kernel - Incidental MPLOCK removal (non-performance)

[dragonfly.git] / sys / netgraph7 / ksocket / ng_ksocket.c

/*
 * ng_ksocket.c
 */

/*-
 * Copyright (c) 1996-1999 Whistle Communications, Inc.
 * All rights reserved.
 * 
 * Subject to the following obligations and disclaimer of warranty, use and
 * redistribution of this software, in source or object code forms, with or
 * without modifications are expressly permitted by Whistle Communications;
 * provided, however, that:
 * 1. Any and all reproductions of the source or object code must include the
 *    copyright notice above and the following disclaimer of warranties; and
 * 2. No rights are granted, in any manner or form, to use Whistle
 *    Communications, Inc. trademarks, including the mark "WHISTLE
 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
 *    such appears in the above copyright notice or in the software.
 * 
 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Author: Archie Cobbs <archie@freebsd.org>
 *
 * $FreeBSD: src/sys/netgraph/ng_ksocket.c,v 1.61 2008/03/07 21:12:56 mav Exp $
 * $Whistle: ng_ksocket.c,v 1.1 1999/11/16 20:04:40 archie Exp $
 */

/*
 * Kernel socket node type.  This node type is basically a kernel-mode
 * version of a socket... kindof like the reverse of the socket node type.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/ctype.h>
#include <sys/protosw.h>
#include <sys/errno.h>
#include <sys/socket.h>
#include <sys/socketops.h>
#include <sys/socketvar.h>
#include <sys/socketvar2.h>
#include <sys/thread2.h>
#include <sys/uio.h>
#include <sys/un.h>

#include <netgraph7/ng_message.h>
#include <netgraph7/netgraph.h>
#include <netgraph7/ng_parse.h>
#include "ng_ksocket.h"

#include <netinet/in.h>

#ifdef NG_SEPARATE_MALLOC
MALLOC_DEFINE(M_NETGRAPH_KSOCKET, "netgraph_ksock", "netgraph ksock node ");
#else
#define M_NETGRAPH_KSOCKET M_NETGRAPH
#endif

#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
#define SADATA_OFFSET   (OFFSETOF(struct sockaddr, sa_data))

/* Node private data */
struct ng_ksocket_private {
        node_p          node;
        hook_p          hook;
        struct socket   *so;
        int             fn_sent;        /* FN call on incoming event was sent */
        LIST_HEAD(, ng_ksocket_private) embryos;
        LIST_ENTRY(ng_ksocket_private)  siblings;
        u_int32_t       flags;
        u_int32_t       response_token;
        ng_ID_t         response_addr;
};
typedef struct ng_ksocket_private *priv_p;

/* Flags for priv_p */
#define KSF_CONNECTING  0x00000001      /* Waiting for connection complete */
#define KSF_ACCEPTING   0x00000002      /* Waiting for accept complete */
#define KSF_EOFSEEN     0x00000004      /* Have sent 0-length EOF mbuf */
#define KSF_CLONED      0x00000008      /* Cloned from an accepting socket */
#define KSF_EMBRYONIC   0x00000010      /* Cloned node with no hooks yet */

/* Netgraph node methods */
static ng_constructor_t ng_ksocket_constructor;
static ng_rcvmsg_t      ng_ksocket_rcvmsg;
static ng_shutdown_t    ng_ksocket_shutdown;
static ng_newhook_t     ng_ksocket_newhook;
static ng_rcvdata_t     ng_ksocket_rcvdata;
static ng_connect_t     ng_ksocket_connect;
static ng_disconnect_t  ng_ksocket_disconnect;

/* Alias structure */
struct ng_ksocket_alias {
        const char      *name;
        const int       value;
        const int       family;
};

/* Protocol family aliases */
static const struct ng_ksocket_alias ng_ksocket_families[] = {
        { "local",      PF_LOCAL        },
        { "inet",       PF_INET         },
        { "inet6",      PF_INET6        },
        { "atm",        PF_ATM          },
        { NULL,         -1              },
};

/* Socket type aliases */
static const struct ng_ksocket_alias ng_ksocket_types[] = {
        { "stream",     SOCK_STREAM     },
        { "dgram",      SOCK_DGRAM      },
        { "raw",        SOCK_RAW        },
        { "rdm",        SOCK_RDM        },
        { "seqpacket",  SOCK_SEQPACKET  },
        { NULL,         -1              },
};

/* Protocol aliases */
static const struct ng_ksocket_alias ng_ksocket_protos[] = {
        { "ip",         IPPROTO_IP,             PF_INET         },
        { "raw",        IPPROTO_RAW,            PF_INET         },
        { "icmp",       IPPROTO_ICMP,           PF_INET         },
        { "igmp",       IPPROTO_IGMP,           PF_INET         },
        { "tcp",        IPPROTO_TCP,            PF_INET         },
        { "udp",        IPPROTO_UDP,            PF_INET         },
        { "gre",        IPPROTO_GRE,            PF_INET         },
        { "esp",        IPPROTO_ESP,            PF_INET         },
        { "ah",         IPPROTO_AH,             PF_INET         },
        { "swipe",      IPPROTO_SWIPE,          PF_INET         },
        { "encap",      IPPROTO_ENCAP,          PF_INET         },
        { "divert",     IPPROTO_DIVERT,         PF_INET         },
        { "pim",        IPPROTO_PIM,            PF_INET         },
        { NULL,         -1                                      },
};

