path: root/camel/providers/imap4/camel-imap4-engine.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*  Camel
 *  Copyright (C) 1999-2004 Jeffrey Stedfast
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Street #330, Boston, MA 02111-1307, USA.
 */


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>
#include <ctype.h>
#include <errno.h>

#include <camel/camel-sasl.h>
#include <camel/camel-stream-buffer.h>
#include <camel/camel-i18n.h>

#include "camel-imap4-summary.h"
#include "camel-imap4-command.h"
#include "camel-imap4-stream.h"
#include "camel-imap4-folder.h"
#include "camel-imap4-utils.h"

#include "camel-imap4-engine.h"

#define d(x) x


static void camel_imap4_engine_class_init (CamelIMAP4EngineClass *klass);
static void camel_imap4_engine_init (CamelIMAP4Engine *engine, CamelIMAP4EngineClass *klass);
static void camel_imap4_engine_finalize (CamelObject *object);


static CamelObjectClass *parent_class = NULL;


CamelType
camel_imap4_engine_get_type (void)
{
    static CamelType type = 0;
    
    if (!type) {
        type = camel_type_register (camel_object_get_type (),
                        "CamelIMAP4Engine",
                        sizeof (CamelIMAP4Engine),
                        sizeof (CamelIMAP4EngineClass),
                        (CamelObjectClassInitFunc) camel_imap4_engine_class_init,
                        NULL,
                        (CamelObjectInitFunc) camel_imap4_engine_init,
                        (CamelObjectFinalizeFunc) camel_imap4_engine_finalize);
    }
    
    return type;
}

static void
camel_imap4_engine_class_init (CamelIMAP4EngineClass *klass)
{
    parent_class = camel_type_get_global_classfuncs (CAMEL_OBJECT_TYPE);
    
    klass->tagprefix = 'A';
}

static void
camel_imap4_engine_init (CamelIMAP4Engine *engine, CamelIMAP4EngineClass *klass)
{
    engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
    engine->level = CAMEL_IMAP4_LEVEL_UNKNOWN;
    
    engine->session = NULL;
    engine->service = NULL;
    engine->url = NULL;
    
    engine->istream = NULL;
    engine->ostream = NULL;
    
    engine->authtypes = g_hash_table_new (g_str_hash, g_str_equal);
    
    engine->capa = 0;
    
    /* this is the suggested default, impacts the max command line length we'll send */
    engine->maxlentype = CAMEL_IMAP4_ENGINE_MAXLEN_LINE;
    engine->maxlen = 1000;
    
    engine->namespaces.personal = NULL;
    engine->namespaces.other = NULL;
    engine->namespaces.shared = NULL;
    
    if (klass->tagprefix > 'Z')
        klass->tagprefix = 'A';
    
    engine->tagprefix = klass->tagprefix++;
    engine->tag = 0;
    
    engine->nextid = 1;
    
    engine->folder = NULL;
    
    e_dlist_init (&engine->queue);
}

static void
camel_imap4_engine_finalize (CamelObject *object)
{
    CamelIMAP4Engine *engine = (CamelIMAP4Engine *) object;
    EDListNode *node;
    
    if (engine->istream)
        camel_object_unref (engine->istream);
    
    if (engine->ostream)
        camel_object_unref (engine->ostream);
    
    g_hash_table_foreach (engine->authtypes, (GHFunc) g_free, NULL);
    g_hash_table_destroy (engine->authtypes);
    
    camel_imap4_namespace_clear (&engine->namespaces.personal);
    camel_imap4_namespace_clear (&engine->namespaces.other);
    camel_imap4_namespace_clear (&engine->namespaces.shared);
    
    if (engine->folder)
        camel_object_unref (engine->folder);
    
    while ((node = e_dlist_remhead (&engine->queue))) {
        node->next = NULL;
        node->prev = NULL;
        
        camel_imap4_command_unref ((CamelIMAP4Command *) node);
    }
}


/**
 * camel_imap4_engine_new:
 * @service: service
 * @reconnect: reconnect callback function
 *
 * Returns a new imap4 engine
 **/
CamelIMAP4Engine *
camel_imap4_engine_new (CamelService *service, CamelIMAP4ReconnectFunc reconnect)
{
    CamelIMAP4Engine *engine;
    
    g_return_val_if_fail (CAMEL_IS_SERVICE (service), NULL);
    
    engine = (CamelIMAP4Engine *) camel_object_new (CAMEL_TYPE_IMAP4_ENGINE);
    engine->session = service->session;
    engine->url = service->url;
    engine->service = service;
    engine->reconnect = reconnect;
    
    return engine;
}


/**
 * camel_imap4_engine_take_stream:
 * @engine: imap4 engine
 * @stream: tcp stream
 * @ex: exception
 *
 * Gives ownership of @stream to @engine and reads the greeting from
 * the stream.
 *
 * Returns 0 on success or -1 on fail.
 *
 * Note: on error, @stream will be unref'd.
 **/
int
camel_imap4_engine_take_stream (CamelIMAP4Engine *engine, CamelStream *stream, CamelException *ex)
{
    camel_imap4_token_t token;
    int code;
    
    g_return_val_if_fail (CAMEL_IS_IMAP4_ENGINE (engine), -1);
    g_return_val_if_fail (CAMEL_IS_STREAM (stream), -1);
    
    if (engine->istream)
        camel_object_unref (engine->istream);
    
    if (engine->ostream)
        camel_object_unref (engine->ostream);
    
    engine->istream = (CamelIMAP4Stream *) camel_imap4_stream_new (stream);
    engine->ostream = camel_stream_buffer_new (stream, CAMEL_STREAM_BUFFER_WRITE);
    engine->state = CAMEL_IMAP4_ENGINE_CONNECTED;
    camel_object_unref (stream);
    
    if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
        goto exception;
    
    if (token.token != '*') {
        camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
        goto exception;
    }
    
    if ((code = camel_imap4_engine_handle_untagged_1 (engine, &token, ex)) == -1) {
        goto exception;
    } else if (code != CAMEL_IMAP4_UNTAGGED_OK && code != CAMEL_IMAP4_UNTAGGED_PREAUTH) {
        camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM, _("Unexpected greeting from IMAP server %s."),
                      engine->url->host);
        goto exception;
    }
    
    return 0;
    
 exception:
    
    engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
    
    camel_object_unref (engine->istream);
    engine->istream = NULL;
    camel_object_unref (engine->ostream);
    engine->ostream = NULL;
    
