plugins/trash/trash-plugin.c

2ronwalf/* Copyright (c) 2005-2018 Dovecot authors, see the included COPYING file */
2ronwalf
2ronwalf#include "lib.h"
2ronwalf#include "array.h"
2ronwalf#include "unichar.h"
2ronwalf#include "istream.h"
2ronwalf#include "mail-namespace.h"
2ronwalf#include "mail-search-build.h"
2ronwalf#include "quota-private.h"
2ronwalf#include "quota-plugin.h"
2ronwalf#include "trash-plugin.h"
2ronwalf
2ronwalf#include <unistd.h>
2ronwalf#include <fcntl.h>
2ronwalf
2ronwalf#define INIT_TRASH_MAILBOX_COUNT 4
2ronwalf#define MAX_RETRY_COUNT 3
2ronwalf
2ronwalf#define TRASH_USER_CONTEXT(obj) \
2ronwalf    MODULE_CONTEXT(obj, trash_user_module)
2ronwalf#define TRASH_USER_CONTEXT_REQUIRE(obj) \
2ronwalf    MODULE_CONTEXT_REQUIRE(obj, trash_user_module)
2ronwalf
2ronwalfstruct trash_mailbox {
2ronwalf    const char *name;
2ronwalf    int priority; /* lower number = higher priority */
2ronwalf
2ronwalf    struct mail_namespace *ns;
2ronwalf
2ronwalf    /* temporarily set while cleaning: */
2ronwalf    struct mailbox *box;
2ronwalf    struct mailbox_transaction_context *trans;
2ronwalf    struct mail_search_context *search_ctx;
2ronwalf    struct mail *mail;
2ronwalf};
2ronwalf
2ronwalfstruct trash_user {
2ronwalf    union mail_user_module_context module_ctx;
2ronwalf
2ronwalf    const char *config_file;
2ronwalf    /* ordered by priority, highest first */
2ronwalf    ARRAY(struct trash_mailbox) trash_boxes;
2ronwalf};
2ronwalf
2ronwalfconst char *trash_plugin_version = DOVECOT_ABI_VERSION;
2ronwalf
2ronwalfstatic MODULE_CONTEXT_DEFINE_INIT(trash_user_module,
                  &mail_user_module_register);
static enum quota_alloc_result (*trash_next_quota_test_alloc)(
        struct quota_transaction_context *, uoff_t,
        const char **error_r);

static int trash_clean_mailbox_open(struct trash_mailbox *trash)
{
    struct mail_search_args *search_args;

    trash->box = mailbox_alloc(trash->ns->list, trash->name, 0);
    mailbox_set_reason(trash->box, "trash plugin");
    if (mailbox_open(trash->box) < 0) {
        mailbox_free(&trash->box);
        return 0;
    }

    if (mailbox_sync(trash->box, MAILBOX_SYNC_FLAG_FULL_READ) < 0)
        return -1;

    trash->trans = mailbox_transaction_begin(trash->box, 0, __func__);

    search_args = mail_search_build_init();
    mail_search_build_add_all(search_args);
    trash->search_ctx = mailbox_search_init(trash->trans,
                        search_args, NULL,
                        MAIL_FETCH_PHYSICAL_SIZE |
                        MAIL_FETCH_RECEIVED_DATE, NULL);
    mail_search_args_unref(&search_args);

    return mailbox_search_next(trash->search_ctx, &trash->mail) ? 1 : 0;
}

static int trash_clean_mailbox_get_next(struct trash_mailbox *trash,
                    time_t *received_time_r)
{
    int ret;

    if (trash->mail == NULL) {
        if (trash->box == NULL)
            ret = trash_clean_mailbox_open(trash);
        else {
            ret = mailbox_search_next(trash->search_ctx,
                          &trash->mail) ? 1 : 0;
        }
        if (ret <= 0) {
            *received_time_r = 0;
            return ret;
        }
    }

    if (mail_get_received_date(trash->mail, received_time_r) < 0)
        return -1;
    return 1;
}

static int trash_try_clean_mails(struct quota_transaction_context *ctx,
                 uint64_t size_needed,
                 unsigned int count_needed)
{
    struct trash_user *tuser = TRASH_USER_CONTEXT_REQUIRE(ctx->quota->user);
    struct trash_mailbox *trashes;
    unsigned int i, j, count, oldest_idx;
    time_t oldest, received = 0;
    uint64_t size, size_expunged = 0;
    unsigned int expunged_count = 0;
    int ret = 0;

