Commit 4aa69fe0 authored by Geoff Thorpe's avatar Geoff Thorpe
Browse files

Minor tweaks and improvements to the tunala demo. 

- Add "-cipher" and "-out_state" command line arguments to control SSL
  cipher-suites and handshake debug output respectively.

- Implemented error handling for SSL handshakes that break down. This uses
  a cheat - storing a non-NULL pointer as "app_data" in the SSL structure
  when the SSL should be killed.
parent b984cd2b

demos/tunala/Makefile

+3 −2
Original line number Diff line number Diff line
@@ -17,8 +17,8 @@ COMPILE=$(CC) $(CFLAGS) -c 
# Edit, particularly the "-ldl" if not building with "dlfcn" support

LINK_FLAGS=-L$(SSL_LIBDIR) -lssl -lcrypto -ldl



SRCS=buffer.c ip.c sm.c tunala.c

OBJS=buffer.o ip.o sm.o tunala.o

SRCS=buffer.c cb.c ip.c sm.c tunala.c

OBJS=buffer.o cb.o ip.o sm.o tunala.o



TARGETS=tunala
@@ -35,6 +35,7 @@ tunala: $(OBJS) 


# Extra dependencies, should really use makedepend

buffer.o: buffer.c tunala.h

cb.o: cb.c tunala.h

ip.o: ip.c tunala.h

sm.o: sm.c tunala.h

tunala.o: tunala.c tunala.h

demos/tunala/buffer.c

+35 −0
Original line number Diff line number Diff line
@@ -101,6 +101,37 @@ int buffer_to_fd(buffer_t *buf, int fd) 


#ifndef NO_OPENSSL



static void int_ssl_check(SSL *s, int ret)

{

	int e = SSL_get_error(s, ret);

	switch(e) {

		/* These seem to be harmless and already "dealt with" by our

		 * non-blocking environment. NB: "ZERO_RETURN" is the clean

		 * "error" indicating a successfully closed SSL tunnel. We let

		 * this happen because our IO loop should not appear to have

		 * broken on this condition - and outside the IO loop, the

		 * "shutdown" state is checked. */

	case SSL_ERROR_NONE:

	case SSL_ERROR_WANT_READ:

	case SSL_ERROR_WANT_WRITE:

	case SSL_ERROR_WANT_X509_LOOKUP:

	case SSL_ERROR_ZERO_RETURN:

		return;

		/* These seem to be indications of a genuine error that should

		 * result in the SSL tunnel being regarded as "dead". */

	case SSL_ERROR_SYSCALL:

	case SSL_ERROR_SSL:

		SSL_set_app_data(s, (char *)1);

		return;

	default:

		break;

	}

	/* For any other errors that (a) exist, and (b) crop up - we need to

	 * interpret what to do with them - so "politely inform" the caller that

	 * the code needs updating here. */

	abort();

}



void buffer_from_SSL(buffer_t *buf, SSL *ssl)

{

	int ret;
@@ -109,6 +140,8 @@ void buffer_from_SSL(buffer_t *buf, SSL *ssl) 
	ret = SSL_read(ssl, buf->data + buf->used, buffer_unused(buf));

	if(ret > 0)

		buf->used += ret;

	if(ret < 0)

		int_ssl_check(ssl, ret);

}



void buffer_to_SSL(buffer_t *buf, SSL *ssl)
@@ -119,6 +152,8 @@ void buffer_to_SSL(buffer_t *buf, SSL *ssl) 
	ret = SSL_write(ssl, buf->data, buf->used);

	if(ret > 0)

		buffer_takedata(buf, NULL, ret);

	if(ret < 0)

		int_ssl_check(ssl, ret);

}



void buffer_from_BIO(buffer_t *buf, BIO *bio)

demos/tunala/cb.c

0 → 100644
+39 −0
Original line number Diff line number Diff line 
#include "tunala.h"



#ifndef NO_OPENSSL



/* For callbacks generating output, here are their file-descriptors. */

static FILE *fp_cb_ssl_info = NULL;



/* This function is largely borrowed from the one used in OpenSSL's "s_client"

 * and "s_server" utilities. */

void cb_ssl_info(SSL *s, int where, int ret)

{

	char *str1, *str2;

	int w;



	if(!fp_cb_ssl_info)

		return;



	w = where & ~SSL_ST_MASK;

	str1 = (w & SSL_ST_CONNECT ? "SSL_connect" : (w & SSL_ST_ACCEPT ?

