/*

 * imap.c -- IMAP2bis/IMAP4 protocol methods

 *

 * Copyright 1997 by Eric S. Raymond

 * For license terms, see the file COPYING in this directory.

 */

#include  "config.h"

#include  <stdio.h>

#include  <string.h>

#include  <strings.h>

#include  <ctype.h>

#if defined(STDC_HEADERS)

#include  <stdlib.h>

#include  <limits.h>

#include  <errno.h>

#endif

#include  "fetchmail.h"

#include  "socket.h"

#include  "i18n.h"

/* imap_version values */

#define IMAP2		-1	/* IMAP2 or IMAP2BIS, RFC1176 */

#define IMAP4		0	/* IMAP4 rev 0, RFC1730 */

#define IMAP4rev1	1	/* IMAP4 rev 1, RFC2060 */

/* global variables: please reinitialize them explicitly for proper

 * working in daemon mode */

/* TODO: session variables to be initialized before server greeting */

static int preauth = FALSE;

/* session variables initialized in capa_probe() or imap_getauth() */

static char capabilities[MSGBUFSIZE+1];

static int imap_version = IMAP4;

static flag do_idle = FALSE, has_idle = FALSE;

static int expunge_period = 1;

/* mailbox variables initialized in imap_getrange() */

static int count = 0, oldcount = 0, recentcount = 0, unseen = 0, deletions = 0;

static unsigned int startcount = 1;

static int expunged = 0;

static unsigned int *unseen_messages;

/* for "IMAP> EXPUNGE" */

static int actual_deletions = 0;

/* for "IMAP> IDLE" */

static int saved_timeout = 0, idle_timeout = 0;

static time_t idle_start_time = 0;

static int imap_untagged_response(int sock, const char *buf)

/* interpret untagged status responses */

{

    /* For each individual check, use a BLANK before the word to avoid

     * confusion with the \Recent flag or similar */

    if (stage == STAGE_GETAUTH

	    && !strncmp(buf, "* CAPABILITY", 12))

    {

	strlcpy(capabilities, buf + 12, sizeof(capabilities));

    }

    else if (stage == STAGE_GETAUTH

	    && !strncmp(buf, "* PREAUTH", 9))

    {

	preauth = TRUE;

    }

    else if (stage != STAGE_LOGOUT

	    && !strncmp(buf, "* BYE", 5))

    {

	/* log the unexpected bye from server as we expect the

	 * connection to be cut-off after this */

	if (outlevel > O_SILENT)

	    report(stderr, GT_("Received BYE response from IMAP server: %s"), buf + 5);

    }

    else if (strstr(buf, " EXISTS"))

    {

	char *t; unsigned long u;

	errno = 0;

	u = strtoul(buf+2, &t, 10);

	/*

	 * Don't trust the message count passed by the server.

	 * Without this check, it might be possible to do a

	 * DNS-spoofing attack that would pass back a ridiculous 

	 * count, and allocate a malloc area that would overlap

	 * a portion of the stack.

	 */

	if (errno /* strtoul failed */

		|| t == buf+2 /* no valid data */

		|| u > (unsigned long)(INT_MAX/sizeof(int)) /* too large */)

	{

	    report(stderr, GT_("bogus message count in \"%s\"!"), buf);

	    return(PS_PROTOCOL);

	}

	count = u; /* safe as long as count <= INT_MAX - checked above */

	if ((recentcount = count - oldcount) < 0)

	    recentcount = 0;

	/*

	 * Nasty kluge to handle RFC2177 IDLE.  If we know we're idling

	 * we can't wait for the tag matching the IDLE; we have to tell the

	 * server the IDLE is finished by shipping back a DONE when we

	 * see an EXISTS.  Only after that will a tagged response be

	 * shipped.  The idling flag also gets cleared on a timeout.

	 */

	if (stage == STAGE_IDLE)

	{

	    /* If IDLE isn't supported, we were only sending NOOPs anyway. */

	    if (has_idle)

	    {

		/* we do our own write and report here to disable tagging */

		SockWrite(sock, "DONE\r\n", 6);

		if (outlevel >= O_MONITOR)

		    report(stdout, "IMAP> DONE\n");

	    }

	    mytimeout = saved_timeout;

	    stage = STAGE_GETRANGE;

	}

    }

    /* we now compute recentcount as a difference between

     * new and old EXISTS, hence disable RECENT check */

# if 0

    else if (strstr(buf, " RECENT"))

    {

	/* fixme: use strto[u]l and error checking */

	recentcount = atoi(buf+2);

    }

# endif

    else if (strstr(buf, " EXPUNGE"))

    {

	unsigned long u; char *t;

	/* the response "* 10 EXPUNGE" means that the currently

	 * tenth (i.e. only one) message has been deleted */

	errno = 0;

	u = strtoul(buf+2, &t, 10);

	if (errno /* conversion error */ || t == buf+2 /* no number found */) {

	    report(stderr, GT_("bogus EXPUNGE count in \"%s\"!"), buf);

	    return PS_PROTOCOL;

	}

	if (u > 0)

	{

	    if (count > 0)

		count--;

	    if (oldcount > 0)

		oldcount--;

	    /* We do expect an EXISTS response immediately

	     * after this, so this updation of recentcount is

	     * just a precaution! */

	    if ((recentcount = count - oldcount) < 0)

		recentcount = 0;

	    actual_deletions++;

	}

    }

    /*

     * The server may decide to make the mailbox read-only, 

     * which causes fetchmail to go into a endless loop

     * fetching the same message over and over again. 

     * 

     * However, for check_only, we use EXAMINE which will

     * mark the mailbox read-only as per the RFC.

     * 

     * This checks for the condition and aborts if 

     * the mailbox is read-only. 

     *

     * See RFC 2060 section 6.3.1 (SELECT).

     * See RFC 2060 section 6.3.2 (EXAMINE).

