/*      $NetBSD: yplib.c,v 1.46 2014/09/18 13:58:20 christos Exp $       */

/*
 * Copyright (c) 1992, 1993 Theo de Raadt <deraadt@fsa.ca>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: yplib.c,v 1.46 2014/09/18 13:58:20 christos Exp $");
#endif

#include "namespace.h"
#include "reentrant.h"

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/uio.h>

#include <arpa/nameser.h>

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <rpc/rpc.h>
#include <rpc/xdr.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>
#include "local.h"

#define BINDINGDIR      "/var/yp/binding"
#define YPBINDLOCK      "/var/run/ypbind.lock"

struct dom_binding *_ypbindlist;
char _yp_domain[MAXHOSTNAMELEN];

#define YPLIB_TIMEOUT           10
#define YPLIB_RPC_RETRIES       4

struct timeval _yplib_timeout = { YPLIB_TIMEOUT, 0 };
struct timeval _yplib_rpc_timeout = { YPLIB_TIMEOUT / YPLIB_RPC_RETRIES,
        1000000 * (YPLIB_TIMEOUT % YPLIB_RPC_RETRIES) / YPLIB_RPC_RETRIES };
int _yplib_nerrs = 5;
int _yplib_bindtries = 0;

#ifdef __weak_alias
__weak_alias(yp_bind, _yp_bind)
__weak_alias(yp_unbind, _yp_unbind)
__weak_alias(yp_get_default_domain, _yp_get_default_domain)
__weak_alias(yp_setbindtries, _yp_setbindtries)
#endif

#ifdef _REENTRANT
static  mutex_t                 _ypmutex = MUTEX_INITIALIZER;
#define YPLOCK()                mutex_lock(&_ypmutex)
#define YPUNLOCK()              mutex_unlock(&_ypmutex)
#else
#define YPLOCK()
#define YPUNLOCK()
#endif

int
yp_setbindtries(int ntries)
{
        int old_val = _yplib_bindtries;

        if (ntries >= 0)
                _yplib_bindtries = ntries;
        return old_val;
}

int
_yp_dobind(const char *dom, struct dom_binding **ypdb)
{
        static int      pid = -1;
        char            path[MAXPATHLEN];
        struct dom_binding *ysd, *ysd2;
        struct ypbind_resp ypbr;
        struct sockaddr_in clnt_sin;
        int             clnt_sock, fd, gpid;
        CLIENT         *client;
        int             new = 0;
        int             nerrs = 0;
        ssize_t         r;

        if (dom == NULL || *dom == '\0')
                return YPERR_BADARGS;

        /*
         * test if YP is running or not
         */
        if ((fd = open(YPBINDLOCK, O_RDONLY | O_CLOEXEC)) == -1)
                return YPERR_YPBIND;
        if (!(flock(fd, LOCK_EX | LOCK_NB) == -1 && errno == EWOULDBLOCK)) {
                (void)close(fd);
                return YPERR_YPBIND;
        }
        (void)close(fd);

        gpid = getpid();
        if (!(pid == -1 || pid == gpid)) {
                ysd = _ypbindlist;
                while (ysd) {
                        if (ysd->dom_client)
                                clnt_destroy(ysd->dom_client);
                        ysd2 = ysd->dom_pnext;
                        free(ysd);
                        ysd = ysd2;
                }
                _ypbindlist = NULL;
        }
        pid = gpid;

        if (ypdb != NULL)
                *ypdb = NULL;

        for (ysd = _ypbindlist; ysd; ysd = ysd->dom_pnext)
                if (strcmp(dom, ysd->dom_domain) == 0)
                        break;
        if (ysd == NULL) {
                if ((ysd = malloc(sizeof *ysd)) == NULL)
                        return YPERR_YPERR;
                (void)memset(ysd, 0, sizeof *ysd);
                ysd->dom_socket = -1;
                ysd->dom_vers = 0;
                new = 1;
        }
again:
        if (ysd->dom_vers == 0) {
                (void) snprintf(path, sizeof(path), "%s/%s.%d",
                                BINDINGDIR, dom, 2);
                if ((fd = open(path, O_RDONLY | O_CLOEXEC)) == -1) {
                        /*
                         * no binding file, YP is dead, or not yet fully
                         * alive.
                         */
                        goto trynet;
                }
                if (flock(fd, LOCK_EX | LOCK_NB) == -1 &&
                    errno == EWOULDBLOCK) {
                        struct iovec    iov[2];
                        struct ypbind_resp ybr;
                        u_short         ypb_port;
                        struct ypbind_binding *bn;

                        iov[0].iov_base = &ypb_port;
                        iov[0].iov_len = sizeof ypb_port;
                        iov[1].iov_base = &ybr;
                        iov[1].iov_len = sizeof ybr;

                        r = readv(fd, iov, 2);
                        if (r != (ssize_t)(iov[0].iov_len + iov[1].iov_len)) {
                                (void)close(fd);
                                ysd->dom_vers = -1;
                                goto again;
                        }
                        (void)memset(&ysd->dom_server_addr, 0,
                                     sizeof ysd->dom_server_addr);
                        ysd->dom_server_addr.sin_len =
                                sizeof(struct sockaddr_in);
                        ysd->dom_server_addr.sin_family = AF_INET;
                        bn = &ybr.ypbind_respbody.ypbind_bindinfo;
                        ysd->dom_server_addr.sin_port =
                                bn->ypbind_binding_port;
                                
                        ysd->dom_server_addr.sin_addr =
                                bn->ypbind_binding_addr;

