This change was a quick experiment that I'd wanted to try that works quite
[openssl.git] / demos / tunala / tunala.c
index 594f00a..dbf155c 100644 (file)
@@ -69,6 +69,7 @@ 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 *dcert, const char *dkey, const char *cipher_list,
+               const char *dh_file, const char *dh_special, int ctx_options,
                int out_state, int out_verify, int verify_mode,
                unsigned int verify_depth);
 static void selector_init(tunala_selector_t *selector);
@@ -79,7 +80,7 @@ static int selector_select(tunala_selector_t *selector);
  * which case *newfd is populated. */
 static int selector_get_listener(tunala_selector_t *selector, int fd, int *newfd);
 static int tunala_world_new_item(tunala_world_t *world, int fd,
-               const unsigned char *ip, unsigned short port);
+               const unsigned char *ip, unsigned short port, int flipped);
 static void tunala_world_del_item(tunala_world_t *world, unsigned int idx);
 static int tunala_item_io(tunala_selector_t *selector, tunala_item_t *item);
 
@@ -97,12 +98,16 @@ static const char *def_dcert = NULL;
 static const char *def_dkey = NULL;
 static const char *def_engine_id = NULL;
 static int def_server_mode = 0;
+static int def_flipped = 0;
 static const char *def_cipher_list = NULL;
+static const char *def_dh_file = NULL;
+static const char *def_dh_special = NULL;
+static int def_ctx_options = 0;
+static int def_verify_mode = 0;
+static unsigned int def_verify_depth = 10;
 static int def_out_state = 0;
 static unsigned int def_out_verify = 0;
 static int def_out_totals = 0;
-static int def_verify_mode = 0;
-static unsigned int def_verify_depth = 10;
 