     */ 

    else if (stage == STAGE_GETRANGE

	    && !check_only && strstr(buf, "[READ-ONLY]"))

    {

	return(PS_LOCKBUSY);

    }

    else

    {

	return(PS_UNTAGGED);

    }

    return(PS_SUCCESS);

}

static int imap_response(int sock, char *argbuf, struct RecvSplit *rs)

/* parse command response */

{

    char buf[MSGBUFSIZE+1];

    do {

	int	ok;

	char	*cp;

	if (rs)

	    ok = gen_recv_split(sock, buf, sizeof(buf), rs);

	else

	    ok = gen_recv(sock, buf, sizeof(buf));

	if (ok != PS_SUCCESS)

	    return(ok);

	/* all tokens in responses are caseblind */

	for (cp = buf; *cp; cp++)

	    if (islower((unsigned char)*cp))

		*cp = toupper((unsigned char)*cp);

	/* untagged responses start with "* " */

	if (buf[0] == '*' && buf[1] == ' ') {

	    ok = imap_untagged_response(sock, buf);

	    if (ok == PS_UNTAGGED)

	    {

		if (argbuf && stage != STAGE_IDLE && tag[0] != '\0')

		{

		    /* if there is an unmatched response, pass it back to

		     * the calling function for further analysis. The

		     * calling function should call imap_response() again

		     * to read the remaining response */

		    strcpy(argbuf, buf);

		    return(ok);

		}

	    }

	    else if (ok != PS_SUCCESS)

		return(ok);

	}

	if (stage == STAGE_IDLE)

	{

	    /* reduce the timeout: servers may not reset their timeout

	     * when they send some information asynchronously */

	    mytimeout = idle_timeout - (time((time_t *) NULL) - idle_start_time);

	    if (mytimeout <= 0)

		return(PS_IDLETIMEOUT);

	}

    } while

	(tag[0] != '\0' && strncmp(buf, tag, strlen(tag)));

    if (tag[0] == '\0')

    {

	if (argbuf)

	    strcpy(argbuf, buf);

	return(PS_SUCCESS); 

    }

    else

    {

	char	*cp;

	/* skip the tag */

	for (cp = buf; !isspace((unsigned char)*cp); cp++)

	    continue;

	while (isspace((unsigned char)*cp))

	    cp++;

        if (strncasecmp(cp, "OK", 2) == 0)

	{

	    if (argbuf)

		strcpy(argbuf, cp);

	    return(PS_SUCCESS);

	}

	else if (strncasecmp(cp, "BAD", 3) == 0)

	    return(PS_ERROR);

	else if (strncasecmp(cp, "NO", 2) == 0)

	{

	    if (stage == STAGE_GETAUTH) 

		return(PS_AUTHFAIL);	/* RFC2060, 6.2.2 */

	    else if (stage == STAGE_GETSIZES)

		return(PS_SUCCESS);	/* see comments in imap_getpartialsizes() */

	    else

		return(PS_ERROR);

	}

	else

	    return(PS_PROTOCOL);

    }

}

static int imap_ok(int sock, char *argbuf)

/* parse command response */

{

    int ok;

    while ((ok = imap_response(sock, argbuf, NULL)) == PS_UNTAGGED)

	; /* wait for the tagged response */

    return(ok);

}

#ifdef NTLM_ENABLE

#include "ntlm.h"

/*

 * NTLM support by Grant Edwards.

 *

 * Handle MS-Exchange NTLM authentication method.  This is the same

 * as the NTLM auth used by Samba for SMB related services. We just

 * encode the packets in base64 instead of sending them out via a

 * network interface.

 * 

 * Much source (ntlm.h, smb*.c smb*.h) was borrowed from Samba.

 */

static int do_imap_ntlm(int sock, struct query *ctl)

{

    int result;

    gen_send(sock, "AUTHENTICATE NTLM");

    if ((result = ntlm_helper(sock, ctl, "IMAP")))

	return result;

    result = imap_ok (sock, NULL);

    if (result == PS_SUCCESS)

	return PS_SUCCESS;

    else

	return PS_AUTHFAIL;

}

#endif /* NTLM */

static void imap_canonicalize(char *result, char *raw, size_t maxlen)

/* encode an IMAP password as per RFC1730's quoting conventions */

{

    size_t i, j;

    j = 0;

    for (i = 0; i < strlen(raw) && i < maxlen; i++)

    {

	if ((raw[i] == '\\') || (raw[i] == '"'))

	    result[j++] = '\\';

	result[j++] = raw[i];

    }

    result[j] = '\0';

}

static int capa_probe(int sock, struct query *ctl)

/* set capability variables from a CAPA probe */

{

    int	ok;

    /* probe to see if we're running IMAP4 and can use RFC822.PEEK */

    capabilities[0] = '\0';

    if ((ok = gen_transact(sock, "CAPABILITY")) == PS_SUCCESS)

    {

	char	*cp;

	/* capability checks are supposed to be caseblind */

	for (cp = capabilities; *cp; cp++)

	    *cp = toupper((unsigned char)*cp);

	/* UW-IMAP server 10.173 notifies in all caps, but RFC2060 says we

	   should expect a response in mixed-case */

	if (strstr(capabilities, "IMAP4REV1"))

	{

	    imap_version = IMAP4rev1;

	    if (outlevel >= O_DEBUG)

		report(stdout, GT_("Protocol identified as IMAP4 rev 1\n"));

	}

	else

	{

	    imap_version = IMAP4;

	    if (outlevel >= O_DEBUG)

		report(stdout, GT_("Protocol identified as IMAP4 rev 0\n"));

	}

    }

    else if (ok == PS_ERROR)

    {

	imap_version = IMAP2;

	if (outlevel >= O_DEBUG)

	    report(stdout, GT_("Protocol identified as IMAP2 or IMAP2BIS\n"));

    }

    else

	return ok;

    /* 

     * Handle idling.  We depend on coming through here on startup

     * and after each timeout (including timeouts during idles).

