src/login-common/login-proxy.c

	login-proxy.c revision 5f5870385cff47efd2f58e7892f251cf13761528
/* Copyright (c) 2004-2012 Dovecot authors, see the included COPYING file */

#include "login-common.h"
#include "ioloop.h"
#include "istream.h"
#include "ostream.h"
#include "llist.h"
#include "md5.h"
#include "str-sanitize.h"
#include "time-util.h"
#include "master-service.h"
#include "ipc-server.h"
#include "dns-lookup.h"
#include "client-common.h"
#include "ssl-proxy.h"
#include "login-proxy-state.h"
#include "login-proxy.h"

#define MAX_PROXY_INPUT_SIZE 4096
#define OUTBUF_THRESHOLD 1024
#define LOGIN_PROXY_DIE_IDLE_SECS 2
#define LOGIN_PROXY_DNS_WARN_MSECS 500
#define LOGIN_PROXY_IPC_PATH "ipc-proxy"
#define LOGIN_PROXY_IPC_NAME "proxy"
#define KILLED_BY_ADMIN_REASON "Killed by admin"

struct login_proxy {
    struct login_proxy *prev, *next;

    struct client *client;
    int client_fd, server_fd;
    struct io *client_io, *server_io;
    struct istream *server_input;
    struct ostream *client_output, *server_output;
    struct ssl_proxy *ssl_server_proxy;
    time_t last_io;

    struct timeval created;
    struct timeout *to, *to_notify;
    struct login_proxy_record *state_rec;

    struct ip_addr ip;
    char *host;
    unsigned int port;
    unsigned int connect_timeout_msecs;
    unsigned int notify_refresh_secs;
    enum login_proxy_ssl_flags ssl_flags;

    proxy_callback_t *callback;

    unsigned int destroying:1;
    unsigned int disconnecting:1;
};

static struct login_proxy_state *proxy_state;
static struct login_proxy *login_proxies = NULL;
static struct login_proxy *login_proxies_pending = NULL;
static struct ipc_server *login_proxy_ipc_server;

static void login_proxy_ipc_cmd(struct ipc_cmd *cmd, const char *line);

static void
login_proxy_free_reason(struct login_proxy **_proxy, const char *reason);

static void login_proxy_free_errno(struct login_proxy **proxy,
                   int err, const char *who)
{
    const char *reason;

    reason = err == 0 || err == EPIPE ?
        t_strdup_printf("Disconnected by %s", who) :
        t_strdup_printf("Disconnected by %s: %s", who, strerror(errno));
    login_proxy_free_reason(proxy, reason);
}

static void server_input(struct login_proxy *proxy)
{
    unsigned char buf[OUTBUF_THRESHOLD];
    ssize_t ret;

    proxy->last_io = ioloop_time;
    if (o_stream_get_buffer_used_size(proxy->client_output) >
        OUTBUF_THRESHOLD) {
        /* client's output buffer is already quite full.
           don't send more until we're below threshold. */
        io_remove(&proxy->server_io);
        return;
    }

    ret = net_receive(proxy->server_fd, buf, sizeof(buf));
    if (ret < 0)
        login_proxy_free_errno(&proxy, errno, "server");
    else if (o_stream_send(proxy->client_output, buf, ret) != ret) {
        login_proxy_free_errno(&proxy,
                       proxy->client_output->stream_errno,
                       "client");
    }
}

static void proxy_client_input(struct login_proxy *proxy)
{
    unsigned char buf[OUTBUF_THRESHOLD];
    ssize_t ret;

    proxy->last_io = ioloop_time;
    if (o_stream_get_buffer_used_size(proxy->server_output) >
        OUTBUF_THRESHOLD) {
        /* proxy's output buffer is already quite full.
           don't send more until we're below threshold. */
        io_remove(&proxy->client_io);
        return;
    }

    ret = net_receive(proxy->client_fd, buf, sizeof(buf));
    if (ret < 0)
        login_proxy_free_errno(&proxy, errno, "client");
    else if (o_stream_send(proxy->server_output, buf, ret) != ret) {
        login_proxy_free_errno(&proxy,
                       proxy->server_output->stream_errno,
                       "server");
    }
}

