path: root/camel/camel-service.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* camel-service.c : Abstract class for an email service */

/*
 *
 * Author :
 *  Bertrand Guiheneuf <bertrand@helixcode.com>
 *
 * Copyright 1999, 2000 Ximian, Inc. (www.ximian.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * 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 Place, Suite 330, Boston, MA 02111-1307
 * USA
 */

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

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

#ifdef ENABLE_THREADS
#include <pthread.h>
#include "e-util/e-msgport.h"
#endif

#include "e-util/e-host-utils.h"

#include "camel-service.h"
#include "camel-session.h"
#include "camel-exception.h"
#include "camel-operation.h"
#include "camel-private.h"

#define d(x)
#define w(x)

static CamelObjectClass *parent_class = NULL;

/* Returns the class for a CamelService */
#define CSERV_CLASS(so) CAMEL_SERVICE_CLASS (CAMEL_OBJECT_GET_CLASS(so))

static void construct (CamelService *service, CamelSession *session,
               CamelProvider *provider, CamelURL *url,
               CamelException *ex);
static gboolean service_connect(CamelService *service, CamelException *ex);
static gboolean service_disconnect(CamelService *service, gboolean clean,
                   CamelException *ex);
static void cancel_connect (CamelService *service);
static GList *query_auth_types (CamelService *service, CamelException *ex);
static char *get_name (CamelService *service, gboolean brief);
static char *get_path (CamelService *service);

static int service_setv (CamelObject *object, CamelException *ex, CamelArgV *args);
static int service_getv (CamelObject *object, CamelException *ex, CamelArgGetV *args);


static void
camel_service_class_init (CamelServiceClass *camel_service_class)
{
    CamelObjectClass *object_class = CAMEL_OBJECT_CLASS (camel_service_class);
    
    parent_class = camel_type_get_global_classfuncs (CAMEL_OBJECT_TYPE);
    
    /* virtual method overloading */
    object_class->setv = service_setv;
    object_class->getv = service_getv;
    
    /* virtual method definition */
    camel_service_class->construct = construct;
    camel_service_class->connect = service_connect;
    camel_service_class->disconnect = service_disconnect;
    camel_service_class->cancel_connect = cancel_connect;
    camel_service_class->query_auth_types = query_auth_types;
    camel_service_class->get_name = get_name;
    camel_service_class->get_path = get_path;
}

static void
camel_service_init (void *o, void *k)
{
    CamelService *service = o;

    service->priv = g_malloc0(sizeof(*service->priv));
#ifdef ENABLE_THREADS
    service->priv->connect_lock = e_mutex_new(E_MUTEX_REC);
    service->priv->connect_op_lock = e_mutex_new(E_MUTEX_SIMPLE);
#endif
}

static void
camel_service_finalize (CamelObject *object)
{
    CamelService *service = CAMEL_SERVICE (object);
    
    if (service->status == CAMEL_SERVICE_CONNECTED) {
        CamelException ex;
        
        camel_exception_init (&ex);
        CSERV_CLASS (service)->disconnect (service, TRUE, &ex);
        if (camel_exception_is_set (&ex)) {
            w(g_warning ("camel_service_finalize: silent disconnect failure: %s",
                     camel_exception_get_description (&ex)));
        }
        camel_exception_clear (&ex);
    }
    
    if (service->url)
        camel_url_free (service->url);
    if (service->session)
        camel_object_unref (CAMEL_OBJECT (service->session));
    
#ifdef ENABLE_THREADS
    e_mutex_destroy (service->priv->connect_lock);
    e_mutex_destroy (service->priv->connect_op_lock);
#endif
    g_free (service->priv);
}



CamelType
camel_service_get_type (void)
{
    static CamelType type = CAMEL_INVALID_TYPE;
    
    if (type == CAMEL_INVALID_TYPE) {
        type =
            camel_type_register (CAMEL_OBJECT_TYPE,
                         "CamelService",
                         sizeof (CamelService),
                         sizeof (CamelServiceClass),
                         (CamelObjectClassInitFunc) camel_service_class_init,
                         NULL,
                         (CamelObjectInitFunc) camel_service_init,
                         camel_service_finalize );
    }
    
    return type;
}


static int
service_setv (CamelObject *object, CamelException *ex, CamelArgV *args)
{
    CamelService *service = (CamelService *) object;
    CamelURL *url = service->url;
    gboolean reconnect = FALSE;
    guint32 tag;
    int i;
    
    for (i = 0; i < args->argc; i++) {
        tag = args->argv[i].tag;
        