     */

    do_idle = ctl->idle;

    if (ctl->idle)

    {

	if (strstr(capabilities, "IDLE"))

	    has_idle = TRUE;

	else

	    has_idle = FALSE;

	if (outlevel >= O_VERBOSE)

	    report(stdout, GT_("will idle after poll\n"));

    }

    peek_capable = (imap_version >= IMAP4);

    return PS_SUCCESS;

}

static int do_authcert (int sock, const char *command, const char *name)

/* do authentication "external" (authentication provided by client cert) */

{

    char buf[256];

    if (name && name[0])

    {

        size_t len = strlen(name);

        if ((len / 3) + ((len % 3) ? 4 : 0)  < sizeof(buf))

            to64frombits (buf, name, strlen(name));

        else

            return PS_AUTHFAIL; /* buffer too small. */

    }

    else

        buf[0]=0;

    return gen_transact(sock, "%s EXTERNAL %s",command,buf);

}

static int imap_getauth(int sock, struct query *ctl, char *greeting)

/* apply for connection authorization */

{

    int ok = 0;

    (void)greeting;

    /*

     * Assumption: expunges are cheap, so we want to do them

     * after every message unless user said otherwise.

     */

    if (NUM_SPECIFIED(ctl->expunge))

	expunge_period = NUM_VALUE_OUT(ctl->expunge);

    else

	expunge_period = 1;

    if ((ok = capa_probe(sock, ctl)))

	return ok;

    /* 

     * If either (a) we saw a PREAUTH token in the greeting, or

     * (b) the user specified ssh preauthentication, then we're done.

     */

    if (preauth || ctl->server.authenticate == A_SSH)

    {

        preauth = FALSE;  /* reset for the next session */

        return(PS_SUCCESS);

    }

#ifdef SSL_ENABLE

    if (maybe_tls(ctl)) {

	char *commonname;

	commonname = ctl->server.pollname;

	if (ctl->server.via)

	    commonname = ctl->server.via;

	if (ctl->sslcommonname)

	    commonname = ctl->sslcommonname;

	if (strstr(capabilities, "STARTTLS")

		|| must_tls(ctl)) /* if TLS is mandatory, ignore capabilities */

	{

	    /* Use "tls1" rather than ctl->sslproto because tls1 is the only

	     * protocol that will work with STARTTLS.  Don't need to worry

	     * whether TLS is mandatory or opportunistic unless SSLOpen() fails

	     * (see below). */

	    if (gen_transact(sock, "STARTTLS") == PS_SUCCESS

		    && (set_timeout(mytimeout), SSLOpen(sock, ctl->sslcert, ctl->sslkey, "tls1", ctl->sslcertck,

			ctl->sslcertfile, ctl->sslcertpath, ctl->sslfingerprint, commonname,

			ctl->server.pollname, &ctl->remotename)) != -1)

	    {

		/*

		 * RFC 2595 says this:

		 *

		 * "Once TLS has been started, the client MUST discard cached

		 * information about server capabilities and SHOULD re-issue the

		 * CAPABILITY command.  This is necessary to protect against

		 * man-in-the-middle attacks which alter the capabilities list prior

		 * to STARTTLS.  The server MAY advertise different capabilities

		 * after STARTTLS."

		 *

		 * Now that we're confident in our TLS connection we can

		 * guarantee a secure capability re-probe.

		 */

		if ((ok = capa_probe(sock, ctl)))

		    return ok;

		if (outlevel >= O_VERBOSE)

		{

		    report(stdout, GT_("%s: upgrade to TLS succeeded.\n"), commonname);

		}

	    } else if (must_tls(ctl)) {

		/* Config required TLS but we couldn't guarantee it, so we must

		 * stop. */

		set_timeout(0);

		report(stderr, GT_("%s: upgrade to TLS failed.\n"), commonname);

		return PS_SOCKET;

	    } else {

		set_timeout(0);

		if (outlevel >= O_VERBOSE) {

		    report(stdout, GT_("%s: opportunistic upgrade to TLS failed, trying to continue\n"), commonname);

		}

		/* We don't know whether the connection is in a working state, so

		 * test by issuing a NOOP. */

		if (gen_transact(sock, "NOOP") != PS_SUCCESS) {

		    /* Not usable.  Empty sslproto to force an unencrypted

		     * connection on the next attempt, and repoll. */

		    ctl->sslproto = xstrdup("");

		    return PS_REPOLL;

		}

		/* Usable.  Proceed with authenticating insecurely. */

	    }

	}

    }

#endif /* SSL_ENABLE */

    /*

     * Time to authenticate the user.

     * Try the protocol variants that don't require passwords first.

     */

    ok = PS_AUTHFAIL;

    /* Yahoo hack - we'll just try ID if it was offered by the server,

     * and IGNORE errors. */

    {

	char *tmp = strstr(capabilities, " ID");

	if (tmp && !isalnum((unsigned char)tmp[3]) && strstr(ctl->server.via ? ctl->server.via : ctl->server.pollname, "yahoo.com")) {

		(void)gen_transact(sock, "ID (\"guid\" \"1\")");

	}

    }

    if ((ctl->server.authenticate == A_ANY 

         || ctl->server.authenticate == A_EXTERNAL)

	&& strstr(capabilities, "AUTH=EXTERNAL"))

    {

        ok = do_authcert(sock, "AUTHENTICATE", ctl->remotename);

	if (ok)

        {

            /* SASL cancellation of authentication */

            gen_send(sock, "*");

            if (ctl->server.authenticate != A_ANY)

                return ok;

        } else {

            return ok;

	}

    }

#ifdef GSSAPI

    if (((ctl->server.authenticate == A_ANY && check_gss_creds("imap", ctl->server.truename) == PS_SUCCESS)

	 || ctl->server.authenticate == A_GSSAPI)

