//
// based on source code from http://www.ols.es/exim/dlext/ by David Saez <david@ols.es>,
// and local_scan.c from Yandex spamoborona http://so.yandex.ru
//
//	warn	set acl_m0	= ${dlfunc{/usr/local/libexec/exim/exim-dlfunc.so}{spamoborona}\
//				{/var/run/sp-daemon.sock}{defer_ok}}
//

//#include "local_scan.h"
//#include "macros.h"
#include "exim.h"

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/un.h>
#include <stdarg.h>
#include <errno.h>

//#define SO_TIMEOUT		120
#define READ_FAIL(x)    ((x) < 0)
#define MAX_SIZE_SO	64 * 1024
#define SO_FAILURE_HDR 	"X-SO-Flag"
#define ERR_WRITE	53
#define ERR_READ	54

extern uschar *tod_stamp(int);

const char temp_dir[] = "/var/spool/spamooborona";

//-------------------------------------------------------------------------

int FakeSMTPCommand (int sock, char *command, char *value) {
    char sCommand[1024];
    char answ [3];
    int  Len;

    sprintf(sCommand, "%s %s", command, value);

debug_printf("Send to socket >> %s\n", sCommand);
    if (send(sock, sCommand, strlen(sCommand), 0) != (int)strlen(sCommand)) {
	log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: socket sending '%s' error %d", sCommand, errno);
//	*yield = string_sprintf("so dlfunc: DEFER: socket sending '%s' error %d", sCommand, errno);
        return ERR_WRITE;
    }

    memset(answ, '\0', sizeof (answ));
    Len = read(sock, answ, sizeof(answ));
    if (READ_FAIL(Len)) {
	log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: read() error %d, len=%d", errno, Len);
//	*yield = string_sprintf("so dlfunc: DEFER: read() error %d, len=%d", errno, Len);
        return ERR_WRITE;
    }
debug_printf("Read from to socket << %s\n", answ);

    if (strncmp (answ, "OK", 2) != 0) {
	log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: server did not confirm, answ=%s", answ);
//	*yield = string_sprintf("so dlfunc: DEFER: server did not confirm, answ=%s", answ);
        return ERR_WRITE;	// Cannot read message error code
    }

    return OK;
}

//-------------------------------------------------------------------------

char *read_response(FILE *daemon_file, char *daemon_buffer, int daemon_buffer_size, int timeout) {
    char *rc;
    int save_errno;

    daemon_buffer[0] = 0;		// In case nothing gets read
    sigalrm_seen = FALSE;
    alarm(timeout);
    rc = Ufgets(daemon_buffer, daemon_buffer_size, daemon_file);
    save_errno = errno;
    alarm(0);
    errno = save_errno;
    return(rc);
}

//-------------------------------------------------------------------------

int spamoborona(uschar **yield, int argc, uschar *argv[]) {
    char	*arg_socket_addr;
    char	*arg_defer_ok;
    int		defer_ok;

    int		so_sock = 0;
    FILE	*so_file = NULL;
    char	mbox_path[512];
    int		mbox_created = 0;
    int		mbox_file = -1;
    FILE	*spool_file = NULL;
    char	spool_path[512];
    static int	miRand = 1;
    uschar	*s;
    header_line *my_header, *header_new, *header_last, *tmp_headerlist;
    header_line *last_received = NULL;
    uschar	*str;
    struct	sockaddr_un server;
    uschar	so_buffer[32600];
    uschar      *address;
    int		i, rejected;
    char	RejectStr[4096];
    int		offset, read_count, wrote_count;

    arg_socket_addr = argv[0];
    arg_defer_ok = argv[1];

    if (argc < 2) {
	defer_ok = 0;
    } else if (
	    (strcmpic(arg_defer_ok,US"1") == 0)
	|| (strcmpic(arg_defer_ok,US"yes") == 0)
	|| (strcmpic(arg_defer_ok,US"true") == 0)
	|| (strcmpic(arg_defer_ok,US"defer_ok") == 0)
	) {
	defer_ok = 1;
    } else {
	defer_ok = 0;
    }
debug_printf("  defer_ok: %d\n", defer_ok);

    if (argc < 1) {
	log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: Bad number of arguments: %d", argc);
	*yield = string_sprintf("so dlfunc: DEFER: Bad number of arguments: %d", argc);
	goto RETURN_DEFER;
    }

    if ((arg_socket_addr == NULL) || (arg_socket_addr[0] == 0)) {
	log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: Socket address expected");
	*yield = string_sprintf("so dlfunc: DEFER: Socket address expected");
	goto RETURN_DEFER;
    }