				"SSL_accept" : "undefined")),

	str2 = SSL_state_string_long(s);



	if (where & SSL_CB_LOOP)

		fprintf(stderr, "%s:%s\n", str1, str2);

	else if (where & SSL_CB_EXIT) {

		if (ret == 0)

			fprintf(stderr, "%s:failed in %s\n", str1, str2);

		else if (ret < 0)

			fprintf(stderr, "%s:error in %s\n", str1, str2);

	}

}



void cb_ssl_info_set_output(FILE *fp)

{

	fp_cb_ssl_info = fp;

}



#endif /* !defined(NO_OPENSSL) */

demos/tunala/sm.c

+10 −9
Original line number Diff line number Diff line
@@ -55,7 +55,7 @@ SSL *state_machine_get_SSL(state_machine_t *machine) 
	return machine->ssl;

}



void state_machine_set_SSL(state_machine_t *machine, SSL *ssl, int is_server)

int state_machine_set_SSL(state_machine_t *machine, SSL *ssl, int is_server)

{

	if(machine->ssl)

		/* Shouldn't ever be set twice */
@@ -75,7 +75,7 @@ void state_machine_set_SSL(state_machine_t *machine, SSL *ssl, int is_server) 
	/* If we're the first one to generate traffic - do it now otherwise we

	 * go into the next select empty-handed and our peer will not send data

	 * but will similarly wait for us. */

	state_machine_churn(machine);

	return state_machine_churn(machine);

}



/* Performs the data-IO loop and returns zero if the machine should close */
@@ -98,14 +98,15 @@ int state_machine_churn(state_machine_t *machine) 
			/* Still buffered data on the clean side to go out */

			return 1;

	}

	if(SSL_get_shutdown(machine->ssl)) {

		/* An SSL shutdown was underway */

		if(buffer_empty(&machine->dirty_out)) {

	/* We close on the SSL side if the info callback noticed some problems

	 * or an SSL shutdown was underway and shutdown traffic had all been

	 * sent. */

	if(SSL_get_app_data(machine->ssl) || (SSL_get_shutdown(machine->ssl) &&

				buffer_empty(&machine->dirty_out))) {

		/* Great, we can seal off the dirty side completely */

		if(!state_machine_close_dirty(machine))

			return 0;

	}

	}

	/* Either the SSL is alive and well, or the closing process still has

	 * outgoing data waiting to be sent */

	return 1;

demos/tunala/tunala.c

+52 −11
Original line number Diff line number Diff line
@@ -67,7 +67,8 @@ typedef struct _tunala_world_t { 
/*****************************/



static SSL_CTX *initialise_ssl_ctx(int server_mode, const char *engine_id,

		const char *CAfile, const char *cert, const char *key);

		const char *CAfile, const char *cert, const char *key,

		const char *cipher_list, int out_state);

static void selector_init(tunala_selector_t *selector);

static void selector_add_listener(tunala_selector_t *selector, int fd);

static void selector_add_tunala(tunala_selector_t *selector, tunala_item_t *t);
@@ -92,6 +93,8 @@ static const char *def_cert = NULL; 
static const char *def_key = NULL;

static const char *def_engine_id = NULL;

static int def_server_mode = 0;

static const char *def_cipher_list = NULL;

static int def_out_state = 0;



static const char *helpstring =

	"\n'Tunala' (A tunneler with a New Zealand accent)\n"
@@ -104,6 +107,8 @@ static const char *helpstring = 
	"    -key <path|NULL>       (default = whatever '-cert' is)\n"

	"    -engine <id|NULL>      (default = NULL)\n"

	"    -server <0|1>          (default = 0, ie. an SSL client)\n"

	"    -cipher <list>         (specifies cipher list to use)\n"

	"    -out_state             (prints SSL handshake states)\n"

	"    -<h|help|?>            (displays this help screen)\n"

	"NB: It is recommended to specify a cert+key when operating as an\n"

	"SSL server. If you only specify '-cert', the same file must\n"
@@ -178,6 +183,8 @@ int main(int argc, char *argv[]) 
	const char *key = def_key;

	const char *engine_id = def_engine_id;

	int server_mode = def_server_mode;

	const char *cipher_list = def_cipher_list;

	int out_state = def_out_state;



/* Parse command-line arguments */

next_arg:
@@ -242,6 +249,15 @@ next_arg: 
			if(!parse_server_mode(*argv, &server_mode))

				return 1;

			goto next_arg;