        /* make sure this arg wasn't already handled */
        if (tag & CAMEL_ARG_IGNORE)
            continue;
        
        /* make sure this is an arg we're supposed to handle */
        if ((tag & CAMEL_ARG_TAG) <= CAMEL_SERVICE_ARG_FIRST ||
            (tag & CAMEL_ARG_TAG) >= CAMEL_SERVICE_ARG_FIRST + 100)
            continue;
        
        if (tag == CAMEL_SERVICE_USERNAME) {
            /* set the username */
            if (strcmp (url->user, args->argv[i].ca_str) != 0) {
                camel_url_set_user (url, args->argv[i].ca_str);
                reconnect = TRUE;
            }
        } else if (tag == CAMEL_SERVICE_AUTH) {
            /* set the auth mechanism */
            if (strcmp (url->authmech, args->argv[i].ca_str) != 0) {
                camel_url_set_authmech (url, args->argv[i].ca_str);
                reconnect = TRUE;
            }
        } else if (tag == CAMEL_SERVICE_HOSTNAME) {
            /* set the hostname */
            if (strcmp (url->host, args->argv[i].ca_str) != 0) {
                camel_url_set_host (url, args->argv[i].ca_str);
                reconnect = TRUE;
            }
        } else if (tag == CAMEL_SERVICE_PORT) {
            /* set the port */
            if (url->port != args->argv[i].ca_int) {
                camel_url_set_port (url, args->argv[i].ca_int);
                reconnect = TRUE;
            }
        } else if (tag == CAMEL_SERVICE_PATH) {
            /* set the path */
            if (strcmp (url->path, args->argv[i].ca_str) != 0) {
                camel_url_set_host (url, args->argv[i].ca_str);
                reconnect = TRUE;
            }
        } else {
            /* error? */
            continue;
        }
        
        /* let our parent know that we've handled this arg */
        camel_argv_ignore (args, i);
    }
    
    /* FIXME: what if we are in the process of connecting? */
    if (reconnect && service->status == CAMEL_SERVICE_CONNECTED) {
        /* reconnect the service using the new URL */
        if (camel_service_disconnect (service, TRUE, ex))
            camel_service_connect (service, ex);
    }
    
    return CAMEL_OBJECT_CLASS (parent_class)->setv (object, ex, args);
}

static int
service_getv (CamelObject *object, CamelException *ex, CamelArgGetV *args)
{
    CamelService *service = (CamelService *) object;
    CamelURL *url = service->url;
    guint32 tag;
    int i;
    
    for (i = 0; i < args->argc; i++) {
        tag = args->argv[i].tag;
        
        /* make sure this is an arg we're supposed to handle */
        if ((tag & CAMEL_ARG_TAG) <= CAMEL_SERVICE_ARG_FIRST ||
            (tag & CAMEL_ARG_TAG) >= CAMEL_SERVICE_ARG_FIRST + 100)
            continue;
        
        switch (tag) {
        case CAMEL_SERVICE_USERNAME:
            /* get the username */
            *args->argv[i].ca_str = url->user;
            break;
        case CAMEL_SERVICE_AUTH:
            /* get the auth mechanism */
            *args->argv[i].ca_str = url->authmech;
            break;
        case CAMEL_SERVICE_HOSTNAME:
            /* get the hostname */
            *args->argv[i].ca_str = url->host;
            break;
        case CAMEL_SERVICE_PORT:
            /* get the port */
            *args->argv[i].ca_int = url->port;
            break;
        case CAMEL_SERVICE_PATH:
            /* get the path */
            *args->argv[i].ca_str = url->path;
            break;
        default:
            /* error? */
            break;
        }
    }
    
    return CAMEL_OBJECT_CLASS (parent_class)->getv (object, ex, args);
}

static void
construct (CamelService *service, CamelSession *session,
       CamelProvider *provider, CamelURL *url, CamelException *ex)
{
    char *url_string;
    