// get message body stream

    sprintf(spool_path, "%s/input/%s-D", spool_directory, message_id);
debug_printf("Open spool file: %s\n", spool_path);
    spool_file = fopen(spool_path, "rb");

    if (!spool_file) {
	log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: Unable to spool message");
	*yield = string_copy((uschar *)"so dlfunc: DEFER: Unable to spool message");
	return(defer_ok ? OK : ERROR);
    }

debug_printf("fseek %d, %d\n", SPOOL_DATA_START_OFFSET, SEEK_SET);
    (void)fseek(spool_file, SPOOL_DATA_START_OFFSET, SEEK_SET);

    for (i = 0; i < 10; i++) {
	sprintf(mbox_path, "%s/%s-%8.8d-%3.3d-%6.6d", temp_dir, message_id, getpid(), miRand++, time(NULL));

	umask ((mode_t) 0);
debug_printf("Create temporary file %s\n", mbox_path);
	if ((mbox_file = open(mbox_path, O_RDWR | O_EXCL | O_CREAT, 0666)) > 0) break;

	if (errno != EEXIST) {	/* Unexpected error */
debug_printf("Unable create temporary file: %d\n", errno);
	    log_write(0, LOG_MAIN|LOG_PANIC,
		"so dlfunc: Unable create temporary file %s: %d", mbox_path, errno);
	    *yield = string_sprintf("so dlfunc: DEFER: Unable create temporary file %s: %d", mbox_path, errno);
	    goto RETURN_DEFER;
	}

	/* Else, for some reason this file exists. Try again after a short sleep */
	sleep(1);
    }

    if (mbox_file <= 0) {
debug_printf("Unable create temporary file\n");
	    log_write(0, LOG_MAIN|LOG_PANIC,
		"so dlfunc: Unable create temporary file %s", mbox_path);
	    *yield = string_sprintf("so dlfunc: DEFER: Unable create temporary file %s", mbox_path);
	    goto RETURN_DEFER;
    }

    address = expand_string(US"${sender_address}");
    if (address && *address) {
	s = string_sprintf("Return-path: <%s>\n", address);
debug_printf("Write to temporary file: %s", s);
	if (write(mbox_file, s, strlen(s)) != strlen(s))
	    goto FILE_WRITE_FAILED;
    }

//    address = expand_string(US"${if def:received_for{$received_for}}");
    address = expand_string(US"${received_for}");
    if (!address || !*address) address = expand_string(US"${recipients}");
    if (!address || !*address) address = expand_string(US"${local_part}@${domain}");
    if (address && *address) {
	s = string_sprintf("Envelope-To: %s\n", address);
debug_printf("Write to temporary file: %s", s);
	if (write(mbox_file, s, strlen(s)) != strlen(s))
	    goto FILE_WRITE_FAILED;
    }

    s = string_sprintf("Delivery-date: %s\n", tod_stamp(tod_full));
debug_printf("Write to temporary file: %s", s);
    if (write(mbox_file, s, strlen(s)) != strlen(s))
        goto FILE_WRITE_FAILED;

    // create a copy of original headers list
    tmp_headerlist = NULL;
    header_last = NULL;
    for (my_header = header_list; my_header; my_header = my_header->next) {
	if ((my_header->type != '*') && (my_header->type != htype_old)) {

	    header_new = store_get(sizeof(header_line));
	    header_new->text = string_copyn(my_header->text, my_header->slen);
	    header_new->slen = my_header->slen;
	    header_new->type = my_header->type;
	    header_new->next = NULL;
//debug_printf("  create a copy of header item: '%s'\n", header_new->text);

	    if (tmp_headerlist == NULL) tmp_headerlist = header_new;
	    if (header_last != NULL) header_last->next = header_new;
	    header_last = header_new;
	}
    }