	&& strstr(capabilities, "AUTH=GSSAPI"))

    {

	if ((ok = do_gssauth(sock, "AUTHENTICATE", "imap",

			ctl->server.truename, ctl->remotename)))

	{

	    if (ctl->server.authenticate != A_ANY)

                return ok;

	} else  {

	    return ok;

	}

    }

#endif /* GSSAPI */

#ifdef KERBEROS_V4

    if ((ctl->server.authenticate == A_ANY 

	 || ctl->server.authenticate == A_KERBEROS_V4

	 || ctl->server.authenticate == A_KERBEROS_V5) 

	&& strstr(capabilities, "AUTH=KERBEROS_V4"))

    {

	if ((ok = do_rfc1731(sock, "AUTHENTICATE", ctl->server.truename)))

	{

	    /* SASL cancellation of authentication */

	    gen_send(sock, "*");

	    if(ctl->server.authenticate != A_ANY)

                return ok;

	}

	else

	    return ok;

    }

#endif /* KERBEROS_V4 */

    /*

     * No such luck.  OK, now try the variants that mask your password

     * in a challenge-response.

     */

    if ((ctl->server.authenticate == A_ANY && strstr(capabilities, "AUTH=CRAM-MD5"))

	|| ctl->server.authenticate == A_CRAM_MD5)

    {

	if ((ok = do_cram_md5 (sock, "AUTHENTICATE", ctl, NULL)))

	{

	    if(ctl->server.authenticate != A_ANY)

                return ok;

	}

	else

	    return ok;

    }

#ifdef OPIE_ENABLE

    if ((ctl->server.authenticate == A_ANY 

	 || ctl->server.authenticate == A_OTP)

	&& strstr(capabilities, "AUTH=X-OTP")) {

	if ((ok = do_otp(sock, "AUTHENTICATE", ctl)))

	{

	    /* SASL cancellation of authentication */

	    gen_send(sock, "*");

	    if(ctl->server.authenticate != A_ANY)

                return ok;

	} else {

	    return ok;

	}

    }

#else

    if (ctl->server.authenticate == A_OTP)

    {

	report(stderr, 

	   GT_("Required OTP capability not compiled into fetchmail\n"));

    }

#endif /* OPIE_ENABLE */

#ifdef NTLM_ENABLE

    if ((ctl->server.authenticate == A_ANY 

	 || ctl->server.authenticate == A_NTLM) 

	&& strstr (capabilities, "AUTH=NTLM")) {

	if ((ok = do_imap_ntlm(sock, ctl)))

	{

	    if(ctl->server.authenticate != A_ANY)

                return ok;

	}

	else

	    return(ok);

    }

#else

    if (ctl->server.authenticate == A_NTLM)

    {

	report(stderr, 

	   GT_("Required NTLM capability not compiled into fetchmail\n"));

    }

#endif /* NTLM_ENABLE */

#ifdef __UNUSED__	/* The Cyrus IMAP4rev1 server chokes on this */

    /* this handles either AUTH=LOGIN or AUTH-LOGIN */

    if ((imap_version >= IMAP4rev1) && (!strstr(capabilities, "LOGIN")))

    {

	report(stderr, 

	       GT_("Required LOGIN capability not supported by server\n"));

    }

#endif /* __UNUSED__ */

    /* 

     * We're stuck with sending the password en clair.

     * The reason for this odd-looking logic is that some

     * servers return LOGINDISABLED even though login 

     * actually works.  So arrange things in such a way that

     * setting auth passwd makes it ignore this capability.

     */

    if((ctl->server.authenticate==A_ANY&&!strstr(capabilities,"LOGINDISABLED"))

	|| ctl->server.authenticate == A_PASSWORD)

    {

	/* these sizes guarantee no buffer overflow */

	char *remotename, *password;

	size_t rnl, pwl;

	rnl = 2 * strlen(ctl->remotename) + 1;

	pwl = 2 * strlen(ctl->password) + 1;

	remotename = (char *)xmalloc(rnl);

	password = (char *)xmalloc(pwl);

	imap_canonicalize(remotename, ctl->remotename, rnl);

	imap_canonicalize(password, ctl->password, pwl);

	snprintf(shroud, sizeof (shroud), "\"%s\"", password);

	ok = gen_transact(sock, "LOGIN \"%s\" \"%s\"", remotename, password);

	memset(shroud, 0x55, sizeof(shroud));

	shroud[0] = '\0';

	memset(password, 0x55, strlen(password));

	free(password);

	free(remotename);

	if (ok)

	{

	    if(ctl->server.authenticate != A_ANY)

                return ok;

	}

	else

	    return(ok);

    }

    return(ok);

}

static int internal_expunge(int sock)

/* ship an expunge, resetting associated counters */

{

    int	ok;

    actual_deletions = 0;

    if ((ok = gen_transact(sock, "EXPUNGE")))

	return(ok);

    /* if there is a mismatch between the number of mails which should

     * have been expunged and the number of mails actually expunged,

     * another email client may be deleting mails. Quit here,

     * otherwise fetchmail gets out-of-sync with the imap server,

     * reports the wrong size to the SMTP server on MAIL FROM: and

     * triggers a "message ... was not the expected length" error on

     * every subsequent mail */

    if (deletions > 0 && deletions != actual_deletions)

    {

	report(stderr,

		GT_("mail expunge mismatch (%d actual != %d expected)\n"),

		actual_deletions, deletions);

	deletions = 0;

	return(PS_ERROR);

    }

    expunged += deletions;

    deletions = 0;

#ifdef IMAP_UID	/* not used */

    expunge_uids(ctl);

#endif /* IMAP_UID */

    return(PS_SUCCESS);

}

static int imap_idle(int sock)

/* start an RFC2177 IDLE, or fake one if unsupported */

{

    int ok;

    saved_timeout = mytimeout;

    if (has_idle) {

	/* special timeout to terminate the IDLE and re-issue it

	 * at least every 28 minutes:

