rpcap-protocol.h - master - githubmirror/libpcap

rpcap-protocol.h
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Denis Ovsienko
Improve a few comments. [skip ci]
19 май 2026, 15:48
19 май 2026, 15:486ed4ce5
/*
 * Copyright (c) 2002 - 2005 NetGroup, Politecnico di Torino (Italy)
 * Copyright (c) 2005 - 2008 CACE Technologies, Davis (California)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Politecnico di Torino, CACE Technologies
 * nor the names of its contributors may be used to endorse or promote
 * products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef __RPCAP_PROTOCOL_H__
#define __RPCAP_PROTOCOL_H__

#define RPCAP_DEFAULT_NETPORT "2002" /* Default port on which the RPCAP daemon is waiting for connections. */
/* Default port on which the client workstation is waiting for connections in case of active mode. */
#define RPCAP_DEFAULT_NETPORT_ACTIVE "2003"
#define RPCAP_DEFAULT_NETADDR ""	/* Default network address on which the RPCAP daemon binds to. */

/*
 * Minimum and maximum supported versions of the protocol.
 *
 * If new message types are added, the protocol version MUST be changed,
 * so that a client knows, from the negotiated protocol version, what
 * messages can be sent to the server.
 *
 * If the format of an existing message type is changed, the protocol
 * version MUST be changed, so that each side knows, from the negotiated
 * protocol version, what format should be used.
 *
 * The RPCAP_MSG_ERROR format MUST not change, as it's used to, among
 * other things, report "incorrect version number" errors, where, if
 * the format changed, the sender of the message might not know what
 * versions the recipient would understand, or might know a version
 * they support (the version number they sent) but might not know
 * the format of the message in that version.
 *
 * Other message versions SHOULD not change, as that would complicate
 * the process of interpreting the message, making it version-dependent.
 * Introducing a new message with a new format is preferable.
 *
 * Version negotiation is done as part of the authentication process:
 *
 * The client sends an authentication request, with a version number
 * of 0.  All servers must accept authentication requests with a version
 * number of 0, even if they don't support version 0 for any other
 * requests.
 *
 * The server attempts to authenticate the client.  If that succeeds,
 * older servers - which only support version 0 - will send an
 * authentication reply with no payload.  Newer servers - which might
 * support other versions - will send an authentication reply with
 * a payload giving the minimum and maximum versions it supports.
 *
 * The client attempts to find the largest version number that is
 * in both its range of supported versions and the server's supported
 * versions.  If it fails, it gives up; otherwise, it uses that version.
 */
#define RPCAP_MIN_VERSION 0
#define RPCAP_MAX_VERSION 0

/*
 * Version numbers are unsigned, so if RPCAP_MIN_VERSION is 0, they
 * are >= the minimum version, by definition; don't check against
 * RPCAP_MIN_VERSION, as you may get compiler warnings that the
 * comparison will always succeed.
 */
#if RPCAP_MIN_VERSION == 0
#define RPCAP_VERSION_IS_SUPPORTED(v)	\
	((v) <= RPCAP_MAX_VERSION)
#else
#define RPCAP_VERSION_IS_SUPPORTED(v)	\
	((v) >= RPCAP_MIN_VERSION && (v) <= RPCAP_MAX_VERSION)
#endif

/*
 * Separators used for the host list.
 *
 * It is used:
 * - by the rpcapd daemon, when you types a list of allowed connecting hosts
 * - by the rpcap client in active mode, when the client waits for incoming
 * connections from other hosts
 */
#define RPCAP_HOSTLIST_SEP " ,;\n\r"