    trashes = array_get_modifiable(&tuser->trash_boxes, &count);
    for (i = 0; i < count; ) {
        /* expunge oldest mails first in all trash boxes with
           same priority */
        oldest_idx = count;
        oldest = (time_t)-1;
        for (j = i; j < count; j++) {
            if (trashes[j].priority != trashes[i].priority)
                break;

            ret = trash_clean_mailbox_get_next(&trashes[j],
                               &received);
            if (ret < 0)
                goto err;
            if (ret > 0) {
                if (oldest == (time_t)-1 || received < oldest) {
                    oldest = received;
                    oldest_idx = j;
                }
            }
        }

        if (oldest_idx < count) {
            if (mail_get_physical_size(trashes[oldest_idx].mail,
                           &size) < 0) {
                /* maybe expunged already? */
                trashes[oldest_idx].mail = NULL;
                continue;
            }

            mail_expunge(trashes[oldest_idx].mail);
            expunged_count++;
            size_expunged += size;
            if (size_expunged >= size_needed &&
                expunged_count >= count_needed)
                break;
            trashes[oldest_idx].mail = NULL;
        } else {
            /* find more mails from next priority's mailbox */
            i = j;
        }
    }

err:
    for (i = 0; i < count; i++) {
        struct trash_mailbox *trash = &trashes[i];

        if (trash->box == NULL)
            continue;

        trash->mail = NULL;
        (void)mailbox_search_deinit(&trash->search_ctx);

        if (size_expunged >= size_needed &&
            expunged_count >= count_needed) {
            (void)mailbox_transaction_commit(&trash->trans);
            (void)mailbox_sync(trash->box, 0);
        } else {
            /* couldn't get enough space, don't expunge anything */
                        mailbox_transaction_rollback(&trash->trans);
        }

        mailbox_free(&trash->box);
    }

    if (size_expunged < size_needed) {
        if (ctx->quota->user->mail_debug) {
            i_debug("trash plugin: Failed to remove enough messages "
                "(needed %"PRIu64" bytes, expunged only %"PRIu64" bytes)",
                size_needed, size_expunged);
        }
        return 0;
    }
    if (expunged_count < count_needed) {
        if (ctx->quota->user->mail_debug) {
            i_debug("trash plugin: Failed to remove enough messages "
                "(needed %u messages, expunged only %u messages)",
                count_needed, expunged_count);
        }
        return 0;
    }

    if (ctx->bytes_over > 0) {
        /* user is over quota. drop the over-bytes first. */
        i_assert(ctx->bytes_over <= size_expunged);
        size_expunged -= ctx->bytes_over;
        ctx->bytes_over = 0;
    }
    if (ctx->count_over > 0) {
        /* user is over quota. drop the over-count first. */
        i_assert(ctx->count_over <= expunged_count);
        expunged_count -= ctx->count_over;
        ctx->count_over = 0;
    }

    if (ctx->bytes_ceil > ((uint64_t)-1 - size_expunged)) {
        ctx->bytes_ceil = (uint64_t)-1;
    } else {
        ctx->bytes_ceil += size_expunged;
    }
    if (ctx->count_ceil < ((uint64_t)-1 - expunged_count)) {
        ctx->count_ceil = (uint64_t)-1;
    } else {
        ctx->count_ceil += expunged_count;
    }
    return 1;
}

static enum quota_alloc_result
trash_quota_test_alloc(struct quota_transaction_context *ctx,
               uoff_t size, const char **error_r)
{
    int i;
    uint64_t size_needed = 0;
    unsigned int count_needed = 0;

    for (i = 0; ; i++) {
        enum quota_alloc_result ret;
        ret = trash_next_quota_test_alloc(ctx, size, error_r);
        if (ret != QUOTA_ALLOC_RESULT_OVER_QUOTA) {
            if (ret == QUOTA_ALLOC_RESULT_OVER_QUOTA_LIMIT &&
                ctx->quota->user->mail_debug)
                i_debug("trash plugin: Mail is larger than "
                    "quota, won't even try to handle");
            return ret;
        }

        if (i == MAX_RETRY_COUNT) {
            /* trash_try_clean_mails() should have returned 0 if
               it couldn't get enough space, but allow retrying
               it a couple of times if there was some extra space
               that was needed.. */
            break;
        }

        if (ctx->bytes_ceil != (uint64_t)-1 &&
            ctx->bytes_ceil < size + ctx->bytes_over)
            size_needed = size + ctx->bytes_over - ctx->bytes_ceil;
        if (ctx->count_ceil != (uint64_t)-1 &&
            ctx->count_ceil < 1 + ctx->count_over)
            count_needed = 1 + ctx->count_over - ctx->count_ceil;