                        ysd->dom_server_port = ysd->dom_server_addr.sin_port;
                        (void)close(fd);
                        goto gotit;
                } else {
                        /* no lock on binding file, YP is dead. */
                        (void)close(fd);
                        if (new)
                                free(ysd);
                        return YPERR_YPBIND;
                }
        }
trynet:
        if (ysd->dom_vers == -1 || ysd->dom_vers == 0) {
                struct ypbind_binding *bn;
                (void)memset(&clnt_sin, 0, sizeof clnt_sin);
                clnt_sin.sin_len = sizeof(struct sockaddr_in);
                clnt_sin.sin_family = AF_INET;
                clnt_sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);

                clnt_sock = RPC_ANYSOCK;
                client = clnttcp_create(&clnt_sin, YPBINDPROG, YPBINDVERS,
                                        &clnt_sock, 0, 0);
                if (client == NULL) {
                        clnt_pcreateerror("clnttcp_create");
                        if (new)
                                free(ysd);
                        return YPERR_YPBIND;
                }
                r = clnt_call(client, (rpcproc_t)YPBINDPROC_DOMAIN,
                    (xdrproc_t)xdr_ypdomain_wrap_string, &dom,
                    (xdrproc_t)xdr_ypbind_resp, &ypbr, _yplib_timeout);
                if (r != RPC_SUCCESS) {
                        if (_yplib_bindtries <= 0 && new == 0 &&
                            ++nerrs == _yplib_nerrs) {
                                nerrs = 0;
                                fprintf(stderr,
                    "YP server for domain %s not responding, still trying\n",
                                    dom);
                        }
                        else if (_yplib_bindtries > 0 &&
                                 ++nerrs == _yplib_bindtries) {
                                free(ysd);
                                return YPERR_YPBIND;
                        }
                        clnt_destroy(client);
                        ysd->dom_vers = -1;
                        goto again;
                }
                clnt_destroy(client);

                (void)memset(&ysd->dom_server_addr, 0, 
                             sizeof ysd->dom_server_addr);
                ysd->dom_server_addr.sin_len = sizeof(struct sockaddr_in);
                ysd->dom_server_addr.sin_family = AF_INET;
                bn = &ypbr.ypbind_respbody.ypbind_bindinfo;
                ysd->dom_server_addr.sin_port =
                        bn->ypbind_binding_port;
                ysd->dom_server_addr.sin_addr.s_addr =
                        bn->ypbind_binding_addr.s_addr;
                ysd->dom_server_port =
                        bn->ypbind_binding_port;
gotit:
                ysd->dom_vers = YPVERS;
                (void)strlcpy(ysd->dom_domain, dom, sizeof(ysd->dom_domain));
        }
        if (ysd->dom_client)
                clnt_destroy(ysd->dom_client);
        ysd->dom_socket = RPC_ANYSOCK;
        ysd->dom_client = clntudp_create(&ysd->dom_server_addr,
            YPPROG, YPVERS, _yplib_rpc_timeout, &ysd->dom_socket);
        if (ysd->dom_client == NULL) {
                clnt_pcreateerror("clntudp_create");
                ysd->dom_vers = -1;
                goto again;
        }
        if (fcntl(ysd->dom_socket, F_SETFD, FD_CLOEXEC) == -1)
                perror("fcntl: F_SETFD");

        if (new) {
                ysd->dom_pnext = _ypbindlist;
                _ypbindlist = ysd;
        }
        if (ypdb != NULL)
                *ypdb = ysd;
        return 0;
}

void
__yp_unbind(struct dom_binding *ypb)
{

        _DIAGASSERT(ypb != NULL);

        clnt_destroy(ypb->dom_client);
        ypb->dom_client = NULL;
        ypb->dom_socket = -1;
}

int
yp_bind(const char *dom)
{
        if (_yp_invalid_domain(dom))
                return YPERR_BADARGS;

        return _yp_dobind(dom, NULL);
}

void
yp_unbind(const char *dom)
{
        struct dom_binding *ypb, *ypbp;

        if (_yp_invalid_domain(dom))
                return;

        ypbp = NULL;
        for (ypb = _ypbindlist; ypb; ypb = ypb->dom_pnext) {
                if (strcmp(dom, ypb->dom_domain) == 0) {
                        clnt_destroy(ypb->dom_client);
                        if (ypbp)
                                ypbp->dom_pnext = ypb->dom_pnext;
                        else
                                _ypbindlist = ypb->dom_pnext;
                        free(ypb);
                        return;
                }
                ypbp = ypb;
        }
        return;
}

int
yp_get_default_domain(char **domp)
{
        if (domp == NULL)
                return YPERR_BADARGS;
        *domp = NULL;
        if (_yp_domain[0] == '\0')
                if (getdomainname(_yp_domain, sizeof _yp_domain))
                        return YPERR_NODOM;
        *domp = _yp_domain;
        return 0;
}

int
_yp_check(char **dom)
{
        char           *unused;
        int             good;

        YPLOCK();

        if (_yp_domain[0] == '\0')
                if (yp_get_default_domain(&unused)) {
                        good = 0;
                        goto done;
                }
        if (dom)
                *dom = _yp_domain;

        good = yp_bind(_yp_domain) == 0;
done:
        YPUNLOCK();
        return good;
}

/*
 * _yp_invalid_domain: check if given domainname isn't legal.
 * returns non-zero if invalid
 */
int
_yp_invalid_domain(const char *dom)
{
        if (dom == NULL || *dom == '\0')
                return 1;

        if (strlen(dom) > YPMAXDOMAIN)
                return 1;

        if (strchr(dom, '/') != NULL)
                return 1;

        return 0;
}