/*
 * In-kernel rpcbind client supporting versions 2, 3, and 4 of the rpcbind
 * protocol
 *
 * Based on RFC 1833: "Binding Protocols for ONC RPC Version 2" and
 * RFC 3530: "Network File System (NFS) version 4 Protocol"
 *
 * Original: Gilles Quillard, Bull Open Source, 2005 <gilles.quillard@bull.net>
 * Updated: Chuck Lever, Oracle Corporation, 2007 <chuck.lever@oracle.com>
 *
 * Descended from net/sunrpc/pmap_clnt.c,
 *  Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/module.h>

#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/kernel.h>
#include <linux/errno.h>

#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/xprtsock.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY        RPCDBG_BIND
#endif

#define RPCBIND_PROGRAM         (100000u)
#define RPCBIND_PORT            (111u)

enum {
        RPCBPROC_NULL,
        RPCBPROC_SET,
        RPCBPROC_UNSET,
        RPCBPROC_GETPORT,
        RPCBPROC_GETADDR = 3,           /* alias for GETPORT */
        RPCBPROC_DUMP,
        RPCBPROC_CALLIT,
        RPCBPROC_BCAST = 5,             /* alias for CALLIT */
        RPCBPROC_GETTIME,
        RPCBPROC_UADDR2TADDR,
        RPCBPROC_TADDR2UADDR,
        RPCBPROC_GETVERSADDR,
        RPCBPROC_INDIRECT,
        RPCBPROC_GETADDRLIST,
        RPCBPROC_GETSTAT,
};

#define RPCB_HIGHPROC_2         RPCBPROC_CALLIT
#define RPCB_HIGHPROC_3         RPCBPROC_TADDR2UADDR
#define RPCB_HIGHPROC_4         RPCBPROC_GETSTAT

/*
 * r_addr
 *
 * Quoting RFC 3530, section 2.2:
 *
 * For TCP over IPv4 and for UDP over IPv4, the format of r_addr is the
 * US-ASCII string:
 *
 *      h1.h2.h3.h4.p1.p2
 *
 * The prefix, "h1.h2.h3.h4", is the standard textual form for
 * representing an IPv4 address, which is always four octets long.
 * Assuming big-endian ordering, h1, h2, h3, and h4, are respectively,
 * the first through fourth octets each converted to ASCII-decimal.
 * Assuming big-endian ordering, p1 and p2 are, respectively, the first
 * and second octets each converted to ASCII-decimal.  For example, if a
 * host, in big-endian order, has an address of 0x0A010307 and there is
 * a service listening on, in big endian order, port 0x020F (decimal
 * 527), then the complete universal address is "10.1.3.7.2.15".
 *
 * ...
 *
 * For TCP over IPv6 and for UDP over IPv6, the format of r_addr is the
 * US-ASCII string:
 *
 *      x1:x2:x3:x4:x5:x6:x7:x8.p1.p2
 *
 * The suffix "p1.p2" is the service port, and is computed the same way
 * as with universal addresses for TCP and UDP over IPv4.  The prefix,
 * "x1:x2:x3:x4:x5:x6:x7:x8", is the standard textual form for
 * representing an IPv6 address as defined in Section 2.2 of [RFC2373].
 * Additionally, the two alternative forms specified in Section 2.2 of
 * [RFC2373] are also acceptable.
 *
 * XXX: Currently this implementation does not explicitly convert the
 *      stored address to US-ASCII on non-ASCII systems.
 */
#define RPCB_MAXADDRLEN         (128u)