 static const char *helpstring =
 "\n'Tunala' (A tunneler with a New Zealand accent)\n"
@@ -117,19 +122,77 @@ static const char *helpstring =
 " -dkey <path|NULL>      (usually for DSA, default = whatever '-dcert' is)\n"
 " -engine <id|NULL>      (default = NULL)\n"
 " -server <0|1>          (default = 0, ie. an SSL client)\n"
+" -flipped <0|1>         (makes SSL servers be network clients, and vice versa)\n"
 " -cipher <list>         (specifies cipher list to use)\n"
-" -out_state             (prints SSL handshake states)\n"
-" -out_verify <0|1|2|3>  (prints certificate verification states: def=1)\n"
-" -out_totals            (prints out byte-totals when a tunnel closes)\n"
+" -dh_file <path>        (a PEM file containing DH parameters to use)\n"
+" -dh_special <NULL|generate|standard> (see below: def=NULL)\n"
+" -no_ssl2               (disable SSLv2)\n"
+" -no_ssl3               (disable SSLv3)\n"
+" -no_tls1               (disable TLSv1)\n"
 " -v_peer                (verify the peer certificate)\n"
 " -v_strict              (do not continue if peer doesn't authenticate)\n"
 " -v_once                (no verification in renegotiates)\n"
 " -v_depth <num>         (limit certificate chain depth, default = 10)\n"
+" -out_state             (prints SSL handshake states)\n"
+" -out_verify <0|1|2|3>  (prints certificate verification states: def=1)\n"
+" -out_totals            (prints out byte-totals when a tunnel closes)\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"
-"contain a matching private key.\n";
+"Notes:\n"
+"(1) It is recommended to specify a cert+key when operating as an SSL server.\n"
+"    If you only specify '-cert', the same file must contain a matching\n"
+"    private key.\n"
+"(2) Either dh_file or dh_special can be used to specify where DH parameters\n"
+"    will be obtained from (or '-dh_special NULL' for the default choice) but\n"
+"    you cannot specify both. For dh_special, 'generate' will create new DH\n"
+"    parameters on startup, and 'standard' will use embedded parameters\n"
+"    instead.\n"
+"(3) Normally an ssl client connects to an ssl server - so that an 'ssl client\n"
+"    tunala' listens for 'clean' client connections and proxies ssl, and an\n"
+"    'ssl server tunala' listens for ssl connections and proxies 'clean'. With\n"
+"    '-flipped 1', this behaviour is reversed so that an 'ssl server tunala'\n"
+"    listens for clean client connections and proxies ssl (but participating\n"
+"    as an ssl *server* in the SSL/TLS protocol), and an 'ssl client tunala'\n"
+"    listens for ssl connections (participating as an ssl *client* in the\n"
+"    SSL/TLS protocol) and proxies 'clean' to the end destination. This can\n"
+"    be useful for allowing network access to 'servers' where only the server\n"
+"    needs to authenticate the client (ie. the other way is not required).\n"
+"    Even with client and server authentication, this 'technique' mitigates\n"
+"    some DoS (denial-of-service) potential as it will be the network client\n"
+"    having to perform the first private key operation rather than the other\n"
+"    way round.\n"
+"(4) The 'technique' used by setting '-flipped 1' is probably compatible with\n"
+"    absolutely nothing except another complimentary instance of 'tunala'\n"
+"    running with '-flipped 1'. :-)\n";
+
+/* Default DH parameters for use with "-dh_special standard" ... stolen striaght
+ * from s_server. */
+static unsigned char dh512_p[]={
+       0xDA,0x58,0x3C,0x16,0xD9,0x85,0x22,0x89,0xD0,0xE4,0xAF,0x75,
+       0x6F,0x4C,0xCA,0x92,0xDD,0x4B,0xE5,0x33,0xB8,0x04,0xFB,0x0F,
+       0xED,0x94,0xEF,0x9C,0x8A,0x44,0x03,0xED,0x57,0x46,0x50,0xD3,
+       0x69,0x99,0xDB,0x29,0xD7,0x76,0x27,0x6B,0xA2,0xD3,0xD4,0x12,
+       0xE2,0x18,0xF4,0xDD,0x1E,0x08,0x4C,0xF6,0xD8,0x00,0x3E,0x7C,
+       0x47,0x74,0xE8,0x33,
+       };
+static unsigned char dh512_g[]={
+       0x02,
+       };
+
+/* And the function that parses the above "standard" parameters, again, straight
+ * out of s_server. */
+static DH *get_dh512(void)
+       {
+       DH *dh=NULL;
+
+       if ((dh=DH_new()) == NULL) return(NULL);
+       dh->p=BN_bin2bn(dh512_p,sizeof(dh512_p),NULL);
+       dh->g=BN_bin2bn(dh512_g,sizeof(dh512_g),NULL);
+       if ((dh->p == NULL) || (dh->g == NULL))
+               return(NULL);
+       return(dh);
+       }
 
+/* Various help/error messages used by main() */
 static int usage(const char *errstr, int isunknownarg)
 {
        if(isunknownarg)
@@ -142,14 +205,13 @@ static int usage(const char *errstr, int isunknownarg)
 
 static int err_str0(const char *str0)
 {
-       fprintf(stderr, str0);
-       fprintf(stderr, "\n");
+       fprintf(stderr, "%s\n", str0);
        return 1;
 }
 
-static int err_str1(const char *str0, const char *str1)
+static int err_str1(const char *fmt, const char *str1)
 {
-       fprintf(stderr, str0, str1);
+       fprintf(stderr, fmt, str1);
        fprintf(stderr, "\n");
        return 1;
 }
@@ -182,6 +244,17 @@ static int parse_server_mode(const char *s, int *servermode)
        return 1;
 }
 
+static int parse_dh_special(const char *s, const char **dh_special)
+{
+       if((strcmp(s, "NULL") == 0) || (strcmp(s, "generate") == 0) ||
+                       (strcmp(s, "standard") == 0)) {
+               *dh_special = s;
+               return 1;
+       }
+       fprintf(stderr, "Error, '%s' is an invalid value for 'dh_special'\n", s);
+       return 0;
+}
+
 static int parse_verify_level(const char *s, unsigned int *verify_level)
 {
        unsigned long l;
@@ -239,12 +312,16 @@ int main(int argc, char *argv[])
        const char *dkey = def_dkey;
        const char *engine_id = def_engine_id;
        int server_mode = def_server_mode;
+       int flipped = def_flipped;
        const char *cipher_list = def_cipher_list;
+       const char *dh_file = def_dh_file;
+       const char *dh_special = def_dh_special;
+       int ctx_options = def_ctx_options;
+       int verify_mode = def_verify_mode;
+       unsigned int verify_depth = def_verify_depth;
        int out_state = def_out_state;
        unsigned int out_verify = def_out_verify;
        int out_totals = def_out_totals;
-       int verify_mode = def_verify_mode;
-       unsigned int verify_depth = def_verify_depth;
 