/* Helper functions */
static int      ng_ksocket_check_accept(priv_p);
static void     ng_ksocket_finish_accept(priv_p);
static void     ng_ksocket_incoming(struct socket *so, void *arg, int waitflag);
static int      ng_ksocket_parse(const struct ng_ksocket_alias *aliases,
                        const char *s, int family);
static void     ng_ksocket_incoming2(node_p node, hook_p hook,
                        void *arg1, int arg2);

/************************************************************************
                        STRUCT SOCKADDR PARSE TYPE
 ************************************************************************/

/* Get the length of the data portion of a generic struct sockaddr */
static int
ng_parse_generic_sockdata_getLength(const struct ng_parse_type *type,
        const u_char *start, const u_char *buf)
{
        const struct sockaddr *sa;

        sa = (const struct sockaddr *)(buf - SADATA_OFFSET);
        return (sa->sa_len < SADATA_OFFSET) ? 0 : sa->sa_len - SADATA_OFFSET;
}

/* Type for the variable length data portion of a generic struct sockaddr */
static const struct ng_parse_type ng_ksocket_generic_sockdata_type = {
        &ng_parse_bytearray_type,
        &ng_parse_generic_sockdata_getLength
};

/* Type for a generic struct sockaddr */
static const struct ng_parse_struct_field
    ng_parse_generic_sockaddr_type_fields[] = {
          { "len",      &ng_parse_uint8_type                    },
          { "family",   &ng_parse_uint8_type                    },
          { "data",     &ng_ksocket_generic_sockdata_type       },
          { NULL }
};
static const struct ng_parse_type ng_ksocket_generic_sockaddr_type = {
        &ng_parse_struct_type,
        &ng_parse_generic_sockaddr_type_fields
};

/* Convert a struct sockaddr from ASCII to binary.  If its a protocol
   family that we specially handle, do that, otherwise defer to the
   generic parse type ng_ksocket_generic_sockaddr_type. */
static int
ng_ksocket_sockaddr_parse(const struct ng_parse_type *type,
        const char *s, int *off, const u_char *const start,
        u_char *const buf, int *buflen)
{
        struct sockaddr *const sa = (struct sockaddr *)buf;
        enum ng_parse_token tok;
        char fambuf[32];
        int family, len;
        char *t;

        /* If next token is a left curly brace, use generic parse type */
        if ((tok = ng_parse_get_token(s, off, &len)) == T_LBRACE) {
                return (*ng_ksocket_generic_sockaddr_type.supertype->parse)
                    (&ng_ksocket_generic_sockaddr_type,
                    s, off, start, buf, buflen);
        }

        /* Get socket address family followed by a slash */
        while (isspace(s[*off]))
                (*off)++;
        if ((t = index(s + *off, '/')) == NULL)
                return (EINVAL);
        if ((len = t - (s + *off)) > sizeof(fambuf) - 1)
                return (EINVAL);
        strncpy(fambuf, s + *off, len);
        fambuf[len] = '\0';
        *off += len + 1;
        if ((family = ng_ksocket_parse(ng_ksocket_families, fambuf, 0)) == -1)
                return (EINVAL);

        /* Set family */
        if (*buflen < SADATA_OFFSET)
                return (ERANGE);
        sa->sa_family = family;

        /* Set family-specific data and length */
        switch (sa->sa_family) {
        case PF_LOCAL:          /* Get pathname */
            {
                const int pathoff = OFFSETOF(struct sockaddr_un, sun_path);
                struct sockaddr_un *const sun = (struct sockaddr_un *)sa;
                int toklen, pathlen;
                char *path;

                if ((path = ng_get_string_token(s, off, &toklen, NULL)) == NULL)
                        return (EINVAL);
                pathlen = strlen(path);
                if (pathlen > SOCK_MAXADDRLEN) {
                        kfree(path, M_NETGRAPH_KSOCKET);
                        return (E2BIG);
                }
                if (*buflen < pathoff + pathlen) {
                        kfree(path, M_NETGRAPH_KSOCKET);
                        return (ERANGE);
                }
                *off += toklen;
                bcopy(path, sun->sun_path, pathlen);
                sun->sun_len = pathoff + pathlen;
                kfree(path, M_NETGRAPH_KSOCKET);
                break;
            }

        case PF_INET:           /* Get an IP address with optional port */
            {
                struct sockaddr_in *const sin = (struct sockaddr_in *)sa;
                int i;

                /* Parse this: <ipaddress>[:port] */
                for (i = 0; i < 4; i++) {
                        u_long val;
                        char *eptr;

                        val = strtoul(s + *off, &eptr, 10);
                        if (val > 0xff || eptr == s + *off)
                                return (EINVAL);
                        *off += (eptr - (s + *off));
                        ((u_char *)&sin->sin_addr)[i] = (u_char)val;
                        if (i < 3) {
                                if (s[*off] != '.')
                                        return (EINVAL);
                                (*off)++;
                        } else if (s[*off] == ':') {
                                (*off)++;
                                val = strtoul(s + *off, &eptr, 10);
                                if (val > 0xffff || eptr == s + *off)
                                        return (EINVAL);
                                *off += (eptr - (s + *off));
                                sin->sin_port = htons(val);
                        } else
                                sin->sin_port = 0;
                }
                bzero(&sin->sin_zero, sizeof(sin->sin_zero));
                sin->sin_len = sizeof(*sin);
                break;
            }

