mirror of
https://github.com/OpenVPN/openvpn.git
synced 2024-09-20 12:02:28 +02:00
9fb45319cb
Signed-off-by: Adriaan de Jong <dejong@fox-it.com> Acked-by: James Yonan <james@openvpn.net> Signed-off-by: David Sommerseth <davids@redhat.com>
508 lines
16 KiB
C
508 lines
16 KiB
C
/*
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* OpenVPN -- An application to securely tunnel IP networks
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* over a single TCP/UDP port, with support for SSL/TLS-based
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* session authentication and key exchange,
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* packet encryption, packet authentication, and
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* packet compression.
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*
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* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
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* Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see the file COPYING included with this
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* distribution); if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/**
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* @file Control Channel SSL/Data channel negotiation module
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*/
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#ifndef OPENVPN_SSL_H
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#define OPENVPN_SSL_H
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#if defined(USE_CRYPTO) && defined(USE_SSL)
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#include "basic.h"
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#include "common.h"
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#include "crypto.h"
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#include "packet_id.h"
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#include "session_id.h"
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#include "reliable.h"
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#include "socket.h"
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#include "mtu.h"
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#include "options.h"
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#include "plugin.h"
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#include "ssl_common.h"
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#include "ssl_verify.h"
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#include "ssl_backend.h"
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/* Used in the TLS PRF function */
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#define KEY_EXPANSION_ID "OpenVPN"
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/* packet opcode (high 5 bits) and key-id (low 3 bits) are combined in one byte */
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#define P_KEY_ID_MASK 0x07
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#define P_OPCODE_SHIFT 3
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/* packet opcodes -- the V1 is intended to allow protocol changes in the future */
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#define P_CONTROL_HARD_RESET_CLIENT_V1 1 /* initial key from client, forget previous state */
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#define P_CONTROL_HARD_RESET_SERVER_V1 2 /* initial key from server, forget previous state */
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#define P_CONTROL_SOFT_RESET_V1 3 /* new key, graceful transition from old to new key */
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#define P_CONTROL_V1 4 /* control channel packet (usually TLS ciphertext) */
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#define P_ACK_V1 5 /* acknowledgement for packets received */
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#define P_DATA_V1 6 /* data channel packet */
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/* indicates key_method >= 2 */
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#define P_CONTROL_HARD_RESET_CLIENT_V2 7 /* initial key from client, forget previous state */
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#define P_CONTROL_HARD_RESET_SERVER_V2 8 /* initial key from server, forget previous state */
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/* define the range of legal opcodes */
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#define P_FIRST_OPCODE 1
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#define P_LAST_OPCODE 8
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/* Should we aggregate TLS
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* acknowledgements, and tack them onto
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* control packets? */
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#define TLS_AGGREGATE_ACK
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/*
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* If TLS_AGGREGATE_ACK, set the
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* max number of acknowledgments that
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* can "hitch a ride" on an outgoing
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* non-P_ACK_V1 control packet.
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*/
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#define CONTROL_SEND_ACK_MAX 4
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/*
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* Define number of buffers for send and receive in the reliability layer.
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*/
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#define TLS_RELIABLE_N_SEND_BUFFERS 4 /* also window size for reliablity layer */
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#define TLS_RELIABLE_N_REC_BUFFERS 8
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/*
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* Various timeouts
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*/
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#define TLS_MULTI_REFRESH 15 /* call tls_multi_process once every n seconds */
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#define TLS_MULTI_HORIZON 2 /* call tls_multi_process frequently for n seconds after
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every packet sent/received action */
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/*
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* The SSL/TLS worker thread will wait at most this many seconds for the
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* interprocess communication pipe to the main thread to be ready to accept
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* writes.
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*/
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#define TLS_MULTI_THREAD_SEND_TIMEOUT 5
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/* Interval that tls_multi_process should call tls_authentication_status */
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#define TLS_MULTI_AUTH_STATUS_INTERVAL 10
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/*
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* Buffer sizes (also see mtu.h).