		} else if(strcmp(*argv, "-cipher") == 0) {

			if(argc < 2)

				return usage("-cipher requires an argument", 0);

			argc--; argv++;

			cipher_list = *argv;

			goto next_arg;

		} else if(strcmp(*argv, "-out_state") == 0) {

			out_state = 1;

			goto next_arg;

		} else if((strcmp(*argv, "-h") == 0) ||

				(strcmp(*argv, "-help") == 0) ||

				(strcmp(*argv, "-?") == 0)) {
@@ -257,7 +273,7 @@ next_arg: 
	err_str0("ip_initialise succeeded");

	/* Create the SSL_CTX */

	if((world.ssl_ctx = initialise_ssl_ctx(server_mode, engine_id,

			cacert, cert, key)) == NULL)

			cacert, cert, key, cipher_list, out_state)) == NULL)

		return err_str1("initialise_ssl_ctx(engine_id=%s) failed",

			(engine_id == NULL) ? "NULL" : engine_id);

	err_str1("initialise_ssl_ctx(engine_id=%s) succeeded",
@@ -306,12 +322,11 @@ main_loop: 
					&newfd) == 1)) {

		/* We have a new connection */

		if(!tunala_world_new_item(&world, newfd,

					proxy_ip, proxy_port)) {

					proxy_ip, proxy_port))

			fprintf(stderr, "tunala_world_new_item failed\n");

			abort();

		}

		fprintf(stderr, "Info, new tunnel opened, now up to %d\n",

				world.tunnels_used);

		else

			fprintf(stderr, "Info, new tunnel opened, now up to "

					"%d\n", world.tunnels_used);

	}

	/* Give each tunnel its moment, note the while loop is because it makes

	 * the logic easier than with "for" to deal with an array that may shift
@@ -344,7 +359,8 @@ main_loop: 
/****************/



static SSL_CTX *initialise_ssl_ctx(int server_mode, const char *engine_id,

		const char *CAfile, const char *cert, const char *key)

		const char *CAfile, const char *cert, const char *key,

		const char *cipher_list, int out_state)

{

	SSL_CTX *ctx, *ret = NULL;

	SSL_METHOD *meth;
@@ -439,6 +455,23 @@ static SSL_CTX *initialise_ssl_ctx(int server_mode, const char *engine_id, 
	} else

		fprintf(stderr, "Info, operating without a cert or key\n");



	/* cipher_list */

	if(cipher_list) {

		if(!SSL_CTX_set_cipher_list(ctx, cipher_list)) {

			fprintf(stderr, "Error setting cipher list '%s'\n",

					cipher_list);

			goto err;

		}

		fprintf(stderr, "Info, set cipher list '%s'\n", cipher_list);

	} else

		fprintf(stderr, "Info, operating with default cipher list\n");



	/* out_state (output of SSL handshake states to screen). */

	if(out_state) {

		SSL_CTX_set_info_callback(ctx, cb_ssl_info);

		cb_ssl_info_set_output(stderr);

	}



	/* Success! */

	ret = ctx;

err:
@@ -577,9 +610,15 @@ static int tunala_world_new_item(tunala_world_t *world, int fd, 
{

	tunala_item_t *item;

	int newfd;

	SSL *new_ssl = NULL;



	if(!tunala_world_make_room(world))

		return 0;

	if((new_ssl = SSL_new(world->ssl_ctx)) == NULL) {

		fprintf(stderr, "Error creating new SSL\n");

		ERR_print_errors_fp(stderr);

		return 0;

	}

	item = world->tunnels + (world->tunnels_used++);

	state_machine_init(&item->sm);

	item->clean_read = item->clean_send =
@@ -596,11 +635,13 @@ static int tunala_world_new_item(tunala_world_t *world, int fd, 
		item->clean_read = item->clean_send = fd;

		item->dirty_read = item->dirty_send = newfd;

	}

	state_machine_set_SSL(&item->sm, SSL_new(world->ssl_ctx),

			world->server_mode);

	/* We use the SSL's "app_data" to indicate a call-back induced "kill" */

	SSL_set_app_data(new_ssl, NULL);

	if(!state_machine_set_SSL(&item->sm, new_ssl, world->server_mode))

		goto err;

	return 1;

err:

	state_machine_close(&item->sm);

	tunala_world_del_item(world, world->tunnels_used - 1);

	return 0;



}