source: branches/samba-3.5.x/nsswitch/libwbclient/wbc_async.c

/*
   Unix SMB/CIFS implementation.
   Infrastructure for async winbind requests
   Copyright (C) Volker Lendecke 2008

     ** NOTE! The following LGPL license applies to the wbclient
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "replace.h"
#include "system/filesys.h"
#include "system/network.h"
#include <talloc.h>
#include <tevent.h>
#include "lib/async_req/async_sock.h"
#include "nsswitch/winbind_struct_protocol.h"
#include "nsswitch/libwbclient/wbclient.h"
#include "nsswitch/libwbclient/wbc_async.h"

wbcErr map_wbc_err_from_errno(int error)
{
        switch(error) {
        case EPERM:
        case EACCES:
                return WBC_ERR_AUTH_ERROR;
        case ENOMEM:
                return WBC_ERR_NO_MEMORY;
        case EIO:
        default:
                return WBC_ERR_UNKNOWN_FAILURE;
        }
}

bool tevent_req_is_wbcerr(struct tevent_req *req, wbcErr *pwbc_err)
{
        enum tevent_req_state state;
        uint64_t error;
        if (!tevent_req_is_error(req, &state, &error)) {
                *pwbc_err = WBC_ERR_SUCCESS;
                return false;
        }

        switch (state) {
        case TEVENT_REQ_USER_ERROR:
                *pwbc_err = error;
                break;
        case TEVENT_REQ_TIMED_OUT:
                *pwbc_err = WBC_ERR_UNKNOWN_FAILURE;
                break;
        case TEVENT_REQ_NO_MEMORY:
                *pwbc_err = WBC_ERR_NO_MEMORY;
                break;
        default:
                *pwbc_err = WBC_ERR_UNKNOWN_FAILURE;
                break;
        }
        return true;
}

wbcErr tevent_req_simple_recv_wbcerr(struct tevent_req *req)
{
        wbcErr wbc_err;

        if (tevent_req_is_wbcerr(req, &wbc_err)) {
                return wbc_err;
        }

        return WBC_ERR_SUCCESS;
}

struct wbc_debug_ops {
        void (*debug)(void *context, enum wbcDebugLevel level,
                      const char *fmt, va_list ap) PRINTF_ATTRIBUTE(3,0);
        void *context;
};

struct wb_context {
        struct tevent_queue *queue;
        int fd;
        bool is_priv;
        const char *dir;
        struct wbc_debug_ops debug_ops;
};

static int make_nonstd_fd(int fd)
{
        int i;
        int sys_errno = 0;
        int fds[3];
        int num_fds = 0;

        if (fd == -1) {
                return -1;
        }
        while (fd < 3) {
                fds[num_fds++] = fd;
                fd = dup(fd);
                if (fd == -1) {
                        sys_errno = errno;
                        break;
                }
        }
        for (i=0; i<num_fds; i++) {
                close(fds[i]);
        }
        if (fd == -1) {
                errno = sys_errno;
        }
        return fd;
}

/****************************************************************************
 Set a fd into blocking/nonblocking mode. Uses POSIX O_NONBLOCK if available,
 else
 if SYSV use O_NDELAY
 if BSD use FNDELAY
 Set close on exec also.
****************************************************************************/

static int make_safe_fd(int fd)
{
        int result, flags;
        int new_fd = make_nonstd_fd(fd);

        if (new_fd == -1) {
                goto fail;
        }

        /* Socket should be nonblocking. */

#ifdef O_NONBLOCK
#define FLAG_TO_SET O_NONBLOCK
#else
#ifdef SYSV
#define FLAG_TO_SET O_NDELAY
#else /* BSD */
#define FLAG_TO_SET FNDELAY
#endif
#endif

        if ((flags = fcntl(new_fd, F_GETFL)) == -1) {
                goto fail;
        }

        flags |= FLAG_TO_SET;
        if (fcntl(new_fd, F_SETFL, flags) == -1) {
                goto fail;
        }