 /* Parse command-line arguments */
 next_arg:
@@ -327,24 +404,46 @@ next_arg:
                        if(!parse_server_mode(*argv, &server_mode))
                                return 1;
                        goto next_arg;
+               } else if(strcmp(*argv, "-flipped") == 0) {
+                       if(argc < 2)
+                               return usage("-flipped requires an argument", 0);
+                       argc--; argv++;
+                       if(!parse_server_mode(*argv, &flipped))
+                               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;
+               } else if(strcmp(*argv, "-dh_file") == 0) {
+                       if(argc < 2)
+                               return usage("-dh_file requires an argument", 0);
+                       if(dh_special)
+                               return usage("cannot mix -dh_file with "
+                                               "-dh_special", 0);
+                       argc--; argv++;
+                       dh_file = *argv;
                        goto next_arg;
-               } else if(strcmp(*argv, "-out_verify") == 0) {
+               } else if(strcmp(*argv, "-dh_special") == 0) {
                        if(argc < 2)
-                               return usage("-out_verify requires an argument", 0);
+                               return usage("-dh_special requires an argument", 0);
+                       if(dh_file)
+                               return usage("cannot mix -dh_file with "
+                                               "-dh_special", 0);
                        argc--; argv++;
-                       if(!parse_verify_level(*argv, &out_verify))
+                       if(!parse_dh_special(*argv, &dh_special))
                                return 1;
                        goto next_arg;
-               } else if(strcmp(*argv, "-out_totals") == 0) {
-                       out_totals = 1;
+               } else if(strcmp(*argv, "-no_ssl2") == 0) {
+                       ctx_options |= SSL_OP_NO_SSLv2;
+                       goto next_arg;
+               } else if(strcmp(*argv, "-no_ssl3") == 0) {
+                       ctx_options |= SSL_OP_NO_SSLv3;
+                       goto next_arg;
+               } else if(strcmp(*argv, "-no_tls1") == 0) {
+                       ctx_options |= SSL_OP_NO_TLSv1;
                        goto next_arg;
                } else if(strcmp(*argv, "-v_peer") == 0) {
                        verify_mode |= SSL_VERIFY_PEER;
@@ -362,6 +461,19 @@ next_arg:
                        if(!parse_verify_depth(*argv, &verify_depth))
                                return 1;
                        goto next_arg;
+               } else if(strcmp(*argv, "-out_state") == 0) {
+                       out_state = 1;
+                       goto next_arg;
+               } else if(strcmp(*argv, "-out_verify") == 0) {
+                       if(argc < 2)
+                               return usage("-out_verify requires an argument", 0);
+                       argc--; argv++;
+                       if(!parse_verify_level(*argv, &out_verify))
+                               return 1;
+                       goto next_arg;
+               } else if(strcmp(*argv, "-out_totals") == 0) {
+                       out_totals = 1;
+                       goto next_arg;
                } else if((strcmp(*argv, "-h") == 0) ||
                                (strcmp(*argv, "-help") == 0) ||
                                (strcmp(*argv, "-?") == 0)) {
@@ -377,8 +489,9 @@ 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, dcert, dkey, cipher_list, out_state,
-                       out_verify, verify_mode, verify_depth)) == NULL)
+                       cacert, cert, key, dcert, dkey, cipher_list, dh_file,
+                       dh_special, ctx_options, out_state, out_verify,
+                       verify_mode, verify_depth)) == 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",
@@ -426,8 +539,8 @@ main_loop:
                                        &world.selector, world.listen_fd,
                                        &newfd) == 1)) {
                /* We have a new connection */
-               if(!tunala_world_new_item(&world, newfd,
-                                       proxy_ip, proxy_port))
+               if(!tunala_world_new_item(&world, newfd, proxy_ip,
+                                               proxy_port, flipped))
                        fprintf(stderr, "tunala_world_new_item failed\n");
                else
                        fprintf(stderr, "Info, new tunnel opened, now up to "
@@ -554,9 +667,61 @@ static int ctx_set_cert(SSL_CTX *ctx, const char *cert, const char *key)
        return toret;
 }
 
