plugins/replication/replication-plugin.c

	replication-plugin.c revision 72d64b868be9810b391482c5b092e87e576ca423
/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "str.h"
#include "strescape.h"
#include "ioloop.h"
#include "net.h"
#include "write-full.h"
#include "mail-user.h"
#include "mail-namespace.h"
#include "mail-storage-private.h"
#include "notify-plugin.h"
#include "replication-common.h"
#include "replication-plugin.h"


#define REPLICATION_SOCKET_NAME "replication-notify"
#define REPLICATION_FIFO_NAME "replication-notify-fifo"
#define REPLICATION_NOTIFY_DELAY_MSECS 500
#define REPLICATION_SYNC_TIMEOUT_SECS 10

#define REPLICATION_USER_CONTEXT(obj) \
    MODULE_CONTEXT(obj, replication_user_module)

struct replication_user {
    union mail_user_module_context module_ctx;

    const char *socket_path;

    struct timeout *to;
    enum replication_priority priority;
    unsigned int sync_secs;
};

struct replication_mail_txn_context {
    struct mail_namespace *ns;
    bool new_messages;
    bool sync_trans;
    char *reason;
};

static MODULE_CONTEXT_DEFINE_INIT(replication_user_module,
                  &mail_user_module_register);
static int fifo_fd;
static bool fifo_failed;
static char *fifo_path;

static int
replication_fifo_notify(struct mail_user *user,
            enum replication_priority priority)
{
    string_t *str;
    ssize_t ret;

    if (fifo_failed)
        return -1;
    if (fifo_fd == -1) {
        fifo_fd = open(fifo_path, O_WRONLY | O_NONBLOCK);
        if (fifo_fd == -1) {
            i_error("open(%s) failed: %m", fifo_path);
            fifo_failed = TRUE;
            return -1;
        }
    }
    /* <username> \t <priority> */
    str = t_str_new(256);
    str_append_tabescaped(str, user->username);
    str_append_c(str, '\t');
    switch (priority) {
    case REPLICATION_PRIORITY_NONE:
    case REPLICATION_PRIORITY_SYNC:
        i_unreached();
    case REPLICATION_PRIORITY_LOW:
        str_append(str, "low");
        break;
    case REPLICATION_PRIORITY_HIGH:
        str_append(str, "high");
        break;
    }
    str_append_c(str, '\n');
    ret = write(fifo_fd, str_data(str), str_len(str));
    i_assert(ret != 0);
    if (ret != (ssize_t)str_len(str)) {
        if (ret > 0)
            i_error("write(%s) wrote partial data", fifo_path);
        else if (errno == EAGAIN) {
            /* busy, try again later */
            return 0;
        } else if (errno != EPIPE) {
            i_error("write(%s) failed: %m", fifo_path);
        } else {
            /* server was probably restarted, don't bother logging
               this. */
        }
        if (close(fifo_fd) < 0)
            i_error("close(%s) failed: %m", fifo_path);
        fifo_fd = -1;
        return -1;
    }
    return 1;
}

static void replication_notify_now(struct mail_user *user)
{
    struct replication_user *ruser = REPLICATION_USER_CONTEXT(user);
    int ret;

    i_assert(ruser != NULL);
    i_assert(ruser->priority != REPLICATION_PRIORITY_NONE);
    i_assert(ruser->priority != REPLICATION_PRIORITY_SYNC);

    if ((ret = replication_fifo_notify(user, ruser->priority)) < 0 &&
        !fifo_failed) {
        /* retry once, in case replication server was restarted */
        ret = replication_fifo_notify(user, ruser->priority);
    }
    if (ret != 0) {
        timeout_remove(&ruser->to);
        ruser->priority = REPLICATION_PRIORITY_NONE;
    }
}

static int replication_notify_sync(struct mail_user *user)
{
    struct replication_user *ruser = REPLICATION_USER_CONTEXT(user);
    string_t *str;
    char buf[1024];
    int fd;
    ssize_t ret;
    bool success = FALSE;

    i_assert(ruser != NULL);

    fd = net_connect_unix(ruser->socket_path);
    if (fd == -1) {
        i_error("net_connect_unix(%s) failed: %m", ruser->socket_path);
        return -1;
    }
    net_set_nonblock(fd, FALSE);