#undef FLAG_TO_SET

        /* Socket should be closed on exec() */
#ifdef FD_CLOEXEC
        result = flags = fcntl(new_fd, F_GETFD, 0);
        if (flags >= 0) {
                flags |= FD_CLOEXEC;
                result = fcntl( new_fd, F_SETFD, flags );
        }
        if (result < 0) {
                goto fail;
        }
#endif
        return new_fd;

 fail:
        if (new_fd != -1) {
                int sys_errno = errno;
                close(new_fd);
                errno = sys_errno;
        }
        return -1;
}

/* Just put a prototype to avoid moving the whole function around */
static const char *winbindd_socket_dir(void);

struct wb_context *wb_context_init(TALLOC_CTX *mem_ctx, const char* dir)
{
        struct wb_context *result;

        result = talloc(mem_ctx, struct wb_context);
        if (result == NULL) {
                return NULL;
        }
        result->queue = tevent_queue_create(result, "wb_trans");
        if (result->queue == NULL) {
                TALLOC_FREE(result);
                return NULL;
        }
        result->fd = -1;
        result->is_priv = false;

        if (dir != NULL) {
                result->dir = talloc_strdup(result, dir);
        } else {
                result->dir = winbindd_socket_dir();
        }
        if (result->dir == NULL) {
                TALLOC_FREE(result);
                return NULL;
        }
        return result;
}

struct wb_connect_state {
        int dummy;
};

static void wbc_connect_connected(struct tevent_req *subreq);

static struct tevent_req *wb_connect_send(TALLOC_CTX *mem_ctx,
                                          struct tevent_context *ev,
                                          struct wb_context *wb_ctx,
                                          const char *dir)
{
        struct tevent_req *result, *subreq;
        struct wb_connect_state *state;
        struct sockaddr_un sunaddr;
        struct stat st;
        char *path = NULL;
        wbcErr wbc_err;

        result = tevent_req_create(mem_ctx, &state, struct wb_connect_state);
        if (result == NULL) {
                return NULL;
        }

        if (wb_ctx->fd != -1) {
                close(wb_ctx->fd);
                wb_ctx->fd = -1;
        }

        /* Check permissions on unix socket directory */

        if (lstat(dir, &st) == -1) {
                wbc_err = WBC_ERR_WINBIND_NOT_AVAILABLE;
                goto post_status;
        }

        if (!S_ISDIR(st.st_mode) ||
            (st.st_uid != 0 && st.st_uid != geteuid())) {
                wbc_err = WBC_ERR_WINBIND_NOT_AVAILABLE;
                goto post_status;
        }

        /* Connect to socket */

        path = talloc_asprintf(mem_ctx, "%s/%s", dir,
                               WINBINDD_SOCKET_NAME);
        if (path == NULL) {
                goto nomem;
        }

        sunaddr.sun_family = AF_UNIX;
        strlcpy(sunaddr.sun_path, path, sizeof(sunaddr.sun_path));
        TALLOC_FREE(path);

        /* If socket file doesn't exist, don't bother trying to connect
           with retry.  This is an attempt to make the system usable when
           the winbindd daemon is not running. */

        if ((lstat(sunaddr.sun_path, &st) == -1)
            || !S_ISSOCK(st.st_mode)
            || (st.st_uid != 0 && st.st_uid != geteuid())) {
                wbc_err = WBC_ERR_WINBIND_NOT_AVAILABLE;
                goto post_status;
        }

        wb_ctx->fd = make_safe_fd(socket(AF_UNIX, SOCK_STREAM, 0));
        if (wb_ctx->fd == -1) {
                wbc_err = map_wbc_err_from_errno(errno);
                goto post_status;
        }

        subreq = async_connect_send(mem_ctx, ev, wb_ctx->fd,
                                    (struct sockaddr *)(void *)&sunaddr,
                                    sizeof(sunaddr));
        if (subreq == NULL) {
                goto nomem;
        }
        tevent_req_set_callback(subreq, wbc_connect_connected, result);
        return result;

 post_status:
        tevent_req_error(result, wbc_err);
        return tevent_req_post(result, ev);
 nomem:
        TALLOC_FREE(result);
        return NULL;
}

static void wbc_connect_connected(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        int res, err;

        res = async_connect_recv(subreq, &err);
        TALLOC_FREE(subreq);
        if (res == -1) {
                tevent_req_error(req, map_wbc_err_from_errno(err));
                return;
        }
        tevent_req_done(req);
}

