plugins/expire/expire-plugin.c

	expire-plugin.c revision 71748cca1bacd74451fd228db5536828bdfeb190
/* Copyright (c) 2006-2016 Dovecot authors, see the included COPYING file */

/* There are several race conditions in this plugin, but they should be
   happening pretty rarely and usually it's not a big problem if the results
   are temporarily wrong. Fixing the races would likely be a lot of work,
   so it's not really worth it. */

#include "lib.h"
#include "ioloop.h"
#include "array.h"
#include "str.h"
#include "master-service.h"
#include "dict.h"
#include "mail-namespace.h"
#include "index-mail.h"
#include "index-storage.h"
#include "expire-set.h"
#include "expire-plugin.h"


#define EXPIRE_CONTEXT(obj) \
    MODULE_CONTEXT(obj, expire_storage_module)
#define EXPIRE_MAIL_CONTEXT(obj) \
    MODULE_CONTEXT(obj, expire_mail_module)
#define EXPIRE_USER_CONTEXT(obj) \
    MODULE_CONTEXT(obj, expire_mail_user_module)

struct expire_mail_index_header {
    uint32_t timestamp;
};

struct expire_mail_user {
    union mail_user_module_context module_ctx;

    struct dict *db;
    struct expire_set *set;
    bool expire_cache;
};

struct expire_mailbox {
    union mailbox_module_context module_ctx;
    uint32_t expire_ext_id;
};

struct expire_transaction_context {
    union mailbox_transaction_module_context module_ctx;

    unsigned int saves:1;
    unsigned int first_expunged:1;
};

const char *expire_plugin_version = DOVECOT_ABI_VERSION;

static MODULE_CONTEXT_DEFINE_INIT(expire_storage_module,
                  &mail_storage_module_register);
static MODULE_CONTEXT_DEFINE_INIT(expire_mail_module, &mail_module_register);
static MODULE_CONTEXT_DEFINE_INIT(expire_mail_user_module,
                  &mail_user_module_register);

static struct mailbox_transaction_context *
expire_mailbox_transaction_begin(struct mailbox *box,
                 enum mailbox_transaction_flags flags)
{
    struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(box);
    struct mailbox_transaction_context *t;
    struct expire_transaction_context *xt;

    t = xpr_box->module_ctx.super.transaction_begin(box, flags);
    xt = i_new(struct expire_transaction_context, 1);

    MODULE_CONTEXT_SET(t, expire_storage_module, xt);
    return t;
}

static void first_save_timestamp(struct mailbox *box, time_t *stamp_r)
{
    struct mailbox_transaction_context *t;
    const struct mail_index_header *hdr;
    struct mail *mail;

    *stamp_r = ioloop_time;

    t = mailbox_transaction_begin(box, 0);
    mail = mail_alloc(t, 0, NULL);

    /* find the first non-expunged mail. we're here because the first
       mail was expunged, so don't bother checking it. */
    hdr = mail_index_get_header(box->view);
    if (hdr->messages_count > 0) {
        mail_set_seq(mail, 1);
        (void)mail_get_save_date(mail, stamp_r);
    }
    mail_free(&mail);
    (void)mailbox_transaction_commit(&t);
}

static uint32_t expire_get_ext_id(struct mailbox *box)
{
    struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(box);

    if (xpr_box->expire_ext_id != (uint32_t)-1)
        return xpr_box->expire_ext_id;

    xpr_box->expire_ext_id =
        mail_index_ext_register(box->index, "expire",
            sizeof(struct expire_mail_index_header), 0, 0);
    return xpr_box->expire_ext_id;
}

static int expire_lookup(struct mailbox *box, const char *key,
             time_t *new_stamp_r)
{
    struct expire_mail_user *euser =
        EXPIRE_USER_CONTEXT(box->storage->user);
    const struct expire_mail_index_header *hdr;
    const void *data;
    size_t data_size;
    const char *value;
    int ret;

    /* default to ioloop_time for newly saved mails. it may not be exactly
       the first message's save time, but a few seconds difference doesn't
       matter */
    *new_stamp_r = ioloop_time;

    if (euser->expire_cache) {
        mail_index_get_header_ext(box->view, expire_get_ext_id(box),
                      &data, &data_size);
        if (data_size == sizeof(*hdr)) {
            hdr = data;
            if (hdr->timestamp == 0)
                return 0;
            /* preserve the original timestamp */
            *new_stamp_r = hdr->timestamp;
            return 1;
        }
        /* cache doesn't exist yet */
    }

    ret = dict_lookup(euser->db, pool_datastack_create(),
              key, &value);
    if (ret <= 0) {
        if (ret < 0)
            return -1;
        first_save_timestamp(box, new_stamp_r);
        return 0;
    }
    return strcmp(value, "0") != 0 ? 1 : 0;
}

static void
expire_update(struct mailbox *box, const char *key, time_t timestamp)
{
    struct expire_mail_user *euser =
        EXPIRE_USER_CONTEXT(box->storage->user);
    struct dict_transaction_context *dctx;
    struct mail_index_transaction *trans;
    struct expire_mail_index_header hdr;

