有几个可用的开源库为C ++提供SSL实现。 是否有任何示例演示如何在C ++中创建HTTPS客户端？
答案 0 :(得分：3)
使用mbedTLS库的简单客户端代码。我使用过这个库，它相对简单，内存占用少，当然还使用Apache-2.0许可证：
/*
* SSL client demonstration program
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#include <stdlib.h>
#define mbedtls_time time
#define mbedtls_time_t time_t
#define mbedtls_fprintf fprintf
#define mbedtls_printf printf
#endif
#if !defined(MBEDTLS_BIGNUM_C) || !defined(MBEDTLS_ENTROPY_C) || \
!defined(MBEDTLS_SSL_TLS_C) || !defined(MBEDTLS_SSL_CLI_C) || \
!defined(MBEDTLS_NET_C) || !defined(MBEDTLS_RSA_C) || \
!defined(MBEDTLS_CERTS_C) || !defined(MBEDTLS_PEM_PARSE_C) || \
!defined(MBEDTLS_CTR_DRBG_C) || !defined(MBEDTLS_X509_CRT_PARSE_C)
int main( void )
{
mbedtls_printf("MBEDTLS_BIGNUM_C and/or MBEDTLS_ENTROPY_C and/or "
"MBEDTLS_SSL_TLS_C and/or MBEDTLS_SSL_CLI_C and/or "
"MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
"MBEDTLS_CTR_DRBG_C and/or MBEDTLS_X509_CRT_PARSE_C "
"not defined.\n");
return( 0 );
}
#else
#include "mbedtls/net_sockets.h"
#include "mbedtls/debug.h"
#include "mbedtls/ssl.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/error.h"
#include "mbedtls/certs.h"
#include <string.h>
#define SERVER_PORT "4433"
#define SERVER_NAME "localhost"
#define GET_REQUEST "GET / HTTP/1.0\r\n\r\n"
#define DEBUG_LEVEL 1
static void my_debug( void *ctx, int level,
const char *file, int line,
const char *str )
{
((void) level);
mbedtls_fprintf( (FILE *) ctx, "%s:%04d: %s", file, line, str );
fflush( (FILE *) ctx );
}
int main( void )
{
int ret, len;
mbedtls_net_context server_fd;
uint32_t flags;
unsigned char buf[1024];
const char *pers = "ssl_client1";
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_ssl_config conf;
mbedtls_x509_crt cacert;
#if defined(MBEDTLS_DEBUG_C)
mbedtls_debug_set_threshold( DEBUG_LEVEL );
#endif
/*
* 0. Initialize the RNG and the session data
*/
mbedtls_net_init( &server_fd );
mbedtls_ssl_init( &ssl );
mbedtls_ssl_config_init( &conf );
mbedtls_x509_crt_init( &cacert );
mbedtls_ctr_drbg_init( &ctr_drbg );
mbedtls_printf( "\n . Seeding the random number generator..." );
fflush( stdout );
mbedtls_entropy_init( &entropy );
if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
(const unsigned char *) pers,
strlen( pers ) ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* 0. Initialize certificates
*/
mbedtls_printf( " . Loading the CA root certificate ..." );
fflush( stdout );
ret = mbedtls_x509_crt_parse( &cacert, (const unsigned char *) mbedtls_test_cas_pem,
mbedtls_test_cas_pem_len );
if( ret < 0 )
{
mbedtls_printf( " failed\n ! mbedtls_x509_crt_parse returned -0x%x\n\n", -ret );
goto exit;
}
mbedtls_printf( " ok (%d skipped)\n", ret );
/*
* 1. Start the connection
*/
mbedtls_printf( " . Connecting to tcp/%s/%s...", SERVER_NAME, SERVER_PORT );
fflush( stdout );
if( ( ret = mbedtls_net_connect( &server_fd, SERVER_NAME,
SERVER_PORT, MBEDTLS_NET_PROTO_TCP ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_connect returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/*
* 2. Setup stuff
*/
mbedtls_printf( " . Setting up the SSL/TLS structure..." );
fflush( stdout );
if( ( ret = mbedtls_ssl_config_defaults( &conf,
MBEDTLS_SSL_IS_CLIENT,
MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_config_defaults returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( " ok\n" );
/* OPTIONAL is not optimal for security,
* but makes interop easier in this simplified example */
mbedtls_ssl_conf_authmode( &conf, MBEDTLS_SSL_VERIFY_OPTIONAL );
mbedtls_ssl_conf_ca_chain( &conf, &cacert, NULL );
mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
mbedtls_ssl_conf_dbg( &conf, my_debug, stdout );
if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_setup returned %d\n\n", ret );
goto exit;
}
if( ( ret = mbedtls_ssl_set_hostname( &ssl, "mbed TLS Server 1" ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_set_hostname returned %d\n\n", ret );
goto exit;
}
mbedtls_ssl_set_bio( &ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL );
/*
* 4. Handshake
*/
mbedtls_printf( " . Performing the SSL/TLS handshake..." );
fflush( stdout );
while( ( ret = mbedtls_ssl_handshake( &ssl ) ) != 0 )
{
if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_handshake returned -0x%x\n\n", -ret );
goto exit;
}
}
mbedtls_printf( " ok\n" );
/*
* 5. Verify the server certificate
*/
mbedtls_printf( " . Verifying peer X.509 certificate..." );
/* In real life, we probably want to bail out when ret != 0 */
if( ( flags = mbedtls_ssl_get_verify_result( &ssl ) ) != 0 )
{
char vrfy_buf[512];
mbedtls_printf( " failed\n" );
mbedtls_x509_crt_verify_info( vrfy_buf, sizeof( vrfy_buf ), " ! ", flags );
mbedtls_printf( "%s\n", vrfy_buf );
}
else
mbedtls_printf( " ok\n" );
/*
* 3. Write the GET request
*/
mbedtls_printf( " > Write to server:" );
fflush( stdout );
len = sprintf( (char *) buf, GET_REQUEST );
while( ( ret = mbedtls_ssl_write( &ssl, buf, len ) ) <= 0 )
{
if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_write returned %d\n\n", ret );
goto exit;
}
}
len = ret;
mbedtls_printf( " %d bytes written\n\n%s", len, (char *) buf );
/*
* 7. Read the HTTP response
*/
mbedtls_printf( " < Read from server:" );
fflush( stdout );
do
{
len = sizeof( buf ) - 1;
memset( buf, 0, sizeof( buf ) );
ret = mbedtls_ssl_read( &ssl, buf, len );
if( ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE )
continue;
if( ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY )
break;
if( ret < 0 )
{
mbedtls_printf( "failed\n ! mbedtls_ssl_read returned %d\n\n", ret );
break;
}
if( ret == 0 )
{
mbedtls_printf( "\n\nEOF\n\n" );
break;
}
len = ret;
mbedtls_printf( " %d bytes read\n\n%s", len, (char *) buf );
}
while( 1 );
mbedtls_ssl_close_notify( &ssl );
exit:
#ifdef MBEDTLS_ERROR_C
if( ret != 0 )
{
char error_buf[100];
mbedtls_strerror( ret, error_buf, 100 );
mbedtls_printf("Last error was: %d - %s\n\n", ret, error_buf );
}
#endif
mbedtls_net_free( &server_fd );
mbedtls_x509_crt_free( &cacert );
mbedtls_ssl_free( &ssl );
mbedtls_ssl_config_free( &conf );
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
#if defined(_WIN32)
mbedtls_printf( " + Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
return( ret );
}
#endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_SSL_TLS_C &&
MBEDTLS_SSL_CLI_C && MBEDTLS_NET_C && MBEDTLS_RSA_C &&
MBEDTLS_CERTS_C && MBEDTLS_PEM_PARSE_C && MBEDTLS_CTR_DRBG_C &&
MBEDTLS_X509_CRT_PARSE_C */