    return -1;
}


/**
 * camel_imap4_engine_capability:
 * @engine: IMAP4 engine
 * @ex: exception
 *
 * Forces the IMAP4 engine to query the IMAP4 server for a list of capabilities.
 *
 * Returns 0 on success or -1 on fail.
 **/
int
camel_imap4_engine_capability (CamelIMAP4Engine *engine, CamelException *ex)
{
    CamelIMAP4Command *ic;
    int id, retval = 0;
    
    ic = camel_imap4_engine_prequeue (engine, NULL, "CAPABILITY\r\n");
    
    while ((id = camel_imap4_engine_iterate (engine)) < ic->id && id != -1)
        ;
    
    if (id == -1 || ic->status != CAMEL_IMAP4_COMMAND_COMPLETE) {
        camel_exception_xfer (ex, &ic->ex);
        retval = -1;
    }
    
    camel_imap4_command_unref (ic);
    
    return retval;
}


/**
 * camel_imap4_engine_namespace:
 * @engine: IMAP4 engine
 * @ex: exception
 *
 * Forces the IMAP4 engine to query the IMAP4 server for a list of namespaces.
 *
 * Returns 0 on success or -1 on fail.
 **/
int
camel_imap4_engine_namespace (CamelIMAP4Engine *engine, CamelException *ex)
{
    camel_imap4_list_t *list;
    GPtrArray *array = NULL;
    CamelIMAP4Command *ic;
    int id, i;
    
    if (engine->capa & CAMEL_IMAP4_CAPABILITY_NAMESPACE) {
        ic = camel_imap4_engine_prequeue (engine, NULL, "NAMESPACE\r\n");
    } else {
        ic = camel_imap4_engine_prequeue (engine, NULL, "LIST \"\" \"\"\r\n");
        camel_imap4_command_register_untagged (ic, "LIST", camel_imap4_untagged_list);
        ic->user_data = array = g_ptr_array_new ();
    }
    
    while ((id = camel_imap4_engine_iterate (engine)) < ic->id && id != -1)
        ;
    
    if (id == -1 || ic->status != CAMEL_IMAP4_COMMAND_COMPLETE) {
        camel_exception_xfer (ex, &ic->ex);
        camel_imap4_command_unref (ic);
        
        if (array != NULL)
            g_ptr_array_free (array, TRUE);
        
        return -1;
    }
    
    if (array != NULL) {
        if (ic->result == CAMEL_IMAP4_RESULT_OK) {
            CamelIMAP4Namespace *namespace;
            
            g_assert (array->len == 1);
            list = array->pdata[0];
            
            namespace = g_new (CamelIMAP4Namespace, 1);
            namespace->next = NULL;
            namespace->path = g_strdup ("");
            namespace->sep = list->delim;
            
            engine->namespaces.personal = namespace;
        } else {
            /* should never *ever* happen */
        }
        
        for (i = 0; i < array->len; i++) {
            list = array->pdata[i];
            g_free (list->name);
            g_free (list);
        }
        
        g_ptr_array_free (array, TRUE);
    }
    
    camel_imap4_command_unref (ic);
    
    return 0;
}


/**
 * camel_imap4_engine_select_folder:
 * @engine: IMAP4 engine
 * @folder: folder to select
 * @ex: exception
 *
 * Convenience function to select @folder.
 *
 * Returns 0 on success or -1 on fail.
 **/
int
camel_imap4_engine_select_folder (CamelIMAP4Engine *engine, CamelFolder *folder, CamelException *ex)
{
    CamelIMAP4RespCode *resp;
    CamelIMAP4Command *ic;
    int id, retval = 0;
    int i;
    
    g_return_val_if_fail (CAMEL_IS_IMAP4_ENGINE (engine), -1);
    g_return_val_if_fail (CAMEL_IS_IMAP4_FOLDER (folder), -1);
    
    /* POSSIBLE FIXME: if the folder to be selected will already
     * be selected by the time the queue is emptied, simply
     * no-op? */
    
    ic = camel_imap4_engine_queue (engine, folder, "SELECT %F\r\n", folder);
    while ((id = camel_imap4_engine_iterate (engine)) < ic->id && id != -1)
        ;
    
    if (id == -1 || ic->status != CAMEL_IMAP4_COMMAND_COMPLETE) {
        camel_exception_xfer (ex, &ic->ex);
        camel_imap4_command_unref (ic);
        return -1;
    }
    
    switch (ic->result) {
    case CAMEL_IMAP4_RESULT_OK:
        /*folder->mode = 0;*/
        for (i = 0; i < ic->resp_codes->len; i++) {
            resp = ic->resp_codes->pdata[i];
            switch (resp->code) {
            case CAMEL_IMAP4_RESP_CODE_PERM_FLAGS:
                folder->permanent_flags = resp->v.flags;
                break;
            case CAMEL_IMAP4_RESP_CODE_READONLY:
                /*folder->mode = CAMEL_FOLDER_MODE_READ_ONLY;*/
                break;
            case CAMEL_IMAP4_RESP_CODE_READWRITE:
                /*folder->mode = CAMEL_FOLDER_MODE_READ_WRITE;*/
                break;
            case CAMEL_IMAP4_RESP_CODE_UIDNEXT:
                camel_imap4_summary_set_uidnext (folder->summary, resp->v.uidnext);
                break;
            case CAMEL_IMAP4_RESP_CODE_UIDVALIDITY:
                camel_imap4_summary_set_uidvalidity (folder->summary, resp->v.uidvalidity);
                break;
            case CAMEL_IMAP4_RESP_CODE_UNSEEN:
                camel_imap4_summary_set_unseen (folder->summary, resp->v.unseen);
                break;
            default:
                break;
            }
        }
        
        /*if (folder->mode == 0) {
          folder->mode = CAMEL_FOLDER_MODE_READ_ONLY;
          g_warning ("Expected to find [READ-ONLY] or [READ-WRITE] in SELECT response");
          }*/
        
        break;
    case CAMEL_IMAP4_RESULT_NO:
        /* FIXME: would be good to save the NO reason into the err message */
        camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                      _("Cannot select folder `%s': Invalid mailbox name"),
                      folder->full_name);
        retval = -1;
        break;
    case CAMEL_IMAP4_RESULT_BAD:
        camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                      _("Cannot select folder `%s': Bad command"),
                      folder->full_name);
        retval = -1;
        break;
    default:
        g_assert_not_reached ();
        retval = -1;
    }
    
    camel_imap4_command_unref (ic);
    
