/*
   SSSD

   Common Responder methods

   Copyright (C) Simo Sorce <ssorce@redhat.com>	2008

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

   This program 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 General Public License for more details.

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

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <string.h>
#include <sys/time.h>
#include <errno.h>
#include "popt.h"
#include "util/util.h"
#include "db/sysdb.h"
#include "confdb/confdb.h"
#include "dbus/dbus.h"
#include "sbus/sssd_dbus.h"
#include "util/btreemap.h"
#include "responder/common/responder.h"
#include "responder/common/responder_packet.h"
#include "providers/data_provider.h"
#include "monitor/monitor_sbus.h"
#include "monitor/monitor_interfaces.h"
#include "sbus/sbus_client.h"

#define NAMES_CONFIG "config/names"

static void set_nonblocking(int fd)
{
    unsigned v;
    v = fcntl(fd, F_GETFL, 0);
    fcntl(fd, F_SETFL, v | O_NONBLOCK);
}

static void set_close_on_exec(int fd)
{
    unsigned v;
    v = fcntl(fd, F_GETFD, 0);
    fcntl(fd, F_SETFD, v | FD_CLOEXEC);
}

static int client_destructor(struct cli_ctx *ctx)
{
    if (ctx->cfd > 0) close(ctx->cfd);
    return 0;
}

static void client_send(struct tevent_context *ev, struct cli_ctx *cctx)
{
    int ret;

    ret = sss_packet_send(cctx->creq->out, cctx->cfd);
    if (ret == EAGAIN) {
        /* not all data was sent, loop again */
        return;
    }
    if (ret != EOK) {
        DEBUG(0, ("Failed to read request, aborting client!\n"));
        talloc_free(cctx);
        return;
    }

    /* ok all sent */
    TEVENT_FD_NOT_WRITEABLE(cctx->cfde);
    TEVENT_FD_READABLE(cctx->cfde);
    talloc_free(cctx->creq);
    cctx->creq = NULL;
    return;
}

static void client_recv(struct tevent_context *ev, struct cli_ctx *cctx)
{
    int ret;

    if (!cctx->creq) {
        cctx->creq = talloc_zero(cctx, struct cli_request);
        if (!cctx->creq) {
            DEBUG(0, ("Failed to alloc request, aborting client!\n"));
            talloc_free(cctx);
            return;
        }
    }

    if (!cctx->creq->in) {
        ret = sss_packet_new(cctx->creq, SSS_PACKET_MAX_RECV_SIZE,
                             0, &cctx->creq->in);
        if (ret != EOK) {
            DEBUG(0, ("Failed to alloc request, aborting client!\n"));
            talloc_free(cctx);
            return;
        }
    }

    ret = sss_packet_recv(cctx->creq->in, cctx->cfd);
    switch (ret) {
    case EOK:
        /* do not read anymore */
        TEVENT_FD_NOT_READABLE(cctx->cfde);
        /* execute command */
        ret = sss_cmd_execute(cctx, cctx->rctx->sss_cmds);
        if (ret != EOK) {
            DEBUG(0, ("Failed to execute request, aborting client!\n"));
            talloc_free(cctx);
        }
        /* past this point cctx can be freed at any time by callbacks
         * in case of error, do not use it */
        return;

    case EAGAIN:
        /* need to read still some data, loop again */
        break;

    case EINVAL:
        DEBUG(6, ("Invalid data from client, closing connection!\n"));
        talloc_free(cctx);
        break;

    case ENODATA:
        DEBUG(5, ("Client disconnected!\n"));
        talloc_free(cctx);
        break;

    default:
        DEBUG(6, ("Failed to read request, aborting client!\n"));
        talloc_free(cctx);
    }

    return;
}

static void client_fd_handler(struct tevent_context *ev,
                              struct tevent_fd *fde,
                              uint16_t flags, void *ptr)
{
    struct cli_ctx *cctx = talloc_get_type(ptr, struct cli_ctx);

    if (flags & TEVENT_FD_READ) {
        client_recv(ev, cctx);
        return;
    }
    if (flags & TEVENT_FD_WRITE) {
        client_send(ev, cctx);
        return;
    }
}