#if 0
        case PF_INET6:
#endif

        default:
                return (EINVAL);
        }

        /* Done */
        *buflen = sa->sa_len;
        return (0);
}

/* Convert a struct sockaddr from binary to ASCII */
static int
ng_ksocket_sockaddr_unparse(const struct ng_parse_type *type,
        const u_char *data, int *off, char *cbuf, int cbuflen)
{
        const struct sockaddr *sa = (const struct sockaddr *)(data + *off);
        int slen = 0;

        /* Output socket address, either in special or generic format */
        switch (sa->sa_family) {
        case PF_LOCAL:
            {
                const int pathoff = OFFSETOF(struct sockaddr_un, sun_path);
                const struct sockaddr_un *sun = (const struct sockaddr_un *)sa;
                const int pathlen = sun->sun_len - pathoff;
                char pathbuf[SOCK_MAXADDRLEN + 1];
                char *pathtoken;

                bcopy(sun->sun_path, pathbuf, pathlen);
                if ((pathtoken = ng_encode_string(pathbuf, pathlen)) == NULL)
                        return (ENOMEM);
                slen += ksnprintf(cbuf, cbuflen, "local/%s", pathtoken);
                kfree(pathtoken, M_NETGRAPH_KSOCKET);
                if (slen >= cbuflen)
                        return (ERANGE);
                *off += sun->sun_len;
                return (0);
            }

        case PF_INET:
            {
                const struct sockaddr_in *sin = (const struct sockaddr_in *)sa;

                slen += ksnprintf(cbuf, cbuflen, "inet/%d.%d.%d.%d",
                  ((const u_char *)&sin->sin_addr)[0],
                  ((const u_char *)&sin->sin_addr)[1],
                  ((const u_char *)&sin->sin_addr)[2],
                  ((const u_char *)&sin->sin_addr)[3]);
                if (sin->sin_port != 0) {
                        slen += ksnprintf(cbuf + strlen(cbuf),
                            cbuflen - strlen(cbuf), ":%d",
                            (u_int)ntohs(sin->sin_port));
                }
                if (slen >= cbuflen)
                        return (ERANGE);
                *off += sizeof(*sin);
                return(0);
            }

#if 0
        case PF_INET6:
#endif

        default:
                return (*ng_ksocket_generic_sockaddr_type.supertype->unparse)
                    (&ng_ksocket_generic_sockaddr_type,
                    data, off, cbuf, cbuflen);
        }
}

/* Parse type for struct sockaddr */
static const struct ng_parse_type ng_ksocket_sockaddr_type = {
        NULL,
        NULL,
        NULL,
        &ng_ksocket_sockaddr_parse,
        &ng_ksocket_sockaddr_unparse,
        NULL            /* no such thing as a default struct sockaddr */
};

/************************************************************************
                STRUCT NG_KSOCKET_SOCKOPT PARSE TYPE
 ************************************************************************/

/* Get length of the struct ng_ksocket_sockopt value field, which is the
   just the excess of the message argument portion over the length of
   the struct ng_ksocket_sockopt. */
static int
ng_parse_sockoptval_getLength(const struct ng_parse_type *type,
        const u_char *start, const u_char *buf)
{
        static const int offset = OFFSETOF(struct ng_ksocket_sockopt, value);
        const struct ng_ksocket_sockopt *sopt;
        const struct ng_mesg *msg;

        sopt = (const struct ng_ksocket_sockopt *)(buf - offset);
        msg = (const struct ng_mesg *)((const u_char *)sopt - sizeof(*msg));
        return msg->header.arglen - sizeof(*sopt);
}

/* Parse type for the option value part of a struct ng_ksocket_sockopt
   XXX Eventually, we should handle the different socket options specially.
   XXX This would avoid byte order problems, eg an integer value of 1 is
   XXX going to be "[1]" for little endian or "[3=1]" for big endian. */
static const struct ng_parse_type ng_ksocket_sockoptval_type = {
        &ng_parse_bytearray_type,
        &ng_parse_sockoptval_getLength
};

/* Parse type for struct ng_ksocket_sockopt */
static const struct ng_parse_struct_field ng_ksocket_sockopt_type_fields[]
        = NG_KSOCKET_SOCKOPT_INFO(&ng_ksocket_sockoptval_type);
static const struct ng_parse_type ng_ksocket_sockopt_type = {
        &ng_parse_struct_type,
        &ng_ksocket_sockopt_type_fields
};

/* Parse type for struct ng_ksocket_accept */
static const struct ng_parse_struct_field ng_ksocket_accept_type_fields[]
        = NGM_KSOCKET_ACCEPT_INFO;
static const struct ng_parse_type ng_ksocket_accept_type = {
        &ng_parse_struct_type,
        &ng_ksocket_accept_type_fields
};