    return retval;
}


static struct {
    const char *name;
    guint32 flag;
} imap4_capabilities[] = {
    { "IMAP4",         CAMEL_IMAP4_CAPABILITY_IMAP4         },
    { "IMAP4REV1",     CAMEL_IMAP4_CAPABILITY_IMAP4REV1     },
    { "STATUS",        CAMEL_IMAP4_CAPABILITY_STATUS        },
    { "NAMESPACE",     CAMEL_IMAP4_CAPABILITY_NAMESPACE     }, /* rfc2342 */
    { "UIDPLUS",       CAMEL_IMAP4_CAPABILITY_UIDPLUS       }, /* rfc2359 */
    { "LITERAL+",      CAMEL_IMAP4_CAPABILITY_LITERALPLUS   }, /* rfc2088 */
    { "LOGINDISABLED", CAMEL_IMAP4_CAPABILITY_LOGINDISABLED },
    { "STARTTLS",      CAMEL_IMAP4_CAPABILITY_STARTTLS      },
    { "QUOTA",         CAMEL_IMAP4_CAPABILITY_QUOTA         }, /* rfc2087 */
    { "ACL",           CAMEL_IMAP4_CAPABILITY_ACL           }, /* rfc2086 */
    { "IDLE",          CAMEL_IMAP4_CAPABILITY_IDLE          }, /* rfc2177 */
    { "MULTIAPPEND",   CAMEL_IMAP4_CAPABILITY_MULTIAPPEND   }, /* rfc3502 */
    { NULL,            0                                    }
};

static gboolean
auth_free (gpointer key, gpointer value, gpointer user_data)
{
    g_free (key);
    return TRUE;
}

static int
engine_parse_capability (CamelIMAP4Engine *engine, int sentinel, CamelException *ex)
{
    camel_imap4_token_t token;
    int i;
    
    engine->capa = CAMEL_IMAP4_CAPABILITY_utf8_search;
    engine->level = 0;
    
    g_hash_table_foreach_remove (engine->authtypes, (GHRFunc) auth_free, NULL);
    
    if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
        return -1;
    
    while (token.token == CAMEL_IMAP4_TOKEN_ATOM) {
        if (!g_ascii_strncasecmp ("AUTH=", token.v.atom, 5)) {
            CamelServiceAuthType *auth;
            
            if ((auth = camel_sasl_authtype (token.v.atom + 5)) != NULL)
                g_hash_table_insert (engine->authtypes, g_strdup (token.v.atom + 5), auth);
        } else {
            for (i = 0; imap4_capabilities[i].name; i++) {
                if (!g_ascii_strcasecmp (imap4_capabilities[i].name, token.v.atom))
                    engine->capa |= imap4_capabilities[i].flag;
            }
        }
        
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
    }
    
    if (token.token != sentinel) {
        camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
        return -1;
    }
    
    /* unget our sentinel token */
    camel_imap4_stream_unget_token (engine->istream, &token);
    
    /* figure out which version of IMAP4 we are dealing with */
    if (engine->capa & CAMEL_IMAP4_CAPABILITY_IMAP4REV1) {
        engine->level = CAMEL_IMAP4_LEVEL_IMAP4REV1;
        engine->capa |= CAMEL_IMAP4_CAPABILITY_STATUS;
    } else if (engine->capa & CAMEL_IMAP4_CAPABILITY_IMAP4) {
        engine->level = CAMEL_IMAP4_LEVEL_IMAP4;
    } else {
        engine->level = CAMEL_IMAP4_LEVEL_UNKNOWN;
    }
    
    return 0;
}

static int
engine_parse_flags_list (CamelIMAP4Engine *engine, CamelIMAP4RespCode *resp, int perm, CamelException *ex)
{
    guint32 flags = 0;
    
    if (camel_imap4_parse_flags_list (engine, &flags, ex) == -1)
        return-1;
    
    if (resp != NULL)
        resp->v.flags = flags;
    
    if (engine->current && engine->current->folder) {
        if (perm)
            ((CamelFolder *) engine->current->folder)->permanent_flags = flags;
        /*else
          ((CamelFolder *) engine->current->folder)->folder_flags = flags;*/
    } else if (engine->folder) {
        if (perm)
            ((CamelFolder *) engine->folder)->permanent_flags = flags;
        /*else
          ((CamelFolder *) engine->folder)->folder_flags = flags;*/
    } else {
        fprintf (stderr, "We seem to be in a bit of a pickle. we've just parsed an untagged %s\n"
             "response for a folder, yet we do not currently have a folder selected?\n",
             perm ? "PERMANENTFLAGS" : "FLAGS");
    }
    
    return 0;
}

static int
engine_parse_flags (CamelIMAP4Engine *engine, CamelException *ex)
{
    camel_imap4_token_t token;
    
    if (engine_parse_flags_list (engine, NULL, FALSE, ex) == -1)
        return -1;
    
    if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
        return -1;
    
    if (token.token != '\n') {
        d(fprintf (stderr, "Expected to find a '\\n' token after the FLAGS response\n"));
        camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
        return -1;
    }
    
    return 0;
}

static int
engine_parse_namespace (CamelIMAP4Engine *engine, CamelException *ex)
{
    CamelIMAP4Namespace *namespaces[3], *node, *tail;
    camel_imap4_token_t token;
    int i, n = 0;
    
    camel_imap4_namespace_clear (&engine->namespaces.personal);
    camel_imap4_namespace_clear (&engine->namespaces.other);
    camel_imap4_namespace_clear (&engine->namespaces.shared);
    
    if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
        return -1;
    
    do {
        namespaces[n] = NULL;
        tail = (CamelIMAP4Namespace *) &namespaces[n];
        
        if (token.token == '(') {
            /* decode the list of namespace pairs */
            if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
                goto exception;
            
            while (token.token == '(') {
                /* decode a namespace pair */
                
                /* get the path name token */
                if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
                    goto exception;
                
                if (token.token != CAMEL_IMAP4_TOKEN_QSTRING) {
                    d(fprintf (stderr, "Expected to find a qstring token as first element in NAMESPACE pair\n"));
                    camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
                    goto exception;
                }
                
                node = g_new (CamelIMAP4Namespace, 1);
                node->next = NULL;
                node->path = g_strdup (token.v.qstring);
                
                /* get the path delimiter token */
                if (camel_imap4_engine_next_token (engine, &token, ex) == -1) {
                    g_free (node->path);
                    g_free (node);
                    
                    goto exception;
                }
                
                if (token.token != CAMEL_IMAP4_TOKEN_QSTRING || strlen (token.v.qstring) > 1) {
                    d(fprintf (stderr, "Expected to find a qstring token as second element in NAMESPACE pair\n"));
                    camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
                    g_free (node->path);
                    g_free (node);
                    
                    goto exception;
                }
                
                node->sep = *token.v.qstring;
                tail->next = node;
                tail = node;
                
                /* canonicalise the namespace path */
                if (node->path[strlen (node->path) - 1] == node->sep)
                    node->path[strlen (node->path) - 1] = '\0';
                