/*
 * r_owner
 *
 * The "owner" is allowed to unset a service in the rpcbind database.
 * We always use the following (arbitrary) fixed string.
 */
#define RPCB_OWNER_STRING       "rpcb"
#define RPCB_MAXOWNERLEN        sizeof(RPCB_OWNER_STRING)

static void                     rpcb_getport_done(struct rpc_task *, void *);
static struct rpc_program       rpcb_program;

struct rpcbind_args {
        struct rpc_xprt *       r_xprt;

        u32                     r_prog;
        u32                     r_vers;
        u32                     r_prot;
        unsigned short          r_port;
        char *                  r_netid;
        char                    r_addr[RPCB_MAXADDRLEN];
        char *                  r_owner;
};

static struct rpc_procinfo rpcb_procedures2[];
static struct rpc_procinfo rpcb_procedures3[];

struct rpcb_info {
        int                     rpc_vers;
        struct rpc_procinfo *   rpc_proc;
};

static struct rpcb_info rpcb_next_version[];
static struct rpcb_info rpcb_next_version6[];

static void rpcb_getport_prepare(struct rpc_task *task, void *calldata)
{
        struct rpcbind_args *map = calldata;
        struct rpc_xprt *xprt = map->r_xprt;
        struct rpc_message msg = {
                .rpc_proc       = rpcb_next_version[xprt->bind_index].rpc_proc,
                .rpc_argp       = map,
                .rpc_resp       = &map->r_port,
        };

        rpc_call_setup(task, &msg, 0);
}

static void rpcb_map_release(void *data)
{
        struct rpcbind_args *map = data;

        xprt_put(map->r_xprt);
        kfree(map);
}

static const struct rpc_call_ops rpcb_getport_ops = {
        .rpc_call_prepare       = rpcb_getport_prepare,
        .rpc_call_done          = rpcb_getport_done,
        .rpc_release            = rpcb_map_release,
};

static void rpcb_wake_rpcbind_waiters(struct rpc_xprt *xprt, int status)
{
        xprt_clear_binding(xprt);
        rpc_wake_up_status(&xprt->binding, status);
}

static struct rpc_clnt *rpcb_create(char *hostname, struct sockaddr *srvaddr,
                                        int proto, int version, int privileged)
{
        struct rpc_create_args args = {
                .protocol       = proto,
                .address        = srvaddr,
                .addrsize       = sizeof(struct sockaddr_in),
                .servername     = hostname,
                .program        = &rpcb_program,
                .version        = version,
                .authflavor     = RPC_AUTH_UNIX,
                .flags          = (RPC_CLNT_CREATE_NOPING |
                                   RPC_CLNT_CREATE_INTR),
        };

        switch (srvaddr->sa_family) {
        case AF_INET:
                ((struct sockaddr_in *)srvaddr)->sin_port = htons(RPCBIND_PORT);
                break;
        case AF_INET6:
                ((struct sockaddr_in6 *)srvaddr)->sin6_port = htons(RPCBIND_PORT);
                break;
        default:
                return NULL;
        }

        if (!privileged)
                args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
        return rpc_create(&args);
}

/**
 * rpcb_register - set or unset a port registration with the local rpcbind svc
 * @prog: RPC program number to bind
 * @vers: RPC version number to bind
 * @prot: transport protocol to use to make this request
 * @port: port value to register
 * @okay: result code
 *
 * port == 0 means unregister, port != 0 means register.
 *
 * This routine supports only rpcbind version 2.
 */
int rpcb_register(u32 prog, u32 vers, int prot, unsigned short port, int *okay)
{
        struct sockaddr_in sin = {
                .sin_family             = AF_INET,
                .sin_addr.s_addr        = htonl(INADDR_LOOPBACK),
        };
        struct rpcbind_args map = {
                .r_prog         = prog,
                .r_vers         = vers,
                .r_prot         = prot,
                .r_port         = port,
        };
        struct rpc_message msg = {
                .rpc_proc       = &rpcb_procedures2[port ?
                                        RPCBPROC_SET : RPCBPROC_UNSET],
                .rpc_argp       = &map,
                .rpc_resp       = okay,
        };
        struct rpc_clnt *rpcb_clnt;
        int error = 0;

        dprintk("RPC:       %sregistering (%u, %u, %d, %u) with local "
                        "rpcbind\n", (port ? "" : "un"),
                        prog, vers, prot, port);

        rpcb_clnt = rpcb_create("localhost", (struct sockaddr *) &sin,
                                        XPRT_TRANSPORT_UDP, 2, 1);
        if (IS_ERR(rpcb_clnt))
                return PTR_ERR(rpcb_clnt);