/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_ksocket_cmds[] = {
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_BIND,
          "bind",
          &ng_ksocket_sockaddr_type,
          NULL
        },
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_LISTEN,
          "listen",
          &ng_parse_int32_type,
          NULL
        },
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_ACCEPT,
          "accept",
          NULL,
          &ng_ksocket_accept_type
        },
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_CONNECT,
          "connect",
          &ng_ksocket_sockaddr_type,
          &ng_parse_int32_type
        },
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_GETNAME,
          "getname",
          NULL,
          &ng_ksocket_sockaddr_type
        },
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_GETPEERNAME,
          "getpeername",
          NULL,
          &ng_ksocket_sockaddr_type
        },
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_SETOPT,
          "setopt",
          &ng_ksocket_sockopt_type,
          NULL
        },
        {
          NGM_KSOCKET_COOKIE,
          NGM_KSOCKET_GETOPT,
          "getopt",
          &ng_ksocket_sockopt_type,
          &ng_ksocket_sockopt_type
        },
        { 0 }
};

/* Node type descriptor */
static struct ng_type ng_ksocket_typestruct = {
        .version =      NG_ABI_VERSION,
        .name =         NG_KSOCKET_NODE_TYPE,
        .constructor =  ng_ksocket_constructor,
        .rcvmsg =       ng_ksocket_rcvmsg,
        .shutdown =     ng_ksocket_shutdown,
        .newhook =      ng_ksocket_newhook,
        .connect =      ng_ksocket_connect,
        .rcvdata =      ng_ksocket_rcvdata,
        .disconnect =   ng_ksocket_disconnect,
        .cmdlist =      ng_ksocket_cmds,
};
NETGRAPH_INIT(ksocket, &ng_ksocket_typestruct);

#define ERROUT(x)       do { error = (x); goto done; } while (0)

/************************************************************************
                        NETGRAPH NODE STUFF
 ************************************************************************/

/*
 * Node type constructor
 * The NODE part is assumed to be all set up.
 * There is already a reference to the node for us.
 */
static int
ng_ksocket_constructor(node_p node)
{
        priv_p priv;

        /* Allocate private structure */
        priv = kmalloc(sizeof(*priv), M_NETGRAPH,
                       M_WAITOK | M_NULLOK | M_ZERO);
        if (priv == NULL)
                return (ENOMEM);

        LIST_INIT(&priv->embryos);
        /* cross link them */
        priv->node = node;
        NG_NODE_SET_PRIVATE(node, priv);

        /* Done */
        return (0);
}

/*
 * Give our OK for a hook to be added. The hook name is of the
 * form "<family>/<type>/<proto>" where the three components may
 * be decimal numbers or else aliases from the above lists.
 *
 * Connecting a hook amounts to opening the socket.  Disconnecting
 * the hook closes the socket and destroys the node as well.
 */
static int
ng_ksocket_newhook(node_p node, hook_p hook, const char *name0)
{
        struct thread *td = curthread->td_proc ? curthread : &thread0;  /* XXX broken */
        const priv_p priv = NG_NODE_PRIVATE(node);
        char *s1, *s2, name[NG_HOOKSIZ];
        int family, type, protocol, error;

        /* Check if we're already connected */
        if (priv->hook != NULL)
                return (EISCONN);

        if (priv->flags & KSF_CLONED) {
                if (priv->flags & KSF_EMBRYONIC) {
                        /* Remove ourselves from our parent's embryo list */
                        LIST_REMOVE(priv, siblings);
                        priv->flags &= ~KSF_EMBRYONIC;
                }
        } else {
                /* Extract family, type, and protocol from hook name */
                ksnprintf(name, sizeof(name), "%s", name0);
                s1 = name;
                if ((s2 = index(s1, '/')) == NULL)
                        return (EINVAL);
                *s2++ = '\0';
                family = ng_ksocket_parse(ng_ksocket_families, s1, 0);
                if (family == -1)
                        return (EINVAL);
                s1 = s2;
                if ((s2 = index(s1, '/')) == NULL)
                        return (EINVAL);
                *s2++ = '\0';
                type = ng_ksocket_parse(ng_ksocket_types, s1, 0);
                if (type == -1)
                        return (EINVAL);
                s1 = s2;
                protocol = ng_ksocket_parse(ng_ksocket_protos, s1, family);
                if (protocol == -1)
                        return (EINVAL);

                /* Create the socket */
                error = socreate(family, &priv->so, type, protocol, td);
                if (error != 0)
                        return (error);

                /* XXX call soreserve() ? */

        }

        /* OK */
        priv->hook = hook;

        /*
         * In case of misconfigured routing a packet may reenter
         * ksocket node recursively. Decouple stack to avoid possible
         * panics about sleeping with locks held.
         */
        NG_HOOK_FORCE_QUEUE(hook);

        return(0);
}

static int
ng_ksocket_connect(hook_p hook)
{
        node_p node = NG_HOOK_NODE(hook);
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct socket *const so = priv->so;