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*/
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/* Maximum length of OCC options string passed as part of auth handshake */
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#define TLS_OPTIONS_LEN 512
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/* Default field in X509 to be username */
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#define X509_USERNAME_FIELD_DEFAULT "CN"
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/*
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* Range of key exchange methods
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*/
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#define KEY_METHOD_MIN 1
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#define KEY_METHOD_MAX 2
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/* key method taken from lower 4 bits */
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#define KEY_METHOD_MASK 0x0F
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/*
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* Measure success rate of TLS handshakes, for debugging only
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*/
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/* #define MEASURE_TLS_HANDSHAKE_STATS */
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/*
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* Used in --mode server mode to check tls-auth signature on initial
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* packets received from new clients.
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*/
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struct tls_auth_standalone
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{
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struct key_ctx_bi tls_auth_key;
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struct crypto_options tls_auth_options;
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struct frame frame;
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};
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/*
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* Prepare the SSL library for use
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*/
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void init_ssl_lib (void);
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/*
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* Free any internal state that the SSL library might have
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*/
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void free_ssl_lib (void);
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/**
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* Build master SSL context object that serves for the whole of OpenVPN
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* instantiation
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*/
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void init_ssl (const struct options *options, struct tls_root_ctx *ctx);
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/** @addtogroup control_processor
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* @{ */
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/** @name Functions for initialization and cleanup of tls_multi structures
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* @{ */
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/**
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* Allocate and initialize a \c tls_multi structure.
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* @ingroup control_processor
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*
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* This function allocates a new \c tls_multi structure, and performs some
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* amount of initialization. Afterwards, the \c tls_multi_init_finalize()
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* function must be called to finalize the structure's initialization
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* process.
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*
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* @param tls_options - The configuration options to be used for this VPN
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* tunnel.
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*
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* @return A newly allocated and initialized \c tls_multi structure.
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*/
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struct tls_multi *tls_multi_init (struct tls_options *tls_options);
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/**
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* Finalize initialization of a \c tls_multi structure.
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* @ingroup control_processor
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*
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* This function initializes the \c TM_ACTIVE \c tls_session, and in
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* server mode also the \c TM_UNTRUSTED \c tls_session, associated with
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* this \c tls_multi structure. It also configures the control channel's
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* \c frame structure based on the data channel's \c frame given in
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* argument \a frame.
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*
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* @param multi - The \c tls_multi structure of which to finalize
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* initialization.
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* @param frame - The data channel's \c frame structure.
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*/
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void tls_multi_init_finalize(struct tls_multi *multi,
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const struct frame *frame);
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/*
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* Initialize a standalone tls-auth verification object.
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*/
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struct tls_auth_standalone *tls_auth_standalone_init (struct tls_options *tls_options,
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struct gc_arena *gc);
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/*
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* Finalize a standalone tls-auth verification object.
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*/
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void tls_auth_standalone_finalize (struct tls_auth_standalone *tas,
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const struct frame *frame);
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/*
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* Set local and remote option compatibility strings.
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* Used to verify compatibility of local and remote option
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* sets.
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*/
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void tls_multi_init_set_options(struct tls_multi* multi,
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const char *local,
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const char *remote);
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/**
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* Cleanup a \c tls_multi structure and free associated memory
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* allocations.
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* @ingroup control_processor
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*
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* This function cleans up a \c tls_multi structure. This includes
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* cleaning up all associated \c tls_session structures.
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*
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* @param multi - The \c tls_multi structure to clean up in free.
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* @param clear - Whether the memory allocated for the \a multi
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* object should be overwritten with 0s.
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*/
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void tls_multi_free (struct tls_multi *multi, bool clear);
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/** @} name Functions for initialization and cleanup of tls_multi structures */
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/** @} addtogroup control_processor */
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#define TLSMP_INACTIVE 0
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#define TLSMP_ACTIVE 1
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#define TLSMP_KILL 2
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/*
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* Called by the top-level event loop.
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*
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* Basically decides if we should call tls_process for
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* the active or untrusted sessions.
