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/*
This example code shows how to write an (optionally encrypting) SSL proxy
with Libevent's bufferevent layer.
XXX It's a little ugly and should probably be cleaned up.
*/
// Get rid of OSX 10.7 and greater deprecation warnings.
#if defined(__APPLE__) && defined(__clang__)
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
#endif
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#ifdef _WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#else
#include <sys/socket.h>
#include <netinet/in.h>
#endif
#include <event2/bufferevent_ssl.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include "util-internal.h"
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include "openssl-compat.h"
static struct event_base *base;
static struct sockaddr_storage listen_on_addr;
static struct sockaddr_storage connect_to_addr;
static int connect_to_addrlen;
static int use_wrapper = 1;
static SSL_CTX *ssl_ctx = NULL;
#define MAX_OUTPUT (512*1024)
static void drained_writecb(struct bufferevent *bev, void *ctx);
static void eventcb(struct bufferevent *bev, short what, void *ctx);
static void
readcb(struct bufferevent *bev, void *ctx)
{
struct bufferevent *partner = ctx;
struct evbuffer *src, *dst;
size_t len;
src = bufferevent_get_input(bev);
len = evbuffer_get_length(src);
if (!partner) {
evbuffer_drain(src, len);
return;
}
dst = bufferevent_get_output(partner);
evbuffer_add_buffer(dst, src);
if (evbuffer_get_length(dst) >= MAX_OUTPUT) {
/* We're giving the other side data faster than it can
* pass it on. Stop reading here until we have drained the
* other side to MAX_OUTPUT/2 bytes. */
bufferevent_setcb(partner, readcb, drained_writecb,
eventcb, bev);
bufferevent_setwatermark(partner, EV_WRITE, MAX_OUTPUT/2,
MAX_OUTPUT);
bufferevent_disable(bev, EV_READ);
}
}
static void
drained_writecb(struct bufferevent *bev, void *ctx)
{
struct bufferevent *partner = ctx;
/* We were choking the other side until we drained our outbuf a bit.
* Now it seems drained. */
bufferevent_setcb(bev, readcb, NULL, eventcb, partner);
bufferevent_setwatermark(bev, EV_WRITE, 0, 0);
if (partner)
bufferevent_enable(partner, EV_READ);
}
static void
close_on_finished_writecb(struct bufferevent *bev, void *ctx)
{
struct evbuffer *b = bufferevent_get_output(bev);
if (evbuffer_get_length(b) == 0) {
bufferevent_free(bev);
}
}
static void
eventcb(struct bufferevent *bev, short what, void *ctx)
{
struct bufferevent *partner = ctx;
if (what & (BEV_EVENT_EOF|BEV_EVENT_ERROR)) {
if (what & BEV_EVENT_ERROR) {
unsigned long err;
while ((err = (bufferevent_get_openssl_error(bev)))) {
const char *msg = (const char*)
ERR_reason_error_string(err);
const char *lib = (const char*)
ERR_lib_error_string(err);
const char *func = (const char*)
ERR_func_error_string(err);
fprintf(stderr,
"%s in %s %s\n", msg, lib, func);
}
if (errno)
perror("connection error");
}
if (partner) {
/* Flush all pending data */
readcb(bev, ctx);
if (evbuffer_get_length(
bufferevent_get_output(partner))) {
/* We still have to flush data from the other
* side, but when that's done, close the other
* side. */
bufferevent_setcb(partner,
NULL, close_on_finished_writecb,
eventcb, NULL);
bufferevent_disable(partner, EV_READ);
} else {
/* We have nothing left to say to the other
* side; close it. */
bufferevent_free(partner);
}
}
bufferevent_free(bev);
}
}
static void
syntax(void)
{
fputs("Syntax:\n", stderr);
fputs(" le-proxy [-s] [-W] <listen-on-addr> <connect-to-addr>\n", stderr);
