/* server-tls-verifycallback.c
 *
 * Copyright (C) 2006-2020 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 requires the client to send "client-cert.pem" */
/* Test using wolfSSL example client: 
./examples/client/client */


/* 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 */
#include <wolfssl/options.h>
#include <wolfssl/ssl.h>

#define DEFAULT_PORT 11111

#define CERT_FILE "../certs/server-cert.pem"
#define KEY_FILE  "../certs/server-key.pem"
#define CLIENT_CERT_FILE "../certs/client-cert.pem"


/* The verify callback is called for every certificate only when
 * --enable-opensslextra is defined because it sets WOLFSSL_ALWAYS_VERIFY_CB and
 * WOLFSSL_VERIFY_CB_ALL_CERTS.
 * Normal cases of the verify callback only occur on certificate failures when the
 * wolfSSL_set_verify(ssl, SSL_VERIFY_PEER, myVerifyCb); is called
*/
static int myVerifyCb(int preverify, WOLFSSL_X509_STORE_CTX* store)
{
    char buffer[WOLFSSL_MAX_ERROR_SZ];
#if defined(OPENSSL_EXTRA) || defined(OPENSSL_EXTRA_X509_SMALL)
    WOLFSSL_X509* peer;
#if defined(SHOW_CERTS) && !defined(NO_FILESYSTEM)
    WOLFSSL_BIO* bio = NULL;
    WOLFSSL_STACK* sk = NULL;
    X509* x509 = NULL;
    int i = 0;
#endif
#endif
    (void)preverify;

    /* Verify Callback Arguments:
     * preverify:           1=Verify Okay, 0=Failure
     * store->error:        Failure error code (0 indicates no failure)
     * store->current_cert: Current WOLFSSL_X509 object (only with OPENSSL_EXTRA)
     * store->error_depth:  Current Index
     * store->domain:       Subject CN as string (null term)
     * store->totalCerts:   Number of certs presented by peer
     * store->certs[i]:     A `WOLFSSL_BUFFER_INFO` with plain DER for each cert
     * store->store:        WOLFSSL_X509_STORE with CA cert chain
     * store->store->cm:    WOLFSSL_CERT_MANAGER
     * store->ex_data:      The WOLFSSL object pointer
     * store->discardSessionCerts: When set to non-zero value session certs
        will be discarded (only with SESSION_CERTS)
     */

    printf("In verification callback, error = %d, %s\n", store->error,
                                 wolfSSL_ERR_error_string(store->error, buffer));
#if defined(OPENSSL_EXTRA) || defined(OPENSSL_EXTRA_X509_SMALL)
    peer = store->current_cert;
    if (peer) {
        char* issuer  = wolfSSL_X509_NAME_oneline(
                                       wolfSSL_X509_get_issuer_name(peer), 0, 0);
        char* subject = wolfSSL_X509_NAME_oneline(
                                      wolfSSL_X509_get_subject_name(peer), 0, 0);
        printf("\tPeer's cert info:\n issuer : %s\n subject: %s\n", issuer,
                                                                  subject);
        XFREE(subject, 0, DYNAMIC_TYPE_OPENSSL);
        XFREE(issuer,  0, DYNAMIC_TYPE_OPENSSL);
#if defined(SHOW_CERTS) && !defined(NO_FILESYSTEM)
/* avoid printing duplicate certs */
        if (store->depth == 1) {
            /* retrieve x509 certs and display them on stdout */
            sk = wolfSSL_X509_STORE_GetCerts(store);

            for (i = 0; i < wolfSSL_sk_X509_num(sk); i++) {
                x509 = wolfSSL_sk_X509_value(sk, i);
                bio = wolfSSL_BIO_new(wolfSSL_BIO_s_file());
                if (bio != NULL) {
                    wolfSSL_BIO_set_fp(bio, stdout, BIO_NOCLOSE);
                    wolfSSL_X509_print(bio, x509);
                    wolfSSL_BIO_free(bio);
                }
            }
            wolfSSL_sk_X509_free(sk);
        }
#endif
    }
    else
        printf("\tPeer has no cert!\n");
#else
    printf("\tPeer certs: %d\n", store->totalCerts);
    #ifdef SHOW_CERTS
    {   int i;
        for (i=0; i<store->totalCerts; i++) {
            WOLFSSL_BUFFER_INFO* cert = &store->certs[i];
            printf("\t\tCert %d: Ptr %p, Len %u\n", i, cert->buffer, cert->length);
        }
    }
    #endif /* SHOW_CERTS */
#endif /* OPENSSL_EXTRA || OPENSSL_EXTRA_X509_SMALL */

    printf("\tSubject's domain name at %d is %s\n", store->error_depth, store->domain);

    /* If error indicate we are overriding it for testing purposes */
    if (store->error != 0) {
        printf("\tAllowing failed certificate check, testing only "
            "(shouldn't do this in production)\n");
    }

