src/imap/main.c

/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "imap-common.h"
#include "ioloop.h"
#include "istream.h"
#include "ostream.h"
#include "path-util.h"
#include "str.h"
#include "base64.h"
#include "process-title.h"
#include "randgen.h"
#include "restrict-access.h"
#include "write-full.h"
#include "settings-parser.h"
#include "master-interface.h"
#include "master-service.h"
#include "master-login.h"
#include "mail-user.h"
#include "mail-storage-service.h"
#include "smtp-submit-settings.h"
#include "imap-master-client.h"
#include "imap-resp-code.h"
#include "imap-commands.h"
#include "imap-fetch.h"

#include <stdio.h>
#include <unistd.h>

#define IS_STANDALONE() \
        (getenv(MASTER_IS_PARENT_ENV) == NULL)

#define IMAP_DIE_IDLE_SECS 10

static bool verbose_proctitle = FALSE;
static struct mail_storage_service_ctx *storage_service;
static struct master_login *master_login = NULL;

imap_client_created_func_t *hook_client_created = NULL;
bool imap_debug = FALSE;

struct event_category event_category_imap = {
    .name = "imap",
};

imap_client_created_func_t *
imap_client_created_hook_set(imap_client_created_func_t *new_hook)
{
    imap_client_created_func_t *old_hook = hook_client_created;

    hook_client_created = new_hook;
    return old_hook;
}

void imap_refresh_proctitle(void)
{
#define IMAP_PROCTITLE_PREFERRED_LEN 80
    struct client *client;
    struct client_command_context *cmd;
    string_t *title = t_str_new(128);
    bool wait_output;

    if (!verbose_proctitle)
        return;

    str_append_c(title, '[');
    switch (imap_client_count) {
    case 0:
        str_append(title, "idling");
        break;
    case 1:
        client = imap_clients;
        str_append(title, client->user->username);
        if (client->user->conn.remote_ip != NULL) {
            str_append_c(title, ' ');
            str_append(title,
                   net_ip2addr(client->user->conn.remote_ip));
        }
        wait_output = FALSE;
        for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {
            if (cmd->name == NULL)
                continue;

            if (str_len(title) < IMAP_PROCTITLE_PREFERRED_LEN) {
                str_append_c(title, ' ');
                str_append(title, cmd->name);
            }
            if (cmd->state == CLIENT_COMMAND_STATE_WAIT_OUTPUT)
                wait_output = TRUE;
        }
        if (wait_output) {
            str_printfa(title, " - %"PRIuSIZE_T" bytes waiting",
                    o_stream_get_buffer_used_size(client->output));
            if (o_stream_is_corked(client->output))
                str_append(title, " corked");
        }
        if (client->destroyed)
            str_append(title, " (deinit)");
        break;
    default:
        str_printfa(title, "%u connections", imap_client_count);
        break;
    }
    str_append_c(title, ']');
    process_title_set(str_c(title));
}

static void client_kill_idle(struct client *client)
{
    if (client->output_cmd_lock != NULL)
        return;

    client_send_line(client, "* BYE Server shutting down.");
    mail_storage_service_io_activate_user(client->service_user);
    client_destroy(client, "Server shutting down.");
}

static void imap_die(void)
{
    struct client *client, *next;
    time_t last_io, now = time(NULL);
    time_t stop_timestamp = now - IMAP_DIE_IDLE_SECS;
    unsigned int stop_msecs;

    for (client = imap_clients; client != NULL; client = next) {
        next = client->next;

        last_io = I_MAX(client->last_input, client->last_output);
        if (last_io <= stop_timestamp)
            client_kill_idle(client);
        else {
            timeout_remove(&client->to_idle);
            stop_msecs = (last_io - stop_timestamp) * 1000;
            client->to_idle = timeout_add(stop_msecs,
                              client_kill_idle, client);
        }
    }
}

struct client_input {
    const char *tag;

    const unsigned char *input;
    size_t input_size;
    bool send_untagged_capability;
};

static void
client_parse_input(const unsigned char *data, size_t len,
           struct client_input *input_r)
{
    size_t taglen;

    i_assert(len > 0);

    i_zero(input_r);

    if (data[0] == '1')
        input_r->send_untagged_capability = TRUE;
    data++; len--;

    input_r->tag = t_strndup(data, len);
    taglen = strlen(input_r->tag) + 1;