    dctx = dict_transaction_begin(euser->db);
    dict_set(dctx, key, dec2str(timestamp));
    if (dict_transaction_commit(&dctx) < 0)
        i_error("expire: dict commit failed");
    else if (euser->expire_cache) {
        memset(&hdr, 0, sizeof(hdr));
        hdr.timestamp = timestamp;

        trans = mail_index_transaction_begin(box->view,
            MAIL_INDEX_TRANSACTION_FLAG_EXTERNAL);
        mail_index_update_header_ext(trans, expire_get_ext_id(box),
                         0, &hdr, sizeof(hdr));
        if (mail_index_transaction_commit(&trans) < 0)
            i_error("expire: index transaction commit failed");
    }
}

static void first_nonexpunged_timestamp(struct mailbox_transaction_context *t,
                    time_t *stamp_r)
{
    struct mail_index_view *view = t->view;
    const struct mail_index_header *hdr;
    struct mail *mail;
    uint32_t seq;

    mail = mail_alloc(t, 0, NULL);

    /* find the first non-expunged mail. we're here because the first
       mail was expunged, so don't bother checking it. */
    hdr = mail_index_get_header(view);
    for (seq = 2; seq <= hdr->messages_count; seq++) {
        if (!mail_index_is_expunged(view, seq)) {
            mail_set_seq(mail, seq);
            if (mail_get_save_date(mail, stamp_r) == 0)
                break;
        }
    }
    mail_free(&mail);

    if (seq > hdr->messages_count) {
        /* everything expunged */
        *stamp_r = 0;
    }
}

static int
expire_mailbox_transaction_commit(struct mailbox_transaction_context *t,
                  struct mail_transaction_commit_changes *changes_r)
{
    struct mail_user *user = t->box->storage->user;
    struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(t->box);
    struct expire_transaction_context *xt = EXPIRE_CONTEXT(t);
    struct mailbox *box = t->box;
    time_t new_stamp = 0;
    bool update_dict = FALSE;
    int ret;

    if (xt->first_expunged) {
        /* first mail expunged. dict needs updating. */
        first_nonexpunged_timestamp(t, &new_stamp);
        if (new_stamp == 0 && xt->saves) {
            /* everything was expunged, but also within this
               transaction a new message was saved */
            new_stamp = ioloop_time;
        }
        if (user->mail_debug) {
            i_debug("expire: Expunging first message in %s, "
                "updating timestamp to %ld",
                box->vname, (long)new_stamp);
        }
        update_dict = TRUE;
    }

    if (xpr_box->module_ctx.super.transaction_commit(t, changes_r) < 0) {
        i_free(xt);
        return -1;
    }
    /* transaction is freed now */
    t = NULL;

    if (xt->first_expunged || xt->saves) T_BEGIN {
        const char *key;

        key = t_strconcat(DICT_EXPIRE_PREFIX,
                  box->storage->user->username, "/",
                  mailbox_get_vname(box), NULL);
        if (xt->first_expunged) {
            /* new_stamp is already set */
        } else {
            i_assert(xt->saves);
            /* saved new mails. dict needs to be updated only if
               this is the first mail in the database */
            ret = expire_lookup(box, key, &new_stamp);
            if (ret <= 0) {
                /* first time saving here with expire enabled.
                   also handle lookup errors by just assuming
                   it didn't exist */
                if (ret < 0) {
                    i_warning("expire: dict lookup failed, "
                          "assuming update is needed");
                }
                update_dict = TRUE;
            } else {
                /* already exists */
            }
            if (user->mail_debug && update_dict) {
                i_debug("expire: Saving first message to %s, "
                    "updating timestamp to %ld",
                    box->vname, (long)new_stamp);
            }
        }

        if (update_dict)
            expire_update(box, key, new_stamp);
    } T_END;
    i_free(xt);
    return 0;
}

static void
expire_mailbox_transaction_rollback(struct mailbox_transaction_context *t)
{
    struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(t->box);
    struct expire_transaction_context *xt = EXPIRE_CONTEXT(t);

    xpr_box->module_ctx.super.transaction_rollback(t);
    i_free(xt);
}

static void expire_mail_expunge(struct mail *_mail)
{
    struct mail_private *mail = (struct mail_private *)_mail;
    union mail_module_context *xpr_mail = EXPIRE_MAIL_CONTEXT(mail);
    struct expire_transaction_context *xt =
        EXPIRE_CONTEXT(_mail->transaction);

    if (_mail->seq == 1) {
        /* first mail expunged, database needs to be updated */
        xt->first_expunged = TRUE;
    }
    xpr_mail->super.expunge(_mail);
}

static void expire_mail_allocated(struct mail *_mail)
{
    struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(_mail->box);
    struct mail_private *mail = (struct mail_private *)_mail;
    struct mail_vfuncs *v = mail->vlast;
    union mail_module_context *xpr_mail;