        error = rpc_call_sync(rpcb_clnt, &msg, 0);

        rpc_shutdown_client(rpcb_clnt);
        if (error < 0)
                printk(KERN_WARNING "RPC: failed to contact local rpcbind "
                                "server (errno %d).\n", -error);
        dprintk("RPC:       registration status %d/%d\n", error, *okay);

        return error;
}

/**
 * rpcb_getport_sync - obtain the port for an RPC service on a given host
 * @sin: address of remote peer
 * @prog: RPC program number to bind
 * @vers: RPC version number to bind
 * @prot: transport protocol to use to make this request
 *
 * Called from outside the RPC client in a synchronous task context.
 * Uses default timeout parameters specified by underlying transport.
 *
 * XXX: Needs to support IPv6, and rpcbind versions 3 and 4
 */
int rpcb_getport_sync(struct sockaddr_in *sin, __u32 prog,
                      __u32 vers, int prot)
{
        struct rpcbind_args map = {
                .r_prog         = prog,
                .r_vers         = vers,
                .r_prot         = prot,
                .r_port         = 0,
        };
        struct rpc_message msg = {
                .rpc_proc       = &rpcb_procedures2[RPCBPROC_GETPORT],
                .rpc_argp       = &map,
                .rpc_resp       = &map.r_port,
        };
        struct rpc_clnt *rpcb_clnt;
        char hostname[40];
        int status;

        dprintk("RPC:       %s(" NIPQUAD_FMT ", %u, %u, %d)\n",
                __FUNCTION__, NIPQUAD(sin->sin_addr.s_addr), prog, vers, prot);

        sprintf(hostname, NIPQUAD_FMT, NIPQUAD(sin->sin_addr.s_addr));
        rpcb_clnt = rpcb_create(hostname, (struct sockaddr *)sin, prot, 2, 0);
        if (IS_ERR(rpcb_clnt))
                return PTR_ERR(rpcb_clnt);

        status = rpc_call_sync(rpcb_clnt, &msg, 0);
        rpc_shutdown_client(rpcb_clnt);

        if (status >= 0) {
                if (map.r_port != 0)
                        return map.r_port;
                status = -EACCES;
        }
        return status;
}
EXPORT_SYMBOL_GPL(rpcb_getport_sync);

/**
 * rpcb_getport_async - obtain the port for a given RPC service on a given host
 * @task: task that is waiting for portmapper request
 *
 * This one can be called for an ongoing RPC request, and can be used in
 * an async (rpciod) context.
 */
void rpcb_getport_async(struct rpc_task *task)
{
        struct rpc_clnt *clnt = task->tk_client;
        int bind_version;
        struct rpc_xprt *xprt = task->tk_xprt;
        struct rpc_clnt *rpcb_clnt;
        static struct rpcbind_args *map;
        struct rpc_task *child;
        struct sockaddr addr;
        int status;
        struct rpcb_info *info;

        dprintk("RPC: %5u %s(%s, %u, %u, %d)\n",
                task->tk_pid, __FUNCTION__,
                clnt->cl_server, clnt->cl_prog, clnt->cl_vers, xprt->prot);

        /* Autobind on cloned rpc clients is discouraged */
        BUG_ON(clnt->cl_parent != clnt);

        if (xprt_test_and_set_binding(xprt)) {
                status = -EAGAIN;       /* tell caller to check again */
                dprintk("RPC: %5u %s: waiting for another binder\n",
                        task->tk_pid, __FUNCTION__);
                goto bailout_nowake;
        }

        /* Put self on queue before sending rpcbind request, in case
         * rpcb_getport_done completes before we return from rpc_run_task */
        rpc_sleep_on(&xprt->binding, task, NULL, NULL);

        /* Someone else may have bound if we slept */
        if (xprt_bound(xprt)) {
                status = 0;
                dprintk("RPC: %5u %s: already bound\n",
                        task->tk_pid, __FUNCTION__);
                goto bailout_nofree;
        }

        rpc_peeraddr(clnt, (void *)&addr, sizeof(addr));