                /* canonicalise if this is an INBOX namespace */
                if (!g_ascii_strncasecmp (node->path, "INBOX", 5) &&
                    (node->path[6] == '\0' || node->path[6] == node->sep))
                    memcpy (node->path, "INBOX", 5);
                
                /* get the closing ')' for this namespace pair */
                if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
                    goto exception;
                
                if (token.token != ')') {
                    d(fprintf (stderr, "Expected to find a ')' token to close the current namespace pair\n"));
                    camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
                    
                    goto exception;
                }
                
                /* get the next token (should be either '(' or ')') */
                if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
                    goto exception;
            }
            
            if (token.token != ')') {
                d(fprintf (stderr, "Expected to find a ')' to close the current namespace list\n"));
                camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
                goto exception;
            }
        } else if (token.token == CAMEL_IMAP4_TOKEN_NIL) {
            /* namespace list is NIL */
            namespaces[n] = NULL;
        } else {
            d(fprintf (stderr, "Expected to find either NIL or '(' token in untagged NAMESPACE response\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        /* get the next token (should be either '(', NIL, or '\n') */
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            goto exception;
        
        n++;
    } while (n < 3);
    
    engine->namespaces.personal = namespaces[0];
    engine->namespaces.other = namespaces[1];
    engine->namespaces.shared = namespaces[2];
    
    return 0;
    
 exception:
    
    for (i = 0; i <= n; i++)
        camel_imap4_namespace_clear (&namespaces[i]);
    
    return -1;
}


/**
 * 
 * resp-text-code  = "ALERT" /
 *                   "BADCHARSET" [SP "(" astring *(SP astring) ")" ] /
 *                   capability-data / "PARSE" /
 *                   "PERMANENTFLAGS" SP "(" [flag-perm *(SP flag-perm)] ")" /
 *                   "READ-ONLY" / "READ-WRITE" / "TRYCREATE" /
 *                   "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number /
 *                   "UNSEEN" SP nz-number /
 *                   atom [SP 1*<any TEXT-CHAR except "]">]
 **/

static struct {
    const char *name;
    camel_imap4_resp_code_t code;
    int save;
} imap4_resp_codes[] = {
    { "ALERT",          CAMEL_IMAP4_RESP_CODE_ALERT,       0 },
    { "BADCHARSET",     CAMEL_IMAP4_RESP_CODE_BADCHARSET,  0 },
    { "CAPABILITY",     CAMEL_IMAP4_RESP_CODE_CAPABILITY,  0 },
    { "PARSE",          CAMEL_IMAP4_RESP_CODE_PARSE,       1 },
    { "PERMANENTFLAGS", CAMEL_IMAP4_RESP_CODE_PERM_FLAGS,  1 },
    { "READ-ONLY",      CAMEL_IMAP4_RESP_CODE_READONLY,    1 },
    { "READ-WRITE",     CAMEL_IMAP4_RESP_CODE_READWRITE,   1 },
    { "TRYCREATE",      CAMEL_IMAP4_RESP_CODE_TRYCREATE,   1 },
    { "UIDNEXT",        CAMEL_IMAP4_RESP_CODE_UIDNEXT,     1 },
    { "UIDVALIDITY",    CAMEL_IMAP4_RESP_CODE_UIDVALIDITY, 1 },
    { "UNSEEN",         CAMEL_IMAP4_RESP_CODE_UNSEEN,      1 },
    { "NEWNAME",        CAMEL_IMAP4_RESP_CODE_NEWNAME,     1 },
    { "APPENDUID",      CAMEL_IMAP4_RESP_CODE_APPENDUID,   1 },
    { "COPYUID",        CAMEL_IMAP4_RESP_CODE_COPYUID,     1 },
    { NULL,             CAMEL_IMAP4_RESP_CODE_UNKNOWN,     0 }
};


/**
 * camel_imap4_engine_parse_resp_code:
 * @engine: IMAP4 engine
 * @ex: exception
 *
 * Parses a RESP-CODE
 *
 * Returns 0 on success or -1 on fail.
 **/
int
camel_imap4_engine_parse_resp_code (CamelIMAP4Engine *engine, CamelException *ex)
{
    CamelIMAP4RespCode *resp = NULL;
    camel_imap4_resp_code_t code;
    camel_imap4_token_t token;
    unsigned char *linebuf;
    size_t len;
    
    if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
        return -1;
    
    if (token.token != '[') {
        d(fprintf (stderr, "Expected a '[' token (followed by a RESP-CODE)\n"));
        camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
        return -1;
    }
    
    if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
        return -1;
    
    if (token.token != CAMEL_IMAP4_TOKEN_ATOM) {
        d(fprintf (stderr, "Expected an atom token containing a RESP-CODE\n"));
        camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
        return -1;
    }
    
    for (code = 0; imap4_resp_codes[code].name; code++) {
        if (!strcmp (imap4_resp_codes[code].name, token.v.atom)) {
            if (engine->current && imap4_resp_codes[code].save) {
                resp = g_new0 (CamelIMAP4RespCode, 1);
                resp->code = code;
            }
            break;
        }
    }
    
    switch (code) {
    case CAMEL_IMAP4_RESP_CODE_BADCHARSET:
        /* apparently we don't support UTF-8 afterall */
        engine->capa &= ~CAMEL_IMAP4_CAPABILITY_utf8_search;
        break;
    case CAMEL_IMAP4_RESP_CODE_CAPABILITY:
        /* capability list follows */
        if (engine_parse_capability (engine, ']', ex) == -1)
            goto exception;
        break;
    case CAMEL_IMAP4_RESP_CODE_PERM_FLAGS:
        /* flag list follows */
        if (engine_parse_flags_list (engine, resp, TRUE, ex) == -1)
            goto exception;
        break;
    case CAMEL_IMAP4_RESP_CODE_READONLY:
        break;
    case CAMEL_IMAP4_RESP_CODE_READWRITE:
        break;
    case CAMEL_IMAP4_RESP_CODE_TRYCREATE:
        break;
    case CAMEL_IMAP4_RESP_CODE_UIDNEXT:
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            goto exception;
        
        if (token.token != CAMEL_IMAP4_TOKEN_NUMBER) {
            d(fprintf (stderr, "Expected an nz_number token as an argument to the UIDNEXT RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.uidnext = token.v.number;
        
        break;
    case CAMEL_IMAP4_RESP_CODE_UIDVALIDITY:
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            goto exception;
        
        if (token.token != CAMEL_IMAP4_TOKEN_NUMBER) {
            d(fprintf (stderr, "Expected an nz_number token as an argument to the UIDVALIDITY RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.uidvalidity = token.v.number;
        
        break;
    case CAMEL_IMAP4_RESP_CODE_UNSEEN:
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token != CAMEL_IMAP4_TOKEN_NUMBER) {
            d(fprintf (stderr, "Expected an nz_number token as an argument to the UNSEEN RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.unseen = token.v.number;
        
        break;
    case CAMEL_IMAP4_RESP_CODE_NEWNAME:
        /* this RESP-CODE may actually be removed - see here:
         * http://www.washington.edu/imap4/listarch/2001/msg00058.html */
        