/*********************************************************
 *                                                       *
 * Protocol messages formats                             *
 *                                                       *
 *********************************************************/
/*
 * WARNING: This file defines some structures that are used to transfer
 * data on the network.
 * Note that your compiler MUST not insert padding into these structures
 * for better alignment.
 * These structures have been created in order to be correctly aligned to
 * a 32-bit boundary, but be careful in any case.
 *
 * The layout of these structures MUST not be changed.  If a packet
 * format is different in different versions of the protocol, versions
 * of the structure should be provided for all the different versions or
 * version ranges (if more than one version of the protocol has the same
 * layout) that we support.
 *
 * We use the C99 intN_t and uintN_t types to indicate fields that are
 * exactly N bits long on the network.  Do not use types that might
 * differ in their lengths.
 *
 * XXX - both libpcap and programs that use it will require significant
 * work if you have machines where integral data types are not multiples
 * of 8-bit bytes.  If, for example, you're trying to get this to work
 * on a PDP-10x, good luck.
 */

/* Common header for all the RPCAP messages */
struct rpcap_header
{
	uint8_t ver;		/* RPCAP version number */
	uint8_t type;		/* RPCAP message type (error, findalldevs, ...) */
	uint16_t value;		/* Message-dependent value (not always used) */
	uint32_t plen;		/* Length of the payload of this RPCAP message */
};

/*
 * Format of data that may appear at the end of an authentication reply,
 * giving the minimum and maximum versions of the protocol that the
 * server supports.
 *
 * Older servers don't provide this; they support only version 0.
 */
struct rpcap_authreply
{
	uint8_t minvers;		/* Minimum version supported */
	uint8_t maxvers;		/* Maximum version supported */
	uint8_t pad[2];			/* Pad to 4-byte boundary **/
	uint32_t byte_order_magic;	/* RPCAP_BYTE_ORDER_MAGIC, in server byte order */
};

/*
 * Any resemblance between this and the pcap file magic number
 * is purely coincidental, trust me.
 */
#define RPCAP_BYTE_ORDER_MAGIC		0xa1b2c3d4U
#define RPCAP_BYTE_ORDER_MAGIC_SWAPPED	0xd4c3b2a1U

/*
 * Older version of authentication reply, without byte order indication
 * and padding.
 */
struct rpcap_authreply_old
{
	uint8_t minvers;	/* Minimum version supported */
	uint8_t maxvers;	/* Maximum version supported */
};

/* Format of the message for the interface description (findalldevs command) */
struct rpcap_findalldevs_if
{
	uint16_t namelen;	/* Length of the interface name */
	uint16_t desclen;	/* Length of the interface description */
	uint32_t flags;		/* Interface flags */
	uint16_t naddr;		/* Number of addresses */
	uint16_t dummy;		/* Must be zero */
};

/*
 * Format of an address as sent over the wire.
 *
 * Do *NOT* use struct sockaddr_storage, as the layout for that is
 * machine-dependent.
 *
 * RFC 2553 gives two sample layouts, both of which are 128 bytes long,
 * both of which are aligned on an 8-byte boundary, and both of which
 * have 2 bytes before the address data.
 *
 * However, one has a 2-byte address family value at the beginning
 * and the other has a 1-byte address length value and a 1-byte
 * address family value; this reflects the fact that the original
 * BSD sockaddr structure had a 2-byte address family value, which
 * was later changed to a 1-byte address length value and a 1-byte
 * address family value, when support for variable-length OSI
 * network-layer addresses was added.
 *
 * Furthermore, Solaris's struct sockaddr_storage is 256 bytes
 * long.
 *
 * This structure is supposed to be aligned on an 8-byte boundary;
 * the message header is 8 bytes long, so we don't have to do
 * anything to ensure it's aligned on that boundary within a packet,
 * so we just define it as 128 bytes long, with a 2-byte address
 * family.  (We only support IPv4 and IPv6 addresses, which are fixed-
 * length.)  That way, it's the same size as sockaddr_storage on
 * Windows, and it'll look like what an older Windows client will
 * expect.
 *
 * In addition, do *NOT* use the host's AF_ value for an address,
 * as the value for AF_INET6 is machine-dependent.  We use the
 * Windows value, so it'll look like what an older Windows client
 * will expect.
 *
 * (The Windows client is the only one that has been distributed
 * as a standard part of *pcap; UN*X clients are probably built
 * from source by the user or administrator, so they're in a
 * better position to upgrade an old client.  Therefore, we
 * try to make what goes over the wire look like what comes
 * from a Windows server.)
 */
struct rpcap_sockaddr
{
	uint16_t	family;		/* Address family */
	char		data[128-2];	/* Data */
};