        /* Add our hook for incoming data and other events */
        priv->so->so_upcallarg = (caddr_t)node;
        priv->so->so_upcall = ng_ksocket_incoming;
        atomic_set_int(&priv->so->so_rcv.ssb_flags, SSB_UPCALL);
        atomic_set_int(&priv->so->so_snd.ssb_flags, SSB_UPCALL);
        /*
         * --Original comment--
         * On a cloned socket we may have already received one or more
         * upcalls which we couldn't handle without a hook.  Handle
         * those now.
         * We cannot call the upcall function directly
         * from here, because until this function has returned our
         * hook isn't connected.
         *
         * ---meta comment for -current ---
         * XXX This is dubius.
         * Upcalls between the time that the hook was
         * first created and now (on another processesor) will
         * be earlier on the queue than the request to finalise the hook.
         * By the time the hook is finalised,
         * The queued upcalls will have happenned and the code
         * will have discarded them because of a lack of a hook.
         * (socket not open).
         *
         * This is a bad byproduct of the complicated way in which hooks
         * are now created (3 daisy chained async events).
         *
         * Since we are a netgraph operation 
         * We know that we hold a lock on this node. This forces the
         * request we make below to be queued rather than implemented
         * immediatly which will cause the upcall function to be called a bit
         * later.
         * However, as we will run any waiting queued operations immediatly
         * after doing this one, if we have not finalised the other end
         * of the hook, those queued operations will fail.
         */
        if (priv->flags & KSF_CLONED) {
                ng_send_fn(node, NULL, &ng_ksocket_incoming2, so, M_WAITOK | M_NULLOK);
        }

        return (0);
}

/*
 * Receive a control message
 */
static int
ng_ksocket_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
        struct thread *td = curthread->td_proc ? curthread : &thread0;  /* XXX broken */
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct socket *const so = priv->so;
        struct ng_mesg *resp = NULL;
        int error = 0;
        struct ng_mesg *msg;

        NGI_GET_MSG(item, msg);
        switch (msg->header.typecookie) {
        case NGM_KSOCKET_COOKIE:
                switch (msg->header.cmd) {
                case NGM_KSOCKET_BIND:
                    {
                        struct sockaddr *const sa
                            = (struct sockaddr *)msg->data;

                        /* Sanity check */
                        if (msg->header.arglen < SADATA_OFFSET
                            || msg->header.arglen < sa->sa_len)
                                ERROUT(EINVAL);
                        if (so == NULL)
                                ERROUT(ENXIO);

                        /* Bind */
                        error = sobind(so, sa, td);
                        break;
                    }
                case NGM_KSOCKET_LISTEN:
                    {
                        /* Sanity check */
                        if (msg->header.arglen != sizeof(int32_t))
                                ERROUT(EINVAL);
                        if (so == NULL)
                                ERROUT(ENXIO);

                        /* Listen */
                        error = solisten(so, *((int32_t *)msg->data), td);
                        break;
                    }

                case NGM_KSOCKET_ACCEPT:
                    {
                        /* Sanity check */
                        if (msg->header.arglen != 0)
                                ERROUT(EINVAL);
                        if (so == NULL)
                                ERROUT(ENXIO);

                        /* Make sure the socket is capable of accepting */
                        if (!(so->so_options & SO_ACCEPTCONN))
                                ERROUT(EINVAL);
                        if (priv->flags & KSF_ACCEPTING)
                                ERROUT(EALREADY);

                        error = ng_ksocket_check_accept(priv);
                        if (error != 0 && error != EWOULDBLOCK)
                                ERROUT(error);

                        /*
                         * If a connection is already complete, take it.
                         * Otherwise let the upcall function deal with
                         * the connection when it comes in.
                         */
                        priv->response_token = msg->header.token;
                        priv->response_addr = NGI_RETADDR(item);
                        if (error == 0) {
                                ng_ksocket_finish_accept(priv);
                        } else
                                priv->flags |= KSF_ACCEPTING;
                        break;
                    }

                case NGM_KSOCKET_CONNECT:
                    {
                        struct sockaddr *const sa
                            = (struct sockaddr *)msg->data;

                        /* Sanity check */
                        if (msg->header.arglen < SADATA_OFFSET
                            || msg->header.arglen < sa->sa_len)
                                ERROUT(EINVAL);
                        if (so == NULL)
                                ERROUT(ENXIO);

                        /* Do connect */
                        if ((so->so_state & SS_ISCONNECTING) != 0)
                                ERROUT(EALREADY);
                        if ((error = soconnect(so, sa, td, TRUE)) != 0) {
                                soclrstate(so, SS_ISCONNECTING);
                                ERROUT(error);
                        }
                        if ((so->so_state & SS_ISCONNECTING) != 0) {
                                /* We will notify the sender when we connect */
                                priv->response_token = msg->header.token;
                                priv->response_addr = NGI_RETADDR(item);
                                priv->flags |= KSF_CONNECTING;
                                ERROUT(EINPROGRESS);
                        }
                        break;
                    }

                case NGM_KSOCKET_GETNAME:
                case NGM_KSOCKET_GETPEERNAME:
                    {
                        struct sockaddr *sa = NULL;
                        int len;

                        /* Sanity check */
                        if (msg->header.arglen != 0)
                                ERROUT(EINVAL);
                        if (so == NULL)
                                ERROUT(ENXIO);

                        /* Get function */
                        if (msg->header.cmd == NGM_KSOCKET_GETPEERNAME) {
                                if ((so->so_state
                                    & (SS_ISCONNECTED|SS_ISCONFIRMING)) == 0) 
                                        ERROUT(ENOTCONN);
                                error = so_pru_peeraddr(so, &sa);
                        } else {
                                error = so_pru_sockaddr(so, &sa);
                        }

                        /* Get local or peer address */
                        if (error != 0)
                                goto bail;
                        len = (sa == NULL) ? 0 : sa->sa_len;