	 * (the server may have an inactivity timeout) */

	mytimeout = idle_timeout = 1680; /* 28 min */

	time(&idle_start_time);

	stage = STAGE_IDLE;

	/* enter IDLE mode */

	ok = gen_transact(sock, "IDLE");

	if (ok == PS_IDLETIMEOUT) {

	    /* send "DONE" continuation */

	    SockWrite(sock, "DONE\r\n", 6);

	    if (outlevel >= O_MONITOR)

		report(stdout, "IMAP> DONE\n");

	    /* reset stage and timeout here: we are not idling any more */

	    mytimeout = saved_timeout;

	    stage = STAGE_GETRANGE;

	    /* get OK IDLE message */

	    ok = imap_ok(sock, NULL);

	}

    } else {  /* no idle support, fake it */

	/* Note: stage and timeout have not been changed here as NOOP

	 * does not idle */

	ok = gen_transact(sock, "NOOP");

	/* no error, but no new mail either */

	if (ok == PS_SUCCESS && recentcount == 0)

	{

	    /* There are some servers who do send new mail

	     * notification out of the blue. This is in compliance

	     * with RFC 2060 section 5.3. Wait for that with a low

	     * timeout */

	    mytimeout = idle_timeout = 28;

	    time(&idle_start_time);

	    stage = STAGE_IDLE;

	    /* We are waiting for notification; no tag needed */

	    tag[0] = '\0';

	    /* wait (briefly) for an unsolicited status update */

	    ok = imap_ok(sock, NULL);

	    if (ok == PS_IDLETIMEOUT) {

		/* no notification came; ok */

		ok = PS_SUCCESS;

	    }

	}

    }

    /* restore normal timeout value */

    set_timeout(0);

    mytimeout = saved_timeout;

    stage = STAGE_GETRANGE;

    return(ok);

}

static int imap_search(int sock, struct query *ctl, int count)

/* search for unseen messages */

{

    int ok;

    char buf[MSGBUFSIZE+1], *cp;

    /* Don't count deleted messages. Enabled only for IMAP4 servers or

     * higher and only when keeping mails. This flag will have an

     * effect only when user has marked some unread mails for deletion

     * using another e-mail client. */

    flag skipdeleted = (imap_version >= IMAP4) && ctl->keep;

    const char *undeleted;

    /* structure to keep the end portion of the incomplete response */

    struct RecvSplit rs;

    /* startcount is higher than count so that if there are no

     * unseen messages, imap_getsizes() will not need to do

     * anything! */

    startcount = count + 1;

    for (;;)

    {

	undeleted = (skipdeleted ? " UNDELETED" : "");

	gen_send(sock, "SEARCH UNSEEN%s", undeleted);

	gen_recv_split_init("* SEARCH", &rs);

	while ((ok = imap_response(sock, buf, &rs)) == PS_UNTAGGED)

	{

	    if ((cp = strstr(buf, "* SEARCH")))

	    {

		char	*ep;

		cp += 8;	/* skip "* SEARCH" */

		while (*cp && unseen < count)

		{

		    /* skip whitespace */

		    while (*cp && isspace((unsigned char)*cp))

			cp++;

		    if (*cp) 

		    {

			unsigned long um;

			errno = 0;

			um = strtoul(cp,&ep,10);

			if (errno == 0 && ep > cp

				&& um <= INT_MAX && um <= (unsigned)count)

			{

			    unseen_messages[unseen++] = um;

			    if (outlevel >= O_DEBUG)

				report(stdout, GT_("%lu is unseen\n"), um);

			    if (startcount > um)

				startcount = um;

			}

			cp = ep;

		    }

		}

	    }

	}

	if (ok != PS_ERROR) /* success or non-protocol error */

	    return(ok);

	/* there is a protocol error. try a different search command. */

	if (skipdeleted)

	{

	    /* retry with "SEARCH UNSEEN" */

	    skipdeleted = FALSE;

	    continue;

	}

	/* try with "FETCH 1:n FLAGS" */

	break;

    }

    if (count == 1)

	gen_send(sock, "FETCH %d FLAGS", count);

    else

	gen_send(sock, "FETCH %d:%d FLAGS", 1, count);

    while ((ok = imap_response(sock, buf, NULL)) == PS_UNTAGGED)

    {

	unsigned int num;

	int consumed;

	/* expected response format:

	 * IMAP< * 1 FETCH (FLAGS (\Seen))

	 * IMAP< * 2 FETCH (FLAGS (\Seen \Deleted))

	 * IMAP< * 3 FETCH (FLAGS ())

	 * IMAP< * 4 FETCH (FLAGS (\Recent))

	 * IMAP< * 5 FETCH (UID 10 FLAGS (\Recent))

	 */

	if (unseen < count

		&& sscanf(buf, "* %u %n", &num, &consumed) == 1

		&& 0 == strncasecmp(buf+consumed, "FETCH", 5)

		&& isspace((unsigned char)buf[consumed+5])

		&& num >= 1 && num <= (unsigned)count

		&& strstr(buf, "FLAGS ")

		&& !strstr(buf, "\\SEEN")

		&& !strstr(buf, "\\DELETED"))

	{

	    unseen_messages[unseen++] = num;

	    if (outlevel >= O_DEBUG)

		report(stdout, GT_("%u is unseen\n"), num);

	    if (startcount > num)

		startcount = num;

	}

    }

    return(ok);

}

static int imap_getrange(int sock, 

			 struct query *ctl, 

			 const char *folder, 

			 int *countp, int *newp, int *bytes)

/* get range of messages to be fetched */

{

    int ok;

    /* find out how many messages are waiting */

    *bytes = -1;

    if (pass > 1)

    {

	/* deleted mails have already been expunged by

	 * end_mailbox_poll().