static wbcErr wb_connect_recv(struct tevent_req *req)
{
        return tevent_req_simple_recv_wbcerr(req);
}

static const char *winbindd_socket_dir(void)
{
#ifdef SOCKET_WRAPPER
        const char *env_dir;

        env_dir = getenv(WINBINDD_SOCKET_DIR_ENVVAR);
        if (env_dir) {
                return env_dir;
        }
#endif

        return WINBINDD_SOCKET_DIR;
}

struct wb_open_pipe_state {
        struct wb_context *wb_ctx;
        struct tevent_context *ev;
        bool need_priv;
        struct winbindd_request wb_req;
};

static void wb_open_pipe_connect_nonpriv_done(struct tevent_req *subreq);
static void wb_open_pipe_ping_done(struct tevent_req *subreq);
static void wb_open_pipe_getpriv_done(struct tevent_req *subreq);
static void wb_open_pipe_connect_priv_done(struct tevent_req *subreq);

static struct tevent_req *wb_open_pipe_send(TALLOC_CTX *mem_ctx,
                                            struct tevent_context *ev,
                                            struct wb_context *wb_ctx,
                                            bool need_priv)
{
        struct tevent_req *result, *subreq;
        struct wb_open_pipe_state *state;

        result = tevent_req_create(mem_ctx, &state, struct wb_open_pipe_state);
        if (result == NULL) {
                return NULL;
        }
        state->wb_ctx = wb_ctx;
        state->ev = ev;
        state->need_priv = need_priv;

        if (wb_ctx->fd != -1) {
                close(wb_ctx->fd);
                wb_ctx->fd = -1;
        }

        subreq = wb_connect_send(state, ev, wb_ctx, wb_ctx->dir);
        if (subreq == NULL) {
                goto fail;
        }
        tevent_req_set_callback(subreq, wb_open_pipe_connect_nonpriv_done,
                                result);
        return result;

 fail:
        TALLOC_FREE(result);
        return NULL;
}

static void wb_open_pipe_connect_nonpriv_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct wb_open_pipe_state *state = tevent_req_data(
                req, struct wb_open_pipe_state);
        wbcErr wbc_err;

        wbc_err = wb_connect_recv(subreq);
        TALLOC_FREE(subreq);
        if (!WBC_ERROR_IS_OK(wbc_err)) {
                state->wb_ctx->is_priv = true;
                tevent_req_error(req, wbc_err);
                return;
        }

        ZERO_STRUCT(state->wb_req);
        state->wb_req.cmd = WINBINDD_INTERFACE_VERSION;
        state->wb_req.pid = getpid();

        subreq = wb_simple_trans_send(state, state->ev, NULL,
                                      state->wb_ctx->fd, &state->wb_req);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, wb_open_pipe_ping_done, req);
}

static void wb_open_pipe_ping_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct wb_open_pipe_state *state = tevent_req_data(
                req, struct wb_open_pipe_state);
        struct winbindd_response *wb_resp;
        int ret, err;

        ret = wb_simple_trans_recv(subreq, state, &wb_resp, &err);
        TALLOC_FREE(subreq);
        if (ret == -1) {
                tevent_req_error(req, map_wbc_err_from_errno(err));
                return;
        }

        if (!state->need_priv) {
                tevent_req_done(req);
                return;
        }

        state->wb_req.cmd = WINBINDD_PRIV_PIPE_DIR;
        state->wb_req.pid = getpid();

        subreq = wb_simple_trans_send(state, state->ev, NULL,
                                      state->wb_ctx->fd, &state->wb_req);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, wb_open_pipe_getpriv_done, req);
}

static void wb_open_pipe_getpriv_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct wb_open_pipe_state *state = tevent_req_data(
                req, struct wb_open_pipe_state);
        struct winbindd_response *wb_resp = NULL;
        int ret, err;

        ret = wb_simple_trans_recv(subreq, state, &wb_resp, &err);
        TALLOC_FREE(subreq);
        if (ret == -1) {
                tevent_req_error(req, map_wbc_err_from_errno(err));
                return;
        }

        close(state->wb_ctx->fd);
        state->wb_ctx->fd = -1;

        subreq = wb_connect_send(state, state->ev, state->wb_ctx,
                                  (char *)wb_resp->extra_data.data);
        TALLOC_FREE(wb_resp);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, wb_open_pipe_connect_priv_done, req);
}

