engine.c

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/*
 *  Copyright (c) 1999-2000 Sendmail, Inc. and its suppliers.
 *	All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 *
 */

#ifndef lint
static char id[] = "@(#)$Id: engine.c,v 8.67.4.14 2000/08/14 08:27:30 gshapiro Exp $";
#endif /* ! lint */

#if _FFR_MILTER
#include "libmilter.h"
#include "sendmail/useful.h"

#if NETINET || NETINET6
# include <arpa/inet.h>
#endif /* NETINET || NETINET6 */

/* generic argument for functions in the command table */
struct arg_struct
{
	size_t		a_len;		/* length of buffer */
	char		*a_buf;		/* argument string */
	int		a_idx;		/* index for macro array */
	SMFICTX_PTR	a_ctx;		/* context */
};

typedef struct arg_struct genarg;

/* structure for commands received from MTA */
struct cmdfct_t
{
	char	cm_cmd;				/* command */
	int	cm_argt;			/* type of arguments expected */
	int	cm_next;			/* next state */
	int	cm_todo;			/* what to do next */
	int	cm_macros;			/* index for macros */
	int	(*cm_fct) __P((genarg *));	/* function to execute */
};

typedef struct cmdfct_t cmdfct;

/* possible values for cm_argt */
#define	CM_ARG0	0	/* no args */
#define	CM_ARG1	1	/* one arg (string) */
#define	CM_ARG2	2	/* two args (strings) */
#define	CM_ARGA	4	/* one string and _SOCK_ADDR */
#define	CM_ARGO	5	/* two integers */
#define	CM_ARGV	8	/* \0 separated list of args, NULL-terminated */
#define	CM_ARGN	9	/* \0 separated list of args (strings) */

/* possible values for cm_todo */
#define	CT_CONT		0x0000	/* continue reading commands */
#define	CT_IGNO		0x0001	/* continue even when error  */

/* not needed right now, done via return code instead */
#define	CT_KEEP		0x0004	/* keep buffer (contains symbols) */
#define	CT_END		0x0008	/* start replying */

/* index in macro array: macros only for these commands */
#define	CI_NONE	(-1)
#define	CI_CONN	0
#define	CI_HELO	1
#define	CI_MAIL	2
#define	CI_RCPT	3
#if CI_RCPT >= MAX_MACROS_ENTRIES
ERROR: do not compile with CI_RCPT >= MAX_MACROS_ENTRIES
#endif

/* function prototypes */
static int	st_abortfct __P((genarg *));
static int	st_macros __P((genarg *));
static int	st_optionneg __P((genarg *));
static int	st_bodychunk __P((genarg *));
static int	st_connectinfo __P((genarg *));
static int	st_bodyend __P((genarg *));
static int	st_helo __P((genarg *));
static int	st_header __P((genarg *));
static int	st_sender __P((genarg *));
static int	st_rcpt __P((genarg *));
static int	st_eoh __P((genarg *));
static int	st_quit __P((genarg *));
static int	sendreply __P((sfsistat, socket_t, struct timeval *, SMFICTX_PTR));
static void	fix_stm __P((SMFICTX_PTR));
static bool	trans_ok __P((int, int));
static char	**dec_argv __P((char *, size_t));
static int	dec_arg2 __P((char *, size_t, char **, char **));

/* states */
#define ST_NONE	(-1)
#define ST_INIT	0	/* initial state */
#define ST_OPTS	1	/* option negotiation */
#define ST_CONN	2	/* connection info */
#define ST_HELO	3	/* helo */
#define ST_MAIL	4	/* mail from */
#define ST_RCPT	5	/* rcpt to */
#define ST_HDRS	6	/* headers */
#define ST_EOHS	7	/* end of headers */
#define ST_BODY	8	/* body */
#define ST_ENDM	9	/* end of message */
#define ST_QUIT	10	/* quit */
#define ST_ABRT	11	/* abort */
#define ST_LAST	ST_ABRT
#define ST_SKIP	15	/* not a state but required for the state table */