static int server_output(struct login_proxy *proxy)
{
    proxy->last_io = ioloop_time;
    if (o_stream_flush(proxy->server_output) < 0) {
        login_proxy_free_errno(&proxy,
                       proxy->server_output->stream_errno,
                       "server");
        return 1;
    }

    if (proxy->client_io == NULL &&
        o_stream_get_buffer_used_size(proxy->server_output) <
        OUTBUF_THRESHOLD) {
        /* there's again space in proxy's output buffer, so we can
           read more from client. */
        proxy->client_io = io_add(proxy->client_fd, IO_READ,
                      proxy_client_input, proxy);
    }
    return 1;
}

static int proxy_client_output(struct login_proxy *proxy)
{
    proxy->last_io = ioloop_time;
    if (o_stream_flush(proxy->client_output) < 0) {
        login_proxy_free_errno(&proxy,
                       proxy->client_output->stream_errno,
                       "client");
        return 1;
    }

    if (proxy->server_io == NULL &&
        o_stream_get_buffer_used_size(proxy->client_output) <
        OUTBUF_THRESHOLD) {
        /* there's again space in client's output buffer, so we can
           read more from proxy. */
        proxy->server_io =
            io_add(proxy->server_fd, IO_READ, server_input, proxy);
    }
    return 1;
}

static void proxy_prelogin_input(struct login_proxy *proxy)
{
    proxy->callback(proxy->client);
}

static void proxy_plain_connected(struct login_proxy *proxy)
{
    proxy->server_input =
        i_stream_create_fd(proxy->server_fd, MAX_PROXY_INPUT_SIZE,
                   FALSE);
    proxy->server_output =
        o_stream_create_fd(proxy->server_fd, (size_t)-1, FALSE);

    proxy->server_io =
        io_add(proxy->server_fd, IO_READ, proxy_prelogin_input, proxy);
}

static void proxy_fail_connect(struct login_proxy *proxy)
{
    if (timeval_cmp(&proxy->created, &proxy->state_rec->last_success) < 0) {
        /* there was a successful connection done since we started
           connecting. perhaps this is just a temporary one-off
           failure. */
    } else {
        proxy->state_rec->last_failure = ioloop_timeval;
    }
    proxy->state_rec->num_waiting_connections--;
    proxy->state_rec = NULL;
}

static void proxy_wait_connect(struct login_proxy *proxy)
{
    int err;

    err = net_geterror(proxy->server_fd);
    if (err != 0) {
        i_error("proxy(%s): connect(%s, %u) failed: %s",
            proxy->client->virtual_user,
            proxy->host, proxy->port, strerror(err));
        proxy_fail_connect(proxy);
                login_proxy_free(&proxy);
        return;
    }
    proxy->state_rec->last_success = ioloop_timeval;
    proxy->state_rec->num_waiting_connections--;
    proxy->state_rec = NULL;

    if (proxy->to != NULL)
        timeout_remove(&proxy->to);

    if ((proxy->ssl_flags & PROXY_SSL_FLAG_YES) != 0 &&
        (proxy->ssl_flags & PROXY_SSL_FLAG_STARTTLS) == 0) {
        if (login_proxy_starttls(proxy) < 0) {
            login_proxy_free(&proxy);
            return;
        }
    } else {
        io_remove(&proxy->server_io);
        proxy_plain_connected(proxy);
    }
}

static void proxy_connect_timeout(struct login_proxy *proxy)
{
    i_error("proxy(%s): connect(%s, %u) timed out",
        proxy->client->virtual_user, proxy->host, proxy->port);
    proxy_fail_connect(proxy);
    login_proxy_free(&proxy);
}

static int login_proxy_connect(struct login_proxy *proxy)
{
    struct login_proxy_record *rec;

