mirror/openssl
2
0
Fork 0
mirror of https://github.com/openssl/openssl.git synced 2025-02-23 14:42:15 +08:00
Code Issues Packages Projects Releases Wiki Activity

Add a TLS non-blocking demo

Browse Source 
Show how to write a TLS client using a non-blocking socket

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21950)
This commit is contained in:
Matt Caswell 2023-08-24 09:14:21 +01:00
parent ebce766bb8
commit 0295364548
2 changed files with 344 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
demos/guide/Makefile
View File

@ -9,7 +9,7 @@ CFLAGS = -I../../include -g
LDFLAGS = -L../..
LDLIBS = -lcrypto -lssl
all: tls-client-block quic-client-block quic-multi-stream
all: tls-client-block quic-client-block quic-multi-stream tls-client-non-block
tls-client-block: tls-client-block.c
$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LDLIBS)
@ -20,5 +20,9 @@ quic-client-block: quic-client-block.c
quic-multi-stream: quic-multi-stream.c
$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LDLIBS)
tls-client-non-block: tls-client-non-block.c
$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LDLIBS)
clean:
$(RM) *.o tls-client-block quic-client-block quic-multi-stream
$(RM) *.o tls-client-block quic-client-block quic-multi-stream \
tls-client-non-block

338
demos/guide/tls-client-non-block.c Normal file
View File

@ -0,0 +1,338 @@
/*
* Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* NB: Changes to this file should also be reflected in
* doc/man7/ossl-guide-tls-client-non-block.pod
*/
#include <string.h>
/* Include the appropriate header file for SOCK_STREAM */
#ifdef _WIN32 /* Windows */
# include <winsock2.h>
#else /* Linux/Unix */
# include <sys/socket.h>
# include <sys/select.h>
#endif
#include <openssl/bio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
/* Helper function to create a BIO connected to the server */
static BIO *create_socket_bio(const char *hostname, const char *port)
{
int sock = -1;
BIO_ADDRINFO *res;
const BIO_ADDRINFO *ai = NULL;
BIO *bio;
/*
* Lookup IP address info for the server.
*/
if (!BIO_lookup_ex(hostname, port, BIO_LOOKUP_CLIENT, 0, SOCK_STREAM, 0,
&res))
return NULL;
/*
* Loop through all the possible addresses for the server and find one
* we can connect to.
*/
for (ai = res; ai != NULL; ai = BIO_ADDRINFO_next(ai)) {
/*
* Create a TCP socket. We could equally use non-OpenSSL calls such
* as "socket" here for this and the subsequent connect and close
* functions. But for portability reasons and also so that we get
* errors on the OpenSSL stack in the event of a failure we use
* OpenSSL's versions of these functions.
*/
sock = BIO_socket(BIO_ADDRINFO_family(ai), SOCK_STREAM, 0, 0);
if (sock == -1)
continue;
/* Connect the socket to the server's address */
if (!BIO_connect(sock, BIO_ADDRINFO_address(ai), BIO_SOCK_NODELAY)) {
BIO_closesocket(sock);
sock = -1;
continue;
}
/* Set to nonblocking mode */
if (!BIO_socket_nbio(sock, 1)) {
sock = -1;
continue;
}
/* We have a connected socket so break out of the loop */
break;
}
/* Free the address information resources we allocated earlier */
BIO_ADDRINFO_free(res);
/* If sock is -1 then we've been unable to connect to the server */
if (sock == -1)
return NULL;
/* Create a BIO to wrap the socket*/
bio = BIO_new(BIO_s_socket());
if (bio == NULL)
BIO_closesocket(sock);
/*
* Associate the newly created BIO with the underlying socket. By
* passing BIO_CLOSE here the socket will be automatically closed when
* the BIO is freed. Alternatively you can use BIO_NOCLOSE, in which
* case you must close the socket explicitly when it is no longer
* needed.
*/
BIO_set_fd(bio, sock, BIO_CLOSE);
return bio;
}
static void wait_for_activity(SSL *ssl, int write)
{
fd_set fds;
int width, sock;
/* Get hold of the underlying file descriptor for the socket */
sock = SSL_get_fd(ssl);
FD_ZERO(&fds);
FD_SET(sock, &fds);
width = sock + 1;
/*
* Wait until the socket is writeable or readable. We use select here for
* the sake of simplicity and portability, but you could equally use
* poll/epoll or similar functions
*/
if (write)
select(width, NULL, &fds, NULL, NULL);
else
select(width, &fds, NULL, NULL, NULL);
}
static int handle_io_failure(SSL *ssl, int res)
{
switch (SSL_get_error(ssl, res)) {
case SSL_ERROR_WANT_READ:
/* Temporary failure. Wait until we can read and try again */
wait_for_activity(ssl, 0);
return 1;
case SSL_ERROR_WANT_WRITE:
/* Temporary failure. Wait until we can write and try again */
wait_for_activity(ssl, 1);
return 1;
case SSL_ERROR_ZERO_RETURN:
/* EOF */
return 0;
case SSL_ERROR_SYSCALL:
return -1;
case SSL_ERROR_SSL:
/*
* If the failure is due to a verification error we can get more
* information about it from SSL_get_verify_result().
*/
if (SSL_get_verify_result(ssl) != X509_V_OK)
printf("Verify error: %s\n",
X509_verify_cert_error_string(SSL_get_verify_result(ssl)));
