freebsd-skq/share/man/man4/ng_pppoe.4

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.\" Author: Archie Cobbs <archie@FreeBSD.org>
.\"
.\" $FreeBSD$
.\" $Whistle: ng_pppoe.8,v 1.1 1999/01/25 23:46:27 archie Exp $
.\"
.Dd October 28, 1999
.Dt NG_PPPOE 4
.Os
.Sh NAME
.Nm ng_pppoe
.Nd RFC 2516 PPPoE protocol netgraph node type
.Sh SYNOPSIS
.In net/ethernet.h
.In netgraph/ng_pppoe.h
.Sh DESCRIPTION
The
.Nm pppoe
node type performs the PPPoE protocol.
It is used in conjunction with the
.Xr netgraph 4
extensions to the Ethernet framework to divert and inject Ethernet packets
to and from a PPP agent (which is not specified).
.Pp
The
.Dv NGM_PPPOE_GET_STATUS
control message can be used at any time to query the current status
of the PPPoE module.
The only statistics presently available are the
total packet counts for input and output.
This node does not yet support
the
.Dv NGM_TEXT_STATUS
control message.
.Sh HOOKS
This node type supports the following hooks:
.Pp
.Bl -tag -width foobarbaz
.It Dv ethernet
The hook that should normally be connected to an Ethernet node.
.It Dv debug
Presently no use.
.It Dv [unspecified]
Any other name is assumed to be a session hook that will be connected to
a PPP client agent, or a PPP server agent.
.El
.Sh CONTROL MESSAGES
This node type supports the generic control messages, plus the following:
.Bl -tag -width foo
.It Dv NGM_PPPOE_GET_STATUS
This command returns status information in a
.Dv "struct ngpppoestat" :
.Bd -literal -offset 4n
struct ngpppoestat {
    u_int   packets_in;     /* packets in from Ethernet */
    u_int   packets_out;    /* packets out towards Ethernet */
};
.Ed
.It Dv NGM_TEXT_STATUS
This generic message returns is a human-readable version of the node status.
(not yet)
.It Dv NGM_PPPOE_CONNECT
Tell a nominated newly created hook that it's session should enter
the state machine in a manner to become a client.
It must be newly created and
a service name can be given as an argument.
It is legal to specify a zero length service name.
This is common on some DSL setups.
A session request packet will be broadcast on the Ethernet.
This command uses the
.Dv ngpppoe_init_data
structure shown below.
.It Dv NGM_PPPOE_LISTEN
Tell a nominated newly created hook that it's session should enter
the state machine in a manner to become a server listener.
The argument
given is the name of the service to listen on behalf of
a zero length service length will match all requests for service.
A matching service request
packet will be passed unmodified back to the process responsible
for starting the service.
It can then examine it and pass it on to
the session that is started to answer the request.
This command uses the
.Dv ngpppoe_init_data
structure shown below.
.It Dv NGM_PPPOE_OFFER
Tell a nominated newly created hook that it's session should enter
the state machine in a manner to become a server.
The argument given is the name of the service to offer.
A zero length service
is legal.
The State machine will progress to a state where it will await
a request packet to be forwarded to it from  the startup server,
which in turn probably received it from a LISTEN mode hook ( see above).
This is so
that information that is required for the session that is embedded in
the original session request packet, is made available to the state machine
that eventually answers the request.
When the Session request packet is
received, the session negotiation will proceed.
This command uses the
.Dv ngpppoe_init_data
structure shown below.
.Pp
The three commands above use a common data structure:
.Bd -literal -offset 4n
struct ngpppoe_init_data {
    char       hook[NG_HOOKSIZ];       /* hook to monitor on */
    u_int16_t  data_len;               /* service name length */
    char       data[0];                /* init data goes here */
};
.Ed
.It Dv NGM_PPPOE_SUCCESS
This command is sent to the node that started this session with one of the
above messages, and reports a state change.
This message reports successful Session negotiation.
It uses the structure shown below, and
reports back the hook name corresponding to the successful session.
.It Dv NGM_NGM_PPPOE_FAIL
This command is sent to the node that started this session with one of the
above messages, and reports a state change.
This message reports failed Session negotiation.
It uses the structure shown below, and
reports back the hook name corresponding to the failed session.
The hook will probably have been removed immediately after sending this message
.It Dv NGM_NGM_PPPOE_CLOSE
This command is sent to the node that started this session with one of the
above messages, and reports a state change.
This message reports a request to close a session.
It uses the structure shown below, and
reports back the hook name corresponding to the closed session.
The hook will probably have been removed immediately after sending this
message.
At present this message is not yet used and a 'failed' message
will be received at closure instead.
.It Dv NGM_PPPOE_ACNAME
This command is sent to the node that started this session with one of the
above messages, and reports the Access Concentrator Name.
.El
.Pp
The four commands above use a common data structure:
.Bd -literal -offset 4n
struct ngpppoe_sts {
    char    hook[NG_HOOKSIZ];    /* hook associated with event session */
};
.Ed
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message, when all session have been disconnected or when the
.Dv ethernet
hook is disconnected.
.Sh SYSCTL VARIABLES
The variable
.Va net.graph.nonstandard_pppoe
controls certain aspects of
.Nm
operation.
Its default value of \-1 corresponds to standard mode
and should suit nearly all purposes.
A value of 1 will turn on compatibility with some particularly
broken PPPoE implementations using nonstandard "ethertypes"
in PPPoE packets.
When in this mode, your PPPoE node will be unable to communicate
with standard nodes.
A value of 0 is deprecated.
It was intended to turn on autodetection of the proper mode.
.Bf -emphasis
It will make your entire PPPoE network vulnerable
to a denial-of-service attack,
therefore its use is strongly discouraged.
.Ef
.Sh EXAMPLES
The following code uses
.Dv libnetgraph
to set up a
.Nm
node and connect it to both a socket node and an Ethernet node.
It can handle the case of when a
.Nm
node is already attached to the Ethernet.
It then starts a client session.
.Bd -literal
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <sysexits.h>
#include <errno.h>
#include <err.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <net/ethernet.h>