    // headers removed by acl_check_data
    if (acl_removed_headers != NULL) {
	for (my_header = tmp_headerlist; my_header != NULL; my_header = my_header->next) {
	    uschar *list;

	    list = acl_removed_headers;

	    int sep = ':';         // This is specified as a colon-separated list
	    uschar buffer[128];
	    while ((str = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL) {
		int len = Ustrlen(str);
		if (header_testname(my_header, str, len, FALSE)) {
//debug_printf("  header removed by acl_check_data: '%s'; '%s'\n", s, my_header->text);
		    my_header->type = htype_old;
		}
	    }
	}
    }

    // headers added by acl_check_data
    my_header = acl_added_headers;
    while (my_header != NULL) {
//debug_printf("  header added by acl_check_data: '%s'\n", my_header->text);

	header_new = store_get(sizeof(header_line));
	header_new->text = string_copyn(my_header->text, my_header->slen);
	header_new->slen = my_header->slen;

	switch(my_header->type) {
	case htype_add_top:
	// add header at top
	    header_new->next = tmp_headerlist;
	    tmp_headerlist = header_new;
	    break;

	case htype_add_rec:
	// add header after Received:
	    if (last_received == NULL) {
    	        last_received = tmp_headerlist;
    	        while (!header_testname(last_received, US"Received", 8, FALSE))
    		    last_received = last_received->next;
    		while (last_received->next != NULL && header_testname(last_received->next, US"Received", 8, FALSE))
    		    last_received = last_received->next;
    	    }
	    header_new->next = last_received->next;
	    last_received->next = header_new;
	    break;

	case htype_add_rfc:
	// add header before any header which is NOT Received: or Resent-
	    last_received = tmp_headerlist;
	    while ( (last_received->next != NULL) &&
            ( (header_testname(last_received->next, US"Received", 8, FALSE)) ||
              (header_testname_incomplete(last_received->next, US"Resent-", 7, FALSE)) ) )
        	last_received = last_received->next;
	// last_received now points to the last Received: or Resent-* header
	// in an uninterrupted chain of those header types (seen from the beginning
	// of all headers. Our current header must follow it.
	    header_new->next = last_received->next;
	    last_received->next = header_new;
	    break;

	default:
	// htype_add_bot
	// add header at bottom
	    header_new->next = NULL;
	    header_last->next = header_new;
	    break;
	}

	if (header_new->next == NULL) header_last = header_new;

	my_header = my_header->next;
    }

    for (my_header = tmp_headerlist; my_header; my_header = my_header->next) {
	if (my_header->type != '*') {
debug_printf("Write to temporary file: %s", my_header->text);
	    if (write(mbox_file, my_header->text, my_header->slen) != my_header->slen)
    		goto FILE_WRITE_FAILED;
	}
    }

    s = string_sprintf("\r\n");
debug_printf("Write to temporary file: %s", s);
    if (write(mbox_file, s, strlen(s)) != strlen(s))
        goto FILE_WRITE_FAILED;

debug_printf("Headers wrote\n");

    do {
        read_count = fread(so_buffer, 1, sizeof(so_buffer) - 1, spool_file);
	so_buffer[read_count] = 0;
//debug_printf("Read %d bytes from file: %s", read_count, so_buffer);
debug_printf("Read %d bytes from spool file\n", read_count);
        if (read_count > 0) {
	    offset = 0;
//debug_printf("Write %d bytes to temporary file\n", wrote_count, so_buffer);
again:
	    wrote_count = write(mbox_file, so_buffer + offset, read_count - offset);
debug_printf("Wrote %d bytes to temporary file\n", wrote_count);
	    if (wrote_count == -1) goto FILE_WRITE_FAILED;
	    if (offset + wrote_count < read_count) {
	        offset += wrote_count;
	        goto again;
	    }
	}
    } while (!feof(spool_file) && !ferror(spool_file));

    if (ferror(spool_file)) {
        log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: error reading spool file: %s", strerror(errno));
	*yield = string_sprintf("so dlfunc: error reading spool file: %s", strerror(errno));
	goto RETURN_DEFER;
    }