/* in a mail transaction? must be before eom according to spec. */
#define ST_IN_MAIL(st)	((st) >= ST_MAIL && (st) < ST_ENDM)

/*
**  set of next states
**  each state (ST_*) corresponds to bit in an int value (1 << state)
**  each state has a set of allowed transitions ('or' of bits of states)
**  so a state transition is valid if the mask of the next state
**  is set in the NX_* value
**  this function is coded in trans_ok(), see below.
*/
#define MASK(x)	(0x0001 << (x))	/* generate a bit "mask" for a state */
#define NX_INIT	(MASK(ST_OPTS))
#define NX_OPTS	(MASK(ST_CONN))
#define NX_CONN	(MASK(ST_HELO) | MASK(ST_MAIL))
#define NX_HELO	(MASK(ST_MAIL))
#define NX_MAIL	(MASK(ST_RCPT) | MASK(ST_ABRT))
#define NX_RCPT	(MASK(ST_HDRS) | MASK(ST_EOHS) | MASK(ST_RCPT) | MASK(ST_ABRT))
#define NX_HDRS	(MASK(ST_EOHS) | MASK(ST_HDRS) | MASK(ST_ABRT))
#define NX_EOHS	(MASK(ST_BODY) | MASK(ST_ENDM) | MASK(ST_ABRT))
#define NX_BODY	(MASK(ST_ENDM) | MASK(ST_BODY) | MASK(ST_ABRT))
#define NX_ENDM	(MASK(ST_QUIT) | MASK(ST_MAIL))
#define NX_QUIT	0
#define NX_ABRT	0
#define NX_SKIP MASK(ST_SKIP)

static int next_states[] =
{
	NX_INIT,
	NX_OPTS,
	NX_CONN,
	NX_HELO,
	NX_MAIL,
	NX_RCPT,
	NX_HDRS,
	NX_EOHS,
	NX_BODY,
	NX_ENDM,
	NX_QUIT,
	NX_ABRT
};

/* commands received by milter */
static cmdfct cmds[] =
{
{SMFIC_ABORT,	CM_ARG0, ST_ABRT,  CT_CONT,	CI_NONE, st_abortfct	},
{SMFIC_MACRO,	CM_ARGV, ST_NONE,  CT_KEEP,	CI_NONE, st_macros	},
{SMFIC_BODY,	CM_ARG1, ST_BODY,  CT_CONT,	CI_NONE, st_bodychunk	},
{SMFIC_CONNECT,	CM_ARG2, ST_CONN,  CT_CONT,	CI_CONN, st_connectinfo	},
{SMFIC_BODYEOB,	CM_ARG1, ST_ENDM,  CT_CONT,	CI_NONE, st_bodyend	},
{SMFIC_HELO,	CM_ARG1, ST_HELO,  CT_CONT,	CI_HELO, st_helo	},
{SMFIC_HEADER,	CM_ARG2, ST_HDRS,  CT_CONT,	CI_NONE, st_header	},
{SMFIC_MAIL,	CM_ARGV, ST_MAIL,  CT_CONT,	CI_MAIL, st_sender	},
{SMFIC_OPTNEG,	CM_ARGO, ST_OPTS,  CT_CONT,	CI_NONE, st_optionneg	},
{SMFIC_EOH,	CM_ARG0, ST_EOHS,  CT_CONT,	CI_NONE, st_eoh		},
{SMFIC_QUIT,	CM_ARG0, ST_QUIT,  CT_END,	CI_NONE, st_quit	},
{SMFIC_RCPT,	CM_ARGV, ST_RCPT,  CT_IGNO,	CI_RCPT, st_rcpt	}
};

/* additional (internal) reply codes */
#define _SMFIS_KEEP	20
#define _SMFIS_ABORT	21
#define _SMFIS_OPTIONS	22
#define _SMFIS_NOREPLY	23
#define _SMFIS_FAIL	(-1)