    if (CAMEL_PROVIDER_NEEDS (provider, CAMEL_URL_PART_USER) &&
        (url->user == NULL || url->user[0] == '\0')) {
        url_string = camel_url_to_string (url, CAMEL_URL_HIDE_PASSWORD);
        camel_exception_setv (ex, CAMEL_EXCEPTION_SERVICE_URL_INVALID,
                      _("URL '%s' needs a username component"),
                      url_string);
        g_free (url_string);
        return;
    } else if (CAMEL_PROVIDER_NEEDS (provider, CAMEL_URL_PART_HOST) &&
           (url->host == NULL || url->host[0] == '\0')) {
        url_string = camel_url_to_string (url, CAMEL_URL_HIDE_PASSWORD);
        camel_exception_setv (ex, CAMEL_EXCEPTION_SERVICE_URL_INVALID,
                      _("URL '%s' needs a host component"),
                      url_string);
        g_free (url_string);
        return;
    } else if (CAMEL_PROVIDER_NEEDS (provider, CAMEL_URL_PART_PATH) &&
           (url->path == NULL || url->path[0] == '\0')) {
        url_string = camel_url_to_string (url, CAMEL_URL_HIDE_PASSWORD);
        camel_exception_setv (ex, CAMEL_EXCEPTION_SERVICE_URL_INVALID,
                      _("URL '%s' needs a path component"),
                      url_string);
        g_free (url_string);
        return;
    }
    
    service->provider = provider;
    service->url = url;
    service->session = session;
    camel_object_ref (CAMEL_OBJECT (session));
    
    service->status = CAMEL_SERVICE_DISCONNECTED;
}

/**
 * camel_service_construct:
 * @service: the CamelService
 * @session: the session for the service
 * @provider: the service's provider
 * @url: the default URL for the service (may be NULL)
 * @ex: a CamelException
 *
 * Constructs a CamelService initialized with the given parameters.
 **/
void
camel_service_construct (CamelService *service, CamelSession *session,
             CamelProvider *provider, CamelURL *url,
             CamelException *ex)
{
    g_return_if_fail (CAMEL_IS_SERVICE (service));
    g_return_if_fail (CAMEL_IS_SESSION (session));
    
    CSERV_CLASS (service)->construct (service, session, provider, url, ex);
}


static gboolean
service_connect (CamelService *service, CamelException *ex)
{
    /* Things like the CamelMboxStore can validly
     * not define a connect function.
     */
     return TRUE;
}

/**
 * camel_service_connect:
 * @service: CamelService object
 * @ex: a CamelException
 *
 * Connect to the service using the parameters it was initialized
 * with.
 *
 * Return value: whether or not the connection succeeded
 **/

gboolean
camel_service_connect (CamelService *service, CamelException *ex)
{
    gboolean ret = FALSE;
    gboolean unreg = FALSE;
    
    g_return_val_if_fail (CAMEL_IS_SERVICE (service), FALSE);
    g_return_val_if_fail (service->session != NULL, FALSE);
    g_return_val_if_fail (service->url != NULL, FALSE);
    
    CAMEL_SERVICE_LOCK (service, connect_lock);
    
    if (service->status == CAMEL_SERVICE_CONNECTED) {
        CAMEL_SERVICE_UNLOCK (service, connect_lock);
        return TRUE;
    }

    /* Register a separate operation for connecting, so that
     * the offline code can cancel it.
     */
    CAMEL_SERVICE_LOCK (service, connect_op_lock);
    service->connect_op = camel_operation_registered ();
    if (!service->connect_op) {
        service->connect_op = camel_operation_new (NULL, NULL);
        camel_operation_register (service->connect_op);
        unreg = TRUE;
    }
    CAMEL_SERVICE_UNLOCK (service, connect_op_lock);

    service->status = CAMEL_SERVICE_CONNECTING;
    ret = CSERV_CLASS (service)->connect (service, ex);
    service->status = ret ? CAMEL_SERVICE_CONNECTED : CAMEL_SERVICE_DISCONNECTED;

    CAMEL_SERVICE_LOCK (service, connect_op_lock);
    if (service->connect_op) {
        if (unreg)
            camel_operation_unregister (service->connect_op);
        
        camel_operation_unref (service->connect_op);
        service->connect_op = NULL;
    }
    CAMEL_SERVICE_UNLOCK (service, connect_op_lock);