debug_printf("Save temporary file: %s\n", mbox_path);
    (void)close(mbox_file);
    mbox_file = -1;
    mbox_created = 1;

debug_printf("Close spool file: %s\n", spool_path);
    (void)fclose(spool_file);
    spool_file = NULL;

    if ((so_sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
        log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: Unable to acquire socket (%s)", strerror(errno));
	*yield = string_sprintf("so dlfunc: DEFER: Unable to acquire socket (%s)", strerror(errno));
	goto RETURN_DEFER;
    }

    server.sun_family = AF_UNIX;
    if (Ustrlen(arg_socket_addr) > sizeof(server.sun_path) -1) {
        log_write(0, LOG_MAIN|LOG_PANIC,
	    "so dlfunc: UNIX socket name %s too long", arg_socket_addr);
	*yield = string_sprintf("so dlfunc: DEFER: UNIX socket name %s too long", arg_socket_addr);
	goto RETURN_DEFER;
    }
    Ustrcpy(server.sun_path, arg_socket_addr);

    if (connect(so_sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0) {
        log_write(0, LOG_MAIN|LOG_PANIC,
            "so dlfunc: Unable to connect to UNIX socket %s (%s)", socket, strerror(errno));
        *yield = string_sprintf("so dlfunc: DEFER: Unable to connect to UNIX socket %s (%s)", socket, strerror(errno));
        goto RETURN_DEFER;
    }
debug_printf("Use UNIX Domain socket %s\n", arg_socket_addr);

    so_file = fdopen(so_sock, "rb");

    // sender IP and hostname
    if (FakeSMTPCommand(so_sock, "CONNECT", (char *)expand_string(US"${sender_host_name} [${sender_host_address}]")) != OK)
        goto WRITE_FAILED;

    // envelope from
    address = expand_string(US"${sender_address}");
    if (FakeSMTPCommand(so_sock, "MAILFROM", ((address == NULL) || (strlen(address) == 0)) ? "MAILER-DAEMON" : (char *)address) != OK)
        goto WRITE_FAILED;

    // envelope rcpto
    for (i = 0; i < recipients_count; i++) {
        if (FakeSMTPCommand(so_sock, "RCPTTO", recipients_list[i].address) != OK)
    	    goto WRITE_FAILED;
    }

    if (FakeSMTPCommand(so_sock, "DATA", mbox_path) != OK)
        goto WRITE_FAILED;
        
    if (FakeSMTPCommand(so_sock, ".", "") != OK)
        goto WRITE_FAILED;

    memset (so_buffer, '\0', sizeof(so_buffer));

    {
        int Len;
	int answer_size;
	char answ[4096];
	char *strP, *tok, *tmp, *tmp2;

	memset (RejectStr, '\0', sizeof(RejectStr));

	Len = read(so_sock, answ, sizeof(answ) - 1);
debug_printf("Read from socket: %s\n", answ);

	if (strncmp(answ, "SODAEMON ", 9) == 0) {
    	    strP = (char *)answ;
    	    for (tok = (char *)strtok (strP, "\n"); tok; tok = (char *)strtok (NULL, "\n")) {
        	// signature always goes first
        	if (strncmp (tok, "SODAEMON ", 9) == 0) {
            	    if (sscanf (tok, "%*s %d", &answer_size) == 1) {
                	if (answer_size == 0) { // empty reply
debug_printf("Zero answer size, check skiped\n");
		    	    Ustrcpy(so_buffer + Ustrlen(so_buffer), SO_FAILURE_HDR);
		    	    Ustrcpy(so_buffer + Ustrlen(so_buffer), ": SKIP\n");
			    goto RETURN_OK;
                	} else {
                    	    if (answer_size > sizeof (answ) - 1) {
debug_printf("daemon answer too long (%d bytes)\n", answer_size);
    				log_write(0, LOG_MAIN|LOG_PANIC,
        			    "so dlfunc: daemon answer too long (%d bytes)", answer_size);
    				*yield = string_sprintf("so dlfunc: DEFER: daemon answer too long (%d bytes)", answer_size);
    				goto RETURN_DEFER;
			    }
			}
            	    }
            	    continue;
        	}