    if (len > taglen) {
        input_r->input = data + taglen;
        input_r->input_size = len - taglen;
    }
}

static void
client_add_input_capability(struct client *client, const unsigned char *client_input,
                size_t client_input_size)
{
    struct ostream *output;
    struct client_input input;

    if (client_input_size > 0) {
        client_parse_input(client_input, client_input_size, &input);
        if (input.input_size > 0 &&
            !i_stream_add_data(client->input, input.input,
                       input.input_size))
            i_panic("Couldn't add client input to stream");
    } else {
        /* IMAPLOGINTAG environment is compatible with mailfront */
        i_zero(&input);
        input.tag = getenv("IMAPLOGINTAG");
    }

    /* cork/uncork around the OK reply to minimize latency */
    output = client->output;
    o_stream_ref(output);
    o_stream_cork(output);
    if (input.tag == NULL) {
        client_send_line(client, t_strconcat(
            "* PREAUTH [CAPABILITY ",
            str_c(client->capability_string), "] "
            "Logged in as ", client->user->username, NULL));
    } else if (input.send_untagged_capability) {
        /* client doesn't seem to understand tagged capabilities. send
           untagged instead and hope that it works. */
        client_send_line(client, t_strconcat("* CAPABILITY ",
            str_c(client->capability_string), NULL));
        client_send_line(client,
                 t_strconcat(input.tag, " OK Logged in", NULL));
    } else {
        client_send_line(client, t_strconcat(
            input.tag, " OK [CAPABILITY ",
            str_c(client->capability_string), "] Logged in", NULL));
    }
    o_stream_uncork(output);
    o_stream_unref(&output);
}

static void
client_add_input_finalize(struct client *client)
{
    struct ostream *output;

    /* try to condense any responses into as few packets as possible */
    output = client->output;
    o_stream_ref(output);
    o_stream_cork(output);
    (void)client_handle_input(client);
    o_stream_uncork(output);
    o_stream_unref(&output);

    /* we could have already handled LOGOUT, or we might need to continue
       pending ambiguous commands. */
    if (client->disconnected)
        client_destroy(client, NULL);
    else
        client_continue_pending_input(client);
}

int client_create_from_input(const struct mail_storage_service_input *input,
                 int fd_in, int fd_out,
                 struct client **client_r, const char **error_r)
{
    struct mail_storage_service_input service_input;
    struct mail_storage_service_user *user;
    struct mail_user *mail_user;
    struct client *client;
    struct imap_settings *imap_set;
    struct smtp_submit_settings *smtp_set;
    struct event *event;
    const char *errstr;

    event = event_create(NULL);
    event_add_category(event, &event_category_imap);
    event_add_fields(event, (const struct event_add_field []){
        { .key = "user", .value = input->username },
        { .key = "session", .value = input->session_id },
        { .key = NULL }
    });

    service_input = *input;
    service_input.parent_event = event;
    if (mail_storage_service_lookup_next(storage_service, &service_input,
                         &user, &mail_user, error_r) <= 0) {
        event_unref(&event);
        return -1;
    }
    restrict_access_allow_coredumps(TRUE);

    smtp_set = mail_storage_service_user_get_set(user)[1];
    imap_set = mail_storage_service_user_get_set(user)[2];
    if (imap_set->verbose_proctitle)
        verbose_proctitle = TRUE;

    if (settings_var_expand(&smtp_submit_setting_parser_info, smtp_set,
                mail_user->pool, mail_user_var_expand_table(mail_user),
                &errstr) <= 0 ||
            settings_var_expand(&imap_setting_parser_info, imap_set,
                mail_user->pool, mail_user_var_expand_table(mail_user),
                &errstr) <= 0) {
        *error_r = t_strdup_printf("Failed to expand settings: %s", errstr);
        mail_user_unref(&mail_user);
        mail_storage_service_user_unref(&user);
        event_unref(&event);
        return -1;
    }

    client = client_create(fd_in, fd_out, input->session_id,
                   event, mail_user, user, imap_set, smtp_set);
    client->userdb_fields = input->userdb_fields == NULL ? NULL :
        p_strarray_dup(client->pool, input->userdb_fields);
    event_unref(&event);
    *client_r = client;
    return 0;
}