/*
**  MI_ENGINE -- receive commands and process them
**
**	Parameters:
**		ctx -- context structure
**
**	Returns:
**		MI_FAILURE/MI_SUCCESS
*/
int
mi_engine(ctx)
	SMFICTX_PTR ctx;
{
	size_t len;
	int i;
	socket_t sd;
	int ret = MI_SUCCESS;
	int ncmds = sizeof(cmds) / sizeof(cmdfct);
	int curstate = ST_INIT;
	int newstate;
	bool call_abort;
	sfsistat r;
	char cmd;
	char *buf = NULL;
	genarg arg;
	struct timeval timeout;
	int (*f) __P((genarg *));
	sfsistat (*fi_abort) __P((SMFICTX *));
	sfsistat (*fi_close) __P((SMFICTX *));

	arg.a_ctx = ctx;
	sd = ctx->ctx_sd;
	fi_abort = ctx->ctx_smfi->xxfi_abort;
	mi_clr_macros(ctx, 0);
	fix_stm(ctx);
	do
	{
		/* call abort only if in a mail transaction */
		call_abort = ST_IN_MAIL(curstate);
		timeout.tv_sec = ctx->ctx_timeout;
		timeout.tv_usec = 0;
		if (mi_stop() == MILTER_ABRT)
		{
			if (ctx->ctx_dbg > 3)
				dprintf("[%d] milter_abort\n",
					(int) ctx->ctx_id);
			ret = MI_FAILURE;
			break;
		}
		if ((buf = mi_rd_cmd(sd, &timeout, &cmd, &len,
				     ctx->ctx_smfi->xxfi_name)) == NULL &&
		    cmd < SMFIC_VALIDCMD)
		{
			if (ctx->ctx_dbg > 5)
				dprintf("[%d] mi_engine: mi_rd_cmd error (%x)\n",
					(int) ctx->ctx_id, (int) cmd);

			/*
			**  eof is currently treated as failure ->
			**  abort() instead of close(), otherwise use:
			**  if (cmd != SMFIC_EOF)
			*/

			ret = MI_FAILURE;
			break;
		}
		if (ctx->ctx_dbg > 4)
			dprintf("[%d] got cmd '%c' len %d\n",
				(int) ctx->ctx_id, cmd, len);
		for (i = 0; i < ncmds; i++)
		{
			if (cmd == cmds[i].cm_cmd)
				break;
		}
		if (i >= ncmds)
		{
			/* unknown command */
			if (ctx->ctx_dbg > 1)
				dprintf("[%d] cmd '%c' unknown\n",
					(int) ctx->ctx_id, cmd);
			ret = MI_FAILURE;
			break;
		}
		if ((f = cmds[i].cm_fct) == NULL)
		{
			/* stop for now */
			if (ctx->ctx_dbg > 1)
				dprintf("[%d] cmd '%c' not impl\n",
					(int) ctx->ctx_id, cmd);
			ret = MI_FAILURE;
			break;
		}

		/* is new state ok? */
		newstate = cmds[i].cm_next;
		if (ctx->ctx_dbg > 5)
			dprintf("[%d] cur %x new %x nextmask %x\n",
				(int) ctx->ctx_id,
				curstate, newstate, next_states[curstate]);

		if (newstate != ST_NONE && !trans_ok(curstate, newstate))
		{
			if (ctx->ctx_dbg > 1)
				dprintf("[%d] abort: cur %d (%x) new %d (%x) next %x\n",
					(int) ctx->ctx_id,
					curstate, MASK(curstate),
					newstate, MASK(newstate),
					next_states[curstate]);

			/* call abort only if in a mail transaction */
			if (fi_abort != NULL && call_abort)
				(void) (*fi_abort)(ctx);

			/*
			**  try to reach the new state from HELO
			**  if it can't be reached, ignore the command.
			*/

			curstate = ST_HELO;
			if (!trans_ok(curstate, newstate))
				continue;
		}
		arg.a_len = len;
		arg.a_buf = buf;
		if (newstate != ST_NONE)
		{
			curstate = newstate;
			ctx->ctx_state = curstate;
		}
		arg.a_idx = cmds[i].cm_macros;