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*/
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int tls_multi_process (struct tls_multi *multi,
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struct buffer *to_link,
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struct link_socket_actual **to_link_addr,
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struct link_socket_info *to_link_socket_info,
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interval_t *wakeup);
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/**************************************************************************/
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/**
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* Determine whether an incoming packet is a data channel or control
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* channel packet, and process accordingly.
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* @ingroup external_multiplexer
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*
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* When OpenVPN is in TLS mode, this is the first function to process an
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* incoming packet. It inspects the packet's one-byte header which
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* contains the packet's opcode and key ID. Depending on the opcode, the
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* packet is processed as a data channel or as a control channel packet.
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*
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* @par Data channel packets
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*
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* If the opcode indicates the packet is a data channel packet, then the
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* packet's key ID is used to find the local TLS state it is associated
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* with. This state is checked whether it is active, authenticated, and
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* its remote peer is the source of this packet. If these checks passed,
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* the state's security parameters are loaded into the \a opt crypto
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* options so that \p openvpn_decrypt() can later use them to authenticate
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* and decrypt the packet.
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*
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* This function then returns false. The \a buf buffer has not been
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* modified, except for removing the header.
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*
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* @par Control channel packets
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*
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* If the opcode indicates the packet is a control channel packet, then
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* this function will process it based on its plaintext header. depending
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* on the packet's opcode and session ID this function determines if it is
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* destined for an active TLS session, or whether a new TLS session should
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* be started. This function also initiates data channel session key
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* renegotiation if the received opcode requests that.
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*
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* If the incoming packet is destined for an active TLS session, then the
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* packet is inserted into the Reliability Layer and will be handled
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* later.
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*
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* @param multi - The TLS multi structure associated with the VPN tunnel
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* of this packet.
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* @param from - The source address of the packet.
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* @param buf - A buffer structure containing the incoming packet.
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* @param opt - A crypto options structure that will be loaded with the
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* appropriate security parameters to handle the packet if it is a
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* data channel packet.
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*
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* @return
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* @li True if the packet is a control channel packet that has been
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* processed successfully.
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* @li False if the packet is a data channel packet, or if an error
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* occurred during processing of a control channel packet.
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*/
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bool tls_pre_decrypt (struct tls_multi *multi,
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const struct link_socket_actual *from,
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struct buffer *buf,
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struct crypto_options *opt);
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/**************************************************************************/
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/** @name Functions for managing security parameter state for data channel packets
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* @{ */
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/**
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* Inspect an incoming packet for which no VPN tunnel is active, and
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* determine whether a new VPN tunnel should be created.
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* @ingroup data_crypto
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*
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* This function receives the initial incoming packet from a client that
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* wishes to establish a new VPN tunnel, and determines the packet is a
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* valid initial packet. It is only used when OpenVPN is running in
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* server mode.
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*
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* The tests performed by this function are whether the packet's opcode is
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* correct for establishing a new VPN tunnel, whether its key ID is 0, and
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* whether its size is not too large. This function also performs the
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* initial HMAC firewall test, if configured to do so.
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*
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* The incoming packet and the local VPN tunnel state are not modified by
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* this function. Its sole purpose is to inspect the packet and determine
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* whether a new VPN tunnel should be created. If so, that new VPN tunnel
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* instance will handle processing of the packet.
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*
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* @param tas - The standalone TLS authentication setting structure for
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* this process.
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* @param from - The source address of the packet.
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* @param buf - A buffer structure containing the incoming packet.
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*
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* @return
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* @li True if the packet is valid and a new VPN tunnel should be created
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* for this client.
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* @li False if the packet is not valid, did not pass the HMAC firewall
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* test, or some other error occurred.
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*/
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bool tls_pre_decrypt_lite (const struct tls_auth_standalone *tas,
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const struct link_socket_actual *from,
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const struct buffer *buf);
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/**
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* Choose the appropriate security parameters with which to process an
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* outgoing packet.
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* @ingroup data_crypto
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*
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* If no appropriate security parameters can be found, or if some other
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* error occurs, then the buffer is set to empty.
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*
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* @param multi - The TLS state for this packet's destination VPN tunnel.
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* @param buf - The buffer containing the outgoing packet.