    rec = login_proxy_state_get(proxy_state, &proxy->ip, proxy->port);
    if (timeval_cmp(&rec->last_failure, &rec->last_success) > 0 &&
        rec->num_waiting_connections != 0) {
        /* the server is down. fail immediately */
        i_error("proxy(%s): Host %s:%u is down",
            proxy->client->virtual_user, proxy->host, proxy->port);
        login_proxy_free(&proxy);
        return -1;
    }

    proxy->server_fd = net_connect_ip(&proxy->ip, proxy->port, NULL);
    if (proxy->server_fd == -1) {
        i_error("proxy(%s): connect(%s, %u) failed: %m",
            proxy->client->virtual_user, proxy->host, proxy->port);
        login_proxy_free(&proxy);
        return -1;
    }
    proxy->server_io = io_add(proxy->server_fd, IO_WRITE,
                  proxy_wait_connect, proxy);
    if (proxy->connect_timeout_msecs != 0) {
        proxy->to = timeout_add(proxy->connect_timeout_msecs,
                    proxy_connect_timeout, proxy);
    }

    proxy->state_rec = rec;
    proxy->state_rec->num_waiting_connections++;
    return 0;
}

static void login_proxy_dns_done(const struct dns_lookup_result *result,
                 struct login_proxy *proxy)
{
    if (result->ret != 0) {
        i_error("proxy(%s): DNS lookup of %s failed: %s",
            proxy->client->virtual_user, proxy->host,
            result->error);
        login_proxy_free(&proxy);
    } else {
        if (result->msecs > LOGIN_PROXY_DNS_WARN_MSECS) {
            i_warning("proxy(%s): DNS lookup for %s took %u.%03u s",
                  proxy->client->virtual_user, proxy->host,
                  result->msecs/1000, result->msecs % 1000);
        }

        proxy->ip = result->ips[0];
        (void)login_proxy_connect(proxy);
    }
}

int login_proxy_new(struct client *client,
            const struct login_proxy_settings *set,
            proxy_callback_t *callback)
{
    struct login_proxy *proxy;
    struct dns_lookup_settings dns_lookup_set;

    i_assert(client->login_proxy == NULL);

    if (set->host == NULL || *set->host == '\0') {
        i_error("proxy(%s): host not given", client->virtual_user);
        return -1;
    }

    proxy = i_new(struct login_proxy, 1);
    proxy->client = client;
    proxy->client_fd = -1;
    proxy->server_fd = -1;
    proxy->created = ioloop_timeval;
    proxy->host = i_strdup(set->host);
    proxy->port = set->port;
    proxy->connect_timeout_msecs = set->connect_timeout_msecs;
    proxy->notify_refresh_secs = set->notify_refresh_secs;
    proxy->ssl_flags = set->ssl_flags;
    client_ref(client);

    memset(&dns_lookup_set, 0, sizeof(dns_lookup_set));
    dns_lookup_set.dns_client_socket_path = set->dns_client_socket_path;
    dns_lookup_set.timeout_msecs = set->connect_timeout_msecs;

    if (net_addr2ip(set->host, &proxy->ip) < 0) {
        if (dns_lookup(set->host, &dns_lookup_set,
                   login_proxy_dns_done, proxy) < 0)
            return -1;
    } else {
        if (login_proxy_connect(proxy) < 0)
            return -1;
    }

    DLLIST_PREPEND(&login_proxies_pending, proxy);

    proxy->callback = callback;
    client->login_proxy = proxy;
    return 0;
}

static void
login_proxy_free_reason(struct login_proxy **_proxy, const char *reason)
{
    struct login_proxy *proxy = *_proxy;
    struct client *client = proxy->client;
    const char *ipstr;