    CAMEL_SERVICE_UNLOCK (service, connect_lock);
    
    return ret;
}

static gboolean
service_disconnect (CamelService *service, gboolean clean, CamelException *ex)
{
    /*service->connect_level--;*/

    /* We let people get away with not having a disconnect
     * function -- CamelMboxStore, for example. 
     */
    
    return TRUE;
}

/**
 * camel_service_disconnect:
 * @service: CamelService object
 * @clean: whether or not to try to disconnect cleanly.
 * @ex: a CamelException
 *
 * Disconnect from the service. If @clean is %FALSE, it should not
 * try to do any synchronizing or other cleanup of the connection.
 *
 * Return value: whether or not the disconnection succeeded without
 * errors. (Consult @ex if %FALSE.)
 **/
gboolean
camel_service_disconnect (CamelService *service, gboolean clean,
              CamelException *ex)
{
    gboolean res = TRUE;
    int unreg = FALSE;

    CAMEL_SERVICE_LOCK (service, connect_lock);
    
    if (service->status != CAMEL_SERVICE_DISCONNECTED
        && service->status != CAMEL_SERVICE_DISCONNECTING) {
        CAMEL_SERVICE_LOCK (service, connect_op_lock);
        service->connect_op = camel_operation_registered ();
        if (!service->connect_op) {
            service->connect_op = camel_operation_new (NULL, NULL);
            camel_operation_register (service->connect_op);
            unreg = TRUE;
        }
        CAMEL_SERVICE_UNLOCK (service, connect_op_lock);

        service->status = CAMEL_SERVICE_DISCONNECTING;
        res = CSERV_CLASS (service)->disconnect (service, clean, ex);
        service->status = CAMEL_SERVICE_DISCONNECTED;

        CAMEL_SERVICE_LOCK (service, connect_op_lock);
        if (unreg)
            camel_operation_unregister (service->connect_op);

        camel_operation_unref (service->connect_op);
        service->connect_op = NULL;
        CAMEL_SERVICE_UNLOCK (service, connect_op_lock);
    }
    
    CAMEL_SERVICE_UNLOCK (service, connect_lock);
    
    return res;
}

static void
cancel_connect (CamelService *service)
{
    camel_operation_cancel (service->connect_op);
}

/**
 * camel_service_cancel_connect:
 * @service: a service
 *
 * If @service is currently attempting to connect to or disconnect
 * from a server, this causes it to stop and fail. Otherwise it is a
 * no-op.
 **/
void
camel_service_cancel_connect (CamelService *service)
{
    CAMEL_SERVICE_LOCK (service, connect_op_lock);
    if (service->connect_op)
        CSERV_CLASS (service)->cancel_connect (service);
    CAMEL_SERVICE_UNLOCK (service, connect_op_lock);
}

/**
 * camel_service_get_url:
 * @service: a service
 *
 * Returns the URL representing a service. The returned URL must be
 * freed when it is no longer needed. For security reasons, this
 * routine does not return the password.
 *
 * Return value: the url name
 **/
char *
camel_service_get_url (CamelService *service)
{
    return camel_url_to_string (service->url, CAMEL_URL_HIDE_PASSWORD);
}


static char *
get_name (CamelService *service, gboolean brief)
{
    w(g_warning ("CamelService::get_name not implemented for `%s'",
             camel_type_to_name (CAMEL_OBJECT_GET_TYPE (service))));
    return g_strdup ("???");
}       

/**
 * camel_service_get_name:
 * @service: the service
 * @brief: whether or not to use a briefer form
 *
 * This gets the name of the service in a "friendly" (suitable for
 * humans) form. If @brief is %TRUE, this should be a brief description
 * such as for use in the folder tree. If @brief is %FALSE, it should
 * be a more complete and mostly unambiguous description.
 *
 * Return value: the description, which the caller must free.
 **/
char *
camel_service_get_name (CamelService *service, gboolean brief)
{
    g_return_val_if_fail (CAMEL_IS_SERVICE (service), NULL);
    g_return_val_if_fail (service->url, NULL);
    
    return CSERV_CLASS (service)->get_name (service, brief);
}


static char *
get_path (CamelService *service)
{
    GString *gpath;
    char *path;
    CamelURL *url = service->url;
    CamelProvider *prov = service->provider;
    