/*
 * Format of an IPv4 address as sent over the wire.
 */
#define RPCAP_AF_INET	2		/* Value on all OSes except for Haiku */
struct rpcap_sockaddr_in
{
	uint16_t family;	/* Address family */
	uint16_t port;		/* Port number */
	uint32_t addr;		/* IPv4 address */
	uint8_t	 zero[8];	/* Padding */
};

/*
 * Format of an IPv6 address as sent over the wire.
 */
#define RPCAP_AF_INET6	23		/* Value on Windows */
struct rpcap_sockaddr_in6
{
	uint16_t family;		/* Address family */
	uint16_t port;		/* Port number */
	uint32_t flowinfo;	/* IPv6 flow information */
	uint8_t  addr[16];	/* IPv6 address */
	uint32_t scope_id;	/* Scope zone index */
};

/* Format of the message for the address listing (findalldevs command) */
struct rpcap_findalldevs_ifaddr
{
	struct rpcap_sockaddr addr;		/* Network address */
	struct rpcap_sockaddr netmask;		/* Netmask for that address */
	struct rpcap_sockaddr broadaddr;	/* Broadcast address for that address */
	struct rpcap_sockaddr dstaddr;		/* P2P destination address for that address */
};

/*
 * \brief Format of the message of the connection opening reply (open command).
 *
 * This structure transfers over the network some of the values useful on the client side.
 */
struct rpcap_openreply
{
	int32_t	linktype;	/* Link type */
	int32_t	tzoff;		/* Timezone offset - not used by newer clients */
};

/* Format of the message that starts a remote capture (startcap command) */
struct rpcap_startcapreq
{
	uint32_t snaplen;	/* Length of the snapshot (number of bytes to capture for each packet) */
	uint32_t read_timeout;	/* Read timeout in milliseconds */
	uint16_t flags;		/* Flags (see RPCAP_STARTCAPREQ_FLAG_xxx) */
	uint16_t portdata;	/* Network port on which the client is waiting at (if 'serveropen') */
};

/* Format of the reply message that devoted to start a remote capture (startcap reply command) */
struct rpcap_startcapreply
{
	int32_t	 bufsize;	/* Size of the user buffer allocated by WinPcap; it can be different from the one we chose */
	uint16_t portdata;	/* Network port on which the server is waiting at (passive mode only) */
	uint16_t dummy;		/* Must be zero */
};

/*
 * \brief Format of the header which encapsulates captured packets when transmitted on the network.
 *
 * This message requires the general header as well, since we want to be able to exchange
 * more information across the network in the future (for example statistics, and kind like that).
 */
struct rpcap_pkthdr
{
	/*
	 * This protocol needs to be updated with a new version before
	 * 2038-01-19 03:14:07 UTC.
	 */
	uint32_t timestamp_sec;		/* 'struct timeval' compatible, it represents the 'tv_sec' field */
	uint32_t timestamp_usec;	/* 'struct timeval' compatible, it represents the 'tv_usec' field */
	uint32_t caplen;		/* Length of portion present in the capture */
	uint32_t len;			/* Real length of this packet (off wire) */
	uint32_t npkt;			/* Ordinal number of the packet (i.e. the first one captured has '1', the second one '2', etc) */
};

/* General header used for the pcap_setfilter() command; keeps just the number of BPF instructions */
struct rpcap_filter
{
	uint16_t filtertype;	/* type of the filter transferred (BPF instructions, ...) */
	uint16_t dummy;		/* Must be zero */
	uint32_t nitems;	/* Number of items contained in the filter (e.g. BPF instructions for BPF filters) */
};

/* Structure that keeps a single BPF instruction; it is repeated 'ninsn' times according to the 'rpcap_filterbpf' header */
struct rpcap_filterbpf_insn
{
	uint16_t	code;	/* opcode of the instruction */
	uint8_t		jt;	/* relative offset to jump to in case of 'true' */
	uint8_t		jf;	/* relative offset to jump to in case of 'false' */
	int32_t		k;	/* instruction-dependent value */
};