        /* Don't ever use rpcbind v2 for AF_INET6 requests */
        switch (addr.sa_family) {
        case AF_INET:
                info = rpcb_next_version;
                break;
        case AF_INET6:
                info = rpcb_next_version6;
                break;
        default:
                status = -EAFNOSUPPORT;
                dprintk("RPC: %5u %s: bad address family\n",
                                task->tk_pid, __FUNCTION__);
                goto bailout_nofree;
        }
        if (info[xprt->bind_index].rpc_proc == NULL) {
                xprt->bind_index = 0;
                status = -EPFNOSUPPORT;
                dprintk("RPC: %5u %s: no more getport versions available\n",
                        task->tk_pid, __FUNCTION__);
                goto bailout_nofree;
        }
        bind_version = info[xprt->bind_index].rpc_vers;

        dprintk("RPC: %5u %s: trying rpcbind version %u\n",
                task->tk_pid, __FUNCTION__, bind_version);

        rpcb_clnt = rpcb_create(clnt->cl_server, &addr, xprt->prot,
                                bind_version, 0);
        if (IS_ERR(rpcb_clnt)) {
                status = PTR_ERR(rpcb_clnt);
                dprintk("RPC: %5u %s: rpcb_create failed, error %ld\n",
                        task->tk_pid, __FUNCTION__, PTR_ERR(rpcb_clnt));
                goto bailout_nofree;
        }

        map = kzalloc(sizeof(struct rpcbind_args), GFP_ATOMIC);
        if (!map) {
                status = -ENOMEM;
                dprintk("RPC: %5u %s: no memory available\n",
                        task->tk_pid, __FUNCTION__);
                goto bailout_nofree;
        }
        map->r_prog = clnt->cl_prog;
        map->r_vers = clnt->cl_vers;
        map->r_prot = xprt->prot;
        map->r_port = 0;
        map->r_xprt = xprt_get(xprt);
        map->r_netid = rpc_peeraddr2str(clnt, RPC_DISPLAY_NETID);
        memcpy(map->r_addr,
               rpc_peeraddr2str(rpcb_clnt, RPC_DISPLAY_UNIVERSAL_ADDR),
               sizeof(map->r_addr));
        map->r_owner = RPCB_OWNER_STRING;       /* ignored for GETADDR */

        child = rpc_run_task(rpcb_clnt, RPC_TASK_ASYNC, &rpcb_getport_ops, map);
        rpc_release_client(rpcb_clnt);
        if (IS_ERR(child)) {
                status = -EIO;
                dprintk("RPC: %5u %s: rpc_run_task failed\n",
                        task->tk_pid, __FUNCTION__);
                goto bailout;
        }
        rpc_put_task(child);

        task->tk_xprt->stat.bind_count++;
        return;

bailout:
        kfree(map);
        xprt_put(xprt);
bailout_nofree:
        rpcb_wake_rpcbind_waiters(xprt, status);
bailout_nowake:
        task->tk_status = status;
}
EXPORT_SYMBOL_GPL(rpcb_getport_async);

/*
 * Rpcbind child task calls this callback via tk_exit.
 */
static void rpcb_getport_done(struct rpc_task *child, void *data)
{
        struct rpcbind_args *map = data;
        struct rpc_xprt *xprt = map->r_xprt;
        int status = child->tk_status;

        /* Garbage reply: retry with a lesser rpcbind version */
        if (status == -EIO)
                status = -EPROTONOSUPPORT;