return -1;
default:
return -1;
}
}
/* Server hostname and port details. Must be in quotes */
#ifndef HOSTNAME
# define HOSTNAME "www.example.com"
#endif
#ifndef PORT
# define PORT "443"
#endif
/*
* Simple application to send a basic HTTP/1.0 request to a server and
* print the response on the screen.
*/
int main(void)
{
SSL_CTX *ctx = NULL;
SSL *ssl = NULL;
BIO *bio = NULL;
int res = EXIT_FAILURE;
int ret;
const char *request =
"GET / HTTP/1.0\r\nConnection: close\r\nHost: "HOSTNAME"\r\n\r\n";
size_t written, readbytes;
char buf[160];
int eof = 0;
/*
* Create an SSL_CTX which we can use to create SSL objects from. We
* want an SSL_CTX for creating clients so we use TLS_client_method()
* here.
*/
ctx = SSL_CTX_new(TLS_client_method());
if (ctx == NULL) {
printf("Failed to create the SSL_CTX\n");
goto end;
}
/*
* Configure the client to abort the handshake if certificate
* verification fails. Virtually all clients should do this unless you
* really know what you are doing.
*/
SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
/* Use the default trusted certificate store */
if (!SSL_CTX_set_default_verify_paths(ctx)) {
printf("Failed to set the default trusted certificate store\n");
goto end;
}
/*
* TLSv1.1 or earlier are deprecated by IETF and are generally to be
* avoided if possible. We require a minimum TLS version of TLSv1.2.
*/
if (!SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION)) {
printf("Failed to set the minimum TLS protocol version\n");
goto end;
}
/* Create an SSL object to represent the TLS connection */
ssl = SSL_new(ctx);
if (ssl == NULL) {
printf("Failed to create the SSL object\n");
goto end;
}
/*
* Create the underlying transport socket/BIO and associate it with the
* connection.
*/
bio = create_socket_bio(HOSTNAME, PORT);
if (bio == NULL) {
printf("Failed to crete the BIO\n");
goto end;
}
SSL_set_bio(ssl, bio, bio);
/*
* Tell the server during the handshake which hostname we are attempting
* to connect to in case the server supports multiple hosts.
*/
if (!SSL_set_tlsext_host_name(ssl, HOSTNAME)) {
printf("Failed to set the SNI hostname\n");
goto end;
}
/*
* Ensure we check during certificate verification that the server has
* supplied a certificate for the hostname that we were expecting.
* Virtually all clients should do this unless you really know what you
* are doing.
*/
if (!SSL_set1_host(ssl, HOSTNAME)) {
printf("Failed to set the certificate verification hostname");
goto end;
}
/* Do the handshake with the server */
while ((ret = SSL_connect(ssl)) != 1) {
if (handle_io_failure(ssl, ret) == 1)
continue; /* Retry */
printf("Failed to connect to server\n");
goto end; /* Cannot retry: error */
}
/* Write an HTTP GET request to the peer */
while (!SSL_write_ex(ssl, request, strlen(request), &written)) {
if (handle_io_failure(ssl, 0) == 1)
continue; /* Retry */
printf("Failed to write HTTP request\n");
goto end; /* Cannot retry: error */
}
do {
/*
* Get up to sizeof(buf) bytes of the response. We keep reading until
* the server closes the connection.
*/
while (!eof && !SSL_read_ex(ssl, buf, sizeof(buf), &readbytes)) {
switch (handle_io_failure(ssl, 0)) {
case 1:
continue; /* Retry */
case 0:
eof = 1;
continue;
case -1:
default:
printf("Failed reading remaining data\n");
goto end; /* Cannot retry: error */
}
}
/*
* OpenSSL does not guarantee that the returned data is a string or
* that it is NUL terminated so we use fwrite() to write the exact
* number of bytes that we read. The data could be non-printable or
* have NUL characters in the middle of it. For this simple example
* we're going to print it to stdout anyway.
*/
if (!eof)
fwrite(buf, 1, readbytes, stdout);
} while (!eof);
/* In case the response didn't finish with a newline we add one now */
printf("\n");
/*
* The peer already shutdown gracefully (we know this because of the
* SSL_ERROR_ZERO_RETURN (i.e. EOF) above). We should do the same back.
*/
while ((ret = SSL_shutdown(ssl)) != 1) {
if (ret < 0 && handle_io_failure(ssl, ret) == 1)
continue; /* Retry */
/*
* ret == 0 is unexpected here because that means "we've sent a
* close_notify and we're waiting for one back". But we already know
* we got one from the peer because of the SSL_ERROR_ZERO_RETURN
* (i.e. EOF) above.
*/
printf("Error shutting down\n");
goto end; /* Cannot retry: error */
}
/* Success! */
res = EXIT_SUCCESS;
end:
/*
* If something bad happened then we will dump the contents of the
* OpenSSL error stack to stderr. There might be some useful diagnostic
* information there.
*/
if (res == EXIT_FAILURE)
ERR_print_errors_fp(stderr);
/*
* Free the resources we allocated. We do not free the BIO object here
* because ownership of it was immediately transferred to the SSL object
* via SSL_set_bio(). The BIO will be freed when we free the SSL object.
*/
SSL_free(ssl);
SSL_CTX_free(ctx);
return res;
}