/* Structure that keeps the data required for the authentication on the remote host */
struct rpcap_auth
{
	uint16_t type;	/* Authentication type */
	uint16_t dummy;	/* Must be zero */
	uint16_t slen1;	/* Length of the first authentication item (e.g. username) */
	uint16_t slen2;	/* Length of the second authentication item (e.g. password) */
};

/* Structure that keeps the statistics about the number of packets captured, dropped, etc. */
struct rpcap_stats
{
	uint32_t ifrecv;	/* Packets received by the kernel filter (i.e. pcap_stats.ps_recv) */
	uint32_t ifdrop;	/* Packets dropped by the network interface (e.g. not enough buffers) (i.e. pcap_stats.ps_ifdrop) */
	uint32_t krnldrop;	/* Packets dropped by the kernel filter (i.e. pcap_stats.ps_drop) */
	uint32_t svrcapt;	/* Packets captured by the RPCAP daemon and sent on the network */
};

/* Structure that is needed to set sampling parameters */
struct rpcap_sampling
{
	uint8_t  method;	/* Sampling method */
	uint8_t  dummy1;	/* Must be zero */
	uint16_t dummy2;	/* Must be zero */
	uint32_t value;		/* Parameter related to the sampling method */
};

/*
 * Messages field coding.
 *
 * These values are used in messages sent over the network, and MUST
 * not be changed.
 */
#define RPCAP_MSG_IS_REPLY		0x080	/* Flag indicating a reply */

#define RPCAP_MSG_ERROR			0x01	/* Message that keeps an error notification */
#define RPCAP_MSG_FINDALLIF_REQ		0x02	/* Request to list all the remote interfaces */
#define RPCAP_MSG_OPEN_REQ		0x03	/* Request to open a remote device */
#define RPCAP_MSG_STARTCAP_REQ		0x04	/* Request to start a capture on a remote device */
#define RPCAP_MSG_UPDATEFILTER_REQ	0x05	/* Send a compiled filter into the remote device */
#define RPCAP_MSG_CLOSE			0x06	/* Close the connection with the remote peer */
#define RPCAP_MSG_PACKET		0x07	/* This is a 'data' message, which carries a network packet */
#define RPCAP_MSG_AUTH_REQ		0x08	/* Message that keeps the authentication parameters */
#define RPCAP_MSG_STATS_REQ		0x09	/* It requires to have network statistics */
#define RPCAP_MSG_ENDCAP_REQ		0x0A	/* Stops the current capture, keeping the device open */
#define RPCAP_MSG_SETSAMPLING_REQ	0x0B	/* Set sampling parameters */

#define RPCAP_MSG_FINDALLIF_REPLY	(RPCAP_MSG_FINDALLIF_REQ | RPCAP_MSG_IS_REPLY)		/* Keeps the list of all the remote interfaces */
#define RPCAP_MSG_OPEN_REPLY		(RPCAP_MSG_OPEN_REQ | RPCAP_MSG_IS_REPLY)		/* The remote device has been opened correctly */
#define RPCAP_MSG_STARTCAP_REPLY	(RPCAP_MSG_STARTCAP_REQ | RPCAP_MSG_IS_REPLY)		/* The capture is starting correctly */
#define RPCAP_MSG_UPDATEFILTER_REPLY	(RPCAP_MSG_UPDATEFILTER_REQ | RPCAP_MSG_IS_REPLY)	/* The filter has been applied correctly on the remote device */
#define RPCAP_MSG_AUTH_REPLY		(RPCAP_MSG_AUTH_REQ | RPCAP_MSG_IS_REPLY)		/* Sends a message that says 'ok, authorization successful' */
#define RPCAP_MSG_STATS_REPLY		(RPCAP_MSG_STATS_REQ | RPCAP_MSG_IS_REPLY)		/* Message that keeps the network statistics */
#define RPCAP_MSG_ENDCAP_REPLY		(RPCAP_MSG_ENDCAP_REQ | RPCAP_MSG_IS_REPLY)		/* Confirms that the capture stopped successfully */
#define RPCAP_MSG_SETSAMPLING_REPLY	(RPCAP_MSG_SETSAMPLING_REQ | RPCAP_MSG_IS_REPLY)		/* Confirms that the capture stopped successfully */

