source: lib/ssl_openssl.c

/********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2012 Wilmer van der Gaast and others                *
  \********************************************************************/

/* SSL module - OpenSSL version                                         */

/*
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 51 Franklin St.,
  Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <openssl/crypto.h>
#include <openssl/rand.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

#include "bitlbee.h"
#include "proxy.h"
#include "ssl_client.h"
#include "sock.h"

int ssl_errno = 0;

static gboolean initialized = FALSE;

struct scd {
        ssl_input_function func;
        gpointer data;
        int fd;
        gboolean established;
        gboolean verify;
        char *hostname;

        int inpa;
        int lasterr;            /* Necessary for SSL_get_error */
        SSL *ssl;
};

static SSL_CTX *ssl_ctx;

static void ssl_conn_free(struct scd *conn);
static gboolean ssl_connected(gpointer data, gint source, b_input_condition cond);
static gboolean ssl_starttls_real(gpointer data, gint source, b_input_condition cond);
static gboolean ssl_handshake(gpointer data, gint source, b_input_condition cond);


void ssl_init(void)
{
        const SSL_METHOD *meth;

#if OPENSSL_VERSION_NUMBER < 0x10100000L
        SSL_library_init();

        meth = SSLv23_client_method();
        ssl_ctx = SSL_CTX_new(meth);
        SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
#else
        meth = TLS_client_method();
        ssl_ctx = SSL_CTX_new(meth);
        SSL_CTX_set_min_proto_version(ssl_ctx, TLS1_VERSION);
#endif

        initialized = TRUE;
}

void *ssl_connect(char *host, int port, gboolean verify, ssl_input_function func, gpointer data)
{
        struct scd *conn = g_new0(struct scd, 1);

        conn->fd = proxy_connect(host, port, ssl_connected, conn);
        if (conn->fd < 0) {
                ssl_conn_free(conn);
                return NULL;
        }

        conn->func = func;
        conn->data = data;
        conn->inpa = -1;
        conn->hostname = g_strdup(host);

        return conn;
}

void *ssl_starttls(int fd, char *hostname, gboolean verify, ssl_input_function func, gpointer data)
{
        struct scd *conn = g_new0(struct scd, 1);

        conn->fd = fd;
        conn->func = func;
        conn->data = data;
        conn->inpa = -1;
        conn->verify = verify && global.conf->cafile;
        conn->hostname = g_strdup(hostname);

        /* This function should be called via a (short) timeout instead of
           directly from here, because these SSL calls are *supposed* to be
           *completely* asynchronous and not ready yet when this function
           (or *_connect, for examle) returns. Also, errors are reported via
           the callback function, not via this function's return value.

           In short, doing things like this makes the rest of the code a lot
           simpler. */

        b_timeout_add(1, ssl_starttls_real, conn);

        return conn;
}

static gboolean ssl_starttls_real(gpointer data, gint source, b_input_condition cond)
{
        struct scd *conn = data;

        return ssl_connected(conn, conn->fd, B_EV_IO_WRITE);
}

static gboolean ssl_connected(gpointer data, gint source, b_input_condition cond)
{
        struct scd *conn = data;

        if (conn->verify) {
                /* Right now we don't have any verification functionality for OpenSSL. */
                conn->func(conn->data, 1, NULL, cond);
                if (source >= 0) {
                        proxy_disconnect(source);
                }
                ssl_conn_free(conn);

                return FALSE;
        }

        if (source == -1) {
                goto ssl_connected_failure;
        }

        if (!initialized) {
                ssl_init();
        }


        if (ssl_ctx == NULL) {
                goto ssl_connected_failure;
        }

        conn->ssl = SSL_new(ssl_ctx);
        if (conn->ssl == NULL) {
                goto ssl_connected_failure;
        }

        /* We can do at least the handshake with non-blocking I/O */
        sock_make_nonblocking(conn->fd);
        SSL_set_fd(conn->ssl, conn->fd);

        if (conn->hostname && !g_hostname_is_ip_address(conn->hostname)) {
                SSL_set_tlsext_host_name(conn->ssl, conn->hostname);
        }

        return ssl_handshake(data, source, cond);

ssl_connected_failure:
        conn->func(conn->data, 0, NULL, cond);
        ssl_disconnect(conn);
        return FALSE;