	 *

	 * recentcount is already set here by the last imap command which

	 * returned EXISTS on detecting new mail. if recentcount is 0, wait

	 * for new mail.

	 *

	 * this is a while loop because imap_idle() might return on other

	 * mailbox changes also */

	while (recentcount == 0 && do_idle) {

	    smtp_close(ctl, 1);

	    ok = imap_idle(sock);

	    if (ok)

	    {

		report(stderr, GT_("re-poll failed\n"));

		return(ok);

	    }

	}

	/* if recentcount is 0, return no mail */

	if (recentcount == 0)

		count = 0;

	if (outlevel >= O_DEBUG)

	    report(stdout, ngettext("%d message waiting after re-poll\n",

				    "%d messages waiting after re-poll\n",

				    count), count);

    }

    else

    {

	oldcount = count = 0;

	ok = gen_transact(sock, 

			  check_only ? "EXAMINE \"%s\"" : "SELECT \"%s\"",

			  folder ? folder : "INBOX");

	/* imap_ok returns PS_LOCKBUSY for READ-ONLY folders,

	 * which we can safely use in fetchall keep only */

	if (ok == PS_LOCKBUSY && ctl->fetchall && ctl-> keep)

	    ok = 0;

	if (ok != 0)

	{

	    report(stderr, GT_("mailbox selection failed\n"));

	    return(ok);

	}

	else if (outlevel >= O_DEBUG)

	    report(stdout, ngettext("%d message waiting after first poll\n",

				    "%d messages waiting after first poll\n",

				    count), count);

	/*

	 * We should have an expunge here to

	 * a) avoid fetching deleted mails during 'fetchall'

	 * b) getting a wrong count of mails during 'no fetchall'

	 */

	if (!check_only && !ctl->keep && count > 0)

	{

	    ok = internal_expunge(sock);

	    if (ok)

	    {

		report(stderr, GT_("expunge failed\n"));

		return(ok);

	    }

	    if (outlevel >= O_DEBUG)

		report(stdout, ngettext("%d message waiting after expunge\n",

					"%d messages waiting after expunge\n",

					count), count);

	}

	if (count == 0 && do_idle)

	{

	    /* no messages?  then we may need to idle until we get some */

	    while (count == 0) {

		ok = imap_idle(sock);

		if (ok)

		{

		    report(stderr, GT_("re-poll failed\n"));

		    return(ok);

		}

	    }

	    if (outlevel >= O_DEBUG)

		report(stdout, ngettext("%d message waiting after re-poll\n",

					"%d messages waiting after re-poll\n",

					count), count);

	}

    }

    *countp = oldcount = count;

    recentcount = 0;

    startcount = 1;

    /* OK, now get a count of unseen messages and their indices */

    if (!ctl->fetchall && count > 0)

    {

	if (unseen_messages)

	    free(unseen_messages);

	unseen_messages = (unsigned int *)xmalloc(count * sizeof(unsigned int));

	memset(unseen_messages, 0, count * sizeof(unsigned int));

	unseen = 0;

	ok = imap_search(sock, ctl, count);

	if (ok != 0)

	{

	    report(stderr, GT_("search for unseen messages failed\n"));

	    return(ok);

	}

	if (outlevel >= O_DEBUG && unseen > 0)

	    report(stdout, GT_("%u is first unseen\n"), startcount);

    } else

	unseen = -1;

    *newp = unseen;

    expunged = 0;

    deletions = 0;

    return(PS_SUCCESS);

}

static int imap_getpartialsizes(int sock, int first, int last, int *sizes)

/* capture the sizes of messages #first-#last */

{

    char buf [MSGBUFSIZE+1];

    int ok;

    /*

     * Some servers (as in, PMDF5.1-9.1 under OpenVMS 6.1)

     * won't accept 1:1 as valid set syntax.  Some implementors

     * should be taken out and shot for excessive anality.

     *

     * Microsoft Exchange (brain-dead piece of crap that it is) 

     * sometimes gets its knickers in a knot about bodiless messages.

     * You may see responses like this:

     *

     *	fetchmail: IMAP> A0004 FETCH 1:9 RFC822.SIZE

     *	fetchmail: IMAP< * 2 FETCH (RFC822.SIZE 1187)

     *	fetchmail: IMAP< * 3 FETCH (RFC822.SIZE 3954)

     *	fetchmail: IMAP< * 4 FETCH (RFC822.SIZE 1944)

     *	fetchmail: IMAP< * 5 FETCH (RFC822.SIZE 2933)

     *	fetchmail: IMAP< * 6 FETCH (RFC822.SIZE 1854)

     *	fetchmail: IMAP< * 7 FETCH (RFC822.SIZE 34054)

     *	fetchmail: IMAP< * 8 FETCH (RFC822.SIZE 5561)

     *	fetchmail: IMAP< * 9 FETCH (RFC822.SIZE 1101)

     *	fetchmail: IMAP< A0004 NO The requested item could not be found.

     *

     * This means message 1 has only headers.  For kicks and grins

     * you can telnet in and look:

     *	A003 FETCH 1 FULL

     *	A003 NO The requested item could not be found.

     *	A004 fetch 1 rfc822.header

     *	A004 NO The requested item could not be found.

     *	A006 FETCH 1 BODY

     *	* 1 FETCH (BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 35 3))

     *	A006 OK FETCH completed.

     *

     * To get around this, we treat the final NO as success and count

     * on the fact that the sizes array has been preinitialized with a

     * known-bad size value.

