244 lines
8.9 KiB
C
244 lines
8.9 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 1999 - 2006, Digium, Inc.
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*
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* Mark Spencer <markster@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*!
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* \file
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*
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* \brief Generic support for tcp/tls servers in Asterisk.
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*
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* \note In order to have TLS/SSL support, we need the openssl libraries.
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* Still we can decide whether or not to use them by commenting
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* in or out the DO_SSL macro.
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*
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* TLS/SSL support is basically implemented by reading from a config file
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* (currently manager.conf, http.conf and pjsip.conf) the names of the certificate
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* files and cipher to use, and then run ssl_setup() to create an appropriate
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* data structure named ssl_ctx.
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*
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* If we support multiple domains, presumably we need to read multiple
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* certificates.
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*
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* When we are requested to open a TLS socket, we run make_file_from_fd()
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* on the socket, to do the necessary setup. At the moment the context's name
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* is hardwired in the function, but we can certainly make it into an extra
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* parameter to the function.
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*
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* We declare most of ssl support variables unconditionally,
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* because their number is small and this simplifies the code.
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*
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* \note The ssl-support variables (ssl_ctx, do_ssl, certfile, cipher)
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* and their setup should be moved to a more central place, e.g. asterisk.conf
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* and the source files that processes it. Similarly, ssl_setup() should
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* be run earlier in the startup process so modules have it available.
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*
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* \ref AstTlsOverview
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*/
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#ifndef _ASTERISK_TCPTLS_H
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#define _ASTERISK_TCPTLS_H
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#include <pthread.h> /* for pthread_t */
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#include <sys/param.h> /* for MAXHOSTNAMELEN */
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#include "asterisk/iostream.h"
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#include "asterisk/netsock2.h" /* for ast_sockaddr */
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#include "asterisk/utils.h" /* for ast_flags */
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/*! SSL support */
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#define AST_CERTFILE "asterisk.pem"
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enum ast_ssl_flags {
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/*! Verify certificate when acting as server */
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AST_SSL_VERIFY_CLIENT = (1 << 0),
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/*! Don't verify certificate when connecting to a server */
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AST_SSL_DONT_VERIFY_SERVER = (1 << 1),
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/*! Don't compare "Common Name" against IP or hostname */
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AST_SSL_IGNORE_COMMON_NAME = (1 << 2),
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/*! Use SSLv2 for outgoing client connections */
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AST_SSL_SSLV2_CLIENT = (1 << 3),
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/*! Use SSLv3 for outgoing client connections */
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AST_SSL_SSLV3_CLIENT = (1 << 4),
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/*! Use TLSv1 for outgoing client connections */
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AST_SSL_TLSV1_CLIENT = (1 << 5),
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/*! Use server cipher order instead of the client order */
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AST_SSL_SERVER_CIPHER_ORDER = (1 << 6),
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/*! Disable TLSv1 support */
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AST_SSL_DISABLE_TLSV1 = (1 << 7),
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/*! Disable TLSv1.1 support */
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AST_SSL_DISABLE_TLSV11 = (1 << 8),
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/*! Disable TLSv1.2 support */
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AST_SSL_DISABLE_TLSV12 = (1 << 9),
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};
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struct ast_tls_config {
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int enabled;
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char *certfile;
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char *pvtfile;
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char *cipher;
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char *cafile;
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char *capath;
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struct ast_flags flags;
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SSL_CTX *ssl_ctx;
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char certhash[41];
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char pvthash[41];
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char cahash[41];
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};
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/*! \page AstTlsOverview TLS Implementation Overview
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*
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* The following code implements a generic mechanism for starting
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* services on a TCP or TLS socket.
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* The service is configured in the struct session_args, and
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* then started by calling server_start(desc) on the descriptor.
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* server_start() first verifies if an instance of the service is active,
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* and in case shuts it down. Then, if the service must be started, creates
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* a socket and a thread in charge of doing the accept().
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*
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* The body of the thread is desc->accept_fn(desc), which the user can define
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* freely. We supply a sample implementation, server_root(), structured as an
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* infinite loop. At the beginning of each iteration it runs periodic_fn()
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* if defined (e.g. to perform some cleanup etc.) then issues a poll()
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* or equivalent with a timeout of 'poll_timeout' milliseconds, and if the
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* following accept() is successful it creates a thread in charge of
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* running the session, whose body is desc->worker_fn(). The argument of
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* worker_fn() is a struct ast_tcptls_session_instance, which contains the address
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* of the other party, a pointer to desc, the file descriptors (fd) on which
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* we can do a select/poll (but NOT I/O), and a FILE *on which we can do I/O.