/* TODO: this is a copy of accept_fd_handler, maybe both can be put into on
 * handler.  */
static void accept_priv_fd_handler(struct tevent_context *ev,
                              struct tevent_fd *fde,
                              uint16_t flags, void *ptr)
{
    /* accept and attach new event handler */
    struct resp_ctx *rctx = talloc_get_type(ptr, struct resp_ctx);
    struct cli_ctx *cctx;
    socklen_t len;
    struct stat stat_buf;
    int ret;

    ret = stat(rctx->priv_sock_name, &stat_buf);
    if (ret == -1) {
        DEBUG(1, ("stat on privileged pipe failed: [%d][%s].\n", errno,
                  strerror(errno)));
        return;
    }

    if ( ! (stat_buf.st_uid == 0 && stat_buf.st_gid == 0 &&
           (stat_buf.st_mode&(S_IFSOCK|S_IRUSR|S_IWUSR)) == stat_buf.st_mode)) {
        DEBUG(1, ("privileged pipe has an illegal status.\n"));
/* TODO: what is the best response to this condition? Terminate? */
        return;
    }


    cctx = talloc_zero(rctx, struct cli_ctx);
    if (!cctx) {
        struct sockaddr_un addr;
        int fd;
        DEBUG(0, ("Out of memory trying to setup client context on privileged pipe!\n"));
        /* accept and close to signal the client we have a problem */
        memset(&addr, 0, sizeof(addr));
        len = sizeof(addr);
        fd = accept(rctx->priv_lfd, (struct sockaddr *)&addr, &len);
        if (fd == -1) {
            return;
        }
        close(fd);
        return;
    }

    len = sizeof(cctx->addr);
    cctx->cfd = accept(rctx->priv_lfd, (struct sockaddr *)&cctx->addr, &len);
    if (cctx->cfd == -1) {
        DEBUG(1, ("Accept failed [%s]", strerror(errno)));
        talloc_free(cctx);
        return;
    }

    cctx->priv = 1;

    cctx->cfde = tevent_add_fd(ev, cctx, cctx->cfd,
                               TEVENT_FD_READ, client_fd_handler, cctx);
    if (!cctx->cfde) {
        close(cctx->cfd);
        talloc_free(cctx);
        DEBUG(2, ("Failed to queue client handler on privileged pipe\n"));
    }

    cctx->ev = ev;
    cctx->rctx = rctx;

    talloc_set_destructor(cctx, client_destructor);

    DEBUG(4, ("Client connected to privileged pipe!\n"));

    return;
}

static void accept_fd_handler(struct tevent_context *ev,
                              struct tevent_fd *fde,
                              uint16_t flags, void *ptr)
{
    /* accept and attach new event handler */
    struct resp_ctx *rctx = talloc_get_type(ptr, struct resp_ctx);
    struct cli_ctx *cctx;
    socklen_t len;

    cctx = talloc_zero(rctx, struct cli_ctx);
    if (!cctx) {
        struct sockaddr_un addr;
        int fd;
        DEBUG(0, ("Out of memory trying to setup client context!\n"));
        /* accept and close to signal the client we have a problem */
        memset(&addr, 0, sizeof(addr));
        len = sizeof(addr);
        fd = accept(rctx->lfd, (struct sockaddr *)&addr, &len);
        if (fd == -1) {
            return;
        }
        close(fd);
        return;
    }

    len = sizeof(cctx->addr);
    cctx->cfd = accept(rctx->lfd, (struct sockaddr *)&cctx->addr, &len);
    if (cctx->cfd == -1) {
        DEBUG(1, ("Accept failed [%s]", strerror(errno)));
        talloc_free(cctx);
        return;
    }

    cctx->cfde = tevent_add_fd(ev, cctx, cctx->cfd,
                               TEVENT_FD_READ, client_fd_handler, cctx);
    if (!cctx->cfde) {
        close(cctx->cfd);
        talloc_free(cctx);
        DEBUG(2, ("Failed to queue client handler\n"));
    }

    cctx->ev = ev;
    cctx->rctx = rctx;

    talloc_set_destructor(cctx, client_destructor);