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token != CAMEL_IMAP4_TOKEN_ATOM && token.token != CAMEL_IMAP4_TOKEN_QSTRING) {
            d(fprintf (stderr, "Expected an atom or qstring token as the first argument to the NEWNAME RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.newname[0] = g_strdup (token.v.atom);
        
        if (token.token != CAMEL_IMAP4_TOKEN_ATOM && token.token != CAMEL_IMAP4_TOKEN_QSTRING) {
            d(fprintf (stderr, "Expected an atom or qstring token as the second argument to the NEWNAME RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.newname[1] = g_strdup (token.v.atom);
        
        break;
    case CAMEL_IMAP4_RESP_CODE_APPENDUID:
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token != CAMEL_IMAP4_TOKEN_NUMBER) {
            d(fprintf (stderr, "Expected an nz_number token as the first argument to the APPENDUID RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.appenduid.uidvalidity = token.v.number;
        
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token != CAMEL_IMAP4_TOKEN_NUMBER) {
            d(fprintf (stderr, "Expected an nz_number token as the second argument to the APPENDUID RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.appenduid.uid = token.v.number;
        
        break;
    case CAMEL_IMAP4_RESP_CODE_COPYUID:
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token != CAMEL_IMAP4_TOKEN_NUMBER) {
            d(fprintf (stderr, "Expected an nz_number token as the first argument to the COPYUID RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.copyuid.uidvalidity = token.v.number;
        
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token != CAMEL_IMAP4_TOKEN_ATOM) {
            d(fprintf (stderr, "Expected an atom token as the second argument to the COPYUID RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.copyuid.srcset = g_strdup (token.v.atom);
        
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token != CAMEL_IMAP4_TOKEN_ATOM) {
            d(fprintf (stderr, "Expected an atom token as the third argument to the APPENDUID RESP-CODE\n"));
            camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
            goto exception;
        }
        
        if (resp != NULL)
            resp->v.copyuid.destset = g_strdup (token.v.atom);
        
        break;
    default:
        d(fprintf (stderr, "Unknown RESP-CODE encountered: %s\n", token.v.atom));
        
        /* extensions are of the form: "[" atom [SPACE 1*<any TEXT_CHAR except "]">] "]" */
        
        /* eat up the TEXT_CHARs */
        while (token.token != ']' && token.token != '\n') {
            if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
                goto exception;
        }
        
        break;
    }
    
    while (token.token != ']' && token.token != '\n') {
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            goto exception;
    }
    
    if (token.token != ']') {
        camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
        d(fprintf (stderr, "Expected to find a ']' token after the RESP-CODE\n"));
        return -1;
    }
    
    if (code == CAMEL_IMAP4_RESP_CODE_ALERT) {
        if (camel_imap4_engine_line (engine, &linebuf, &len, ex) == -1)
            goto exception;
        
        camel_session_alert_user (engine->session, CAMEL_SESSION_ALERT_INFO, linebuf, FALSE);
        g_free (linebuf);
    } else if (resp != NULL && code == CAMEL_IMAP4_RESP_CODE_PARSE) {
        if (camel_imap4_engine_line (engine, &linebuf, &len, ex) == -1)
            goto exception;
        
        resp->v.parse = linebuf;
    } else {
        /* eat up the rest of the response */
        if (camel_imap4_engine_line (engine, NULL, NULL, ex) == -1)
            goto exception;
    }
    
    if (resp != NULL)
        g_ptr_array_add (engine->current->resp_codes, resp);
    
    return 0;
    
 exception:
    
    if (resp != NULL)
        camel_imap4_resp_code_free (resp);
    
    return -1;
}


/**
 * camel_imap4_engine_handle_untagged_1:
 * @engine: IMAP4 engine
 * @token: IMAP4 token
 * @ex: exception
 *
 * Handles a single untagged response
 *
 * Returns -1 on error or one of
 * CAMEL_IMAP4_UNTAGGED_[OK,NO,BAD,PREAUTH,HANDLED] on success
 **/
int
camel_imap4_engine_handle_untagged_1 (CamelIMAP4Engine *engine, camel_imap4_token_t *token, CamelException *ex)
{
    int code = CAMEL_IMAP4_UNTAGGED_HANDLED;
    CamelIMAP4Command *ic = engine->current;
    CamelIMAP4UntaggedCallback untagged;
    CamelFolder *folder;
    unsigned int v;
    
    if (camel_imap4_engine_next_token (engine, token, ex) == -1)
        return -1;
    
    if (token->token == CAMEL_IMAP4_TOKEN_ATOM) {
        if (!strcmp ("BYE", token->v.atom)) {
            /* we don't care if we fail here, either way we've been disconnected */
            if (camel_imap4_engine_next_token (engine, token, NULL) == 0) {
                if (token->token == '[') {
                    camel_imap4_stream_unget_token (engine->istream, token);
                    camel_imap4_engine_parse_resp_code (engine, NULL);
                } else {
                    camel_imap4_engine_line (engine, NULL, NULL, NULL);
                }
            }
            
            engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
            
            /* we don't return -1 here because there may be more untagged responses after the BYE */
        } else if (!strcmp ("CAPABILITY", token->v.atom)) {
            /* capability tokens follow */
            if (engine_parse_capability (engine, '\n', ex) == -1)
                return -1;
            
            /* find the eoln token */
            if (camel_imap4_engine_next_token (engine, token, ex) == -1)
                return -1;
            
            if (token->token != '\n') {
                camel_imap4_utils_set_unexpected_token_error (ex, engine, token);
                return -1;
            }
        } else if (!strcmp ("FLAGS", token->v.atom)) {
            /* flags list follows */
            if (engine_parse_flags (engine, ex) == -1)
                return -1;
        } else if (!strcmp ("NAMESPACE", token->v.atom)) {
            if (engine_parse_namespace (engine, ex) == -1)
                return -1;
        } else if (!strcmp ("NO", token->v.atom) || !strcmp ("BAD", token->v.atom)) {
            code = !strcmp ("NO", token->v.atom) ? CAMEL_IMAP4_UNTAGGED_NO : CAMEL_IMAP4_UNTAGGED_BAD;
            