     */

    /* expunges change the fetch numbers */

    first -= expunged;

    last -= expunged;

    if (last == first)

	gen_send(sock, "FETCH %d RFC822.SIZE", last);

    else if (last > first)

	gen_send(sock, "FETCH %d:%d RFC822.SIZE", first, last);

    else /* no unseen messages! */

	return(PS_SUCCESS);

    while ((ok = imap_response(sock, buf, NULL)) == PS_UNTAGGED)

    {

	unsigned int size;

	int num;

	int consumed;

	char *ptr;

	/* expected response formats:

	 * IMAP> A0005 FETCH 1 RFC822.SIZE

	 * IMAP< * 1 FETCH (RFC822.SIZE 1187)

	 * IMAP< * 1 FETCH (UID 16 RFC822.SIZE 1447)

	 */

	if (sscanf(buf, "* %d %n", &num, &consumed) == 1

	    && 0 == strncasecmp(buf + consumed, "FETCH", 5)

	    && isspace((unsigned char)buf[consumed + 5])

		&& (ptr = strstr(buf, "RFC822.SIZE "))

		&& sscanf(ptr, "RFC822.SIZE %u", &size) == 1)

	{

	    if (num >= first && num <= last)

		sizes[num - first] = size;

	    else

		report(stderr,

			GT_("Warning: ignoring bogus data for message sizes returned by the server.\n"));

	}

    }

    return(ok);

}

static int imap_getsizes(int sock, int count, int *sizes)

/* capture the sizes of all messages */

{

    return imap_getpartialsizes(sock, 1, count, sizes);

}

static int imap_is_old(int sock, struct query *ctl, int number)

/* is the given message old? */

{

    flag seen = TRUE;

    int i;

    (void)sock;

    (void)ctl;

    /* 

     * Expunges change the fetch numbers, but unseen_messages contains

     * indices from before any expungees were done.  So neither the

     * argument nor the values in message_sequence need to be decremented.

     */

    seen = TRUE;

    for (i = 0; i < unseen; i++)

	if (unseen_messages[i] == (unsigned)number)

	{

	    seen = FALSE;

	    break;

	}

    return(seen);

}

#if 0

static char *skip_token(char *ptr)

{

    while(isspace((unsigned char)*ptr)) ptr++;

    while(!isspace((unsigned char)*ptr) && !iscntrl((unsigned char)*ptr)) ptr++;

    while(isspace((unsigned char)*ptr)) ptr++;

    return(ptr);

}

#endif

static int imap_fetch_headers(int sock, struct query *ctl,int number,int *lenp)

/* request headers of nth message */

{

    char buf [MSGBUFSIZE+1];

    int	num;

    int ok;

    char *ptr;

    (void)ctl;

    /* expunges change the fetch numbers */

    number -= expunged;

    /*

     * This is blessed by RFC1176, RFC1730, RFC2060.

     * According to the RFCs, it should *not* set the \Seen flag.

     */

    gen_send(sock, "FETCH %d RFC822.HEADER", number);

    /* looking for FETCH response */

    if ((ok = imap_response(sock, buf, NULL)) == PS_UNTAGGED)

    {

		int consumed;

	/* expected response formats:

	 * IMAP> A0006 FETCH 1 RFC822.HEADER

	 * IMAP< * 1 FETCH (RFC822.HEADER {1360}

	 * IMAP< * 1 FETCH (UID 16 RFC822.HEADER {1360}

	 * IMAP< * 1 FETCH (UID 16 RFC822.SIZE 4029 RFC822.HEADER {1360}

	 */

	if (sscanf(buf, "* %d %n", &num, &consumed) == 1

	    && 0 == strncasecmp(buf + consumed, "FETCH", 5)

	    && isspace((unsigned char)buf[5+consumed])

		&& num == number

		&& (ptr = strstr(buf, "RFC822.HEADER"))

		&& sscanf(ptr, "RFC822.HEADER {%d}%n", lenp, &consumed) == 1

		&& ptr[consumed-1] == '}')

	{

	    return(PS_SUCCESS);

	}

	/* wait for a tagged response */

	imap_ok (sock, 0);

	/* try to recover for some responses */

	if (!strncmp(buf, "* NO", 4) ||

		!strncmp(buf, "* BAD", 5) ||

		strstr(buf, "FETCH ()"))

	{

	    return(PS_TRANSIENT);

	}

	/* a response which does not match any of the above */

	if (outlevel > O_SILENT)

	    report(stderr, GT_("Incorrect FETCH response: %s.\n"), buf);

	return(PS_ERROR);

    }

    else if (ok == PS_SUCCESS)

    {

	/* an unexpected tagged response */

	if (outlevel > O_SILENT)

	    report(stderr, GT_("Incorrect FETCH response: %s.\n"), buf);

	return(PS_TRANSIENT);

    }

    return(ok);

}

static int imap_fetch_body(int sock, struct query *ctl, int number, int *lenp)

/* request body of nth message */

{

    char buf [MSGBUFSIZE+1], *cp;

    int	num;

    (void)ctl;

    /* expunges change the fetch numbers */

    number -= expunged;

    /*

     * If we're using IMAP4, we can fetch the message without setting its

     * seen flag.  This is good!  It means that if the protocol exchange

     * craps out during the message, it will still be marked `unseen' on

     * the server.

     *

     * According to RFC2060, and Mark Crispin the IMAP maintainer,

     * FETCH %d BODY[TEXT] and RFC822.TEXT are "functionally 

     * equivalent".  However, we know of at least one server that

     * treats them differently in the presence of MIME attachments;

     * the latter form downloads the attachment, the former does not.

     * The server is InterChange, and the fool who implemented this

     * misfeature ought to be strung up by his thumbs.  

     *

     * When I tried working around this by disabling use of the 4rev1 form,

     * I found that doing this breaks operation with M$ Exchange.

     * Annoyingly enough, Exchange's refusal to cope is technically legal

     * under RFC2062.  Trust Microsoft, the Great Enemy of interoperability

     * standards, to find a way to make standards compliance irritating....