		/* call function to deal with command */
		r = (*f)(&arg);
		if (r != _SMFIS_KEEP && buf != NULL)
		{
			free(buf);
			buf = NULL;
		}
		if (sendreply(r, sd, &timeout, ctx) != MI_SUCCESS)
		{
			ret = MI_FAILURE;
			break;
		}

		call_abort = ST_IN_MAIL(curstate);
		if (r == SMFIS_ACCEPT)
		{
			/* accept mail, no further actions taken */
			curstate = ST_HELO;
		}
		else if (r == SMFIS_REJECT || r == SMFIS_DISCARD ||
			 r ==  SMFIS_TEMPFAIL)
		{
			/*
			**  further actions depend on current state
			**  if the IGNO bit is set: "ignore" the error,
			**  i.e., stay in the current state
			*/
			if (!bitset(CT_IGNO, cmds[i].cm_todo))
				curstate = ST_HELO;
		}
		else if (r == _SMFIS_ABORT)
		{
			if (ctx->ctx_dbg > 5)
				dprintf("[%d] function returned abort\n",
					(int) ctx->ctx_id);
			ret = MI_FAILURE;
			break;
		}
	} while (!bitset(CT_END, cmds[i].cm_todo));

	if (ret != MI_SUCCESS)
	{
		/* call abort only if in a mail transaction */
		if (fi_abort != NULL && call_abort)
			(void) (*fi_abort)(ctx);
	}

	/* close must always be called */
	if ((fi_close = ctx->ctx_smfi->xxfi_close) != NULL)
		(void) (*fi_close)(ctx);
	if (buf != NULL)
		free(buf);
	mi_clr_macros(ctx, 0);
	return ret;
}
/*
**  SENDREPLY -- send a reply to the MTA
**
**	Parameters:
**		r -- reply code
**		sd -- socket descriptor
**		timeout_ptr -- (ptr to) timeout to use for sending
**		ctx -- context structure
**
**	Returns:
**		MI_SUCCESS/MI_FAILURE
*/

static int
sendreply(r, sd, timeout_ptr, ctx)
	sfsistat r;
	socket_t sd;
	struct timeval *timeout_ptr;
	SMFICTX_PTR ctx;
{
	int ret = MI_SUCCESS;

	switch(r)
	{
	  case SMFIS_CONTINUE:
		ret = mi_wr_cmd(sd, timeout_ptr, SMFIR_CONTINUE, NULL, 0);
		break;
	  case SMFIS_TEMPFAIL:
	  case SMFIS_REJECT:
		if (ctx->ctx_reply != NULL)
		{
			ret = mi_wr_cmd(sd, timeout_ptr, SMFIR_REPLYCODE,
					ctx->ctx_reply,
					strlen(ctx->ctx_reply) + 1);
			free(ctx->ctx_reply);
			ctx->ctx_reply = NULL;
		}
		else
		{
			ret = mi_wr_cmd(sd, timeout_ptr, r == SMFIS_REJECT ?
					SMFIR_REJECT : SMFIR_TEMPFAIL, NULL, 0);
		}
		break;
	  case SMFIS_DISCARD:
		ret = mi_wr_cmd(sd, timeout_ptr, SMFIR_DISCARD, NULL, 0);
		break;
	  case SMFIS_ACCEPT:
		ret = mi_wr_cmd(sd, timeout_ptr, SMFIR_ACCEPT, NULL, 0);
		break;
	  case _SMFIS_OPTIONS:
		{
			char buf[MILTER_OPTLEN];
			mi_int32 v;

			v = htonl(ctx->ctx_smfi->xxfi_version);
			(void) memcpy(&(buf[0]), (void *) &v, MILTER_LEN_BYTES);
			v = htonl(ctx->ctx_smfi->xxfi_flags);
			(void) memcpy(&(buf[MILTER_LEN_BYTES]), (void *) &v,
				      MILTER_LEN_BYTES);
			v = htonl(ctx->ctx_pflags);
			(void) memcpy(&(buf[MILTER_LEN_BYTES * 2]), (void *) &v,
				      MILTER_LEN_BYTES);
			ret = mi_wr_cmd(sd, timeout_ptr, SMFIC_OPTNEG, buf,
				       MILTER_OPTLEN);
		}
		break;
	  default:	/* don't send a reply */
		break;
	}
	return ret;
}