                        /* Send it back in a response */
                        NG_MKRESPONSE(resp, msg, len, M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                goto bail;
                        }
                        bcopy(sa, resp->data, len);

                bail:
                        /* Cleanup */
                        if (sa != NULL)
                                kfree(sa, M_SONAME);
                        break;
                    }

                case NGM_KSOCKET_GETOPT:
                    {
                        struct ng_ksocket_sockopt *ksopt = 
                            (struct ng_ksocket_sockopt *)msg->data;
                        struct sockopt sopt;

                        /* Sanity check */
                        if (msg->header.arglen != sizeof(*ksopt))
                                ERROUT(EINVAL);
                        if (so == NULL)
                                ERROUT(ENXIO);

                        /* Get response with room for option value */
                        NG_MKRESPONSE(resp, msg, sizeof(*ksopt)
                            + NG_KSOCKET_MAX_OPTLEN, M_WAITOK | M_NULLOK);
                        if (resp == NULL)
                                ERROUT(ENOMEM);

                        /* Get socket option, and put value in the response */
                        sopt.sopt_dir = SOPT_GET;
                        sopt.sopt_level = ksopt->level;
                        sopt.sopt_name = ksopt->name;
                        sopt.sopt_td = NULL;
                        sopt.sopt_valsize = NG_KSOCKET_MAX_OPTLEN;
                        ksopt = (struct ng_ksocket_sockopt *)resp->data;
                        sopt.sopt_val = ksopt->value;
                        if ((error = sogetopt(so, &sopt)) != 0) {
                                NG_FREE_MSG(resp);
                                break;
                        }

                        /* Set actual value length */
                        resp->header.arglen = sizeof(*ksopt)
                            + sopt.sopt_valsize;
                        break;
                    }

                case NGM_KSOCKET_SETOPT:
                    {
                        struct ng_ksocket_sockopt *const ksopt = 
                            (struct ng_ksocket_sockopt *)msg->data;
                        const int valsize = msg->header.arglen - sizeof(*ksopt);
                        struct sockopt sopt;

                        /* Sanity check */
                        if (valsize < 0)
                                ERROUT(EINVAL);
                        if (so == NULL)
                                ERROUT(ENXIO);

                        /* Set socket option */
                        sopt.sopt_dir = SOPT_SET;
                        sopt.sopt_level = ksopt->level;
                        sopt.sopt_name = ksopt->name;
                        sopt.sopt_val = ksopt->value;
                        sopt.sopt_valsize = valsize;
                        sopt.sopt_td = NULL;
                        error = sosetopt(so, &sopt);
                        break;
                    }

                default:
                        error = EINVAL;
                        break;
                }
                break;
        default:
                error = EINVAL;
                break;
        }
done:
        NG_RESPOND_MSG(error, node, item, resp);
        NG_FREE_MSG(msg);
        return (error);
}

/*
 * Receive incoming data on our hook.  Send it out the socket.
 */
static int
ng_ksocket_rcvdata(hook_p hook, item_p item)
{
        struct thread *td = curthread->td_proc ? curthread : &thread0;  /* XXX broken */
        const node_p node = NG_HOOK_NODE(hook);
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct socket *const so = priv->so;
        struct sockaddr *sa = NULL;
        int error;
        struct mbuf *m;
        struct sa_tag *stag;

        /* Extract data */
        NGI_GET_M(item, m);
        NG_FREE_ITEM(item);

        /*
         * Look if socket address is stored in packet tags.
         * If sockaddr is ours, or provided by a third party (zero id),
         * then we accept it.
         */
        if (((stag = (struct sa_tag *)m_tag_locate(m, NGM_KSOCKET_COOKIE,
            NG_KSOCKET_TAG_SOCKADDR, NULL)) != NULL) &&
            (stag->id == NG_NODE_ID(node) || stag->id == 0))
                sa = &stag->sa;

        /* Reset specific mbuf flags to prevent addressing problems. */
        m->m_flags &= ~(M_BCAST|M_MCAST);

        /* Send packet */
        error = sosend(so, sa, 0, m, 0, 0, td);

        return (error);
}

/*
 * Destroy node
 */
static int
ng_ksocket_shutdown(node_p node)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        priv_p embryo;

        /* Close our socket (if any) */
        if (priv->so != NULL) {
                atomic_clear_int(&priv->so->so_rcv.ssb_flags, SSB_UPCALL);
                atomic_clear_int(&priv->so->so_snd.ssb_flags, SSB_UPCALL);
                priv->so->so_upcall = NULL;
                soclose(priv->so, FNONBLOCK);
                priv->so = NULL;
        }

        /* If we are an embryo, take ourselves out of the parent's list */
        if (priv->flags & KSF_EMBRYONIC) {
                LIST_REMOVE(priv, siblings);
                priv->flags &= ~KSF_EMBRYONIC;
        }

        /* Remove any embryonic children we have */
        while (!LIST_EMPTY(&priv->embryos)) {
                embryo = LIST_FIRST(&priv->embryos);
                ng_rmnode_self(embryo->node);
        }

        /* Take down netgraph node */
        bzero(priv, sizeof(*priv));
        kfree(priv, M_NETGRAPH);
        NG_NODE_SET_PRIVATE(node, NULL);
        NG_NODE_UNREF(node);            /* let the node escape */
        return (0);
}

/*
 * Hook disconnection
 */
static int
ng_ksocket_disconnect(hook_p hook)
{
        KASSERT(NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0,
            ("%s: numhooks=%d?", __func__,
            NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook))));
        if (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))
                ng_rmnode_self(NG_HOOK_NODE(hook));
        return (0);
}