    /* A non-zero return code indicates failure override */
    return preverify;
}


int main()
{
    int                sockfd = SOCKET_INVALID;
    int                connd  = SOCKET_INVALID;
    struct sockaddr_in servAddr;
    struct sockaddr_in clientAddr;
    socklen_t          size = sizeof(clientAddr);
    char               buff[256];
    size_t             len;
    int                shutdown = 0;
    int                ret;
    const char*        reply = "I hear ya fa shizzle!\n";

    /* declare wolfSSL objects */
    WOLFSSL_CTX* ctx = NULL;
    WOLFSSL*     ssl = NULL;



    /* Initialize wolfSSL */
    wolfSSL_Init();



    /* 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;
    }



    /* Create and initialize WOLFSSL_CTX */
    if ((ctx = wolfSSL_CTX_new(wolfTLSv1_2_server_method())) == NULL) {
        fprintf(stderr, "ERROR: failed to create WOLFSSL_CTX\n");
        ret = -1;
        goto exit;
    }

    /* Load server certificates 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 server 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 the trusted certificates */
    /* May be called multiple times to continue loading trusted certs into the 
        wolfSSL Certificate Manager */
    if ((ret = wolfSSL_CTX_load_verify_locations(ctx, CLIENT_CERT_FILE, NULL)) 
        != WOLFSSL_SUCCESS) {
        fprintf(stderr, "ERROR: failed to load %s, please check the file.\n",
                CLIENT_CERT_FILE);
        goto exit;
    }

    /* require client certificate and verify all peers */
    wolfSSL_CTX_set_verify(ctx, 
        (WOLFSSL_VERIFY_PEER | WOLFSSL_VERIFY_FAIL_IF_NO_PEER_CERT), 
        myVerifyCb);


    /* 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 */
    servAddr.sin_addr.s_addr = INADDR_ANY;          /* from anywhere   */



    /* Bind the server socket to our port */
    if (bind(sockfd, (struct sockaddr*)&servAddr, sizeof(servAddr)) == -1) {
        fprintf(stderr, "ERROR: failed to bind\n");
        ret = -1;
        goto exit;
    }

    /* Listen for a new connection, allow 5 pending connections */
    if (listen(sockfd, 5) == -1) {
        fprintf(stderr, "ERROR: failed to listen\n");
        ret = -1;
        goto exit;
    }



    /* Continue to accept clients until shutdown is issued */
    while (!shutdown) {
        printf("Waiting for a connection...\n");

        /* Accept client connections */
        if ((connd = accept(sockfd, (struct sockaddr*)&clientAddr, &size))
            == -1) {
            fprintf(stderr, "ERROR: failed to accept the connection\n\n");
            ret = -1;
            goto exit;
        }

        /* 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 */
        wolfSSL_set_fd(ssl, connd);

        /* Establish TLS connection */
        ret = wolfSSL_accept(ssl);
        if (ret != WOLFSSL_SUCCESS) {
            fprintf(stderr, "wolfSSL_accept error = %d\n",
                wolfSSL_get_error(ssl, ret));
            goto exit;
        }


        printf("Client connected successfully\n");



        /* Read the client data into our buff array */
        memset(buff, 0, sizeof(buff));
        if ((ret = wolfSSL_read(ssl, buff, sizeof(buff)-1)) == -1) {
            fprintf(stderr, "ERROR: failed to read\n");
            goto exit;
        }

        /* Print to stdout any data the client sends */
        printf("Client: %s\n", buff);

        /* Check for server shutdown command */
        if (strncmp(buff, "shutdown", 8) == 0) {
            printf("Shutdown command issued!\n");
            shutdown = 1;
        }



        /* Write our reply into buff */
        memset(buff, 0, sizeof(buff));
        memcpy(buff, reply, strlen(reply));
        len = strnlen(buff, sizeof(buff));

        /* Reply back to the client */
        if ((ret = wolfSSL_write(ssl, buff, len)) != len) {
            fprintf(stderr, "ERROR: failed to write\n");
            goto exit;
        }



        /* Cleanup after this connection */
        wolfSSL_free(ssl);      /* Free the wolfSSL object              */
        ssl = NULL;
        close(connd);           /* Close the connection to the client   */
    }

    printf("Shutdown complete\n");

    ret = 0;

exit:
    /* Cleanup and return */
    if (ssl)
        wolfSSL_free(ssl);      /* Free the wolfSSL object              */
    if (connd != SOCKET_INVALID)
        close(connd);           /* Close the connection to the client   */
    if (sockfd != SOCKET_INVALID)
        close(sockfd);          /* Close the socket listening for clients   */
    if (ctx)
        wolfSSL_CTX_free(ctx);  /* Free the wolfSSL context object          */
    wolfSSL_Cleanup();          /* Cleanup the wolfSSL environment          */

    return ret;               /* Return reporting a success               */
}