        /* rpcbind server doesn't support this rpcbind protocol version */
        if (status == -EPROTONOSUPPORT)
                xprt->bind_index++;

        if (status < 0) {
                /* rpcbind server not available on remote host? */
                xprt->ops->set_port(xprt, 0);
        } else if (map->r_port == 0) {
                /* Requested RPC service wasn't registered on remote host */
                xprt->ops->set_port(xprt, 0);
                status = -EACCES;
        } else {
                /* Succeeded */
                xprt->ops->set_port(xprt, map->r_port);
                xprt_set_bound(xprt);
                status = 0;
        }

        dprintk("RPC: %5u rpcb_getport_done(status %d, port %u)\n",
                        child->tk_pid, status, map->r_port);

        rpcb_wake_rpcbind_waiters(xprt, status);
}

static int rpcb_encode_mapping(struct rpc_rqst *req, __be32 *p,
                               struct rpcbind_args *rpcb)
{
        dprintk("RPC:       rpcb_encode_mapping(%u, %u, %d, %u)\n",
                        rpcb->r_prog, rpcb->r_vers, rpcb->r_prot, rpcb->r_port);
        *p++ = htonl(rpcb->r_prog);
        *p++ = htonl(rpcb->r_vers);
        *p++ = htonl(rpcb->r_prot);
        *p++ = htonl(rpcb->r_port);

        req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
        return 0;
}

static int rpcb_decode_getport(struct rpc_rqst *req, __be32 *p,
                               unsigned short *portp)
{
        *portp = (unsigned short) ntohl(*p++);
        dprintk("RPC:      rpcb_decode_getport result %u\n",
                        *portp);
        return 0;
}

static int rpcb_decode_set(struct rpc_rqst *req, __be32 *p,
                           unsigned int *boolp)
{
        *boolp = (unsigned int) ntohl(*p++);
        dprintk("RPC:      rpcb_decode_set result %u\n",
                        *boolp);
        return 0;
}

static int rpcb_encode_getaddr(struct rpc_rqst *req, __be32 *p,
                               struct rpcbind_args *rpcb)
{
        dprintk("RPC:       rpcb_encode_getaddr(%u, %u, %s)\n",
                        rpcb->r_prog, rpcb->r_vers, rpcb->r_addr);
        *p++ = htonl(rpcb->r_prog);
        *p++ = htonl(rpcb->r_vers);

        p = xdr_encode_string(p, rpcb->r_netid);
        p = xdr_encode_string(p, rpcb->r_addr);
        p = xdr_encode_string(p, rpcb->r_owner);

        req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);

        return 0;
}

static int rpcb_decode_getaddr(struct rpc_rqst *req, __be32 *p,
                               unsigned short *portp)
{
        char *addr;
        u32 addr_len;
        int c, i, f, first, val;

        *portp = 0;
        addr_len = ntohl(*p++);

        /*
         * Simple sanity check.  The smallest possible universal
         * address is an IPv4 address string containing 11 bytes.
         */
        if (addr_len < 11 || addr_len > RPCB_MAXADDRLEN)
                goto out_err;

        /*
         * Start at the end and walk backwards until the first dot
         * is encountered.  When the second dot is found, we have
         * both parts of the port number.
         */
        addr = (char *)p;
        val = 0;
        first = 1;
        f = 1;
        for (i = addr_len - 1; i > 0; i--) {
                c = addr[i];
                if (c >= '0' && c <= '9') {
                        val += (c - '0') * f;
                        f *= 10;
                } else if (c == '.') {
                        if (first) {
                                *portp = val;
                                val = first = 0;
                                f = 1;
                        } else {
                                *portp |= (val << 8);
                                break;
                        }
                }
        }

        /*
         * Simple sanity check.  If we never saw a dot in the reply,
         * then this was probably just garbage.
         */
        if (first)
                goto out_err;

        dprintk("RPC:       rpcb_decode_getaddr port=%u\n", *portp);
        return 0;

out_err:
        dprintk("RPC:       rpcbind server returned malformed reply\n");
        return -EIO;
}

#define RPCB_program_sz         (1u)
#define RPCB_version_sz         (1u)
#define RPCB_protocol_sz        (1u)
#define RPCB_port_sz            (1u)
#define RPCB_boolean_sz         (1u)