     */

    switch (imap_version)

    {

    case IMAP4rev1:	/* RFC 2060 */

	gen_send(sock, "FETCH %d BODY.PEEK[TEXT]", number);

	break;

    case IMAP4:		/* RFC 1730 */

	gen_send(sock, "FETCH %d RFC822.TEXT.PEEK", number);

	break;

    default:		/* RFC 1176 */

	gen_send(sock, "FETCH %d RFC822.TEXT", number);

	break;

    }

    /* looking for FETCH response */

    do {

	int	ok;

	if ((ok = gen_recv(sock, buf, sizeof(buf))))

	    return(ok);

    } while

	(!strstr(buf+4, "FETCH") || sscanf(buf+2, "%d", &num) != 1);

    if (num != number)

	return(PS_ERROR);

    /* Understand "NIL" as length => no body present

     * (MS Exchange, BerliOS Bug #11980) */

    if (strstr(buf+10, "NIL)")) {

	    *lenp = 0;

	    return PS_SUCCESS;

    }

    /* Understand the empty string. Seen on Yahoo. */

    /* XXX FIXME: we should be able to handle strings here. */

    if (strstr(buf+10, "\"\")")) {

	    *lenp = 0;

	    return PS_SUCCESS;

    }

    /*

     * Try to extract a length from the FETCH response.  RFC2060 requires

     * it to be present, but at least one IMAP server (Novell GroupWise)

     * botches this.  The overflow check is needed because of a broken

     * server called dbmail that returns huge garbage lengths.

     */

    if ((cp = strchr(buf, '{'))) {

	long l; char *t;

        errno = 0;

	++ cp;

	l = strtol(cp, &t, 10);

        if (errno || t == cp || (t && !strchr(t, '}')) /* parse error */

		    || l < 0 || l > INT_MAX /* range check */) {

	    *lenp = -1;

	} else {

	    *lenp = l;

	}

    } else {

	*lenp = -1;	/* missing length part in FETCH reponse */

    }

    return PS_SUCCESS;

}

static int imap_trail(int sock, struct query *ctl, const char *tag)

/* discard tail of FETCH response after reading message text */

{

    /* expunges change the fetch numbers */

    /* number -= expunged; */

    (void)ctl;

    (void)tag;

    return imap_ok(sock, NULL);

}

static int imap_delete(int sock, struct query *ctl, int number)

/* set delete flag for given message */

{

    int	ok;

    /* Select which flags to set on message deletion: */

    const char delflags_seen[] = "\\Seen \\Deleted";

    static const char *delflags;

    /* Which environment variable to look for: */

    /* DEFAULT since many fetchmail versions <= 6.3.X */

    delflags = delflags_seen;

    (void)ctl;

    /* expunges change the fetch numbers */

    number -= expunged;

    /*

     * Use SILENT if possible as a minor throughput optimization.

     * Note: this has been dropped from IMAP4rev1.

     *

     * We set \Seen because there are some IMAP servers (notably HP

     * OpenMail and MS Exchange) do message-receipt DSNs,

     * but only when the seen bit gets set.

     * This is the appropriate time -- we get here right

     * after the local SMTP response that says delivery was

     * successful.

     */

    if ((ok = gen_transact(sock,

			imap_version == IMAP4 

				? "STORE %d +FLAGS.SILENT (%s)"

				: "STORE %d +FLAGS (%s)",

			number, delflags)))

	return(ok);

    else

	deletions++;

    /*

     * We do an expunge after expunge_period messages, rather than

     * just before quit, so that a line hit during a long session

     * won't result in lots of messages being fetched again during

     * the next session.

     */

    if (NUM_NONZERO(expunge_period) && (deletions % expunge_period) == 0)

    {

	if ((ok = internal_expunge(sock)))

	    return(ok);

    }

    return(PS_SUCCESS);

}

static int imap_mark_seen(int sock, struct query *ctl, int number)

/* mark the given message as seen */

{

    (void)ctl;

    /* expunges change the message numbers */

    number -= expunged;

    return(gen_transact(sock,

	imap_version == IMAP4

	? "STORE %d +FLAGS.SILENT (\\Seen)"

	: "STORE %d +FLAGS (\\Seen)",

	number));

}

static int imap_end_mailbox_poll(int sock, struct query *ctl)

/* cleanup mailbox before we idle or switch to another one */

{

    (void)ctl;

    if (deletions)

	internal_expunge(sock);

    return(PS_SUCCESS);

}

static int imap_logout(int sock, struct query *ctl)

/* send logout command */

{

    (void)ctl;

    /* if any un-expunged deletions remain, ship an expunge now */

    if (deletions)

	internal_expunge(sock);

#ifdef USE_SEARCH

    /* Memory clean-up */

    if (unseen_messages)

	free(unseen_messages);

#endif /* USE_SEARCH */

    return(gen_transact(sock, "LOGOUT"));

}

static const struct method imap =

{

    "IMAP",		/* Internet Message Access Protocol */

    "imap",		/* service (plain and TLS) */

    "imaps",		/* service (SSL) */

    TRUE,		/* this is a tagged protocol */

    FALSE,		/* no message delimiter */

    imap_ok,		/* parse command response */

    imap_getauth,	/* get authorization */

    imap_getrange,	/* query range of messages */

    imap_getsizes,	/* get sizes of messages (used for ESMTP SIZE option) */

    imap_getpartialsizes,	/* get sizes of subset of messages (used for ESMTP SIZE option) */

    imap_is_old,	/* no UID check */

    imap_fetch_headers,	/* request given message headers */

    imap_fetch_body,	/* request given message body */

    imap_trail,		/* eat message trailer */

    imap_delete,	/* delete the message */

    imap_mark_seen,	/* how to mark a message as seen */

    imap_end_mailbox_poll,	/* end-of-mailbox processing */

    imap_logout,	/* expunge and exit */

    TRUE,		/* yes, we can re-poll */

};

int doIMAP(struct query *ctl)

/* retrieve messages using IMAP Version 2bis or Version 4 */

{

    return(do_protocol(ctl, &imap));

}

/* imap.c ends here */