static void main_stdio_run(const char *username)
{
    struct client *client;
    struct mail_storage_service_input input;
    const char *value, *error, *input_base64;

    i_zero(&input);
    input.module = input.service = "imap";
    input.username = username != NULL ? username : getenv("USER");
    if (input.username == NULL && IS_STANDALONE())
        input.username = getlogin();
    if (input.username == NULL)
        i_fatal("USER environment missing");
    if ((value = getenv("IP")) != NULL)
        (void)net_addr2ip(value, &input.remote_ip);
    if ((value = getenv("LOCAL_IP")) != NULL)
        (void)net_addr2ip(value, &input.local_ip);

    if (client_create_from_input(&input, STDIN_FILENO, STDOUT_FILENO,
                     &client, &error) < 0)
        i_fatal("%s", error);

    input_base64 = getenv("CLIENT_INPUT");
    if (input_base64 == NULL)
        client_add_input_capability(client, NULL, 0);
    else {
        const buffer_t *input_buf = t_base64_decode_str(input_base64);
        client_add_input_capability(client, input_buf->data, input_buf->used);
    }

    if (client_create_finish(client, &error) < 0)
        i_fatal("%s", error);
    client_add_input_finalize(client);
    /* client may be destroyed now */
}

static void
login_client_connected(const struct master_login_client *login_client,
               const char *username, const char *const *extra_fields)
{
#define MSG_BYE_INTERNAL_ERROR "* BYE "MAIL_ERRSTR_CRITICAL_MSG"\r\n"
    struct mail_storage_service_input input;
    struct client *client;
    enum mail_auth_request_flags flags = login_client->auth_req.flags;
    const char *error;

    i_zero(&input);
    input.module = input.service = "imap";
    input.local_ip = login_client->auth_req.local_ip;
    input.remote_ip = login_client->auth_req.remote_ip;
    input.local_port = login_client->auth_req.local_port;
    input.remote_port = login_client->auth_req.remote_port;
    input.username = username;
    input.userdb_fields = extra_fields;
    input.session_id = login_client->session_id;
    if ((flags & MAIL_AUTH_REQUEST_FLAG_CONN_SECURED) != 0)
        input.conn_secured = TRUE;
    if ((flags & MAIL_AUTH_REQUEST_FLAG_CONN_SSL_SECURED) != 0)
        input.conn_ssl_secured = TRUE;

    if (client_create_from_input(&input, login_client->fd, login_client->fd,
                     &client, &error) < 0) {
        int fd = login_client->fd;

        if (write(fd, MSG_BYE_INTERNAL_ERROR,
              strlen(MSG_BYE_INTERNAL_ERROR)) < 0) {
            if (errno != EAGAIN && errno != EPIPE)
                i_error("write(client) failed: %m");
        }
        i_error("%s", error);
        i_close_fd(&fd);
        master_service_client_connection_destroyed(master_service);
        return;
    }
    if ((flags & MAIL_AUTH_REQUEST_FLAG_TLS_COMPRESSION) != 0)
        client->tls_compression = TRUE;
    client_add_input_capability(client, login_client->data,
             login_client->auth_req.data_size);

    /* finish initializing the user (see comment in main()) */
    if (client_create_finish(client, &error) < 0) {
        if (write_full(login_client->fd, MSG_BYE_INTERNAL_ERROR,
                   strlen(MSG_BYE_INTERNAL_ERROR)) < 0)
            if (errno != EAGAIN && errno != EPIPE)
                i_error("write_full(client) failed: %m");

        i_error("%s", error);
        client_destroy(client, error);
        return;
    }

    client_add_input_finalize(client);
    /* client may be destroyed now */
}

static void login_client_failed(const struct master_login_client *client,
                const char *errormsg)
{
    struct client_input input;
    const char *msg;

    client_parse_input(client->data, client->auth_req.data_size, &input);
    msg = t_strdup_printf("%s NO ["IMAP_RESP_CODE_UNAVAILABLE"] %s\r\n",
                  input.tag, errormsg);
    if (write(client->fd, msg, strlen(msg)) < 0) {
        /* ignored */
    }
}

static void client_connected(struct master_service_connection *conn)
{
    /* when running standalone, we shouldn't even get here */
    i_assert(master_login != NULL);