    if (xpr_box == NULL)
        return;

    xpr_mail = p_new(mail->pool, union mail_module_context, 1);
    xpr_mail->super = *v;
    mail->vlast = &xpr_mail->super;

    v->expunge = expire_mail_expunge;
    MODULE_CONTEXT_SET_SELF(mail, expire_mail_module, xpr_mail);
}

static int expire_save_finish(struct mail_save_context *ctx)
{
    struct expire_transaction_context *xt =
        EXPIRE_CONTEXT(ctx->transaction);
    struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(ctx->transaction->box);

    xt->saves = TRUE;
    return xpr_box->module_ctx.super.save_finish(ctx);
}

static int
expire_copy(struct mail_save_context *ctx, struct mail *mail)
{
    struct expire_transaction_context *xt =
        EXPIRE_CONTEXT(ctx->transaction);
    struct expire_mailbox *xpr_box = EXPIRE_CONTEXT(ctx->transaction->box);

    xt->saves = TRUE;
    return xpr_box->module_ctx.super.copy(ctx, mail);
}

static void expire_mailbox_allocate_init(struct mailbox *box)
{
    struct mailbox_vfuncs *v = box->vlast;
    struct expire_mailbox *xpr_box;

    xpr_box = p_new(box->pool, struct expire_mailbox, 1);
    xpr_box->module_ctx.super = *v;
    box->vlast = &xpr_box->module_ctx.super;
    xpr_box->expire_ext_id = (uint32_t)-1;

    v->transaction_begin = expire_mailbox_transaction_begin;
    v->transaction_commit = expire_mailbox_transaction_commit;
    v->transaction_rollback = expire_mailbox_transaction_rollback;
    v->save_finish = expire_save_finish;
    v->copy = expire_copy;

    MODULE_CONTEXT_SET(box, expire_storage_module, xpr_box);
}

static void expire_mailbox_allocated(struct mailbox *box)
{
    struct expire_mail_user *euser =
        EXPIRE_USER_CONTEXT(box->storage->user);

    if (euser != NULL && expire_set_lookup(euser->set, box->vname))
        expire_mailbox_allocate_init(box);
}

static void expire_mail_user_deinit(struct mail_user *user)
{
    struct expire_mail_user *euser = EXPIRE_USER_CONTEXT(user);

    dict_deinit(&euser->db);
    expire_set_deinit(&euser->set);

    euser->module_ctx.super.deinit(user);
}

static const char *const *expire_get_patterns(struct mail_user *user)
{
    ARRAY_TYPE(const_string) patterns;
    const char *str;
    char set_name[6+MAX_INT_STRLEN+1];
    unsigned int i;

    t_array_init(&patterns, 16);
    str = mail_user_set_plugin_getenv(user->set, "expire");
    for (i = 2; str != NULL; i++) {
        array_append(&patterns, &str, 1);

        if (i_snprintf(set_name, sizeof(set_name), "expire%u", i) < 0)
            i_unreached();
        str = mail_user_set_plugin_getenv(user->set, set_name);
    }
    array_append_zero(&patterns);
    return array_idx(&patterns, 0);
}

static void expire_mail_namespaces_created(struct mail_namespace *ns)
{
    struct mail_user *user = ns->user;
    struct mail_user_vfuncs *v = user->vlast;
    struct expire_mail_user *euser;
    struct dict *db;
    const char *dict_uri, *error;

    if (!mail_user_plugin_getenv_bool(user, "expire")) {
        if (user->mail_debug)
            i_debug("expire: No expire setting - plugin disabled");
        return;
    }

    dict_uri = mail_user_plugin_getenv(user, "expire_dict");
    if (dict_uri == NULL) {
        i_error("expire plugin: expire_dict setting missing");
        return;
    }
    /* we're using only shared dictionary, the username doesn't matter. */
    if (dict_init(dict_uri, DICT_DATA_TYPE_UINT32, "",
              user->set->base_dir, &db, &error) < 0) {
        i_error("expire plugin: dict_init(%s) failed: %s",
            dict_uri, error);
        return;
    }

    euser = p_new(user->pool, struct expire_mail_user, 1);
    euser->module_ctx.super = *v;
    user->vlast = &euser->module_ctx.super;
    v->deinit = expire_mail_user_deinit;

    euser->db = db;
    euser->set = expire_set_init(expire_get_patterns(user));
    euser->expire_cache = mail_user_plugin_getenv_bool(user, "expire_cache");
    MODULE_CONTEXT_SET(user, expire_mail_user_module, euser);
}

static struct mail_storage_hooks expire_mail_storage_hooks = {
    .mail_namespaces_created = expire_mail_namespaces_created,
    .mailbox_allocated = expire_mailbox_allocated,
    .mail_allocated = expire_mail_allocated
};

void expire_plugin_init(struct module *module)
{
    mail_storage_hooks_add(module, &expire_mail_storage_hooks);
}

void expire_plugin_deinit(void)
{
    mail_storage_hooks_remove(&expire_mail_storage_hooks);
}