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wolfssl-examples/tls/client-ech.c

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/* client-ech.c
*
* Copyright (C) 2006-2022 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
*/
/* the usual suspects */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
/* socket includes */
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
#include <wolfssl/options.h>
#include <wolfssl/wolfcrypt/settings.h>
#include <wolfssl/ssl.h>
#include <wolfssl/test.h>
#define SERV_PORT 443
#define CERT_FILE "../certs/ech-client-cert.pem"
#define RDBUFF_LEN 512
#define ECHBUFF_LEN 256
#ifdef HAVE_ECH
int main(void)
{
int ret = 0;
byte rd_buf[RDBUFF_LEN];
int sockfd = -1;
WOLFSSL_CTX* ctx = NULL;
WOLFSSL* ssl = NULL;
struct sockaddr_in servAddr;
const char message[] =
"GET /cdn-cgi/trace/ HTTP/1.1\r\n"
"Host: crypto.cloudflare.com\r\n"
"User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:105.0) Gecko/20100101 Firefox/105.0\r\n"
"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8\r\n"
"Accept-Language: en-US,en;q=0.5\r\n"
"Referer: https://www.google.com/\r\n"
"DNT: 1\r\n"
"Connection: keep-alive\r\n"
"Upgrade-Insecure-Requests: 1\r\n"
"Sec-Fetch-Dest: document\r\n"
"Sec-Fetch-Mode: navigate\r\n"
"Sec-Fetch-Site: cross-site\r\n"
"Pragma: no-cache\r\n"
"Cache-Control: no-cache\r\n"
"\r\n";
const char publicIP[] = "104.18.11.118";
const char publicSNI[] = "cloudflare-ech.com";
const char privateSNI[] = "crypto.cloudflare.com";
byte echConfigs[ECHBUFF_LEN];
word32 echConfigsLen = ECHBUFF_LEN;
/* Initialize wolfSSL */
if ((ret = wolfSSL_Init()) != WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: Failed to initialize the library\n");
goto cleanup;
}
/* 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 cleanup;
}
/*---------------------------------------------------*/
/* Start of wolfSSL GREASE connection */
/*---------------------------------------------------*/
/* this first tls connection is only used to get the retry configs - these
* configs can also be retrieved from DNS
* i.e. `$ dig cloudflare-ech.com HTTPS` */
/* 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 cleanup;
}
/* 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(SERV_PORT); /* on DEFAULT_PORT */
/* set the ip string to the cloudflare ECH server */
servAddr.sin_addr.s_addr = inet_addr( publicIP );
/* Connect to the server */
if ((ret = connect(sockfd, (struct sockaddr*) &servAddr, sizeof(servAddr)))
== -1) {
fprintf(stderr, "ERROR: failed to connect\n");
goto cleanup;
}
/* Load client certificates into WOLFSSL_CTX */
if ((ret = wolfSSL_CTX_load_verify_locations(ctx, CERT_FILE, NULL))
!= WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: failed to load %s, please check the file.\n",
CERT_FILE);
goto ctx_cleanup;
}
/* Create a WOLFSSL object */
if ((ssl = wolfSSL_new(ctx)) == NULL) {
fprintf(stderr, "ERROR: failed to create WOLFSSL object\n");
ret = -1;
goto ctx_cleanup;
}
/* Set SNI to the ECH server
* Take care not to set this to the private SNI because that would leak
* information about it. The private SNI will only be encrypted once the ECH
* configs are set. */
if ((ret = wolfSSL_UseSNI(ssl, WOLFSSL_SNI_HOST_NAME, publicSNI,
strlen(publicSNI))) != WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: Failed to set public SNI %d\n", ret);
ret = -1;
goto ssl_cleanup;
}
/* Attach wolfSSL to the socket */
if ((ret = wolfSSL_set_fd(ssl, sockfd)) != WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: Failed to set the file descriptor %d\n", ret);
goto ssl_cleanup;
}
/* Connect to Cloudflare ECH server */