    DEBUG(4, ("Client connected!\n"));

    return;
}

static int sss_sbus_init(struct resp_ctx *rctx)
{
    int ret;
    char *sbus_address;
    struct service_sbus_ctx *ss_ctx;
    struct sbus_method_ctx *sm_ctx;

    /* Set up SBUS connection to the monitor */
    ret = monitor_get_sbus_address(rctx, rctx->cdb, &sbus_address);
    if (ret != EOK) {
        DEBUG(0, ("Could not locate monitor address.\n"));
        return ret;
    }

    ret = monitor_init_sbus_methods(rctx, rctx->sss_sbus_methods, &sm_ctx);
    if (ret != EOK) {
        DEBUG(0, ("Could not initialize SBUS methods.\n"));
        return ret;
    }

    ret = sbus_client_init(rctx, rctx->ev,
                           sbus_address, sm_ctx,
                           NULL /* Private Data */,
                           NULL /* Destructor */,
                           &ss_ctx);
    if (ret != EOK) {
        DEBUG(0, ("Failed to connect to monitor services.\n"));
        return ret;
    }

    /* Set up NSS-specific listeners */
    /* None currently used */

    rctx->ss_ctx = ss_ctx;

    return EOK;
}

/* create a unix socket and listen to it */
static int set_unix_socket(struct resp_ctx *rctx)
{
    struct sockaddr_un addr;

/* for future use */
#if 0
    char *default_pipe;
    int ret;

    default_pipe = talloc_asprintf(rctx, "%s/%s", PIPE_PATH,
                                   rctx->sss_pipe_name);
    if (!default_pipe) {
        return ENOMEM;
    }

    ret = confdb_get_string(rctx->cdb, rctx,
                            rctx->confdb_socket_path, "unixSocket",
                            default_pipe, &rctx->sock_name);
    if (ret != EOK) {
        talloc_free(default_pipe);
        return ret;
    }
    talloc_free(default_pipe);

    default_pipe = talloc_asprintf(rctx, "%s/private/%s", PIPE_PATH,
                                   rctx->sss_pipe_name);
    if (!default_pipe) {
        return ENOMEM;
    }

    ret = confdb_get_string(rctx->cdb, rctx,
                            rctx->confdb_socket_path, "privUnixSocket",
                            default_pipe, &rctx->priv_sock_name);
    if (ret != EOK) {
        talloc_free(default_pipe);
        return ret;
    }
    talloc_free(default_pipe);
#endif

    if (rctx->sock_name != NULL ) {
        rctx->lfd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (rctx->lfd == -1) {
            return EIO;
        }

        /* Set the umask so that permissions are set right on the socket.
         * It must be readable and writable by anybody on the system. */
        umask(0111);

        set_nonblocking(rctx->lfd);
        set_close_on_exec(rctx->lfd);

        memset(&addr, 0, sizeof(addr));
        addr.sun_family = AF_UNIX;
        strncpy(addr.sun_path, rctx->sock_name, sizeof(addr.sun_path));