    *_proxy = NULL;

    if (proxy->destroying)
        return;
    proxy->destroying = TRUE;

    if (proxy->to != NULL)
        timeout_remove(&proxy->to);
    if (proxy->to_notify != NULL)
        timeout_remove(&proxy->to_notify);

    if (proxy->state_rec != NULL)
        proxy->state_rec->num_waiting_connections--;
    if (proxy->to != NULL)
        timeout_remove(&proxy->to);

    if (proxy->server_io != NULL)
        io_remove(&proxy->server_io);
    if (proxy->server_input != NULL)
        i_stream_destroy(&proxy->server_input);
    if (proxy->server_output != NULL)
        o_stream_destroy(&proxy->server_output);

    if (proxy->client_fd != -1) {
        /* detached proxy */
        DLLIST_REMOVE(&login_proxies, proxy);

        ipstr = net_ip2addr(&proxy->client->ip);
        i_info("proxy(%s): disconnecting %s%s",
               proxy->client->virtual_user,
               ipstr != NULL ? ipstr : "",
               reason == NULL ? "" : t_strdup_printf(" (%s)", reason));

        if (proxy->client_io != NULL)
            io_remove(&proxy->client_io);
        if (proxy->client_output != NULL)
            o_stream_destroy(&proxy->client_output);
        net_disconnect(proxy->client_fd);
    } else {
        i_assert(proxy->client_io == NULL);
        i_assert(proxy->client_output == NULL);

        DLLIST_REMOVE(&login_proxies_pending, proxy);

        if (proxy->callback != NULL)
            proxy->callback(proxy->client);
    }

    if (proxy->server_fd != -1)
        net_disconnect(proxy->server_fd);

    if (proxy->ssl_server_proxy != NULL)
        ssl_proxy_free(&proxy->ssl_server_proxy);
    i_free(proxy->host);
    i_free(proxy);

    client->login_proxy = NULL;
    client_unref(&client);
}

void login_proxy_free(struct login_proxy **_proxy)
{
    login_proxy_free_reason(_proxy, NULL);
}

bool login_proxy_is_ourself(const struct client *client, const char *host,
                unsigned int port, const char *destuser)
{
    struct ip_addr ip;

    if (port != client->local_port)
        return FALSE;

    if (net_addr2ip(host, &ip) < 0)
        return FALSE;
    if (!net_ip_compare(&ip, &client->local_ip))
        return FALSE;

    return strcmp(client->virtual_user, destuser) == 0;
}

struct istream *login_proxy_get_istream(struct login_proxy *proxy)
{
    return proxy->disconnecting ? NULL : proxy->server_input;
}

struct ostream *login_proxy_get_ostream(struct login_proxy *proxy)
{
    return proxy->server_output;
}

const char *login_proxy_get_host(const struct login_proxy *proxy)
{
    return proxy->host;
}

unsigned int login_proxy_get_port(const struct login_proxy *proxy)
{
    return proxy->port;
}

enum login_proxy_ssl_flags
login_proxy_get_ssl_flags(const struct login_proxy *proxy)
{
    return proxy->ssl_flags;
}

static void login_proxy_notify(struct login_proxy *proxy)
{
    login_proxy_state_notify(proxy_state, proxy->client->proxy_user);
}

void login_proxy_detach(struct login_proxy *proxy)
{
    struct client *client = proxy->client;
    const unsigned char *data;
    size_t size;

    i_assert(proxy->client_fd == -1);
    i_assert(proxy->server_output != NULL);

    proxy->client_fd = i_stream_get_fd(client->input);
    proxy->client_output = client->output;

    o_stream_set_max_buffer_size(client->output, (size_t)-1);
    o_stream_set_flush_callback(client->output, proxy_client_output, proxy);
    client->output = NULL;

    /* send all pending client input to proxy and get rid of the stream */
    data = i_stream_get_data(client->input, &size);
    if (size != 0)
        (void)o_stream_send(proxy->server_output, data, size);

    /* from now on, just do dummy proxying */
    io_remove(&proxy->server_io);
    proxy->server_io =
        io_add(proxy->server_fd, IO_READ, server_input, proxy);
    proxy->client_io =
        io_add(proxy->client_fd, IO_READ, proxy_client_input, proxy);
    o_stream_set_flush_callback(proxy->server_output, server_output, proxy);
    i_stream_destroy(&proxy->server_input);

    if (proxy->notify_refresh_secs != 0) {
        proxy->to_notify =
            timeout_add(proxy->notify_refresh_secs * 1000,
                    login_proxy_notify, proxy);
    }

    proxy->callback = NULL;

    if (login_proxy_ipc_server == NULL) {
        login_proxy_ipc_server =
            ipc_server_init(LOGIN_PROXY_IPC_PATH,
                    LOGIN_PROXY_IPC_NAME,
                    login_proxy_ipc_cmd);
    }