    /* A sort of ad-hoc default implementation that works for our
     * current set of services.
     */
    
    gpath = g_string_new (service->provider->protocol);
    if (CAMEL_PROVIDER_ALLOWS (prov, CAMEL_URL_PART_USER)) {
        if (CAMEL_PROVIDER_ALLOWS (prov, CAMEL_URL_PART_HOST)) {
            g_string_sprintfa (gpath, "/%s@%s",
                       url->user ? url->user : "",
                       url->host ? url->host : "");
            
            if (url->port)
                g_string_sprintfa (gpath, ":%d", url->port);
        } else {
            g_string_sprintfa (gpath, "/%s%s",
                       url->user ? url->user : "",
                       CAMEL_PROVIDER_NEEDS (prov, CAMEL_URL_PART_USER) ? "" : "@");
        }
    } else if (CAMEL_PROVIDER_ALLOWS (prov, CAMEL_URL_PART_HOST)) {
        g_string_sprintfa (gpath, "/%s%s",
                   CAMEL_PROVIDER_NEEDS (prov, CAMEL_URL_PART_HOST) ? "" : "@",
                   url->host ? url->host : "");
        
        if (url->port)
            g_string_sprintfa (gpath, ":%d", url->port);
    }
    if (CAMEL_PROVIDER_NEEDS (prov, CAMEL_URL_PART_PATH)) {
        g_string_sprintfa (gpath, "%s%s",
                   *url->path == '/' ? "" : "/",
                   url->path);
    }
    
    path = gpath->str;
    g_string_free (gpath, FALSE);
    return path;
}       

/**
 * camel_service_get_path:
 * @service: the service
 *
 * This gets a valid UNIX relative path describing the service, which
 * is guaranteed to be different from the path returned for any
 * different service. This path MUST start with the name of the
 * provider, followed by a "/", but after that, it is up to the
 * provider.
 *
 * Return value: the path, which the caller must free.
 **/
char *
camel_service_get_path (CamelService *service)
{
    g_return_val_if_fail (CAMEL_IS_SERVICE (service), NULL);
    g_return_val_if_fail (service->url, NULL);
    
    return CSERV_CLASS (service)->get_path (service);
}


/**
 * camel_service_get_session:
 * @service: a service
 *
 * Returns the CamelSession associated with the service.
 *
 * Return value: the session
 **/
CamelSession *
camel_service_get_session (CamelService *service)
{
    return service->session;
}

/**
 * camel_service_get_provider:
 * @service: a service
 *
 * Returns the CamelProvider associated with the service.
 *
 * Return value: the provider
 **/
CamelProvider *
camel_service_get_provider (CamelService *service)
{
    return service->provider;
}

static GList *
query_auth_types (CamelService *service, CamelException *ex)
{
    return NULL;
}

/**
 * camel_service_query_auth_types:
 * @service: a CamelService
 * @ex: a CamelException
 *
 * This is used by the mail source wizard to get the list of
 * authentication types supported by the protocol, and information
 * about them.
 *
 * Return value: a list of CamelServiceAuthType records. The caller
 * must free the list with g_list_free() when it is done with it.
 **/
GList *
camel_service_query_auth_types (CamelService *service, CamelException *ex)
{
    GList *ret;
    
    /* note that we get the connect lock here, which means the callee
       must not call the connect functions itself */
    CAMEL_SERVICE_LOCK (service, connect_lock);
    ret = CSERV_CLASS (service)->query_auth_types (service, ex);
    CAMEL_SERVICE_UNLOCK (service, connect_lock);
    
    return ret;
}

/* URL utility routines */

/**
 * camel_service_gethost:
 * @service: a CamelService
 * @ex: a CamelException
 *
 * This is a convenience function to do a gethostbyname on the host
 * for the service's URL.
 *
 * Return value: a (statically-allocated) hostent.
 **/
struct hostent *
camel_service_gethost (CamelService *service, CamelException *ex)
{
    char *hostname;
    
    if (service->url->host)
        hostname = service->url->host;
    else
        hostname = "localhost";
    
    return camel_gethostbyname (hostname, ex);
}

#ifdef offsetof
#define STRUCT_OFFSET(type, field)        ((gint) offsetof (type, field))
#else
#define STRUCT_OFFSET(type, field)        ((gint) ((gchar*) &((type *) 0)->field))
#endif