/************************************************************************
                        HELPER STUFF
 ************************************************************************/
/* 
 * You should not "just call" a netgraph node function from an external
 * asynchronous event. This is because in doing so you are ignoring the
 * locking on the netgraph nodes. Instead call your function via ng_send_fn().
 * This will call the function you chose, but will first do all the 
 * locking rigmarole. Your function MAY only be called at some distant future
 * time (several millisecs away) so don't give it any arguments
 * that may be revoked soon (e.g. on your stack).
 *
 * To decouple stack, we use queue version of ng_send_fn().
 */

static void
ng_ksocket_incoming(struct socket *so, void *arg, int waitflag)
{
        const node_p node = arg;
        const priv_p priv = NG_NODE_PRIVATE(node);
        int wait = ((waitflag & M_WAITOK) ? NG_WAITOK : 0) | NG_QUEUE;

        /*
         * Even if node is not locked, as soon as we are called, we assume
         * it exist and it's private area is valid. With some care we can
         * access it. Mark node that incoming event for it was sent to
         * avoid unneded queue trashing.
         */
        if (atomic_cmpset_int(&priv->fn_sent, 0, 1) &&
            ng_send_fn1(node, NULL, &ng_ksocket_incoming2, so, 0, wait)) {
                atomic_store_rel_int(&priv->fn_sent, 0);
        }
}


/*
 * When incoming data is appended to the socket, we get notified here.
 * This is also called whenever a significant event occurs for the socket.
 * Our original caller may have queued this even some time ago and 
 * we cannot trust that he even still exists. The node however is being
 * held with a reference by the queueing code and guarantied to be valid.
 */
static void
ng_ksocket_incoming2(node_p node, hook_p hook, void *arg1, int arg2)
{
        struct socket *so = arg1;
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct ng_mesg *response;
        int flags, error;

        crit_enter();

        /* so = priv->so; *//* XXX could have derived this like so */
        KASSERT(so == priv->so, ("%s: wrong socket", __func__));
        
        /* Allow next incoming event to be queued. */
        atomic_store_rel_int(&priv->fn_sent, 0);

        /* Check whether a pending connect operation has completed */
        if (priv->flags & KSF_CONNECTING) {
                if ((error = so->so_error) != 0) {
                        so->so_error = 0;
                        soclrstate(so, SS_ISCONNECTING);
                }
                if (!(so->so_state & SS_ISCONNECTING)) {
                        NG_MKMESSAGE(response, NGM_KSOCKET_COOKIE,
                            NGM_KSOCKET_CONNECT, sizeof(int32_t), M_WAITOK | M_NULLOK);
                        if (response != NULL) {
                                response->header.flags |= NGF_RESP;
                                response->header.token = priv->response_token;
                                *(int32_t *)response->data = error;
                                /* 
                                 * send an async "response" message
                                 * to the node that set us up
                                 * (if it still exists)
                                 */
                                NG_SEND_MSG_ID(error, node,
                                    response, priv->response_addr, 0);
                        }
                        priv->flags &= ~KSF_CONNECTING;
                }
        }

        /* Check whether a pending accept operation has completed */
        if (priv->flags & KSF_ACCEPTING) {
                error = ng_ksocket_check_accept(priv);
                if (error != EWOULDBLOCK)
                        priv->flags &= ~KSF_ACCEPTING;
                if (error == 0)
                        ng_ksocket_finish_accept(priv);
        }

        /*
         * If we don't have a hook, we must handle data events later.  When
         * the hook gets created and is connected, this upcall function
         * will be called again.
         */
        if (priv->hook == NULL) {
                crit_exit();
                return;
        }

        /* Read and forward available mbuf's */
        while (1) {
                struct sockaddr *sa = NULL;
                struct sockbuf sio;
                struct mbuf *n;

                sbinit(&sio, 1000000000);
                flags = MSG_DONTWAIT;

                /* Try to get next packet from socket */
                error = soreceive(so,
                                ((so->so_state & SS_ISCONNECTED) ? NULL : &sa),
                                NULL, &sio, NULL, &flags);
                if (error)
                        break;

                /* See if we got anything */
                if (sio.sb_mb == NULL) {
                        if (sa != NULL)
                                kfree(sa, M_SONAME);
                        break;
                }

                /*
                 * Don't trust the various socket layers to get the
                 * packet header and length correct (e.g. kern/15175).
                 *
                 * Also, do not trust that soreceive() will clear m_nextpkt
                 * for us (e.g. kern/84952, kern/82413).
                 */
                sio.sb_mb->m_pkthdr.csum_flags = 0;
                sio.sb_mb->m_pkthdr.len = 0;
                for (n = sio.sb_mb; n != NULL; n = n->m_next) {
                        sio.sb_mb->m_pkthdr.len += n->m_len;
                        n->m_nextpkt = NULL;
                }

                /* Put peer's socket address (if any) into a tag */
                if (sa != NULL) {
                        struct sa_tag   *stag;