    DLLIST_REMOVE(&login_proxies_pending, proxy);
    DLLIST_PREPEND(&login_proxies, proxy);

    client->fd = -1;
    client->login_proxy = NULL;
}

static int login_proxy_ssl_handshaked(void *context)
{
    struct login_proxy *proxy = context;

    if ((proxy->ssl_flags & PROXY_SSL_FLAG_ANY_CERT) != 0)
        return 0;

    if (ssl_proxy_has_broken_client_cert(proxy->ssl_server_proxy)) {
        client_log_err(proxy->client, t_strdup_printf(
            "proxy: Received invalid SSL certificate from %s:%u",
            proxy->host, proxy->port));
    } else if (!ssl_proxy_has_valid_client_cert(proxy->ssl_server_proxy)) {
        client_log_err(proxy->client, t_strdup_printf(
            "proxy: SSL certificate not received from %s:%u",
            proxy->host, proxy->port));
    } else if (ssl_proxy_cert_match_name(proxy->ssl_server_proxy,
                         proxy->host) < 0) {
        client_log_err(proxy->client, t_strdup_printf(
            "proxy: hostname doesn't match SSL certificate at %s:%u",
            proxy->host, proxy->port));
    } else {
        return 0;
    }
    proxy->disconnecting = TRUE;
    return -1;
}

int login_proxy_starttls(struct login_proxy *proxy)
{
    int fd;

    if (proxy->server_input != NULL)
        i_stream_destroy(&proxy->server_input);
    if (proxy->server_output != NULL)
        o_stream_destroy(&proxy->server_output);
    io_remove(&proxy->server_io);

    fd = ssl_proxy_client_alloc(proxy->server_fd, &proxy->client->ip,
                    proxy->client->set,
                    login_proxy_ssl_handshaked, proxy,
                    &proxy->ssl_server_proxy);
    if (fd < 0) {
        client_log_err(proxy->client, t_strdup_printf(
            "proxy: SSL handshake failed to %s:%u",
            proxy->host, proxy->port));
        return -1;
    }
    ssl_proxy_set_client(proxy->ssl_server_proxy, proxy->client);
    ssl_proxy_start(proxy->ssl_server_proxy);

    proxy->server_fd = fd;
    proxy_plain_connected(proxy);
    return 0;
}

static void proxy_kill_idle(struct login_proxy *proxy)
{
    login_proxy_free_reason(&proxy, KILLED_BY_ADMIN_REASON);
}

void login_proxy_kill_idle(void)
{
    struct login_proxy *proxy, *next;
    time_t now = time(NULL);
    time_t stop_timestamp = now - LOGIN_PROXY_DIE_IDLE_SECS;
    unsigned int stop_msecs;

    for (proxy = login_proxies; proxy != NULL; proxy = next) {
        next = proxy->next;

        if (proxy->last_io <= stop_timestamp)
            proxy_kill_idle(proxy);
        else {
            i_assert(proxy->to == NULL);
            stop_msecs = (proxy->last_io - stop_timestamp) * 1000;
            proxy->to = timeout_add(stop_msecs,
                        proxy_kill_idle, proxy);
        }
    }
}

static void
login_proxy_cmd_kick(struct ipc_cmd *cmd, const char *const *args)
{
    struct login_proxy *proxy, *next;
    unsigned int count = 0;

    if (args[0] == NULL) {
        ipc_cmd_fail(&cmd, "Missing parameter");
        return;
    }

    for (proxy = login_proxies; proxy != NULL; proxy = next) {
        next = proxy->next;

        if (strcmp(proxy->client->virtual_user, args[0]) == 0) {
            login_proxy_free_reason(&proxy, KILLED_BY_ADMIN_REASON);
            count++;
        }
    }
    for (proxy = login_proxies_pending; proxy != NULL; proxy = next) {
        next = proxy->next;