        	// reject or accept flag
        	if (strncmp (tok, "REJECT ", 7) == 0) {
            	    sscanf (tok, "%*s %d", &rejected);

            	    continue;
        	}

        	// reject string
        	if (strncmp (tok, "REJECTSTR ", 10) == 0) {
		    if (rejected) {
            		tmp = strchr(tok, ' ');
			tmp2 = tmp;
			if ((tmp2 != NULL) && (tmp2[0] == ' ')) tmp2++;
			if ((tmp2 == NULL) || (Ustrlen(tmp2) == 0)) {
			    Ustrcpy(RejectStr, "Spam message rejected");
			} else {
			    Ustrcpy(RejectStr, tmp2);
			}
		    }
               
            	    continue;
        	}
        	// spam flag
        	if (strncmp (tok, "SPAM ", 5) == 0) {

            	    continue;
        	}

        	// spam label
        	if (strncmp (tok, "SPAMSTR ", 8) == 0) {
                    
            	    continue;
        	}

		Ustrcpy(so_buffer + Ustrlen(so_buffer), tok);
		Ustrcpy(so_buffer + Ustrlen(so_buffer), "\n");
    	    }
	} else {
    	    log_write(0, LOG_MAIN|LOG_PANIC,
        	"so dlfunc: wrong signature in answer: %s", answ);
    	    *yield = string_sprintf("so dlfunc: DEFER: wrong signature in answer: %s", answ);
    	    goto RETURN_DEFER;
	}
    }

    goto RETURN_OK;

FILE_WRITE_FAILED:
{
    log_write(0, LOG_MAIN|LOG_PANIC,
	"so dlfunc: Unable to write to temporary file %s", mbox_path);
    *yield = string_sprintf("so dlfunc: DEFER: Unable to write to temporary file %s", mbox_path);
    goto RETURN_DEFER;
}

WRITE_FAILED:
{
//    log_write(0, LOG_MAIN|LOG_PANIC,
//	"so dlfunc: %s on so socket", strerror(errno));
    *yield = string_sprintf("so dlfunc: DEFER: %s on so socket", strerror(errno));
    goto RETURN_DEFER;
}

RESPONSE_FAILED:
{
    int code;
    int save_errno;
    int more_errno;
    uschar message_buffer[256];
    uschar *message;

    save_errno = errno;

    message = &message_buffer[0];

    log_write(0, LOG_MAIN|LOG_PANIC, "so dlfunc: %s", message);
    *yield = string_sprintf("so dlfunc: DEFER: %s", message);

    goto RETURN_DEFER;
}

RETURN_DEFER:
{
    if (so_file > 0) (void)fclose(so_file);
    if (so_sock > 0) (void)close(so_sock);
    if (spool_file > 0) (void)fclose(spool_file);
    if (mbox_file > 0) {
	(void)close(mbox_file);
	mbox_file = -1;
    }
    if (mbox_created > 0) {
debug_printf("Remove temporary file %s\n", mbox_path);
	unlink(mbox_path);
	mbox_created = 0;
    }

    if ((*yield == NULL) || (*yield[0] == '\0'))
	*yield = string_sprintf("so dlfunc: DEFER");

    return(defer_ok ? OK : ERROR);
}

RETURN_OK:
{
    if (so_file > 0) (void)fclose(so_file);
    if (so_sock > 0) (void)close(so_sock);
    if (spool_file > 0) (void)fclose(spool_file);
    if (mbox_file > 0) {
	(void)close(mbox_file);
	mbox_file = -1;
    }
    if (mbox_created > 0) {
debug_printf("Remove temporary file %s\n", mbox_path);
	unlink(mbox_path);
	mbox_created = 0;
    }

    if (rejected) {
	*yield = string_sprintf("so dlfunc: REJECT: %s\n%s", RejectStr, so_buffer);
    } else {
	*yield = string_sprintf("so dlfunc: ACCEPT\n%s", so_buffer);
    }
//    if ((*yield == NULL) || (*yield[0] == '\0'))
//	*yield = string_sprintf("so dlfunc: ACCEPT");

    return OK;
}

    return OK;
}