        /* make sure we have no old sockets around */
        unlink(rctx->sock_name);

        if (bind(rctx->lfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
            DEBUG(0,("Unable to bind on socket '%s'\n", rctx->sock_name));
            goto failed;
        }
        if (listen(rctx->lfd, 10) != 0) {
            DEBUG(0,("Unable to listen on socket '%s'\n", rctx->sock_name));
            goto failed;
        }

        rctx->lfde = tevent_add_fd(rctx->ev, rctx, rctx->lfd,
                                   TEVENT_FD_READ, accept_fd_handler, rctx);
        if (!rctx->lfde) {
            DEBUG(0, ("Failed to queue handler on pipe\n"));
            goto failed;
        }
    }

    if (rctx->priv_sock_name != NULL ) {
        /* create privileged pipe */
        rctx->priv_lfd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (rctx->priv_lfd == -1) {
            close(rctx->lfd);
            return EIO;
        }

        umask(0177);

        set_nonblocking(rctx->priv_lfd);
        set_close_on_exec(rctx->priv_lfd);

        memset(&addr, 0, sizeof(addr));
        addr.sun_family = AF_UNIX;
        strncpy(addr.sun_path, rctx->priv_sock_name, sizeof(addr.sun_path));

        unlink(rctx->priv_sock_name);

        if (bind(rctx->priv_lfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
            DEBUG(0,("Unable to bind on socket '%s'\n", rctx->priv_sock_name));
            goto failed;
        }
        if (listen(rctx->priv_lfd, 10) != 0) {
            DEBUG(0,("Unable to listen on socket '%s'\n", rctx->priv_sock_name));
            goto failed;
        }

        rctx->priv_lfde = tevent_add_fd(rctx->ev, rctx, rctx->priv_lfd,
                                   TEVENT_FD_READ, accept_priv_fd_handler, rctx);
        if (!rctx->priv_lfde) {
            DEBUG(0, ("Failed to queue handler on privileged pipe\n"));
            goto failed;
        }
    }

    /* we want default permissions on created files to be very strict,
       so set our umask to 0177 */
    umask(0177);
    return EOK;

failed:
    /* we want default permissions on created files to be very strict,
       so set our umask to 0177 */
    umask(0177);
    close(rctx->lfd);
    close(rctx->priv_lfd);
    return EIO;
}

int sss_names_init(struct resp_ctx *rctx)
{
    struct sss_names_ctx *ctx;
    const char *errstr;
    int errval;
    int errpos;
    int ret;

    ctx = talloc_zero(rctx, struct sss_names_ctx);
    if (!ctx) return ENOMEM;

    ret = confdb_get_string(rctx->cdb, ctx, NAMES_CONFIG,
                            "re-expression", NULL, &ctx->re_pattern);
    if (ret != EOK) goto done;

    if (!ctx->re_pattern) {
        ctx->re_pattern = talloc_strdup(ctx,
                                "(?<name>[^@]+)@?(?<domain>[^@]*$)");
        if (!ctx->re_pattern) {
            ret = ENOMEM;
            goto done;
        }
    }

    ret = confdb_get_string(rctx->cdb, ctx, NAMES_CONFIG,
                            "full-name-format", NULL, &ctx->fq_fmt);
    if (ret != EOK) goto done;

    if (!ctx->fq_fmt) {
        ctx->fq_fmt = talloc_strdup(ctx, "%1$s@%2$s");
        if (!ctx->fq_fmt) {
            ret = ENOMEM;
            goto done;
        }
    }

    ctx->re = pcre_compile2(ctx->re_pattern,
                            PCRE_DUPNAMES | PCRE_EXTENDED,
                            &errval, &errstr, &errpos, NULL);
    if (!ctx->re) {
        DEBUG(1, ("Invalid Regular Expression pattern at position %d."
                  " (Error: %d [%s])\n", errpos, errval, errstr));
        ret = EFAULT;
        goto done;
    }

    rctx->names = ctx;
    ret = EOK;

done:
    if (ret != EOK) {
        talloc_free(ctx);
    }
    return ret;
}

int sss_process_init(TALLOC_CTX *mem_ctx,
                     struct tevent_context *ev,
                     struct confdb_ctx *cdb,
                     struct sbus_method sss_sbus_methods[],
                     struct sss_cmd_table sss_cmds[],
                     const char *sss_pipe_name,
                     const char *sss_priv_pipe_name,
                     const char *confdb_service_path,
                     struct sbus_method dp_methods[],
                     struct resp_ctx **responder_ctx)
{
    struct resp_ctx *rctx;
    int ret;