#define RPCAP_STARTCAPREQ_FLAG_PROMISC		0x00000001	/* Enables promiscuous mode (default: disabled) */
#define RPCAP_STARTCAPREQ_FLAG_DGRAM		0x00000002	/* Use a datagram (i.e. UDP) connection for the data stream (default: use TCP)*/
#define RPCAP_STARTCAPREQ_FLAG_SERVEROPEN	0x00000004	/* The server has to open the data connection toward the client */
#define RPCAP_STARTCAPREQ_FLAG_INBOUND		0x00000008	/* Capture only inbound packets (take care: the flag has no effect with promiscuous enabled) */
#define RPCAP_STARTCAPREQ_FLAG_OUTBOUND		0x00000010	/* Capture only outbound packets (take care: the flag has no effect with promiscuous enabled) */

#define RPCAP_UPDATEFILTER_BPF 1			/* This code tells us that the filter is encoded with the BPF/NPF syntax */

/*
 * Network error codes.
 *
 * These values are used in messages sent over the network, and MUST
 * not be changed.
 */
#define PCAP_ERR_NETW			1	/* Network error */
#define PCAP_ERR_INITTIMEOUT		2	/* The RPCAP initial timeout has expired */
#define PCAP_ERR_AUTH			3	/* Generic authentication error */
#define PCAP_ERR_FINDALLIF		4	/* Generic findalldevs error */
#define PCAP_ERR_NOREMOTEIF		5	/* The findalldevs was ok, but the remote end had no interfaces to list */
#define PCAP_ERR_OPEN			6	/* Generic pcap_open error */
#define PCAP_ERR_UPDATEFILTER		7	/* Generic updatefilter error */
#define PCAP_ERR_GETSTATS		8	/* Generic pcap_stats error */
#define PCAP_ERR_READEX			9	/* Generic pcap_next_ex error */
#define PCAP_ERR_HOSTNOAUTH		10	/* The host is not authorized to connect to this server */
#define PCAP_ERR_REMOTEACCEPT		11	/* Generic pcap_remoteaccept error */
#define PCAP_ERR_STARTCAPTURE		12	/* Generic pcap_startcapture error */
#define PCAP_ERR_ENDCAPTURE		13	/* Generic pcap_endcapture error */
#define PCAP_ERR_RUNTIMETIMEOUT		14	/* The RPCAP run-time timeout has expired */
#define PCAP_ERR_SETSAMPLING		15	/* Error during the settings of sampling parameters */
#define PCAP_ERR_WRONGMSG		16	/* The other end endpoint sent a message which has not been recognized */
#define PCAP_ERR_WRONGVER		17	/* The other end endpoint has a version number that is not compatible with our */
#define PCAP_ERR_AUTH_FAILED		18	/* The user couldn't be authenticated */
#define PCAP_ERR_TLS_REQUIRED		19	/* The server requires TLS to connect */
#define PCAP_ERR_AUTH_TYPE_NOTSUP	20	/* The authentication type isn't supported */

/*
 * \brief Buffer used by socket functions to send-receive packets.
 * In case you plan to have messages larger than this value, you have to increase it.
 */
#define RPCAP_NETBUF_SIZE 64000

/*********************************************************
 *                                                       *
 * Routines used by the rpcap client and rpcap daemon    *
 *                                                       *
 *********************************************************/

#include "sockutils.h"
#include "sslutils.h"

extern void rpcap_createhdr(struct rpcap_header *header, uint8_t ver, uint8_t type, uint16_t value, uint32_t length);
extern const char *rpcap_msg_type_string(uint8_t type);
extern int rpcap_senderror(PCAP_SOCKET sock, SSL *ssl, uint8_t ver, uint16_t errcode, const char *error, char *errbuf);

#endif