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nickfox-taterli/tls_proxy_smtp.c

Created December 6, 2022 12:32
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tls_proxy_smtp.c
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tls_proxy_smtp.c
// SSL/TLS 中继 SMTP 流量,由于Gmail证书精准识别,因此只能出此下策.
#include "mbedtls/build_info.h"
#include "mbedtls/platform.h"
#include <stdlib.h>
#include <string.h>
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/x509.h"
#include "mbedtls/ssl.h"
#include "mbedtls/net_sockets.h"
#include "mbedtls/error.h"
#include "mbedtls/debug.h"
#include "test/certs.h"
#if defined(MBEDTLS_SSL_CACHE_C)
#include "mbedtls/ssl_cache.h"
#endif
#define DEBUG_LEVEL 0
// 没办法,为了和其他交互.
static mbedtls_ssl_context ssl_client;
static void 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 ssl_relayclient( int init_or_exit )
{
int ret = 1, len;
int exit_code = MBEDTLS_EXIT_FAILURE;
static mbedtls_net_context server_fd;
uint32_t flags;
unsigned char buf[1024];
const char *pers = "ssl_client";
static mbedtls_entropy_context entropy;
static mbedtls_ctr_drbg_context ctr_drbg;
static mbedtls_ssl_config conf;
static mbedtls_x509_crt cacert;
if(init_or_exit){
#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_client );
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 );
for(;;);
}
mbedtls_printf( " ok\n" );
/*
* 1. Initialize certificates (反正也不验证,随便Load一个测试证书.)
*/
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", (unsigned int) -ret );
for(;;);
}
mbedtls_printf( " ok (%d skipped)\n", ret );
/*
* 2. Start the connection
*/
mbedtls_printf( " . Connecting to tcp/%s:%d...", "smtp.gmail.com", 465 );
fflush( stdout );
if( ( ret = mbedtls_net_connect( &server_fd, "smtp.gmail.com",
"465", MBEDTLS_NET_PROTO_TCP ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_connect returned %d\n\n", ret );
for(;;);
}
mbedtls_printf( " ok\n" );
/*
* 3. 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 );
for(;;);
}
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, debug, stdout );
mbedtls_ssl_conf_read_timeout( &conf, 1000 );
if( ( ret = mbedtls_ssl_setup( &ssl_client, &conf ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_setup returned %d\n\n", ret );
for(;;);
}
if( ( ret = mbedtls_ssl_set_hostname( &ssl_client, "smtp.gmail.com" ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_set_hostname returned %d\n\n", ret );
for(;;);
}
mbedtls_ssl_set_bio( &ssl_client, &server_fd, mbedtls_net_send, mbedtls_net_recv, mbedtls_net_recv_timeout );
/*
* 4. Handshake
*/
mbedtls_printf( " . Performing the SSL/TLS handshake..." );
fflush( stdout );
while( ( ret = mbedtls_ssl_handshake( &ssl_client ) ) != 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", (unsigned int) -ret );
for(;;);
}
}
mbedtls_printf( " ok\n" );
}else{
mbedtls_net_free( &server_fd );
mbedtls_x509_crt_free( &cacert );
mbedtls_ssl_free( &ssl_client );
mbedtls_ssl_config_free( &conf );
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
}
}
int main( void )
{
int ret, len;
mbedtls_net_context listen_fd, client_fd;
unsigned char buf[1024];
const char *pers = "ssl_server";
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_ssl_config conf;
mbedtls_x509_crt srvcert;
mbedtls_pk_context pkey;
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_cache_context cache;
#endif
mbedtls_net_init( &listen_fd );
mbedtls_net_init( &client_fd );
mbedtls_ssl_init( &ssl );
mbedtls_ssl_config_init( &conf );
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_cache_init( &cache );
#endif
mbedtls_x509_crt_init( &srvcert );
mbedtls_pk_init( &pkey );
mbedtls_entropy_init( &entropy );
mbedtls_ctr_drbg_init( &ctr_drbg );
#if defined(MBEDTLS_DEBUG_C)
mbedtls_debug_set_threshold( DEBUG_LEVEL );
#endif
/*
* 1. Seed the RNG
*/
mbedtls_printf( " . Seeding the random number generator..." );
fflush( stdout );
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 );
for(;;);
}
mbedtls_printf( " ok\n" );
/*
* 2. Load the certificates and private RSA key
*/
mbedtls_printf( "\n . Loading the server cert. and key..." );
fflush( stdout );
/*
* This demonstration program uses embedded test certificates.
* Instead, you may want to use mbedtls_x509_crt_parse_file() to read the
* server and CA certificates, as well as mbedtls_pk_parse_keyfile().