fputs("Example:\n", stderr);
fputs(" le-proxy 127.0.0.1:8888 1.2.3.4:80\n", stderr);
exit(1);
}
static void
accept_cb(struct evconnlistener *listener, evutil_socket_t fd,
struct sockaddr *a, int slen, void *p)
{
struct bufferevent *b_out, *b_in;
/* Create two linked bufferevent objects: one to connect, one for the
* new connection */
b_in = bufferevent_socket_new(base, fd,
BEV_OPT_CLOSE_ON_FREE|BEV_OPT_DEFER_CALLBACKS);
if (!ssl_ctx || use_wrapper)
b_out = bufferevent_socket_new(base, -1,
BEV_OPT_CLOSE_ON_FREE|BEV_OPT_DEFER_CALLBACKS);
else {
SSL *ssl = SSL_new(ssl_ctx);
b_out = bufferevent_openssl_socket_new(base, -1, ssl,
BUFFEREVENT_SSL_CONNECTING,
BEV_OPT_CLOSE_ON_FREE|BEV_OPT_DEFER_CALLBACKS);
}
assert(b_in && b_out);
if (bufferevent_socket_connect(b_out,
(struct sockaddr*)&connect_to_addr, connect_to_addrlen)<0) {
perror("bufferevent_socket_connect");
bufferevent_free(b_out);
bufferevent_free(b_in);
return;
}
if (ssl_ctx && use_wrapper) {
struct bufferevent *b_ssl;
SSL *ssl = SSL_new(ssl_ctx);
b_ssl = bufferevent_openssl_filter_new(base,
b_out, ssl, BUFFEREVENT_SSL_CONNECTING,
BEV_OPT_CLOSE_ON_FREE|BEV_OPT_DEFER_CALLBACKS);
if (!b_ssl) {
perror("Bufferevent_openssl_new");
bufferevent_free(b_out);
bufferevent_free(b_in);
return;
}
b_out = b_ssl;
}
bufferevent_setcb(b_in, readcb, NULL, eventcb, b_out);
bufferevent_setcb(b_out, readcb, NULL, eventcb, b_in);
bufferevent_enable(b_in, EV_READ|EV_WRITE);
bufferevent_enable(b_out, EV_READ|EV_WRITE);
}
int
main(int argc, char **argv)
{
int i;
int socklen;
int use_ssl = 0;
struct evconnlistener *listener;
#ifdef _WIN32
WORD wVersionRequested;
WSADATA wsaData;
wVersionRequested = MAKEWORD(2, 2);
(void) WSAStartup(wVersionRequested, &wsaData);
#endif
if (argc < 3)
syntax();
for (i=1; i < argc; ++i) {
if (!strcmp(argv[i], "-s")) {
use_ssl = 1;
} else if (!strcmp(argv[i], "-W")) {
use_wrapper = 0;
} else if (argv[i][0] == '-') {
syntax();
} else
break;
}
if (i+2 != argc)
syntax();
memset(&listen_on_addr, 0, sizeof(listen_on_addr));
socklen = sizeof(listen_on_addr);
if (evutil_parse_sockaddr_port(argv[i],
(struct sockaddr*)&listen_on_addr, &socklen)<0) {
int p = atoi(argv[i]);
struct sockaddr_in *sin = (struct sockaddr_in*)&listen_on_addr;
if (p < 1 || p > 65535)
syntax();
sin->sin_port = htons(p);
sin->sin_addr.s_addr = htonl(0x7f000001);
sin->sin_family = AF_INET;
socklen = sizeof(struct sockaddr_in);
}
memset(&connect_to_addr, 0, sizeof(connect_to_addr));
connect_to_addrlen = sizeof(connect_to_addr);
if (evutil_parse_sockaddr_port(argv[i+1],
(struct sockaddr*)&connect_to_addr, &connect_to_addrlen)<0)
syntax();
base = event_base_new();
if (!base) {
perror("event_base_new()");
return 1;
}
if (use_ssl) {
int r;
#if (OPENSSL_VERSION_NUMBER < 0x10100000L) || \
(defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x20700000L)
SSL_library_init();
ERR_load_crypto_strings();
SSL_load_error_strings();
OpenSSL_add_all_algorithms();
#endif
r = RAND_poll();
if (r == 0) {
fprintf(stderr, "RAND_poll() failed.\n");
return 1;
}
ssl_ctx = SSL_CTX_new(TLS_method());
}
listener = evconnlistener_new_bind(base, accept_cb, NULL,
LEV_OPT_CLOSE_ON_FREE|LEV_OPT_CLOSE_ON_EXEC|LEV_OPT_REUSEABLE,
-1, (struct sockaddr*)&listen_on_addr, socklen);
if (! listener) {
fprintf(stderr, "Couldn't open listener.\n");
event_base_free(base);
return 1;
}
event_base_dispatch(base);
evconnlistener_free(listener);
event_base_free(base);
#ifdef _WIN32
WSACleanup();
#endif
return 0;
}
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