+static int ctx_set_dh(SSL_CTX *ctx, const char *dh_file, const char *dh_special)
+{
+       DH *dh = NULL;
+       FILE *fp = NULL;
+
+       if(dh_special) {
+               if(strcmp(dh_special, "NULL") == 0)
+                       return 1;
+               if(strcmp(dh_special, "standard") == 0) {
+                       if((dh = get_dh512()) == NULL) {
+                               fprintf(stderr, "Error, can't parse 'standard'"
+                                               " DH parameters\n");
+                               return 0;
+                       }
+                       fprintf(stderr, "Info, using 'standard' DH parameters\n");
+                       goto do_it;
+               }
+               if(strcmp(dh_special, "generate") != 0)
+                       /* This shouldn't happen - screening values is handled
+                        * in main(). */
+                       abort();
+               fprintf(stderr, "Info, generating DH parameters ... ");
+               fflush(stderr);
+               if((dh = DH_generate_parameters(512, DH_GENERATOR_5,
+                                       NULL, NULL)) == NULL) {
+                       fprintf(stderr, "error!\n");
+                       return 0;
+               }
+               fprintf(stderr, "complete\n");
+               goto do_it;
+       }
+       /* So, we're loading dh_file */
+       if((fp = fopen(dh_file, "r")) == NULL) {
+               fprintf(stderr, "Error, couldn't open '%s' for DH parameters\n",
+                               dh_file);
+               return 0;
+       }
+       dh = PEM_read_DHparams(fp, NULL, NULL, NULL);
+       fclose(fp);
+       if(dh == NULL) {
+               fprintf(stderr, "Error, could not parse DH parameters from '%s'\n",
+                               dh_file);
+               return 0;
+       }
+       fprintf(stderr, "Info, using DH parameters from file '%s'\n", dh_file);
+do_it:
+       SSL_CTX_set_tmp_dh(ctx, dh);
+       DH_free(dh);
+       return 1;
+}
+
 static SSL_CTX *initialise_ssl_ctx(int server_mode, const char *engine_id,
                const char *CAfile, const char *cert, const char *key,
                const char *dcert, const char *dkey, const char *cipher_list,
+               const char *dh_file, const char *dh_special, int ctx_options,
                int out_state, int out_verify, int verify_mode,
                unsigned int verify_depth)
 {
@@ -620,6 +785,13 @@ static SSL_CTX *initialise_ssl_ctx(int server_mode, const char *engine_id,
        } else
                fprintf(stderr, "Info, operating with default cipher list\n");
 
+       /* dh_file & dh_special */
+       if((dh_file || dh_special) && !ctx_set_dh(ctx, dh_file, dh_special))
+               goto err;
+
+       /* ctx_options */
+       SSL_CTX_set_options(ctx, ctx_options);
+
        /* out_state (output of SSL handshake states to screen). */
        if(out_state)
                cb_ssl_info_set_output(stderr);
@@ -763,7 +935,7 @@ static int tunala_world_make_room(tunala_world_t *world)
 }
 
 static int tunala_world_new_item(tunala_world_t *world, int fd,
-               const unsigned char *ip, unsigned short port)
+               const unsigned char *ip, unsigned short port, int flipped)
 {
        tunala_item_t *item;
        int newfd;
@@ -784,8 +956,10 @@ static int tunala_world_new_item(tunala_world_t *world, int fd,
                goto err;
        /* Which way round? If we're a server, "fd" is the dirty side and the
         * connection we open is the clean one. For a client, it's the other way
-        * around. */
-       if(world->server_mode) {
+        * around. Unless, of course, we're "flipped" in which case everything
+        * gets reversed. :-) */
+       if((world->server_mode && !flipped) ||
+                       (!world->server_mode && flipped)) {
                item->dirty_read = item->dirty_send = fd;
                item->clean_read = item->clean_send = newfd;
        } else {