    /* <username> \t "sync" */
    str = t_str_new(256);
    str_append_tabescaped(str, user->username);
    str_append(str, "\tsync\n");
    alarm(ruser->sync_secs);
    if (write_full(fd, str_data(str), str_len(str)) < 0) {
        i_error("write(%s) failed: %m", ruser->socket_path);
    } else {
        /* + | - */
        ret = read(fd, buf, sizeof(buf));
        if (ret < 0) {
            if (errno != EINTR) {
                i_error("read(%s) failed: %m",
                    ruser->socket_path);
            } else {
                i_warning("replication(%s): Sync failure: "
                      "Timeout in %u secs",
                      user->username, ruser->sync_secs);
            }
        } else if (ret == 0) {
            i_error("read(%s) failed: EOF", ruser->socket_path);
        } else if (buf[0] == '+') {
            /* success */
            success = TRUE;
        } else if (buf[0] == '-') {
            /* failure */
            if (buf[ret-1] == '\n') ret--;
            i_warning("replication(%s): Sync failure: %s",
                  user->username, t_strndup(buf+1, ret-1));
            i_warning("replication(%s): "
                  "Remote sent invalid input: %s",
                  user->username, t_strndup(buf, ret));
        }
    }
    alarm(0);
    if (close(fd) < 0)
        i_error("close(%s) failed: %m", ruser->socket_path);
    return success ? 0 : -1;
}

static void replication_notify(struct mail_namespace *ns,
                   enum replication_priority priority,
                   const char *event)
{
    struct replication_user *ruser;

    ruser = REPLICATION_USER_CONTEXT(ns->user);
    if (ruser == NULL)
        return;

    if (ns->user->mail_debug) {
        i_debug("replication: Replication requested by '%s', priority=%d",
            event, priority);
    }

    if (priority == REPLICATION_PRIORITY_SYNC) {
        if (replication_notify_sync(ns->user) == 0) {
            timeout_remove(&ruser->to);
            ruser->priority = REPLICATION_PRIORITY_NONE;
            return;
        }
        /* sync replication failed, try as "high" via fifo */
        priority = REPLICATION_PRIORITY_HIGH;
    }

    if (ruser->priority < priority)
        ruser->priority = priority;
    if (ruser->to == NULL) {
        ruser->to = timeout_add_short(REPLICATION_NOTIFY_DELAY_MSECS,
                          replication_notify_now, ns->user);
    }
}

static void *
replication_mail_transaction_begin(struct mailbox_transaction_context *t)
{
    struct replication_mail_txn_context *ctx;

    ctx = i_new(struct replication_mail_txn_context, 1);
    ctx->ns = mailbox_get_namespace(t->box);
    ctx->reason = i_strdup(t->reason);
    if ((t->flags & MAILBOX_TRANSACTION_FLAG_SYNC) != 0) {
        /* Transaction is from dsync. Don't trigger replication back. */
        ctx->sync_trans = TRUE;
    }
    return ctx;
}

static void replication_mail_save(void *txn, struct mail *mail ATTR_UNUSED)
{
    struct replication_mail_txn_context *ctx =
        (struct replication_mail_txn_context *)txn;

    ctx->new_messages = TRUE;
}

static void replication_mail_copy(void *txn, struct mail *src,
                  struct mail *dst)
{
    struct replication_mail_txn_context *ctx =
        (struct replication_mail_txn_context *)txn;

    if (src->box->storage != dst->box->storage) {
        /* copy between storages, e.g. new mail delivery */
        ctx->new_messages = TRUE;
    } else {
        /* copy within storage, which isn't as high priority since the
           mail already exists. and especially copies to Trash or to
           lazy-expunge namespace is pretty low priority. */
    }
}

static void
replication_mail_transaction_commit(void *txn,
                    struct mail_transaction_commit_changes *changes)
{
    struct replication_mail_txn_context *ctx =
        (struct replication_mail_txn_context *)txn;
    struct replication_user *ruser =
        REPLICATION_USER_CONTEXT(ctx->ns->user);
    enum replication_priority priority;

    if (ruser != NULL && !ctx->sync_trans &&
        (ctx->new_messages || changes->changed)) {
        priority = !ctx->new_messages ? REPLICATION_PRIORITY_LOW :
            ruser->sync_secs == 0 ? REPLICATION_PRIORITY_HIGH :
            REPLICATION_PRIORITY_SYNC;
        replication_notify(ctx->ns, priority, ctx->reason);
    }
    i_free(ctx->reason);
    i_free(ctx);
}