#define RPCB_netid_sz           (1+XDR_QUADLEN(RPCBIND_MAXNETIDLEN))
#define RPCB_addr_sz            (1+XDR_QUADLEN(RPCB_MAXADDRLEN))
#define RPCB_ownerstring_sz     (1+XDR_QUADLEN(RPCB_MAXOWNERLEN))

#define RPCB_mappingargs_sz     RPCB_program_sz+RPCB_version_sz+        \
                                RPCB_protocol_sz+RPCB_port_sz
#define RPCB_getaddrargs_sz     RPCB_program_sz+RPCB_version_sz+        \
                                RPCB_netid_sz+RPCB_addr_sz+             \
                                RPCB_ownerstring_sz

#define RPCB_setres_sz          RPCB_boolean_sz
#define RPCB_getportres_sz      RPCB_port_sz

/*
 * Note that RFC 1833 does not put any size restrictions on the
 * address string returned by the remote rpcbind database.
 */
#define RPCB_getaddrres_sz      RPCB_addr_sz

#define PROC(proc, argtype, restype)                                    \
        [RPCBPROC_##proc] = {                                           \
                .p_proc         = RPCBPROC_##proc,                      \
                .p_encode       = (kxdrproc_t) rpcb_encode_##argtype,   \
                .p_decode       = (kxdrproc_t) rpcb_decode_##restype,   \
                .p_arglen       = RPCB_##argtype##args_sz,              \
                .p_replen       = RPCB_##restype##res_sz,               \
                .p_statidx      = RPCBPROC_##proc,                      \
                .p_timer        = 0,                                    \
                .p_name         = #proc,                                \
        }

/*
 * Not all rpcbind procedures described in RFC 1833 are implemented
 * since the Linux kernel RPC code requires only these.
 */
static struct rpc_procinfo rpcb_procedures2[] = {
        PROC(SET,               mapping,        set),
        PROC(UNSET,             mapping,        set),
        PROC(GETADDR,           mapping,        getport),
};

static struct rpc_procinfo rpcb_procedures3[] = {
        PROC(SET,               mapping,        set),
        PROC(UNSET,             mapping,        set),
        PROC(GETADDR,           getaddr,        getaddr),
};

static struct rpc_procinfo rpcb_procedures4[] = {
        PROC(SET,               mapping,        set),
        PROC(UNSET,             mapping,        set),
        PROC(GETVERSADDR,       getaddr,        getaddr),
};

static struct rpcb_info rpcb_next_version[] = {
#ifdef CONFIG_SUNRPC_BIND34
        { 4, &rpcb_procedures4[RPCBPROC_GETVERSADDR] },
        { 3, &rpcb_procedures3[RPCBPROC_GETADDR] },
#endif
        { 2, &rpcb_procedures2[RPCBPROC_GETPORT] },
        { 0, NULL },
};

static struct rpcb_info rpcb_next_version6[] = {
#ifdef CONFIG_SUNRPC_BIND34
        { 4, &rpcb_procedures4[RPCBPROC_GETVERSADDR] },
        { 3, &rpcb_procedures3[RPCBPROC_GETADDR] },
#endif
        { 0, NULL },
};

static struct rpc_version rpcb_version2 = {
        .number         = 2,
        .nrprocs        = RPCB_HIGHPROC_2,
        .procs          = rpcb_procedures2
};

static struct rpc_version rpcb_version3 = {
        .number         = 3,
        .nrprocs        = RPCB_HIGHPROC_3,
        .procs          = rpcb_procedures3
};

static struct rpc_version rpcb_version4 = {
        .number         = 4,
        .nrprocs        = RPCB_HIGHPROC_4,
        .procs          = rpcb_procedures4
};

static struct rpc_version *rpcb_version[] = {
        NULL,
        NULL,
        &rpcb_version2,
        &rpcb_version3,
        &rpcb_version4
};

static struct rpc_stat rpcb_stats;

static struct rpc_program rpcb_program = {
        .name           = "rpcbind",
        .number         = RPCBIND_PROGRAM,
        .nrvers         = ARRAY_SIZE(rpcb_version),
        .version        = rpcb_version,
        .stats          = &rpcb_stats,
};