}

static gboolean ssl_handshake(gpointer data, gint source, b_input_condition cond)
{
        struct scd *conn = data;
        int st;

        if ((st = SSL_connect(conn->ssl)) < 0) {
                conn->lasterr = SSL_get_error(conn->ssl, st);
                if (conn->lasterr != SSL_ERROR_WANT_READ && conn->lasterr != SSL_ERROR_WANT_WRITE) {
                        conn->func(conn->data, 0, NULL, cond);
                        ssl_disconnect(conn);
                        return FALSE;
                }

                conn->inpa = b_input_add(conn->fd, ssl_getdirection(conn), ssl_handshake, data);
                return FALSE;
        }

        conn->established = TRUE;
        sock_make_blocking(conn->fd);           /* For now... */
        conn->func(conn->data, 0, conn, cond);
        return FALSE;
}

int ssl_read(void *conn, char *buf, int len)
{
        int st;

        if (!((struct scd*) conn)->established) {
                ssl_errno = SSL_NOHANDSHAKE;
                return -1;
        }

        st = SSL_read(((struct scd*) conn)->ssl, buf, len);

        ssl_errno = SSL_OK;
        if (st <= 0) {
                ((struct scd*) conn)->lasterr = SSL_get_error(((struct scd*) conn)->ssl, st);
                if (((struct scd*) conn)->lasterr == SSL_ERROR_WANT_READ || ((struct scd*) conn)->lasterr ==
                    SSL_ERROR_WANT_WRITE) {
                        ssl_errno = SSL_AGAIN;
                }
        }

        if (0 && getenv("BITLBEE_DEBUG") && st > 0) {
                write(1, buf, st);
        }

        return st;
}

int ssl_write(void *conn, const char *buf, int len)
{
        int st;

        if (!((struct scd*) conn)->established) {
                ssl_errno = SSL_NOHANDSHAKE;
                return -1;
        }

        st = SSL_write(((struct scd*) conn)->ssl, buf, len);

        if (0 && getenv("BITLBEE_DEBUG") && st > 0) {
                write(1, buf, st);
        }

        ssl_errno = SSL_OK;
        if (st <= 0) {
                ((struct scd*) conn)->lasterr = SSL_get_error(((struct scd*) conn)->ssl, st);
                if (((struct scd*) conn)->lasterr == SSL_ERROR_WANT_READ || ((struct scd*) conn)->lasterr ==
                    SSL_ERROR_WANT_WRITE) {
                        ssl_errno = SSL_AGAIN;
                }
        }

        return st;
}

int ssl_pending(void *conn)
{
        return (((struct scd*) conn) && ((struct scd*) conn)->established) ?
               SSL_pending(((struct scd*) conn)->ssl) > 0 : 0;
}

static void ssl_conn_free(struct scd *conn)
{
        SSL_free(conn->ssl);
        g_free(conn->hostname);
        g_free(conn);

}

void ssl_disconnect(void *conn_)
{
        struct scd *conn = conn_;

        if (conn->inpa != -1) {
                b_event_remove(conn->inpa);
        }

        if (conn->established) {
                SSL_shutdown(conn->ssl);
        }

        proxy_disconnect(conn->fd);

        ssl_conn_free(conn);
}

int ssl_getfd(void *conn)
{
        return(((struct scd*) conn)->fd);
}

b_input_condition ssl_getdirection(void *conn)
{
        return(((struct scd*) conn)->lasterr == SSL_ERROR_WANT_WRITE ? B_EV_IO_WRITE : B_EV_IO_READ);
}

char *ssl_verify_strerror(int code)
{
        return g_strdup("SSL certificate verification not supported by BitlBee OpenSSL code.");
}

size_t ssl_des3_encrypt(const unsigned char *key, size_t key_len, const unsigned char *input, size_t input_len,
                        const unsigned char *iv, unsigned char **res)
{
        int output_length = 0;
        EVP_CIPHER_CTX *ctx;

        *res = g_new0(unsigned char, 72);

        /* Don't set key or IV because we will modify the parameters */
        ctx = EVP_CIPHER_CTX_new();
        EVP_CipherInit_ex(ctx, EVP_des_ede3_cbc(), NULL, NULL, NULL, 1);
        EVP_CIPHER_CTX_set_key_length(ctx, key_len);
        EVP_CIPHER_CTX_set_padding(ctx, 0);
        /* We finished modifying parameters so now we can set key and IV */
        EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, 1);
        EVP_CipherUpdate(ctx, *res, &output_length, input, input_len);
        EVP_CipherFinal_ex(ctx, *res, &output_length);
        EVP_CIPHER_CTX_free(ctx);
        //EVP_cleanup();

        return output_length;
}