static void wb_open_pipe_connect_priv_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct wb_open_pipe_state *state = tevent_req_data(
                req, struct wb_open_pipe_state);
        wbcErr wbc_err;

        wbc_err = wb_connect_recv(subreq);
        TALLOC_FREE(subreq);
        if (!WBC_ERROR_IS_OK(wbc_err)) {
                tevent_req_error(req, wbc_err);
                return;
        }
        state->wb_ctx->is_priv = true;
        tevent_req_done(req);
}

static wbcErr wb_open_pipe_recv(struct tevent_req *req)
{
        return tevent_req_simple_recv_wbcerr(req);
}

struct wb_trans_state {
        struct wb_trans_state *prev, *next;
        struct wb_context *wb_ctx;
        struct tevent_context *ev;
        struct winbindd_request *wb_req;
        struct winbindd_response *wb_resp;
        bool need_priv;
};

static bool closed_fd(int fd)
{
        struct timeval tv;
        fd_set r_fds;
        int selret;

        if (fd < 0 || fd >= FD_SETSIZE) {
                return true;
        }

        FD_ZERO(&r_fds);
        FD_SET(fd, &r_fds);
        ZERO_STRUCT(tv);

        selret = select(fd+1, &r_fds, NULL, NULL, &tv);
        if (selret == -1) {
                return true;
        }
        if (selret == 0) {
                return false;
        }
        return (FD_ISSET(fd, &r_fds));
}

static void wb_trans_trigger(struct tevent_req *req, void *private_data);
static void wb_trans_connect_done(struct tevent_req *subreq);
static void wb_trans_done(struct tevent_req *subreq);
static void wb_trans_retry_wait_done(struct tevent_req *subreq);

struct tevent_req *wb_trans_send(TALLOC_CTX *mem_ctx,
                                 struct tevent_context *ev,
                                 struct wb_context *wb_ctx, bool need_priv,
                                 struct winbindd_request *wb_req)
{
        struct tevent_req *req;
        struct wb_trans_state *state;

        req = tevent_req_create(mem_ctx, &state, struct wb_trans_state);
        if (req == NULL) {
                return NULL;
        }
        state->wb_ctx = wb_ctx;
        state->ev = ev;
        state->wb_req = wb_req;
        state->need_priv = need_priv;

        if (!tevent_queue_add(wb_ctx->queue, ev, req, wb_trans_trigger,
                              NULL)) {
                tevent_req_nomem(NULL, req);
                return tevent_req_post(req, ev);
        }
        return req;
}

static void wb_trans_trigger(struct tevent_req *req, void *private_data)
{
        struct wb_trans_state *state = tevent_req_data(
                req, struct wb_trans_state);
        struct tevent_req *subreq;

        if ((state->wb_ctx->fd != -1) && closed_fd(state->wb_ctx->fd)) {
                close(state->wb_ctx->fd);
                state->wb_ctx->fd = -1;
        }

        if ((state->wb_ctx->fd == -1)
            || (state->need_priv && !state->wb_ctx->is_priv)) {
                subreq = wb_open_pipe_send(state, state->ev, state->wb_ctx,
                                           state->need_priv);
                if (tevent_req_nomem(subreq, req)) {
                        return;
                }
                tevent_req_set_callback(subreq, wb_trans_connect_done, req);
                return;
        }

        state->wb_req->pid = getpid();

        subreq = wb_simple_trans_send(state, state->ev, NULL,
                                      state->wb_ctx->fd, state->wb_req);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, wb_trans_done, req);
}

static bool wb_trans_retry(struct tevent_req *req,
                           struct wb_trans_state *state,
                           wbcErr wbc_err)
{
        struct tevent_req *subreq;

        if (WBC_ERROR_IS_OK(wbc_err)) {
                return false;
        }

        if (wbc_err == WBC_ERR_WINBIND_NOT_AVAILABLE) {
                /*
                 * Winbind not around or we can't connect to the pipe. Fail
                 * immediately.
                 */
                tevent_req_error(req, wbc_err);
                return true;
        }