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* @param opt - The crypto options structure into which the appropriate
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* security parameters should be loaded.
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*/
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void tls_pre_encrypt (struct tls_multi *multi,
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struct buffer *buf, struct crypto_options *opt);
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/**
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* Prepend the one-byte OpenVPN header to the packet, and perform some
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* accounting for the key state used.
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* @ingroup data_crypto
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*
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* @param multi - The TLS state for this packet's destination VPN tunnel.
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* @param buf - The buffer containing the outgoing packet.
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*/
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void tls_post_encrypt (struct tls_multi *multi, struct buffer *buf);
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/** @} name Functions for managing security parameter state for data channel packets */
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/*
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* Setup private key file password. If auth_file is given, use the
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* credentials stored in the file.
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*/
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void pem_password_setup (const char *auth_file);
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/*
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* Setup authentication username and password. If auth_file is given, use the
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* credentials stored in the file.
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*/
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void auth_user_pass_setup (const char *auth_file, const struct static_challenge_info *sc_info);
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/*
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* Ensure that no caching is performed on authentication information
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*/
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void ssl_set_auth_nocache (void);
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/*
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* Purge any stored authentication information, both for key files and tunnel
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* authentication. If PCKS #11 is enabled, purge authentication for that too.
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*/
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void ssl_purge_auth (const bool auth_user_pass_only);
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void ssl_set_auth_token (const char *token);
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#ifdef ENABLE_CLIENT_CR
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/*
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* ssl_get_auth_challenge will parse the server-pushed auth-failed
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* reason string and return a dynamically allocated
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* auth_challenge_info struct.
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*/
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void ssl_purge_auth_challenge (void);
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void ssl_put_auth_challenge (const char *cr_str);
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#endif
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/*
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* Reserve any extra space required on frames.
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*/
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void tls_adjust_frame_parameters(struct frame *frame);
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/*
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* Send a payload over the TLS control channel
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*/
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bool tls_send_payload (struct tls_multi *multi,
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const uint8_t *data,
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int size);
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/*
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* Receive a payload through the TLS control channel
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*/
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bool tls_rec_payload (struct tls_multi *multi,
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struct buffer *buf);
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#ifdef MANAGEMENT_DEF_AUTH
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static inline char *
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tls_get_peer_info(const struct tls_multi *multi)
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{
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return multi->peer_info;
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}
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#endif
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/*
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* inline functions
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*/
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static inline bool
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tls_initial_packet_received (const struct tls_multi *multi)
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{
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return multi->n_sessions > 0;
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}
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static inline bool
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tls_test_auth_deferred_interval (const struct tls_multi *multi)
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{
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if (multi)
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{
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const struct key_state *ks = &multi->session[TM_ACTIVE].key[KS_PRIMARY];
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return now < ks->auth_deferred_expire;
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}
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return false;
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}
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static inline int
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tls_test_payload_len (const struct tls_multi *multi)
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{
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if (multi)
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{
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const struct key_state *ks = &multi->session[TM_ACTIVE].key[KS_PRIMARY];
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if (ks->state >= S_ACTIVE)
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return BLEN (&ks->plaintext_read_buf);
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}
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return 0;
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}
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static inline void
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tls_set_single_session (struct tls_multi *multi)
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{
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if (multi)
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multi->opt.single_session = true;
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}
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/*
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* protocol_dump() flags
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*/
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#define PD_TLS_AUTH_HMAC_SIZE_MASK 0xFF
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#define PD_SHOW_DATA (1<<8)
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#define PD_TLS (1<<9)
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#define PD_VERBOSE (1<<10)
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const char *protocol_dump (struct buffer *buffer,
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unsigned int flags,
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struct gc_arena *gc);
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/*
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* debugging code
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*/
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#ifdef MEASURE_TLS_HANDSHAKE_STATS
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void show_tls_performance_stats(void);
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#endif
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/*#define EXTRACT_X509_FIELD_TEST*/
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void extract_x509_field_test (void);
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#endif /* USE_CRYPTO && USE_SSL */
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#endif
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