            /* our command has been rejected */
            if (camel_imap4_engine_next_token (engine, token, ex) == -1)
                return -1;
            
            if (token->token == '[') {
                /* we have a resp code */
                camel_imap4_stream_unget_token (engine->istream, token);
                if (camel_imap4_engine_parse_resp_code (engine, ex) == -1)
                    return -1;
            } else if (token->token != '\n') {
                /* we just have resp text */
                if (camel_imap4_engine_line (engine, NULL, NULL, ex) == -1)
                    return -1;
            }
        } else if (!strcmp ("OK", token->v.atom)) {
            code = CAMEL_IMAP4_UNTAGGED_OK;
            
            if (engine->state == CAMEL_IMAP4_ENGINE_CONNECTED) {
                /* initial server greeting */
                engine->state = CAMEL_IMAP4_ENGINE_PREAUTH;
            }
            
            if (camel_imap4_engine_next_token (engine, token, ex) == -1)
                return -1;
            
            if (token->token == '[') {
                /* we have a resp code */
                camel_imap4_stream_unget_token (engine->istream, token);
                if (camel_imap4_engine_parse_resp_code (engine, ex) == -1)
                    return -1;
            } else {
                /* we just have resp text */
                if (camel_imap4_engine_line (engine, NULL, NULL, ex) == -1)
                    return -1;
            }
        } else if (!strcmp ("PREAUTH", token->v.atom)) {
            code = CAMEL_IMAP4_UNTAGGED_PREAUTH;
            
            if (engine->state == CAMEL_IMAP4_ENGINE_CONNECTED)
                engine->state = CAMEL_IMAP4_ENGINE_AUTHENTICATED;
            
            if (camel_imap4_engine_parse_resp_code (engine, ex) == -1)
                return -1;
        } else if (ic && (untagged = g_hash_table_lookup (ic->untagged, token->v.atom))) {
            /* registered untagged handler for imap4 command */
            if (untagged (engine, ic, 0, token, ex) == -1)
                return -1;
        } else {
            d(fprintf (stderr, "Unhandled atom token in untagged response: %s", token->v.atom));
            
            if (camel_imap4_engine_eat_line (engine, ex) == -1)
                return -1;
        }
    } else if (token->token == CAMEL_IMAP4_TOKEN_NUMBER) {
        /* we probably have something like "* 1 EXISTS" */
        v = token->v.number;
        
        if (camel_imap4_engine_next_token (engine, token, ex) == -1)
            return -1;
        
        if (token->token != CAMEL_IMAP4_TOKEN_ATOM) {
            camel_imap4_utils_set_unexpected_token_error (ex, engine, token);
            
            return -1;
        }
        
        /* which folder is this EXISTS/EXPUNGE/RECENT acting on? */
        if (engine->current && engine->current->folder)
            folder = (CamelFolder *) engine->current->folder;
        else if (engine->folder)
            folder = (CamelFolder *) engine->folder;
        else
            folder = NULL;
        
        /* NOTE: these can be over-ridden by a registered untagged response handler */
        if (!strcmp ("EXISTS", token->v.atom)) {
            camel_imap4_summary_set_exists (folder->summary, v);
        } else if (!strcmp ("EXPUNGE", token->v.atom)) {
            camel_imap4_summary_expunge (folder->summary, (int) v);
        } else if (!strcmp ("RECENT", token->v.atom)) {
            camel_imap4_summary_set_recent (folder->summary, v);
        } else if (ic && (untagged = g_hash_table_lookup (ic->untagged, token->v.atom))) {
            /* registered untagged handler for imap4 command */
            if (untagged (engine, ic, v, token, ex) == -1)
                return -1;
        } else {
            d(fprintf (stderr, "Unrecognized untagged response: * %u %s\n", v, token->v.atom));
        }
        
        /* find the eoln token */
        if (camel_imap4_engine_eat_line (engine, ex) == -1)
            return -1;
    } else {
        camel_imap4_utils_set_unexpected_token_error (ex, engine, token);
        
        return -1;
    }
    
    return code;
}


/**
 * camel_imap4_engine_handle_untagged:
 * @engine: IMAP4 engine
 * @ex: exception
 *
 * Handle a stream of untagged responses.
 **/
void
camel_imap4_engine_handle_untagged (CamelIMAP4Engine *engine, CamelException *ex)
{
    camel_imap4_token_t token;
    
    g_return_if_fail (CAMEL_IS_IMAP4_ENGINE (engine));
    
    do {
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            goto exception;
        
        if (token.token != '*')
            break;
        
        if (camel_imap4_engine_handle_untagged_1 (engine, &token, ex) == -1)
            goto exception;
    } while (1);
    
    camel_imap4_stream_unget_token (engine->istream, &token);
    
    return;
    
 exception:
    
    engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
}


static int
imap4_process_command (CamelIMAP4Engine *engine, CamelIMAP4Command *ic)
{
    int retval;
    
    while ((retval = camel_imap4_command_step (ic)) == 0)
        ;
    
    if (retval == -1) {
        engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
        return -1;
    }
    
    return 0;
}


static void
engine_prequeue_folder_select (CamelIMAP4Engine *engine)
{
    CamelIMAP4Command *ic;
    const char *cmd;
    
    ic = (CamelIMAP4Command *) engine->queue.head;
    cmd = (const char *) ic->parts->buffer;
    
    if (!ic->folder || ic->folder == engine->folder ||
        !strncmp (cmd, "SELECT ", 7) || !strncmp (cmd, "EXAMINE ", 8)) {
        /* no need to pre-queue a SELECT */
        return;
    }
    
    /* we need to pre-queue a SELECT */
    ic = camel_imap4_engine_prequeue (engine, (CamelFolder *) ic->folder, "SELECT %F\r\n", ic->folder);
    ic->user_data = engine;
    
    camel_imap4_command_unref (ic);
}


static int
engine_state_change (CamelIMAP4Engine *engine, CamelIMAP4Command *ic)
{
    const char *cmd;
    int retval = 0;
    
    cmd = ic->parts->buffer;
    if (!strncmp (cmd, "SELECT ", 7) || !strncmp (cmd, "EXAMINE ", 8)) {
        if (ic->result == CAMEL_IMAP4_RESULT_OK) {
            /* Update the selected folder */
            camel_object_ref (ic->folder);
            if (engine->folder)
                camel_object_unref (engine->folder);
            engine->folder = ic->folder;
            
            engine->state = CAMEL_IMAP4_ENGINE_SELECTED;
        } else if (ic->user_data == engine) {
            /* the engine pre-queued this SELECT command */
            retval = -1;
        }
    } else if (!strncmp (cmd, "CLOSE", 5)) {
        if (ic->result == CAMEL_IMAP4_RESULT_OK)
            engine->state = CAMEL_IMAP4_ENGINE_AUTHENTICATED;
    } else if (!strncmp (cmd, "LOGOUT", 6)) {
        engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
    }
    
    return retval;
}


/**
 * camel_imap4_engine_iterate:
 * @engine: IMAP4 engine
 *
 * Processes the first command in the queue.
 *
 * Returns the id of the processed command, 0 if there were no
 * commands to process, or -1 on error.
 *
 * Note: more details on the error will be held on the
 * CamelIMAP4Command that failed.
 **/
int
camel_imap4_engine_iterate (CamelIMAP4Engine *engine)
{
    CamelIMAP4Command *ic, *nic;
    GPtrArray *resp_codes;
    int retval = -1;
    
    if (e_dlist_empty (&engine->queue))
        return 0;
    