        /*
         * The transfer as such failed, retry after one second
         */

        if (state->wb_ctx->fd != -1) {
                close(state->wb_ctx->fd);
                state->wb_ctx->fd = -1;
        }

        subreq = tevent_wakeup_send(state, state->ev,
                                    tevent_timeval_current_ofs(1, 0));
        if (tevent_req_nomem(subreq, req)) {
                return true;
        }
        tevent_req_set_callback(subreq, wb_trans_retry_wait_done, req);
        return true;
}

static void wb_trans_retry_wait_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct wb_trans_state *state = tevent_req_data(
                req, struct wb_trans_state);
        bool ret;

        ret = tevent_wakeup_recv(subreq);
        TALLOC_FREE(subreq);
        if (!ret) {
                tevent_req_error(req, WBC_ERR_UNKNOWN_FAILURE);
                return;
        }

        subreq = wb_open_pipe_send(state, state->ev, state->wb_ctx,
                                   state->need_priv);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, wb_trans_connect_done, req);
}

static void wb_trans_connect_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct wb_trans_state *state = tevent_req_data(
                req, struct wb_trans_state);
        wbcErr wbc_err;

        wbc_err = wb_open_pipe_recv(subreq);
        TALLOC_FREE(subreq);

        if (wb_trans_retry(req, state, wbc_err)) {
                return;
        }

        subreq = wb_simple_trans_send(state, state->ev, NULL,
                                      state->wb_ctx->fd, state->wb_req);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, wb_trans_done, req);
}

static void wb_trans_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct wb_trans_state *state = tevent_req_data(
                req, struct wb_trans_state);
        int ret, err;

        ret = wb_simple_trans_recv(subreq, state, &state->wb_resp, &err);
        TALLOC_FREE(subreq);
        if ((ret == -1)
            && wb_trans_retry(req, state, map_wbc_err_from_errno(err))) {
                return;
        }

        tevent_req_done(req);
}

wbcErr wb_trans_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
                     struct winbindd_response **presponse)
{
        struct wb_trans_state *state = tevent_req_data(
                req, struct wb_trans_state);
        wbcErr wbc_err;

        if (tevent_req_is_wbcerr(req, &wbc_err)) {
                return wbc_err;
        }

        *presponse = talloc_move(mem_ctx, &state->wb_resp);
        return WBC_ERR_SUCCESS;
}

/********************************************************************
 * Debug wrapper functions, modeled (with lot's of code copied as is)
 * after the tevent debug wrapper functions
 ********************************************************************/

/*
  this allows the user to choose their own debug function
*/
int wbcSetDebug(struct wb_context *wb_ctx,
                void (*debug)(void *context,
                              enum wbcDebugLevel level,
                              const char *fmt,
                              va_list ap) PRINTF_ATTRIBUTE(3,0),
                void *context)
{
        wb_ctx->debug_ops.debug = debug;
        wb_ctx->debug_ops.context = context;
        return 0;
}

/*
  debug function for wbcSetDebugStderr
*/
static void wbcDebugStderr(void *private_data,
                           enum wbcDebugLevel level,
                           const char *fmt,
                           va_list ap) PRINTF_ATTRIBUTE(3,0);
static void wbcDebugStderr(void *private_data,
                           enum wbcDebugLevel level,
                           const char *fmt, va_list ap)
{
        if (level <= WBC_DEBUG_WARNING) {
                vfprintf(stderr, fmt, ap);
        }
}

/*
  convenience function to setup debug messages on stderr
  messages of level WBC_DEBUG_WARNING and higher are printed
*/
int wbcSetDebugStderr(struct wb_context *wb_ctx)
{
        return wbcSetDebug(wb_ctx, wbcDebugStderr, wb_ctx);
}

/*
 * log a message
 *
 * The default debug action is to ignore debugging messages.
 * This is the most appropriate action for a library.
 * Applications using the library must decide where to
 * redirect debugging messages
*/
void wbcDebug(struct wb_context *wb_ctx, enum wbcDebugLevel level,
              const char *fmt, ...)
{
        va_list ap;
        if (!wb_ctx) {
                return;
        }
        if (wb_ctx->debug_ops.debug == NULL) {
                return;
        }
        va_start(ap, fmt);
        wb_ctx->debug_ops.debug(wb_ctx->debug_ops.context, level, fmt, ap);
        va_end(ap);
}