/*
**  CLR_MACROS -- clear set of macros starting from a given index
**
**	Parameters:
**		ctx -- context structure
**		m -- index from which to clear all macros
**
**	Returns:
**		None.
*/
void
mi_clr_macros(ctx, m)
	SMFICTX_PTR ctx;
	int m;
{
	int i;

	for (i = m; i < MAX_MACROS_ENTRIES; i++)
	{
		if (ctx->ctx_mac_ptr[i] != NULL)
		{
			free(ctx->ctx_mac_ptr[i]);
			ctx->ctx_mac_ptr[i] = NULL;
		}
		if (ctx->ctx_mac_buf[i] != NULL)
		{
			free(ctx->ctx_mac_buf[i]);
			ctx->ctx_mac_buf[i] = NULL;
		}
	}
}
/*
**  ST_OPTIONNEG -- negotiate options
**
**	Parameters:
**		g -- generic argument structure
**
**	Returns:
**		abort/send options/continue
*/

static int
st_optionneg(g)
	genarg *g;
{
	mi_int32 i, v;

	if (g == NULL || g->a_ctx->ctx_smfi == NULL)
		return SMFIS_CONTINUE;
	mi_clr_macros(g->a_ctx, g->a_idx + 1);

	/* check for minimum length */
	if (g->a_len < MILTER_OPTLEN)
	{
		smi_log(SMI_LOG_ERR,
			"%s: st_optionneg[%d]: len too short %d < %d",
			g->a_ctx->ctx_smfi->xxfi_name,
			(int) g->a_ctx->ctx_id, g->a_len,
			MILTER_OPTLEN);
		return _SMFIS_ABORT;
	}

	(void) memcpy((void *) &i, (void *) &(g->a_buf[0]),
		      MILTER_LEN_BYTES);
	v = ntohl(i);
	if (v < g->a_ctx->ctx_smfi->xxfi_version)
	{
		/* hard failure for now! */
		smi_log(SMI_LOG_ERR,
			"%s: st_optionneg[%d]: version mismatch MTA: %d < milter: %d",
			g->a_ctx->ctx_smfi->xxfi_name,
			(int) g->a_ctx->ctx_id, (int) v,
			g->a_ctx->ctx_smfi->xxfi_version);
		return _SMFIS_ABORT;
	}

	(void) memcpy((void *) &i, (void *) &(g->a_buf[MILTER_LEN_BYTES]),
		      MILTER_LEN_BYTES);
	v = ntohl(i);

	/* no flags? set to default value for V1 actions */
	if (v == 0)
		v = SMFI_V1_ACTS;
	i = g->a_ctx->ctx_smfi->xxfi_flags;
	if ((v & i) != i)
	{
		smi_log(SMI_LOG_ERR,
			"%s: st_optionneg[%d]: 0x%x does not fulfill action requirements 0x%x",
			g->a_ctx->ctx_smfi->xxfi_name,
			(int) g->a_ctx->ctx_id, v, i);
		return _SMFIS_ABORT;
	}

	(void) memcpy((void *) &i, (void *) &(g->a_buf[MILTER_LEN_BYTES * 2]),
		      MILTER_LEN_BYTES);
	v = ntohl(i);

	/* no flags? set to default value for V1 protocol */
	if (v == 0)
		v = SMFI_V1_PROT;
	i = g->a_ctx->ctx_pflags;
	if ((v & i) != i)
	{
		smi_log(SMI_LOG_ERR,
			"%s: st_optionneg[%d]: 0x%x does not fulfill protocol requirements 0x%x",
			g->a_ctx->ctx_smfi->xxfi_name,
			(int) g->a_ctx->ctx_id, v, i);
		return _SMFIS_ABORT;
	}

	return _SMFIS_OPTIONS;
}
/*
**  ST_CONNECTINFO -- receive connection information
**
**	Parameters:
**		g -- generic argument structure
**
**	Returns:
**		continue or filter-specified value
*/

static int
st_connectinfo(g)
	genarg *g;
{
	size_t l;