static void replication_mailbox_create(struct mailbox *box)
{
    replication_notify(mailbox_get_namespace(box),
               REPLICATION_PRIORITY_LOW, "mailbox create");
}

static void
replication_mailbox_delete_commit(void *txn ATTR_UNUSED,
                  struct mailbox *box)
{
    replication_notify(mailbox_get_namespace(box),
               REPLICATION_PRIORITY_LOW, "mailbox delete");
}

static void
replication_mailbox_rename(struct mailbox *src ATTR_UNUSED,
               struct mailbox *dest)
{
    replication_notify(mailbox_get_namespace(dest),
               REPLICATION_PRIORITY_LOW, "mailbox rename");
}

static void replication_mailbox_set_subscribed(struct mailbox *box,
                           bool subscribed ATTR_UNUSED)
{
    replication_notify(mailbox_get_namespace(box),
               REPLICATION_PRIORITY_LOW, "mailbox subscribe");
}

static void replication_user_deinit(struct mail_user *user)
{
    struct replication_user *ruser = REPLICATION_USER_CONTEXT(user);

    i_assert(ruser != NULL);

    if (ruser->to != NULL) {
        replication_notify_now(user);
        if (ruser->to != NULL) {
            i_warning("%s: Couldn't send final notification "
                  "due to fifo being busy", fifo_path);
            timeout_remove(&ruser->to);
        }
    }

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

static void replication_user_created(struct mail_user *user)
{
    struct mail_user_vfuncs *v = user->vlast;
    struct replication_user *ruser;
    const char *value;

    value = mail_user_plugin_getenv(user, "mail_replica");
    if (value == NULL || value[0] == '\0') {
        if (user->mail_debug)
            i_debug("replication: No mail_replica setting - replication disabled");
        return;
    }

    if (user->dsyncing) {
        /* we're running dsync, which means that the remote is telling
           us about a change. don't trigger a replication back to it */
        if (user->mail_debug)
            i_debug("replication: We're running dsync - replication disabled");
        return;
    }

    ruser = p_new(user->pool, struct replication_user, 1);
    ruser->module_ctx.super = *v;
    user->vlast = &ruser->module_ctx.super;
    v->deinit = replication_user_deinit;
    MODULE_CONTEXT_SET(user, replication_user_module, ruser);

    if (fifo_path == NULL) {
        /* we'll assume that all users have the same base_dir.
           they really should. */
        fifo_path = i_strconcat(user->set->base_dir,
                    "/"REPLICATION_FIFO_NAME, NULL);
    }
    ruser->socket_path = p_strconcat(user->pool, user->set->base_dir,
                     "/"REPLICATION_SOCKET_NAME, NULL);
    value = mail_user_plugin_getenv(user, "replication_sync_timeout");
    if (value != NULL && str_to_uint(value, &ruser->sync_secs) < 0) {
        i_error("replication(%s): "
            "Invalid replication_sync_timeout value: %s",
            user->username, value);
    }
}

static const struct notify_vfuncs replication_vfuncs = {
    .mail_transaction_begin = replication_mail_transaction_begin,
    .mail_save = replication_mail_save,
    .mail_copy = replication_mail_copy,
    .mail_transaction_commit = replication_mail_transaction_commit,
    .mailbox_create = replication_mailbox_create,
    .mailbox_delete_commit = replication_mailbox_delete_commit,
    .mailbox_rename = replication_mailbox_rename,
    .mailbox_set_subscribed = replication_mailbox_set_subscribed
};

static struct notify_context *replication_ctx;

static struct mail_storage_hooks replication_mail_storage_hooks = {
    .mail_user_created = replication_user_created
};

void replication_plugin_init(struct module *module)
{
    fifo_fd = -1;
    replication_ctx = notify_register(&replication_vfuncs);
    mail_storage_hooks_add(module, &replication_mail_storage_hooks);
}

void replication_plugin_deinit(void)
{
    i_close_fd_path(&fifo_fd, fifo_path);
    i_free_and_null(fifo_path);

    mail_storage_hooks_remove(&replication_mail_storage_hooks);
    notify_unregister(replication_ctx);
}

const char *replication_plugin_dependencies[] = { "notify", NULL };