struct _lookup_msg {
#ifdef ENABLE_THREADS
    EMsg msg;
#endif
    const char *name;
    int len;
    int type;
    int result;
    int herr;
    struct hostent hostbuf;
    int hostbuflen;
    char *hostbufmem;
};

static void *
get_hostbyname(void *data)
{
    struct _lookup_msg *info = data;

    while ((info->result = e_gethostbyname_r(info->name, &info->hostbuf, info->hostbufmem, info->hostbuflen, &info->herr)) == ERANGE) {
        d(printf("gethostbyname fialed?\n"));
#ifdef ENABLE_THREADS
        pthread_testcancel();
#endif
                info->hostbuflen *= 2;
                info->hostbufmem = g_realloc(info->hostbufmem, info->hostbuflen);
    }

    d(printf("gethostbyname ok?\n"));

#ifdef ENABLE_THREADS
    e_msgport_reply((EMsg *)info);
#endif
    return NULL;
}

struct hostent *
camel_gethostbyname (const char *name, CamelException *ex)
{
#ifdef ENABLE_THREADS
    int fdmax, status, fd, cancel_fd;
#endif
    struct _lookup_msg *msg;

    g_return_val_if_fail(name != NULL, NULL);

    if (camel_operation_cancel_check(NULL)) {
        camel_exception_setv(ex, CAMEL_EXCEPTION_USER_CANCEL, _("Cancelled"));
        return NULL;
    }

    camel_operation_start_transient(NULL, _("Resolving: %s"), name);

    msg = g_malloc0(sizeof(*msg));
    msg->hostbuflen = 1024;
    msg->hostbufmem = g_malloc(msg->hostbuflen);
    msg->name = name;

#ifdef ENABLE_THREADS
    cancel_fd = camel_operation_cancel_fd(NULL);
    if (cancel_fd == -1) {
#endif
        get_hostbyname(msg);
#ifdef ENABLE_THREADS
    } else {
        EMsgPort *reply_port;
        pthread_t id;
        fd_set rdset;

        reply_port = msg->msg.reply_port = e_msgport_new();
        fd = e_msgport_fd(msg->msg.reply_port);
        if (pthread_create(&id, NULL, get_hostbyname, msg) == 0) {
            d(printf("waiting for name return/cancellation in main process\n"));
            do {
                FD_ZERO(&rdset);
                FD_SET(cancel_fd, &rdset);
                FD_SET(fd, &rdset);
                fdmax = MAX(fd, cancel_fd) + 1;
                status = select (fdmax, &rdset, NULL, 0, NULL);
            } while (status == -1 && errno == EINTR);
            
            if (status == -1) {
                camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                              _("Failure in name lookup: %s"),
                              g_strerror (errno));
                d(printf("Cancelling lookup thread\n"));
                pthread_cancel(id);
            } else if (FD_ISSET(cancel_fd, &rdset)) {
                d(printf("Cancelling lookup thread\n"));
                camel_exception_setv(ex, CAMEL_EXCEPTION_USER_CANCEL, _("Cancelled"));
                pthread_cancel(id);
            } else {
                struct _lookup_msg *reply = (struct _lookup_msg *)e_msgport_get(reply_port);

                g_assert(reply == msg);
            }
            d(printf("waiting for child to exit\n"));
            pthread_join(id, NULL);
            d(printf("child done\n"));
        }
        e_msgport_destroy(reply_port);
    }
#endif

    camel_operation_end(NULL);

    if (msg->herr) {
        if (!camel_exception_is_set(ex)) {
            if (msg->herr == HOST_NOT_FOUND || msg->herr == NO_DATA)
                camel_exception_setv(ex, 1, _("Host lookup failed: %s: host not found"), name);
            else
                camel_exception_setv(ex, 1, _("Host lookup failed: %s: unknown reason"), name);
        }
        g_free(msg->hostbufmem);
        g_free(msg);
        return NULL;
    } else {
        return &msg->hostbuf;
    }
}


static void *
get_hostbyaddr (void *data)
{
    struct _lookup_msg *info = data;

    while ((info->result = e_gethostbyaddr_r (info->name, info->len, info->type, &info->hostbuf,
                          info->hostbufmem, info->hostbuflen, &info->herr)) == ERANGE) {
        d(printf ("gethostbyaddr fialed?\n"));
#ifdef ENABLE_THREADS
        pthread_testcancel ();
#endif
                info->hostbuflen *= 2;
                info->hostbufmem = g_realloc (info->hostbufmem, info->hostbuflen);
    }
    
    d(printf ("gethostbyaddr ok?\n"));
    