    master_service_client_connection_accept(conn);
    if (strcmp(conn->name, "imap-master") == 0) {
        /* restoring existing IMAP connection (e.g. from imap-idle) */
        imap_master_client_create(conn->fd);
    } else {
        master_login_add(master_login, conn->fd);
    }
}

int main(int argc, char *argv[])
{
    static const struct setting_parser_info *set_roots[] = {
        &smtp_submit_setting_parser_info,
        &imap_setting_parser_info,
        NULL
    };
    struct master_login_settings login_set;
    enum master_service_flags service_flags =
        MASTER_SERVICE_FLAG_SEND_STATS;
    enum mail_storage_service_flags storage_service_flags =
        /*
         * We include MAIL_STORAGE_SERVICE_FLAG_NO_NAMESPACES so
         * that the mail_user initialization is fast and we can
         * quickly send back the OK response to LOGIN/AUTHENTICATE.
         * Otherwise we risk a very slow namespace initialization to
         * cause client timeouts on login.
         */
        MAIL_STORAGE_SERVICE_FLAG_NO_NAMESPACES;
    const char *username = NULL, *auth_socket_path = "auth-master";
    int c;

    i_zero(&login_set);
    login_set.postlogin_timeout_secs = MASTER_POSTLOGIN_TIMEOUT_DEFAULT;
    login_set.request_auth_token = TRUE;

    if (IS_STANDALONE() && getuid() == 0 &&
        net_getpeername(1, NULL, NULL) == 0) {
        printf("* BAD [ALERT] imap binary must not be started from "
               "inetd, use imap-login instead.\n");
        return 1;
    }

    if (IS_STANDALONE()) {
        service_flags |= MASTER_SERVICE_FLAG_STANDALONE |
            MASTER_SERVICE_FLAG_STD_CLIENT;
    } else {
        service_flags |= MASTER_SERVICE_FLAG_KEEP_CONFIG_OPEN;
    }

    master_service = master_service_init("imap", service_flags,
                         &argc, &argv, "a:Dt:u:");
    while ((c = master_getopt(master_service)) > 0) {
        switch (c) {
        case 'a':
            auth_socket_path = optarg;
            break;
        case 't':
            if (str_to_uint(optarg, &login_set.postlogin_timeout_secs) < 0 ||
                login_set.postlogin_timeout_secs == 0)
                i_fatal("Invalid -t parameter: %s", optarg);
            break;
        case 'u':
            storage_service_flags |=
                MAIL_STORAGE_SERVICE_FLAG_USERDB_LOOKUP;
            username = optarg;
            break;
        case 'D':
            imap_debug = TRUE;
            break;
        default:
            return FATAL_DEFAULT;
        }
    }

    master_service_set_die_callback(master_service, imap_die);

    /* plugins may want to add commands, so this needs to be called early */
    commands_init();
    imap_fetch_handlers_init();
    imap_master_clients_init();

    const char *error;
    if (t_abspath(auth_socket_path, &login_set.auth_socket_path, &error) < 0)
        i_fatal("t_abspath(%s) failed: %s", auth_socket_path, error);

    if (argv[optind] != NULL) {
        if (t_abspath(argv[optind], &login_set.postlogin_socket_path, &error) < 0)
            i_fatal("t_abspath(%s) failed: %s", argv[optind], error);
    }
    login_set.callback = login_client_connected;
    login_set.failure_callback = login_client_failed;

    if (!IS_STANDALONE())
        master_login = master_login_init(master_service, &login_set);

    storage_service =
        mail_storage_service_init(master_service,
                      set_roots, storage_service_flags);
    master_service_init_finish(master_service);
    /* NOTE: login_set.*_socket_path are now invalid due to data stack
       having been freed */

    /* fake that we're running, so we know if client was destroyed
       while handling its initial input */
    io_loop_set_running(current_ioloop);

    if (IS_STANDALONE()) {
        T_BEGIN {
            main_stdio_run(username);
        } T_END;
    } else {
        io_loop_set_running(current_ioloop);
    }

    if (io_loop_is_running(current_ioloop))
        master_service_run(master_service, client_connected);
    clients_destroy_all();

    if (master_login != NULL)
        master_login_deinit(&master_login);
    mail_storage_service_deinit(&storage_service);

    imap_fetch_handlers_deinit();
    commands_deinit();
    imap_master_clients_deinit();

    master_service_deinit(&master_service);
    return 0;
}