        /* not enough space. try deleting some from mailbox. */
        if (trash_try_clean_mails(ctx, size_needed, count_needed) <= 0) {
            *error_r = t_strdup_printf(
                "Allocating %"PRIuUOFF_T" bytes would exceed quota", size);
            return QUOTA_ALLOC_RESULT_OVER_QUOTA;
        }
    }
    *error_r = t_strdup_printf(
        "Allocating %"PRIuUOFF_T" bytes would exceed quota", size);
    return QUOTA_ALLOC_RESULT_OVER_QUOTA;
}

static bool trash_find_storage(struct mail_user *user,
                   struct trash_mailbox *trash)
{
    struct mail_namespace *ns;

    ns = mail_namespace_find(user->namespaces, trash->name);
    if ((ns->flags & NAMESPACE_FLAG_UNUSABLE) != 0)
        return FALSE;

    trash->ns = ns;
    return TRUE;
}

static int trash_mailbox_priority_cmp(const struct trash_mailbox *t1,
                      const struct trash_mailbox *t2)
{
    return t1->priority - t2->priority;
}

static int read_configuration(struct mail_user *user, const char *path)
{
    struct trash_user *tuser = TRASH_USER_CONTEXT_REQUIRE(user);
    struct istream *input;
    const char *line, *name;
    struct trash_mailbox *trash;
    int fd, ret = 0;

    fd = open(path, O_RDONLY);
    if (fd == -1) {
        i_error("trash plugin: open(%s) failed: %m", path);
        return -1;
    }

    p_array_init(&tuser->trash_boxes, user->pool, INIT_TRASH_MAILBOX_COUNT);

    input = i_stream_create_fd(fd, (size_t)-1);
    i_stream_set_return_partial_line(input, TRUE);
    while ((line = i_stream_read_next_line(input)) != NULL) {
        /* <priority> <mailbox name> */
        name = strchr(line, ' ');
        if (name == NULL || name[1] == '\0' || *line == '#')
            continue;

        trash = array_append_space(&tuser->trash_boxes);
        trash->name = p_strdup(user->pool, name+1);
        if (str_to_int(t_strdup_until(line, name),
                   &trash->priority) < 0) {
            i_error("trash: Invalid priority for mailbox '%s'",
                trash->name);
            ret = -1;
        }

        if (!uni_utf8_str_is_valid(trash->name)) {
            i_error("trash: Mailbox name not UTF-8: %s",
                trash->name);
            ret = -1;
        }
        if (!trash_find_storage(user, trash)) {
            i_error("trash: Namespace not found for mailbox '%s'",
                trash->name);
            ret = -1;
        }

        if (user->mail_debug) {
            i_debug("trash plugin: Added '%s' with priority %d",
                trash->name, trash->priority);
        }
    }
    i_stream_destroy(&input);
    i_close_fd(&fd);

    array_sort(&tuser->trash_boxes, trash_mailbox_priority_cmp);
    return ret;
}

static void
trash_mail_user_created(struct mail_user *user)
{
    struct quota_user *quser = QUOTA_USER_CONTEXT(user);
    struct trash_user *tuser;
    const char *env;

    env = mail_user_plugin_getenv(user, "trash");
    if (env == NULL) {
        if (user->mail_debug)
            i_debug("trash: No trash setting - plugin disabled");
    } else if (quser == NULL) {
        i_error("trash plugin: quota plugin not initialized");
    } else {
        tuser = p_new(user->pool, struct trash_user, 1);
        tuser->config_file = env;
        MODULE_CONTEXT_SET(user, trash_user_module, tuser);
    }
}

static void
trash_mail_namespaces_created(struct mail_namespace *namespaces)
{
    struct mail_user *user = namespaces->user;
    struct trash_user *tuser = TRASH_USER_CONTEXT(user);
    struct quota_user *quser = QUOTA_USER_CONTEXT(user);

    if (tuser != NULL && read_configuration(user, tuser->config_file) == 0) {
        i_assert(quser != NULL);
        trash_next_quota_test_alloc =
            quser->quota->set->test_alloc;
        quser->quota->set->test_alloc = trash_quota_test_alloc;
    }
}

static struct mail_storage_hooks trash_mail_storage_hooks = {
    .mail_user_created = trash_mail_user_created,
    .mail_namespaces_created = trash_mail_namespaces_created,
};

void trash_plugin_init(struct module *module)
{
    mail_storage_hooks_add(module, &trash_mail_storage_hooks);
}

void trash_plugin_deinit(void)
{
    mail_storage_hooks_remove(&trash_mail_storage_hooks);
}

const char *trash_plugin_dependencies[] = { "quota", NULL };