    /* This sucks... it would be nicer if we didn't have to check the stream's disconnected status */
    if ((engine->state == CAMEL_IMAP4_ENGINE_DISCONNECTED || engine->istream->disconnected) && !engine->reconnecting) {
        CamelException rex;
        gboolean connected;
        
        camel_exception_init (&rex);
        engine->reconnecting = TRUE;
        connected = engine->reconnect (engine, &rex);
        engine->reconnecting = FALSE;
        
        if (!connected) {
            /* pop the first command and act as tho it failed (which, technically, it did...) */
            ic = (CamelIMAP4Command *) e_dlist_remhead (&engine->queue);
            ic->status = CAMEL_IMAP4_COMMAND_ERROR;
            camel_exception_xfer (&ic->ex, &rex);
            return -1;
        }
    }
    
    /* check to see if we need to pre-queue a SELECT, if so do it */
    engine_prequeue_folder_select (engine);
    
    engine->current = ic = (CamelIMAP4Command *) e_dlist_remhead (&engine->queue);
    ic->status = CAMEL_IMAP4_COMMAND_ACTIVE;
    
    if (imap4_process_command (engine, ic) != -1) {
        if (engine_state_change (engine, ic) == -1) {
            /* This can ONLY happen if @ic was the pre-queued SELECT command
             * and it got a NO or BAD response.
             *
             * We have to pop the next imap4 command or we'll get into an
             * infinite loop. In order to provide @nic's owner with as much
             * information as possible, we move all @ic status information
             * over to @nic and pretend we just processed @nic.
             **/
            
            nic = (CamelIMAP4Command *) e_dlist_remhead (&engine->queue);
            
            nic->status = ic->status;
            nic->result = ic->result;
            resp_codes = nic->resp_codes;
            nic->resp_codes = ic->resp_codes;
            ic->resp_codes = resp_codes;
            
            camel_exception_xfer (&nic->ex, &ic->ex);
            
            camel_imap4_command_unref (ic);
            ic = nic;
        }
        
        retval = ic->id;
    }
    
    camel_imap4_command_unref (ic);
    
    return retval;
}


/**
 * camel_imap4_engine_queue:
 * @engine: IMAP4 engine
 * @folder: IMAP4 folder that the command will affect (or %NULL if it doesn't matter)
 * @format: command format
 * @Varargs: arguments
 *
 * Basically the same as camel_imap4_command_new() except that this
 * function also places the command in the engine queue.
 *
 * Returns the CamelIMAP4Command.
 **/
CamelIMAP4Command *
camel_imap4_engine_queue (CamelIMAP4Engine *engine, CamelFolder *folder, const char *format, ...)
{
    CamelIMAP4Command *ic;
    va_list args;
    
    g_return_val_if_fail (CAMEL_IS_IMAP4_ENGINE (engine), NULL);
    
    va_start (args, format);
    ic = camel_imap4_command_newv (engine, (CamelIMAP4Folder *) folder, format, args);
    va_end (args);
    
    ic->id = engine->nextid++;
    e_dlist_addtail (&engine->queue, (EDListNode *) ic);
    camel_imap4_command_ref (ic);
    
    return ic;
}


/**
 * camel_imap4_engine_prequeue:
 * @engine: IMAP4 engine
 * @folder: IMAP4 folder that the command will affect (or %NULL if it doesn't matter)
 * @format: command format
 * @Varargs: arguments
 *
 * Same as camel_imap4_engine_queue() except this places the new
 * command at the head of the queue.
 *
 * Returns the CamelIMAP4Command.
 **/
CamelIMAP4Command *
camel_imap4_engine_prequeue (CamelIMAP4Engine *engine, CamelFolder *folder, const char *format, ...)
{
    CamelIMAP4Command *ic;
    va_list args;
    
    g_return_val_if_fail (CAMEL_IS_IMAP4_ENGINE (engine), NULL);
    
    va_start (args, format);
    ic = camel_imap4_command_newv (engine, (CamelIMAP4Folder *) folder, format, args);
    va_end (args);
    
    if (e_dlist_empty (&engine->queue)) {
        e_dlist_addtail (&engine->queue, (EDListNode *) ic);
        ic->id = engine->nextid++;
    } else {
        CamelIMAP4Command *nic;
        EDListNode *node;
        
        node = (EDListNode *) ic;
        e_dlist_addhead (&engine->queue, node);
        nic = (CamelIMAP4Command *) node->next;
        ic->id = nic->id - 1;
        
        if (ic->id == 0) {
            /* increment all command ids */
            node = engine->queue.head;
            while (node->next) {
                nic = (CamelIMAP4Command *) node;
                node = node->next;
                nic->id++;
            }
        }
    }
    
    camel_imap4_command_ref (ic);
    
    return ic;
}


/**
 * camel_imap4_engine_dequeue:
 * @engine: IMAP4 engine
 * @ic: IMAP4 command
 *
 * Removes @ic from the processing queue.
 **/
void
camel_imap4_engine_dequeue (CamelIMAP4Engine *engine, CamelIMAP4Command *ic)
{
    EDListNode *node = (EDListNode *) ic;
    
    if (node->next == NULL && node->prev == NULL)
        return;
    
    e_dlist_remove (node);
    node->next = NULL;
    node->prev = NULL;
    
    camel_imap4_command_unref (ic);
}


/**
 * camel_imap4_engine_next_token:
 * @engine: IMAP4 engine
 * @token: IMAP4 token
 * @ex: exception
 *
 * Wraps camel_imap4_stream_next_token() to set an exception on
 * failure and updates the engine state to DISCONNECTED if the stream
 * gets disconencted.
 *
 * Returns 0 on success or -1 on fail.
 **/
int
camel_imap4_engine_next_token (CamelIMAP4Engine *engine, camel_imap4_token_t *token, CamelException *ex)
{
    if (camel_imap4_stream_next_token (engine->istream, token) == -1) {
        camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                      _("IMAP4 server %s unexpectedly disconnected: %s"),
                      engine->url->host, errno ? g_strerror (errno) : _("Unknown"));
        
        engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
        
        return -1;
    }
    
    return 0;
}


/**
 * camel_imap4_engine_eat_line:
 * @engine: IMAP4 engine
 * @ex: exception
 *
 * Gobbles up the remainder of the response line.
 *
 * Returns 0 on success or -1 on fail
 **/
int
camel_imap4_engine_eat_line (CamelIMAP4Engine *engine, CamelException *ex)
{
    camel_imap4_token_t token;
    unsigned char *literal;
    int retval;
    size_t n;
    
    do {
        if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
            return -1;
        
        if (token.token == CAMEL_IMAP4_TOKEN_LITERAL) {
            while ((retval = camel_imap4_stream_literal (engine->istream, &literal, &n)) == 1)
                ;
            
            if (retval == -1) {
                camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                              _("IMAP4 server %s unexpectedly disconnected: %s"),
                              engine->url->host, errno ? g_strerror (errno) : _("Unknown"));
                
                engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
                
                return -1;
            }
        }
    } while (token.token != '\n');
    
    return 0;
}


/**
 * camel_imap4_engine_line:
 * @engine: IMAP4 engine
 * @line: line pointer
 * @len: length pointer
 * @ex: exception
 *
 * Reads in a single line of input from the IMAP4 server and updates
 * @line to point to the line buffer. @len is set to the length of the
 * line buffer. @line must be free'd using g_free().
 *
 * Returns 0 on success or -1 on fail
 **/
int
camel_imap4_engine_line (CamelIMAP4Engine *engine, unsigned char **line, size_t *len, CamelException *ex)
{
    GByteArray *linebuf = NULL;
    unsigned char *buf;
    size_t buflen;
    int retval;
    
    if (line != NULL)
        linebuf = g_byte_array_new ();
    
    while ((retval = camel_imap4_stream_line (engine->istream, &buf, &buflen)) > 0) {
        if (linebuf != NULL)
            g_byte_array_append (linebuf, buf, buflen);
    }
    
    if (retval == -1) {
        camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                      _("IMAP4 server %s unexpectedly disconnected: %s"),
                      engine->url->host, errno ? g_strerror (errno) : _("Unknown"));
        
        if (linebuf != NULL)
            g_byte_array_free (linebuf, TRUE);
        
        engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
        
        return -1;
    }
    
    if (linebuf != NULL) {
        g_byte_array_append (linebuf, buf, buflen);
        
        *line = linebuf->data;
        *len = linebuf->len;
        
        g_byte_array_free (linebuf, FALSE);
    }
    
    return 0;
}


/**
 * camel_imap4_engine_literal:
 * @engine: IMAP4 engine
 * @literal: literal pointer
 * @len: len pointer
 * @ex: exception
 *
 * Reads in an entire literal string and updates @literal to point to
 * it. @len is set to the length of the literal. @literal will also
 * conveniently be terminated with a nul-byte. @literal must be free'd
 * using g_free().
 *
 * Returns 0 on success or -1 on fail.
 **/
int
camel_imap4_engine_literal (CamelIMAP4Engine *engine, unsigned char **literal, size_t *len, CamelException *ex)
{
    GByteArray *literalbuf = NULL;
    unsigned char *buf;
    size_t buflen;
    int retval;
    
    if (literal != NULL)
        literalbuf = g_byte_array_new ();
    
    while ((retval = camel_imap4_stream_literal (engine->istream, &buf, &buflen)) > 0) {
        if (literalbuf != NULL)
            g_byte_array_append (literalbuf, buf, buflen);
    }
    
    if (retval == -1) {
        camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                      _("IMAP4 server %s unexpectedly disconnected: %s"),
                      engine->url->host, errno ? g_strerror (errno) : _("Unknown"));
        
        if (literalbuf != NULL)
            g_byte_array_free (literalbuf, TRUE);
        
        engine->state = CAMEL_IMAP4_ENGINE_DISCONNECTED;
        
        return -1;
    }
    
    if (literalbuf != NULL) {
        g_byte_array_append (literalbuf, buf, buflen);
        g_byte_array_append (literalbuf, "", 1);
        
        *literal = literalbuf->data;
        *len = literalbuf->len - 1;
        
        g_byte_array_free (literalbuf, FALSE);
    }
    
    return 0;
}


/**
 * camel_imap4_engine_nstring:
 * @engine: IMAP4 engine
 * @nstring: nstring pointer
 * @ex: exception
 *
 * Reads in an nstring (NIL, atom, qstring or literal) and updates
 * @nstring to point to it. @nstring must be free'd using g_free().
 *
 * Returns 0 on success or -1 on fail.
 **/
int
camel_imap4_engine_nstring (CamelIMAP4Engine *engine, unsigned char **nstring, CamelException *ex)
{
    camel_imap4_token_t token;
    size_t n;
    
    if (camel_imap4_engine_next_token (engine, &token, ex) == -1)
        return -1;
    
    switch (token.token) {
    case CAMEL_IMAP4_TOKEN_NIL:
        *nstring = NULL;
        break;
    case CAMEL_IMAP4_TOKEN_ATOM:
        *nstring = g_strdup (token.v.atom);
        break;
    case CAMEL_IMAP4_TOKEN_QSTRING:
        *nstring = g_strdup (token.v.qstring);
        break;
    case CAMEL_IMAP4_TOKEN_LITERAL:
        if (camel_imap4_engine_literal (engine, nstring, &n, ex) == -1)
            return -1;
        break;
    default:
        camel_imap4_utils_set_unexpected_token_error (ex, engine, &token);
        return -1;
    }
    
    return 0;
}


/**
 * camel_imap4_resp_code_free:
 * @rcode: RESP-CODE
 *
 * Free's the RESP-CODE
 **/
void
camel_imap4_resp_code_free (CamelIMAP4RespCode *rcode)
{
    switch (rcode->code) {
    case CAMEL_IMAP4_RESP_CODE_PARSE:
        g_free (rcode->v.parse);
        break;
    case CAMEL_IMAP4_RESP_CODE_NEWNAME:
        g_free (rcode->v.newname[0]);
        g_free (rcode->v.newname[1]);
        break;
    case CAMEL_IMAP4_RESP_CODE_COPYUID:
        g_free (rcode->v.copyuid.srcset);
        g_free (rcode->v.copyuid.destset);
        break;
    default:
        break;
    }
    
    g_free (rcode);
}