/*
 * Copyright (c) 2004, Stefan Walter
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above
 *       copyright notice, this list of conditions and the
 *       following disclaimer.
 *     * 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.
 *     * The names of contributors to this software may not 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.
 *
 *
 * CONTRIBUTORS
 *  Stef Walter <stef@memberwebs.com>
 *
 */

#ifndef __SMTPPASS_H__
#define __SMTPPASS_H__

/* Forward declarations */
struct sockaddr_any;
struct spctx;

/* -----------------------------------------------------------------------------
 * BUFFERED MULTIPLEXING IO
 *
 * This isn't meant to be a replacement library for all sorts of IO
 * only things that are currently used go here.
 */

/*
 * A generous maximum line length. It needs to be longer than
 * a full path on this system can be, because we pass the file
 * name to clamd.
 */

#if 2000 > MAXPATHLEN
    #define SP_LINE_LENGTH 2000
#else
    #define SP_LINE_LENGTH (MAXPATHLEN + 128)
#endif

typedef struct spio
{
    int fd;                             /* The file descriptor wrapped */
    const char* name;                   /* The name for logging */
    time_t last_action;                 /* Time of last action on descriptor */
    char peername[MAXPATHLEN];          /* Name of the peer on other side of socket */
    char localname[MAXPATHLEN];         /* Address where we accepted the connection */

    /* Internal use only */
    char line[SP_LINE_LENGTH];
    char* _nx;
    size_t _ln;
}
spio_t;

#define spio_valid(io)      ((io) && (io)->fd != -1)

/* Setup the io structure (allocated elsewhere) */
void spio_init(spio_t* io, const char* name);

/* Attach an open descriptor to a socket, optionally returning the peer */
void spio_attach(struct spctx* ctx, spio_t* io, int fd, struct sockaddr_any* peer);

/* Connect and disconnect from sockets */
int  spio_connect(struct spctx* ctx, spio_t* io, const struct sockaddr_any* sdst,
                  const char* dstname, const struct sockaddr_any* ssrc, const char* srcname);
void spio_disconnect(struct spctx* ctx, spio_t* io);

#define SPIO_TRIM           0x00000001
#define SPIO_DISCARD        0x00000002
#define SPIO_QUIET          0x00000004

/* Read a line from a socket. Use options above. Line
 * will be found in io->line */
int spio_read_line(struct spctx* ctx, spio_t* io, int opts);

/* Write data to socket (must supply line endings if needed).
 * Guaranteed to accept all data or fail. */
int spio_write_data(struct spctx* ctx, spio_t* io, const char* data);
int spio_write_dataf(struct spctx* ctx, spio_t* io, const char* fmt, ...);
int spio_write_data_raw(struct spctx* ctx, spio_t* io, const unsigned char* buf, int len);

/* Empty the given socket */
void spio_read_junk(struct spctx* sp, spio_t* io);

/* Pass up to 31 spio_t*, followed by NULL. Returns bitmap of ready for reading */
unsigned int  spio_select(struct spctx* ctx, ...);


/* -----------------------------------------------------------------------------
 * SMTP PASS THROUGH FUNCTIONALITY
 */

/* Log lines have to be under roughly 900 chars otherwise
 * they get truncated by syslog. */
#define SP_LOG_LINE_LEN  768

typedef struct spctx
{
    unsigned int id;                /* Identifier for the connection */

    spio_t client;                  /* Connection to client */
    spio_t server;                  /* Connection to server */

    FILE* cachefile;                /* The file handle for the cached file */
    char cachename[MAXPATHLEN];     /* The name of the file that we cache into */
    char logline[SP_LOG_LINE_LEN];  /* Log line */

    char* sender;                   /* The email of the sender */
    char* recipients;               /* The email of the recipients */
    char* xforwardaddr;             /* The IP address proxied for */
    char* xforwardhelo;             /* The HELO/EHLO proxied for */
    int authenticated;              /* Whether the client authenticated successfully */

    int _crlf;                      /* Private data */
}
spctx_t;

/*
 * sp_init initializes the SMTP Pass-Through functionality
 * The name passed is the name of the app
 */
void sp_init(const char* name);

/*
 * This starts up the smtp pass thru program. It will call
 * the cb_* functions as appropriate.
 */
int sp_run(const char* configfile, const char* pidfile, int dbg_level);

