src/pop3/main.c

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

#include "pop3-common.h"
#include "ioloop.h"
#include "buffer.h"
#include "istream.h"
#include "ostream.h"
#include "path-util.h"
#include "base64.h"
#include "str.h"
#include "process-title.h"
#include "restrict-access.h"
#include "settings-parser.h"
#include "master-service.h"
#include "master-login.h"
#include "master-interface.h"
#include "var-expand.h"
#include "mail-error.h"
#include "mail-user.h"
#include "mail-namespace.h"
#include "mail-storage-service.h"

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

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

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

pop3_client_created_func_t *hook_client_created = NULL;

pop3_client_created_func_t *
pop3_client_created_hook_set(pop3_client_created_func_t *new_hook)
{
    pop3_client_created_func_t *old_hook = hook_client_created;

    hook_client_created = new_hook;
    return old_hook;
}

void pop3_refresh_proctitle(void)
{
    struct client *client;
    string_t *title = t_str_new(128);

    if (!verbose_proctitle)
        return;

    str_append_c(title, '[');
    switch (pop3_client_count) {
    case 0:
        str_append(title, "idling");
        break;
    case 1:
        client = pop3_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));
        }
        if (client->destroyed)
            str_append(title, " (deinit)");
        break;
    default:
        str_printfa(title, "%u connections", pop3_client_count);
        break;
    }
    str_append_c(title, ']');
    process_title_set(str_c(title));
}

static void pop3_die(void)
{
    /* do nothing. pop3 connections typically die pretty quick anyway. */
}

static void client_add_input(struct client *client, const buffer_t *buf)
{
    struct ostream *output;

    if (buf != NULL && buf->used > 0) {
        if (!i_stream_add_data(client->input, buf->data, buf->used))
            i_panic("Couldn't add client input to stream");
    }

    output = client->output;
    o_stream_ref(output);
    o_stream_cork(output);
    (void)client_handle_input(client);
    o_stream_uncork(output);
    o_stream_unref(&output);
}

static 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)
{
    const char *lookup_error_str =
        "-ERR [SYS/TEMP] "MAIL_ERRSTR_CRITICAL_MSG"\r\n";
    struct mail_storage_service_user *user;
    struct mail_user *mail_user;
    struct pop3_settings *set;
    const char *errstr;

    if (mail_storage_service_lookup_next(storage_service, input,
                         &user, &mail_user, error_r) <= 0) {
        if (write(fd_out, lookup_error_str, strlen(lookup_error_str)) < 0) {
            /* ignored */
        }
        return -1;
    }
    restrict_access_allow_coredumps(TRUE);

    set = mail_storage_service_user_get_set(user)[1];
    if (set->verbose_proctitle)
        verbose_proctitle = TRUE;

    if (settings_var_expand(&pop3_setting_parser_info, 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);
        return -1;
    }

    *client_r = client_create(fd_in, fd_out, input->session_id,
                  mail_user, user, set);

    return 0;
}

static int lock_session(struct client *client)
{
    int ret;

    i_assert(client->user->namespaces != NULL);
    i_assert(client->set->pop3_lock_session);

    if ((ret = pop3_lock_session(client)) <= 0) {
        client_send_line(client, ret < 0 ?
            "-ERR [SYS/TEMP] Failed to create POP3 session lock." :
            "-ERR [IN-USE] Mailbox is locked by another POP3 session.");
        client_destroy(client, "Couldn't lock POP3 session");
        return -1;
    }

    return 0;
}

#define MSG_BYE_INTERNAL_ERROR "-ERR "MAIL_ERRSTR_CRITICAL_MSG
static int init_namespaces(struct client *client, bool already_logged_in)
{
    const char *error;

    /* finish initializing the user (see comment in main()) */
    if (mail_namespaces_init(client->user, &error) < 0) {
        if (!already_logged_in)
            client_send_line(client, MSG_BYE_INTERNAL_ERROR);

        i_error("%s", error);
        client_destroy(client, error);
        return -1;
    }

    i_assert(client->inbox_ns == NULL);
    client->inbox_ns = mail_namespace_find_inbox(client->user->namespaces);
    i_assert(client->inbox_ns != NULL);

    return 0;
}

static void add_input(struct client *client,
              const buffer_t *input_buf)
{
    const char *error;

    /*
     * RFC 1939 requires that the session lock gets acquired before the
     * positive response is sent to the client indicating a transition
     * to the TRANSACTION state.
     *
     * Since the session lock is stored under the INBOX's storage
     * directory, the locking code requires that the namespaces are
     * initialized first.
     *
     * If the system administrator configured dovecot to not use session
     * locks, we can send back the positive response before the
     * potentially long-running namespace initialization occurs.  This
     * avoids the client possibly timing out during authentication due
     * to storage initialization taking too long.
     */
    if (client->set->pop3_lock_session) {
        if (init_namespaces(client, FALSE) < 0)
            return; /* no need to propagate an error */

        if (lock_session(client) < 0)
            return; /* no need to propagate an error */

        if (!IS_STANDALONE())
            client_send_line(client, "+OK Logged in.");
    } else {
        if (!IS_STANDALONE())
            client_send_line(client, "+OK Logged in.");

        if (init_namespaces(client, TRUE) < 0)
            return; /* no need to propagate an error */
    }

    if (client_init_mailbox(client, &error) < 0) {
        i_error("%s", error);
        client_destroy(client, error);
        return;
    }

    client_add_input(client, input_buf);
}

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

    i_zero(&input);
    input.module = input.service = "pop3";
    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);

    input_base64 = getenv("CLIENT_INPUT");
    input_buf = input_base64 == NULL ? NULL :
        t_base64_decode_str(input_base64);

    if (client_create_from_input(&input, STDIN_FILENO, STDOUT_FILENO,
                     &client, &error) < 0)
        i_fatal("%s", error);
    add_input(client, input_buf);
    /* 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)
{
    struct client *client;
    struct mail_storage_service_input input;
    enum mail_auth_request_flags flags = login_client->auth_req.flags;
    const char *error;
    buffer_t input_buf;

    i_zero(&input);
    input.module = input.service = "pop3";
    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;

    buffer_create_from_const_data(&input_buf, login_client->data,
                      login_client->auth_req.data_size);
    if (client_create_from_input(&input, login_client->fd, login_client->fd,
                     &client, &error) < 0) {
        int fd = login_client->fd;

        i_error("%s", error);
        i_close_fd(&fd);
        master_service_client_connection_destroyed(master_service);
        return;
    }
    add_input(client, &input_buf);
    /* client may be destroyed now */
}

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

    msg = t_strdup_printf("-ERR [SYS/TEMP] %s\r\n", 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);
    master_login_add(master_login, conn->fd);
}

int main(int argc, char *argv[])
{
    static const struct setting_parser_info *set_roots[] = {
        &pop3_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 = 0;
    const char *username = NULL, *auth_socket_path = "auth-master";
    int c;

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

    if (IS_STANDALONE() && getuid() == 0 &&
        net_getpeername(1, NULL, NULL) == 0) {
        printf("-ERR [SYS/PERM] pop3 binary must not be started from "
               "inetd, use pop3-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;
    }

    /*
     * 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.
     */
    storage_service_flags |= MAIL_STORAGE_SERVICE_FLAG_NO_NAMESPACES;

    master_service = master_service_init("pop3", service_flags,
                         &argc, &argv, "a:t: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;
        default:
            return FATAL_DEFAULT;
        }
    }

    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);

    master_service_set_die_callback(master_service, pop3_die);

    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);
    master_service_deinit(&master_service);
    return 0;
}