    rctx = talloc_zero(mem_ctx, struct resp_ctx);
    if (!rctx) {
        DEBUG(0, ("fatal error initializing resp_ctx\n"));
        return ENOMEM;
    }
    rctx->ev = ev;
    rctx->cdb = cdb;
    rctx->sss_sbus_methods = sss_sbus_methods;
    rctx->sss_cmds = sss_cmds;
    rctx->sock_name = sss_pipe_name;
    rctx->priv_sock_name = sss_priv_pipe_name;
    rctx->confdb_service_path = confdb_service_path;
    rctx->dp_methods = dp_methods;

    ret = confdb_get_domains(rctx->cdb, rctx, &rctx->domains);
    if (ret != EOK) {
        DEBUG(0, ("fatal error setting up domain map\n"));
        return ret;
    }

    ret = sss_sbus_init(rctx);
    if (ret != EOK) {
        DEBUG(0, ("fatal error setting up message bus\n"));
        return ret;
    }

    ret = sss_dp_init(rctx, rctx->dp_methods);
    if (ret != EOK) {
        DEBUG(0, ("fatal error setting up backend connector\n"));
        return ret;
    }
    else if (!rctx->dp_ctx) {
        DEBUG(0, ("Data Provider is not yet available. Retrying.\n"));
        return EIO;
    }

    ret = sysdb_init(rctx, ev, cdb, NULL, &rctx->sysdb);
    if (ret != EOK) {
        DEBUG(0, ("fatal error initializing resp_ctx\n"));
        return ret;
    }

    ret = sss_names_init(rctx);
    if (ret != EOK) {
        DEBUG(0, ("fatal error initializing regex data\n"));
        return ret;
    }

    /* after all initializations we are ready to listen on our socket */
    ret = set_unix_socket(rctx);
    if (ret != EOK) {
        DEBUG(0, ("fatal error initializing socket\n"));
        return ret;
    }

    DEBUG(1, ("Responder Initialization complete\n"));

    *responder_ctx = rctx;
    return EOK;
}

int sss_parse_name(TALLOC_CTX *memctx,
                   struct sss_names_ctx *snctx,
                   const char *orig, char **domain, char **name)
{
    pcre *re = snctx->re;
    const char *result;
    int ovec[30];
    int origlen;
    int ret, strnum;

    origlen = strlen(orig);

    ret = pcre_exec(re, NULL, orig, origlen, 0, PCRE_NOTEMPTY, ovec, 30);
    if (ret < 0) {
        DEBUG(2, ("PCRE Matching error, %d\n", ret));
        return EINVAL;
    }

    if (ret == 0) {
        DEBUG(1, ("Too many matches, the pattern is invalid.\n"));
    }

    strnum = ret;

    result = NULL;
    ret = pcre_get_named_substring(re, orig, ovec, strnum, "name", &result);
    if (ret < 0  || !result) {
        DEBUG(2, ("Name not found!\n"));
        return EINVAL;
    }
    *name = talloc_strdup(memctx, result);
    pcre_free_substring(result);
    if (!*name) return ENOMEM;


    result = NULL;
    ret = pcre_get_named_substring(re, orig, ovec, strnum, "domain", &result);
    if (ret < 0  || !result) {
        DEBUG(4, ("Domain not provided!\n"));
        *domain = NULL;
    } else {
        /* ignore "" string */
        if (*result) {
            *domain = talloc_strdup(memctx, result);
            pcre_free_substring(result);
            if (!*domain) return ENOMEM;
        } else {
            pcre_free_substring(result);
            *domain = NULL;
        }
    }

    return EOK;
}