if ((ret = wolfSSL_connect(ssl)) != WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: failed to connect to Cloudflare ECH server\n");
fprintf(stderr, "%d %d\n", ret, wolfSSL_get_error(ssl, ret));
goto ssl_cleanup;
}
/* If the GREASE was successful then retry configs sent by the server
* should be available. Store these in echConfigs for encrypting the
* upcoming ECH connection. */
if ((ret = wolfSSL_GetEchConfigs(ssl, echConfigs, &echConfigsLen)) !=
WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: unable to get GREASE configs %d\n", ret);
goto ssl_cleanup;
}
while (wolfSSL_shutdown(ssl) == WOLFSSL_SHUTDOWN_NOT_DONE) {
; /* do nothing */
}
/* frees all data before client termination */
wolfSSL_free(ssl);
close(sockfd);
ssl = NULL;
sockfd = -1;
/*---------------------------------------------------*/
/* Start of wolfSSL ECH connection */
/*---------------------------------------------------*/
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
fprintf(stderr, "ERROR: failed to create the socket\n");
ret = -1;
goto ctx_cleanup;
}
memset(&servAddr, 0, sizeof(servAddr));
servAddr.sin_family = AF_INET; /* using IPv4 */
servAddr.sin_port = htons(SERV_PORT); /* on DEFAULT_PORT */
servAddr.sin_addr.s_addr = inet_addr( publicIP );
if ((ret = connect(sockfd, (struct sockaddr*) &servAddr, sizeof(servAddr)))
== -1) {
fprintf(stderr, "ERROR: failed to connect\n");
goto ctx_cleanup;
}
/* Create a WOLFSSL object */
if ((ssl = wolfSSL_new(ctx)) == NULL) {
fprintf(stderr, "ERROR: failed to create WOLFSSL object\n");
ret = -1;
goto ctx_cleanup;
}
/* set the ECH configs with configs taken from the GREASE connection */
if ((ret = wolfSSL_SetEchConfigs(ssl, echConfigs, echConfigsLen)) !=
WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: failed to set GREASE configs %d\n", ret);
goto ssl_cleanup;
}
/* Now that ECH configs are set the private SNI will be encrypted, therefore
* it is now fine (and correct) to set the private SNI here */
if ((ret = wolfSSL_UseSNI(ssl, WOLFSSL_SNI_HOST_NAME, privateSNI,
strlen(privateSNI))) != WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: Failed to set private SNI %d\n", ret);
ret = -1;
goto ssl_cleanup;
}
/* Attach wolfSSL to the socket */
if ((ret = wolfSSL_set_fd(ssl, sockfd)) != WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: Failed to set the file descriptor %d\n", ret);
goto ssl_cleanup;
}
/* Connect to Cloudflare */
if ((ret = wolfSSL_connect(ssl)) != WOLFSSL_SUCCESS) {
fprintf(stderr, "ERROR: failed to connect to Cloudflare\n");
fprintf(stderr, "%d %d\n", ret, wolfSSL_get_error(ssl, ret));
goto ssl_cleanup;
}
/* Write the message that will ask the server for information on the
* connection */
if ((ret = wolfSSL_write(ssl, message, strlen(message))) !=
strlen(message)) {
fprintf(stderr, "ERROR: failed to write entire message\n");
fprintf(stderr, "%d bytes of %d bytes were sent",
ret, (int)strlen(message));
goto ssl_cleanup;
}
/* Retrieve the server's response:
* If ECH is being correctly used then 'sni=encrypted' should show up */
do
{
ret = wolfSSL_read(ssl, rd_buf, RDBUFF_LEN);
if (ret <= 0)
break;
fprintf(stdout, "%.*s", ret, rd_buf);
/* read until the chunk size is 0 */
} while (rd_buf[0] != '0');
while (wolfSSL_shutdown(ssl) == WOLFSSL_SHUTDOWN_NOT_DONE) {
; /* do nothing */
}
ret = 0;
ssl_cleanup:
wolfSSL_free(ssl);
ssl = NULL;
ctx_cleanup:
wolfSSL_CTX_free(ctx);
cleanup:
wolfSSL_Cleanup();
close(sockfd);
sockfd = -1;
return ret;
}
#else
int main(void)
{
fprintf(stderr, "Please build wolfssl with ./configure --enable-ech\n");
return 1;
}
#endif
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