                        stag = (struct sa_tag *)m_tag_alloc(NGM_KSOCKET_COOKIE,
                            NG_KSOCKET_TAG_SOCKADDR, sizeof(ng_ID_t) +
                            sa->sa_len, M_NOWAIT);
                        if (stag == NULL) {
                                kfree(sa, M_SONAME);
                                goto sendit;
                        }
                        bcopy(sa, &stag->sa, sa->sa_len);
                        kfree(sa, M_SONAME);
                        stag->id = NG_NODE_ID(node);
                        m_tag_prepend(sio.sb_mb, &stag->tag);
                }

sendit:         /* Forward data with optional peer sockaddr as packet tag */
                NG_SEND_DATA_ONLY(error, priv->hook, sio.sb_mb);
        }

        /*
         * If the peer has closed the connection, forward a 0-length mbuf
         * to indicate end-of-file.
         */
        if (so->so_state & SS_CANTRCVMORE && !(priv->flags & KSF_EOFSEEN)) {
                struct mbuf *m;

                MGETHDR(m, M_NOWAIT, MT_DATA);
                if (m != NULL) {
                        m->m_len = m->m_pkthdr.len = 0;
                        NG_SEND_DATA_ONLY(error, priv->hook, m);
                }
                priv->flags |= KSF_EOFSEEN;
        }
        crit_exit();
}

/*
 * Check for a completed incoming connection and return 0 if one is found.
 * Otherwise return the appropriate error code.
 */
static int
ng_ksocket_check_accept(priv_p priv)
{
        struct socket *const head = priv->so;
        int error;

        if ((error = head->so_error) != 0) {
                head->so_error = 0;
                return error;
        }
        /* Unlocked read. */
        if (TAILQ_EMPTY(&head->so_comp)) {
                if (head->so_state & SS_CANTRCVMORE)
                        return ECONNABORTED;
                return EWOULDBLOCK;
        }
        return 0;
}

/*
 * Handle the first completed incoming connection, assumed to be already
 * on the socket's so_comp queue.
 */
static void
ng_ksocket_finish_accept(priv_p priv)
{
        struct socket *const head = priv->so;
        struct socket *so;
        struct sockaddr *sa = NULL;
        struct ng_mesg *resp;
        struct ng_ksocket_accept *resp_data;
        node_p node;
        priv_p priv2;
        int len;
        int error;

        lwkt_getpooltoken(head);
        so = TAILQ_FIRST(&head->so_comp);
        if (so == NULL) {       /* Should never happen */
                lwkt_relpooltoken(head);
                return;
        }
        TAILQ_REMOVE(&head->so_comp, so, so_list);
        head->so_qlen--;
        soclrstate(so, SS_COMP);
        so->so_head = NULL;
        soreference(so);
        lwkt_relpooltoken(head);

        /* XXX KNOTE(&head->so_rcv.ssb_sel.si_note, 0); */

        soaccept(so, &sa);

        len = OFFSETOF(struct ng_ksocket_accept, addr);
        if (sa != NULL)
                len += sa->sa_len;

        NG_MKMESSAGE(resp, NGM_KSOCKET_COOKIE, NGM_KSOCKET_ACCEPT, len,
            M_WAITOK | M_NULLOK);
        if (resp == NULL) {
                soclose(so, FNONBLOCK);
                goto out;
        }
        resp->header.flags |= NGF_RESP;
        resp->header.token = priv->response_token;

        /* Clone a ksocket node to wrap the new socket */
        error = ng_make_node_common(&ng_ksocket_typestruct, &node);
        if (error) {
                kfree(resp, M_NETGRAPH);
                soclose(so, FNONBLOCK);
                goto out;
        }

        if (ng_ksocket_constructor(node) != 0) {
                NG_NODE_UNREF(node);
                kfree(resp, M_NETGRAPH);
                soclose(so, FNONBLOCK);
                goto out;
        }

        priv2 = NG_NODE_PRIVATE(node);
        priv2->so = so;
        priv2->flags |= KSF_CLONED | KSF_EMBRYONIC;

        /*
         * Insert the cloned node into a list of embryonic children
         * on the parent node.  When a hook is created on the cloned
         * node it will be removed from this list.  When the parent
         * is destroyed it will destroy any embryonic children it has.
         */
        LIST_INSERT_HEAD(&priv->embryos, priv2, siblings);

        so->so_upcallarg = (caddr_t)node;
        so->so_upcall = ng_ksocket_incoming;
        atomic_set_int(&priv->so->so_rcv.ssb_flags, SSB_UPCALL);
        atomic_set_int(&priv->so->so_snd.ssb_flags, SSB_UPCALL);

        /* Fill in the response data and send it or return it to the caller */
        resp_data = (struct ng_ksocket_accept *)resp->data;
        resp_data->nodeid = NG_NODE_ID(node);
        if (sa != NULL)
                bcopy(sa, &resp_data->addr, sa->sa_len);
        NG_SEND_MSG_ID(error, node, resp, priv->response_addr, 0);

out:
        if (sa != NULL)
                kfree(sa, M_SONAME);
}

/*
 * Parse out either an integer value or an alias.
 */
static int
ng_ksocket_parse(const struct ng_ksocket_alias *aliases,
        const char *s, int family)
{
        int k, val;
        char *eptr;

        /* Try aliases */
        for (k = 0; aliases[k].name != NULL; k++) {
                if (strcmp(s, aliases[k].name) == 0
                    && aliases[k].family == family)
                        return aliases[k].value;
        }

        /* Try parsing as a number */
        val = (int)strtoul(s, &eptr, 10);
        if (val < 0 || *eptr != '\0')
                return (-1);
        return (val);
}