le-proxy.c

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Author : Nick Mathewson
Date : 2009-10-30 21:08:29
Hash : 516452b7
Message : Keep openssl errors associated with the right bufferevent object. OpenSSL has a per-thread error stack, and really doesn't like you leaving errors on the stack. Rather than discard the errors or force the user to handle them, this patch pulls them off the openssl stack and puts them on a stack associated with the bufferevent_openssl. If the user leaves them on the stack then, it won't affect any other connections. This bug was found by Roman Puls. Thanks! svn:r1481
sample/le-proxy.c
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include <sys/socket.h>
#include <netinet/in.h>

#include <event2/bufferevent_ssl.h>
#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>

#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/rand.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);
		}
		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;

	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;
		SSL_library_init();
		ERR_load_crypto_strings();
		SSL_load_error_strings();
		OpenSSL_add_all_algorithms();
		r = RAND_poll();
		if (r == 0) {
			fprintf(stderr, "RAND_poll() failed.\n");
			return 1;
		}
		ssl_ctx = SSL_CTX_new(SSLv23_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);

	event_base_dispatch(base);

	return 0;
}
kc3-lang/libevent/sample/le-proxy.c

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kc3-lang/libevent /sample/le-proxy.c