*/
ret = mbedtls_x509_crt_parse_file( &srvcert, "/etc/letsencrypt/live/lax-01.taterli.cyou/fullchain.pem" );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_x509_crt_parse returned %d\n\n", ret );
for(;;);
}
ret = mbedtls_x509_crt_parse_file( &srvcert, "/etc/letsencrypt/live/lax-01.taterli.cyou/fullchain.pem" );
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_x509_crt_parse returned %d\n\n", ret );
for(;;);
}
ret = mbedtls_pk_parse_keyfile( &pkey, "/etc/letsencrypt/live/lax-01.taterli.cyou/privkey.pem", NULL,mbedtls_ctr_drbg_random, &ctr_drbg);
if( ret != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_pk_parse_key returned %d\n\n", ret );
for(;;);
}
mbedtls_printf( " ok\n" );
/*
* 3. Setup the listening TCP socket
*/
mbedtls_printf( " . Bind on https://0.0.0.0:465/ ..." );
fflush( stdout );
if( ( ret = mbedtls_net_bind( &listen_fd, NULL, "465", MBEDTLS_NET_PROTO_TCP ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_bind returned %d\n\n", ret );
for(;;);
}
mbedtls_printf( " ok\n" );
/*
* 4. Setup stuff
*/
mbedtls_printf( " . Setting up the SSL data...." );
fflush( stdout );
if( ( ret = mbedtls_ssl_config_defaults( &conf,
MBEDTLS_SSL_IS_SERVER,
MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_config_defaults returned %d\n\n", ret );
for(;;);
}
mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
mbedtls_ssl_conf_dbg( &conf, debug, stdout );
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_conf_session_cache( &conf, &cache,
mbedtls_ssl_cache_get,
mbedtls_ssl_cache_set );
#endif
mbedtls_ssl_conf_ca_chain( &conf, srvcert.next, NULL );
if( ( ret = mbedtls_ssl_conf_own_cert( &conf, &srvcert, &pkey ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_conf_own_cert returned %d\n\n", ret );
for(;;);
}
if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_setup returned %d\n\n", ret );
for(;;);
}
mbedtls_printf( " ok\n" );
reset:
#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( &client_fd );
mbedtls_ssl_session_reset( &ssl );
/*
* 3. Wait until a client connects
*/
mbedtls_printf( " . Waiting for a remote connection ..." );
fflush( stdout );
if( ( ret = mbedtls_net_accept( &listen_fd, &client_fd,
NULL, 0, NULL ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_accept returned %d\n\n", ret );
for(;;);
}
mbedtls_ssl_set_bio( &ssl, &client_fd, mbedtls_net_send, mbedtls_net_recv, NULL );
mbedtls_printf( " ok\n" );
/*
* 5. 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 %d\n\n", ret );
goto reset;
}
}
mbedtls_printf( " ok\n" );
// 这里开始建立到另一边的TCP SSL链接,并修改部分数据
ssl_relayclient(1); // 初始化客户端
do
{
// 第一圈,从远端的送到客户端
len = sizeof( buf ) - 1;
memset( buf, 0, sizeof( buf ) );
ret = mbedtls_ssl_read( &ssl_client, buf, len ); /* 会从对面服务器获取数据 */
if( ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY )
break;
if(ret > 0){
// 假定成功(事实上要判断ret)
len = ret;
mbedtls_printf( " %d bytes read\n\n%s", len, (char *) buf );
mbedtls_printf( " > Write to client:" );
fflush( stdout );
// 这里针对地处理(比如替换GMIAL特征)
while( ( ret = mbedtls_ssl_write( &ssl, buf, len ) ) <= 0 )
{
if( ret == MBEDTLS_ERR_NET_CONN_RESET )
{
mbedtls_printf( " failed\n ! peer closed the connection\n\n" );
goto reset;
}
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 );
for(;;);
}
}
len = ret;
mbedtls_printf( " %d bytes written\n\n%s\n", len, (char *) buf );
}
// 第二圈,从客户端的送到远端.
len = sizeof( buf ) - 1;
memset( buf, 0, sizeof( buf ) );
ret = mbedtls_ssl_read( &ssl, buf, len ); /* 会从对面服务器获取数据 */
// 假定成功(事实上要判断ret)
if( ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY )
break;
len = ret;
mbedtls_printf( " %d bytes read\n\n%s", ret, (char *) buf );
mbedtls_printf( " > Read from client:" );
fflush( stdout );
while( ( ret = mbedtls_ssl_write( &ssl_client, buf, len ) ) <= 0 )
{
if( ret == MBEDTLS_ERR_NET_CONN_RESET )
{
mbedtls_printf( " failed\n ! peer closed the connection\n\n" );
goto reset;
}
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 );
for(;;);
}
}
len = ret;
mbedtls_printf( " %d bytes read\n\n%s\n", len, (char *) buf );
}
while( 1 );
mbedtls_printf( " . Closing the connection..." );
mbedtls_ssl_close_notify( &ssl_client );
ssl_relayclient(0); // 取消客户端的初始化
while( ( ret = mbedtls_ssl_close_notify( &ssl ) ) < 0 )
{
if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
ret != MBEDTLS_ERR_SSL_WANT_WRITE )
{
mbedtls_printf( " failed\n ! mbedtls_ssl_close_notify returned %d\n\n", ret );
goto reset;
}
}
mbedtls_printf( " ok\n" );
ret = 0;
goto reset;
#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( &client_fd );
mbedtls_net_free( &listen_fd );
mbedtls_x509_crt_free( &srvcert );
mbedtls_pk_free( &pkey );
mbedtls_ssl_free( &ssl );
mbedtls_ssl_config_free( &conf );
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_cache_free( &cache );
#endif
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
mbedtls_exit( ret );
}
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