/*
 * Mark the application as shutting down.
 * A signal will interupt most IO.
 */
void sp_quit();

/*
 * Check if the application has been marked to quit.
 * Useful for checking after interupted IO.
 */
int sp_is_quit();

/*
 * Called to cleanup SMTP Pass-Through functionality just
 * before the application quits.
 */
void sp_done();

/*
 * clamsmtpd used to accept command line args. In order to
 * process those args it needs to send the values to the
 * config file routines. This is how it does that.
 */
#ifdef SP_LEGACY_OPTIONS
int sp_parse_option(const char* name, const char* option);
#endif


/*
 * The following functions are to be called from within
 * the spc_check_data function.
 */

/*
 * Adds a piece of info to the log line
 */
void sp_add_log(spctx_t* ctx, char* prefix, char* line);

/*
 * Tells client to start sending data. Sends appropriate
 * response code.
 */
int sp_start_data(spctx_t* ctx);

/*
 * Reads a line of DATA from client. Or less than a line if
 * line is longer than LINE_LENGTH. No trimming or anything
 * is done on the read line. This will end automatically
 * when <CRLF>.<CRLF> is detected (in which case 0 will
 * be returned). The data is returned in data.
 */
int sp_read_data(spctx_t* ctx, const char** data);

/*
 * Writes a line (or piece) of data to a file buffer which is
 * later sent to the client using sp_done_data. Calling it with
 * a NULL buffer closes the cache file. Guaranteed to accept
 * all data given to it or fail.
 */
int sp_write_data(spctx_t* ctx, const char* buf, int buflen);

/*
 * Sends all DATA from the client into the cache. The cache
 * file is then available (in spctx_t->cachename) for use.
 */
int sp_cache_data(spctx_t* ctx);

/*
 * Sends the data in file buffer off to server. This is
 * completes a successful mail transfer.
 */
int sp_done_data(spctx_t* ctx, const char *header);

/*
 * Fails the data, deletes any temp data, and sends given
 * status to client or if NULL then SMTP_DATAFAILED
 */
int sp_fail_data(spctx_t* ctx, const char* smtp_status);

/*
 * Helper method to pass through the entire DATA part of
 * the email to the server. No processing is done, and no
 * other sp_xxxx_data() calls are necessary.
 */
int sp_pass_data(spctx_t* ctx);

/*
 * Just sends a failure message to the client.
 */
int sp_fail_msg(spctx_t* ctx, const char* smtp_status);

/*
 * Setup the environment with context info. This is useful
 * if you're going to fork another process. Be sure to exec
 * soon after to prevent the strings from going out of scope.
 */
void sp_setup_forked(spctx_t* ctx, int file);

/*
 * Log a message. levels are syslog levels. Syntax is just
 * like printf etc.. Can specify a ctx of NULL in which case
 * no connection prefix is prepended.
 */
void sp_message(spctx_t* ctx, int level, const char* msg, ...);
void sp_messagex(spctx_t* ctx, int level, const char* msg, ...);

/*
 * Lock or unlock the main mutex around thread common
 * functionality.
 */
void sp_lock();
void sp_unlock();


/* -----------------------------------------------------------------------------
 * CALLBACKS IMPLMEMENTED BY PROGRAM
 */

/*
 * The following functions create and destroy contexts for a new
 * thread. Perform initialization in there and return a spctx
 * structure for the thread to use. Return NULL failed. Be sure
 * to log message.
 */
extern spctx_t* cb_new_context();
extern void cb_del_context(spctx_t* ctx);

/*
 * Called when an email envelope is staring to be sent.
 * If this function returns a string, it is used as a failure
 * message.
 */
extern int cb_check_pre(spctx_t* ctx);

/*
 * Called when the data section of an email is being transferred.
 * Once inside this function you can transfer files using
 * sp_read_data, sp_write_data.
 *
 * After scanning or figuring out the status call either
 * sp_done_data or sp_fail_data. Most failures should be handled
 * internally using sp_fail_data, unless it's an out of memory
 * condition, or sp_fail_data failed.
 */
extern int cb_check_data(spctx_t* ctx);

/*
 * Parse options from the config file. The memory for these
 * options will stay around until sp_done is called. Return 0
 * for unrecognized options, 1 for recognized, and quit the
 * program for invalid.
 */
extern int cb_parse_option(const char* name, const char* value);


#endif /* __SMTPPASS_H__ */