#ifdef ENABLE_THREADS
    e_msgport_reply ((EMsg *) info);
#endif
    return NULL;
}


struct hostent *
camel_gethostbyaddr (const char *addr, int len, int type, CamelException *ex)
{
#ifdef ENABLE_THREADS
    int fdmax, status, fd, cancel_fd;
#endif
    struct _lookup_msg *msg;
    
    g_return_val_if_fail (addr != NULL, NULL);
    
    if (camel_operation_cancel_check (NULL)) {
        camel_exception_setv (ex, CAMEL_EXCEPTION_USER_CANCEL, _("Cancelled"));
        return NULL;
    }
    
    camel_operation_start_transient (NULL, _("Resolving address"));
    
    msg = g_malloc0 (sizeof (struct _lookup_msg));
    msg->hostbuflen = 1024;
    msg->hostbufmem = g_malloc (msg->hostbuflen);
    msg->name = addr;
    msg->len = len;
    msg->type = type;
    
#ifdef ENABLE_THREADS
    cancel_fd = camel_operation_cancel_fd (NULL);
    if (cancel_fd == -1) {
#endif
        get_hostbyaddr (msg);
#ifdef ENABLE_THREADS
    } else {
        EMsgPort *reply_port;
        pthread_t id;
        fd_set rdset;
        
        reply_port = msg->msg.reply_port = e_msgport_new ();
        fd = e_msgport_fd (msg->msg.reply_port);
        if (pthread_create (&id, NULL, get_hostbyaddr, msg) == 0) {
            d(printf("waiting for name return/cancellation in main process\n"));
            do {
                FD_ZERO(&rdset);
                FD_SET(cancel_fd, &rdset);
                FD_SET(fd, &rdset);
                fdmax = MAX(fd, cancel_fd) + 1;
                status = select (fdmax, &rdset, NULL, 0, NULL);
            } while (status == -1 && errno == EINTR);
            
            if (status == -1) {
                camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
                              _("Failure in name lookup: %s"), g_strerror (errno));
                d(printf ("Cancelling lookup thread\n"));
                pthread_cancel (id);
            } else if (FD_ISSET(cancel_fd, &rdset)) {
                d(printf ("Cancelling lookup thread\n"));
                camel_exception_setv (ex, CAMEL_EXCEPTION_USER_CANCEL, _("Cancelled"));
                pthread_cancel (id);
            } else {
                struct _lookup_msg *reply = (struct _lookup_msg *) e_msgport_get (reply_port);
                
                g_assert (reply == msg);
            }
            
            d(printf ("waiting for child to exit\n"));
            pthread_join (id, NULL);
            d(printf ("child done\n"));
        }
        
        e_msgport_destroy (reply_port);
    }
#endif
    
    camel_operation_end (NULL);
    
    if (msg->herr) {
        if (!camel_exception_is_set (ex)) {
            if (msg->herr == HOST_NOT_FOUND || msg->herr == NO_DATA)
                camel_exception_set (ex, CAMEL_EXCEPTION_SYSTEM,
                             _("Host lookup failed: host not found"));
            else
                camel_exception_set (ex, CAMEL_EXCEPTION_SYSTEM,
                             _("Host lookup failed: unknown reason"));
        }
        
        g_free (msg->hostbufmem);
        g_free (msg);
        return NULL;
    } else {
        return &msg->hostbuf;
    }
}

void camel_free_host(struct hostent *h)
{
    struct _lookup_msg *msg;

    g_return_if_fail(h != NULL);

    /* yeah this looks ugly but it is safe.  we passed out a reference to inside our structure, this maps it
       to the base structure, so we can free everything right without having to keep track of it separately */
    msg = (struct _lookup_msg *)(((char *)h) - STRUCT_OFFSET(struct _lookup_msg, hostbuf));

    g_free(msg->hostbufmem);
    g_free(msg);
}