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* We have both because we want to support plain and SSL sockets, and
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* going through a FILE * lets us provide the encryption/decryption
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* on the stream without using an auxiliary thread.
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*/
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/*! \brief
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* arguments for the accepting thread
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*/
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struct ast_tcptls_session_args {
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struct ast_sockaddr local_address;
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struct ast_sockaddr old_address; /*!< copy of the local or remote address depending on if its a client or server session */
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struct ast_sockaddr remote_address;
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char hostname[MAXHOSTNAMELEN]; /*!< only necessary for SSL clients so we can compare to common name */
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struct ast_tls_config *tls_cfg; /*!< points to the SSL configuration if any */
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int accept_fd;
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int poll_timeout;
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/*! Server accept_fn thread ID used for external shutdown requests. */
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pthread_t master;
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void *(*accept_fn)(void *); /*!< the function in charge of doing the accept */
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void (*periodic_fn)(void *);/*!< something we may want to run before after select on the accept socket */
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void *(*worker_fn)(void *); /*!< the function in charge of doing the actual work */
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const char *name;
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struct ast_tls_config *old_tls_cfg; /*!< copy of the SSL configuration to determine whether changes have been made */
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};
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/*! \brief
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* describes a server instance
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*/
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struct ast_tcptls_session_instance {
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int client;
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struct ast_sockaddr remote_address;
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struct ast_tcptls_session_args *parent;
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/* Sometimes, when an entity reads TCP data, multiple
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* logical messages might be read at the same time. In such
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* a circumstance, there needs to be a place to stash the
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* extra data.
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*/
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struct ast_str *overflow_buf;
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/*! ao2 stream object associated with this session. */
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struct ast_iostream *stream;
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/*! ao2 object private data of parent->worker_fn */
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void *private_data;
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};
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/*!
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* \brief Attempt to connect and start a tcptls session within the given timeout
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*
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* \note On error the tcptls_session's ref count is decremented, fd and file
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* are closed, and NULL is returned.
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*
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* \param tcptls_session The session instance to connect and start
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* \param timeout How long (in milliseconds) to attempt to connect (-1 equals infinite)
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*
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* \return The tcptls_session, or NULL on error
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*/
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struct ast_tcptls_session_instance *ast_tcptls_client_start_timeout(
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struct ast_tcptls_session_instance *tcptls_session, int timeout);
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/*!
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* \brief Attempt to connect and start a tcptls session
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*
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* Blocks until a connection is established, or an error occurs.
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*
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* \note On error the tcptls_session's ref count is decremented, fd and file
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* are closed, and NULL is returned.
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*
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* \param tcptls_session The session instance to connect and start
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*
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* \return The tcptls_session, or NULL on error
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*/
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struct ast_tcptls_session_instance *ast_tcptls_client_start(struct ast_tcptls_session_instance *tcptls_session);
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/*! \brief Creates a client connection's ast_tcptls_session_instance. */
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struct ast_tcptls_session_instance *ast_tcptls_client_create(struct ast_tcptls_session_args *desc);
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void *ast_tcptls_server_root(void *);
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/*!
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* \brief Closes a tcptls session instance's file and/or file descriptor.
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* The tcptls_session will be set to NULL and it's file descriptor will be set to -1
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* by this function.
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*/
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void ast_tcptls_close_session_file(struct ast_tcptls_session_instance *tcptls_session);
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/*!
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* \brief This is a generic (re)start routine for a TCP server,
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* which does the socket/bind/listen and starts a thread for handling
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* accept().
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* \version 1.6.1 changed desc parameter to be of ast_tcptls_session_args type
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*/
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void ast_tcptls_server_start(struct ast_tcptls_session_args *desc);
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/*!
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* \brief Shutdown a running server if there is one
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* \version 1.6.1 changed desc parameter to be of ast_tcptls_session_args type
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*/
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void ast_tcptls_server_stop(struct ast_tcptls_session_args *desc);
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/*!
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* \brief Set up an SSL server
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*
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* \param cfg Configuration for the SSL server
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* \retval 1 Success
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* \retval 0 Failure
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*/
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int ast_ssl_setup(struct ast_tls_config *cfg);
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/*!
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* \brief free resources used by an SSL server
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*
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* \note This only needs to be called if ast_ssl_setup() was
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* directly called first.
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* \param cfg Configuration for the SSL server
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*/
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void ast_ssl_teardown(struct ast_tls_config *cfg);
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/*!
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* \brief Used to parse conf files containing tls/ssl options.
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*/
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int ast_tls_read_conf(struct ast_tls_config *tls_cfg, struct ast_tcptls_session_args *tls_desc, const char *varname, const char *value);
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#endif /* _ASTERISK_TCPTLS_H */
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