE_PEM))
+        != WOLFSSL_SUCCESS) {
+        fprintf(stderr, "ERROR: failed to load %s, please check the file.\n",
+                KEY_FILE);
+        goto exit;
+    }
+
+    /* Load CA certificate into WOLFSSL_CTX */
+    if ((ret = wolfSSL_CTX_load_verify_locations(ctx, CA_FILE, NULL))
+         != WOLFSSL_SUCCESS) {
+        fprintf(stderr, "ERROR: failed to load %s, please check the file.\n",
+                CA_FILE);
+        goto exit;
+    }
+
+    /* Load the CA certificate name to send in certificate_authorities extension
+     */
+    if ((caName = wolfSSL_load_client_CA_file(CA_FILE)) == NULL) {
+        fprintf(stderr, "ERROR: failed to load CA name from %s, please check "
+                "the file.\n", CA_FILE);
+        goto exit;
+    }
+
+    /* Set CA name to send in certificate_authorities extension */
+    wolfSSL_CTX_set0_CA_list(ctx, caName);
+
+    /* Create a WOLFSSL object */
+    if ((ssl = wolfSSL_new(ctx)) == NULL) {
+        fprintf(stderr, "ERROR: failed to create WOLFSSL object\n");
+        ret = -1; goto exit;
+    }
+
+    /* Attach wolfSSL to the socket */
+    if ((ret = wolfSSL_set_fd(ssl, sockfd)) != WOLFSSL_SUCCESS) {
+        fprintf(stderr, "ERROR: Failed to set the file descriptor\n");
+        goto exit;
+    }
+
+#ifdef HAVE_SECRET_CALLBACK
+    /* required for getting random used */
+    wolfSSL_KeepArrays(ssl);
+
+    /* optional logging for wireshark */
+    wolfSSL_set_tls13_secret_cb(ssl, Tls13SecretCallback,
+        (void*)WOLFSSL_SSLKEYLOGFILE_OUTPUT);
+#endif
+
+    /* Connect to wolfSSL on the server side */
+    if ((ret = wolfSSL_connect(ssl)) != WOLFSSL_SUCCESS) {
+        fprintf(stderr, "ERROR: failed to connect to wolfSSL\n");
+        goto exit;
+    }
+
+#ifdef HAVE_SECRET_CALLBACK
+    wolfSSL_FreeArrays(ssl);
+#endif
+
+    /* Get a message for the server from stdin */
+    printf("Message for server: ");
+    memset(buff, 0, sizeof(buff));
+    if (fgets(buff, sizeof(buff), stdin) == NULL) {
+        fprintf(stderr, "ERROR: failed to get message for server\n");
+        ret = -1; goto exit;
+    }
+    len = strnlen(buff, sizeof(buff));
+
+    /* Send the message to the server */
+    if ((ret = wolfSSL_write(ssl, buff, len)) != len) {
+        fprintf(stderr, "ERROR: failed to write entire message\n");
+        fprintf(stderr, "%d bytes of %d bytes were sent", ret, (int) len);
+        goto exit;
+    }
+
+    /* Read the server data into our buff array */
+    memset(buff, 0, sizeof(buff));
+    if ((ret = wolfSSL_read(ssl, buff, sizeof(buff)-1)) < 0) {
+        fprintf(stderr, "ERROR: failed to read\n");
+        goto exit;
+    }
+
+    /* Print to stdout any data the server sends */
+    printf("Server: %s\n", buff);
+
+    /* Return reporting a success */
+    ret = 0;
+
+exit:
+    /* Cleanup and return */
+    if (sockfd != SOCKET_INVALID)
+        close(sockfd);          /* Close the connection to the server       */
+    if (ssl)
+        wolfSSL_free(ssl);      /* Free the wolfSSL object                  */
+    if (ctx)
+        wolfSSL_CTX_free(ctx);  /* Free the wolfSSL context object          */
+    wolfSSL_Cleanup();          /* Cleanup the wolfSSL environment          */
+#else
+    printf("Example requires TLS v1.3\n");
+#endif
+    (void)argc;
+    (void)argv;
+
+    return ret;
+}