        if (strcmp(proxy->client->virtual_user, args[0]) == 0) {
            client_destroy(proxy->client, "Connection kicked");
            count++;
        }
    }
    ipc_cmd_success_reply(&cmd, t_strdup_printf("%u", count));
}

static unsigned int director_username_hash(const char *username)
{
    /* NOTE: If you modify this, modify also
       user_directory_get_username_hash() in director/user-director.c */
    unsigned char md5[MD5_RESULTLEN];
    unsigned int i, hash = 0;

    md5_get_digest(username, strlen(username), md5);
    for (i = 0; i < sizeof(hash); i++)
        hash = (hash << CHAR_BIT) | md5[i];
    return hash;
}

static void
login_proxy_cmd_kick_director_hash(struct ipc_cmd *cmd, const char *const *args)
{
    struct login_proxy *proxy, *next;
    unsigned int hash, count = 0;

    if (args[0] == NULL || str_to_uint(args[0], &hash) < 0) {
        ipc_cmd_fail(&cmd, "Invalid parameters");
        return;
    }

    for (proxy = login_proxies; proxy != NULL; proxy = next) {
        next = proxy->next;

        if (director_username_hash(proxy->client->virtual_user) == hash) {
            login_proxy_free_reason(&proxy, KILLED_BY_ADMIN_REASON);
            count++;
        }
    }
    for (proxy = login_proxies_pending; proxy != NULL; proxy = next) {
        next = proxy->next;

        if (director_username_hash(proxy->client->virtual_user) == hash) {
            client_destroy(proxy->client, "Connection kicked");
            count++;
        }
    }
    ipc_cmd_success_reply(&cmd, t_strdup_printf("%u", count));
}

static void
login_proxy_cmd_list_reply(struct ipc_cmd *cmd,
               struct login_proxy *proxy)
{
    T_BEGIN {
        const char *reply;

        reply = t_strdup_printf("%s\t%s\t%s\t%s\t%u",
                    proxy->client->virtual_user,
                    login_binary->protocol,
                    net_ip2addr(&proxy->client->ip),
                    net_ip2addr(&proxy->ip), proxy->port);
        ipc_cmd_send(cmd, reply);
    } T_END;
}

static void
login_proxy_cmd_list(struct ipc_cmd *cmd, const char *const *args ATTR_UNUSED)
{
    struct login_proxy *proxy;

    for (proxy = login_proxies; proxy != NULL; proxy = proxy->next)
        login_proxy_cmd_list_reply(cmd, proxy);
    for (proxy = login_proxies_pending; proxy != NULL; proxy = proxy->next)
        login_proxy_cmd_list_reply(cmd, proxy);
    ipc_cmd_success(&cmd);
}

static void login_proxy_ipc_cmd(struct ipc_cmd *cmd, const char *line)
{
    const char *const *args = t_strsplit(line, "\t");
    const char *name = args[0];

    args++;
    if (strcmp(name, "KICK") == 0)
        login_proxy_cmd_kick(cmd, args);
    else if (strcmp(name, "KICK-DIRECTOR-HASH") == 0)
        login_proxy_cmd_kick_director_hash(cmd, args);
    else if (strcmp(name, "LIST") == 0)
        login_proxy_cmd_list(cmd, args);
    else
        ipc_cmd_fail(&cmd, "Unknown command");
}

void login_proxy_init(const char *proxy_notify_pipe_path)
{
    proxy_state = login_proxy_state_init(proxy_notify_pipe_path);
}

void login_proxy_deinit(void)
{
    struct login_proxy *proxy;

    while (login_proxies != NULL) {
        proxy = login_proxies;
        login_proxy_free_reason(&proxy, KILLED_BY_ADMIN_REASON);
    }
    if (login_proxy_ipc_server != NULL)
        ipc_server_deinit(&login_proxy_ipc_server);
    login_proxy_state_deinit(&proxy_state);
}