#include <netgraph.h>
#include <netgraph/ng_ether.h>
#include <netgraph/ng_pppoe.h>
#include <netgraph/ng_socket.h>
static int setup(char *ethername, char *service, char *sessname,
				int *dfd, int *cfd);

int
main()
{
	int  fd1, fd2;
	setup("xl0", NULL, "fred", &fd1, &fd2);
	sleep (30);
}

static int
setup(char *ethername, char *service, char *sessname,
			int *dfd, int *cfd)
{
	struct ngm_connect ngc;	/* connect */
	struct ngm_mkpeer mkp;	/* mkpeer */
	/******** nodeinfo stuff **********/
	u_char          rbuf[2 * 1024];
	struct ng_mesg *const resp = (struct ng_mesg *) rbuf;
	struct hooklist *const hlist
			= (struct hooklist *) resp->data;
	struct nodeinfo *const ninfo = &hlist->nodeinfo;
	int             ch, no_hooks = 0;
	struct linkinfo *link;
	struct nodeinfo *peer;
	/****message to connect PPPoE session*****/
	struct {
		struct ngpppoe_init_data idata;
		char            service[100];
	}               message;
	/********tracking our little graph ********/
	char            path[100];
	char            source_ID[NG_NODESIZ];
	char            pppoe_node_name[100];
	int             k;

	/*
	 * Create the data and control sockets
	 */
	if (NgMkSockNode(NULL, cfd, dfd) < 0) {
		return (errno);
	}
	/*
	 * find the ether node of the name requested by asking it for
	 * it's inquiry information.
	 */
	if (strlen(ethername) > 16)
		return (EINVAL);
	sprintf(path, "%s:", ethername);
	if (NgSendMsg(*cfd, path, NGM_GENERIC_COOKIE,
		      NGM_LISTHOOKS, NULL, 0) < 0) {
		return (errno);
	}
	/*
	 * the command was accepted so it exists. Await the reply (It's
	 * almost certainly already waiting).
	 */
	if (NgRecvMsg(*cfd, resp, sizeof(rbuf), NULL) < 0) {
		return (errno);
	}
	/**
	 * The following is available about the node:
	 * ninfo->name		(string)
	 * ninfo->type		(string)
	 * ninfo->id		(u_int32_t)
	 * ninfo->hooks		(u_int32_t) (count of hooks)
	 * check it is the correct type. and get it's ID for use
	 * with mkpeer later.
	 */
	if (strncmp(ninfo->type, NG_ETHER_NODE_TYPE,
		    strlen(NG_ETHER_NODE_TYPE)) != 0) {
		return (EPROTOTYPE);
	}
	sprintf(source_ID, "[%08x]:", ninfo->id);

	/*
	 * look for a hook already attached.
	 */
	for (k = 0; k < ninfo->hooks; k++) {
		/**
		 * The following are available about each hook.
		 * link->ourhook	(string)
		 * link->peerhook	(string)
		 * peer->name		(string)
		 * peer->type		(string)
		 * peer->id		(u_int32_t)
		 * peer->hooks		(u_int32_t)
		 */
		link = &hlist->link[k];
		peer = &hlist->link[k].nodeinfo;

		/* Ignore debug hooks */
		if (strcmp("debug", link->ourhook) == 0)
			continue;

		/* If the orphans hook is attached, use that */
		if (strcmp(NG_ETHER_HOOK_ORPHAN,
		    link->ourhook) == 0) {
			break;
		}
		/* the other option is the 'divert' hook */
		if (strcmp("NG_ETHER_HOOK_DIVERT",
		    link->ourhook) == 0) {
			break;
		}
	}

	/*
	 * See if we found a hook there.
	 */
	if (k < ninfo->hooks) {
		if (strcmp(peer->type, NG_PPPOE_NODE_TYPE) == 0) {
			/*
			 * If it's a type PPPoE, we skip making one
			 * ourself, but we continue, using
			 * the existing one.
			 */
			sprintf(pppoe_node_name, "[%08x]:", peer->id);
		} else {
			/*
			 * There is already someone hogging the data,
			 * return an error. Some day we'll try
			 * daisy-chaining..
			 */
			return (EBUSY);
		}
	} else {

		/*
		 * Try make a node of type PPPoE against node "ID"
		 * On hook NG_ETHER_HOOK_ORPHAN.
		 */
		snprintf(mkp.type, sizeof(mkp.type),
			 "%s", NG_PPPOE_NODE_TYPE);
		snprintf(mkp.ourhook, sizeof(mkp.ourhook),
			 "%s", NG_ETHER_HOOK_ORPHAN);
		snprintf(mkp.peerhook, sizeof(mkp.peerhook),
			 "%s", NG_PPPOE_HOOK_ETHERNET);
		/* Send message */
		if (NgSendMsg(*cfd, source_ID, NGM_GENERIC_COOKIE,
			      NGM_MKPEER, &mkp, sizeof(mkp)) < 0) {
			return (errno);
		}
		/*
		 * Work out a name for the new node.
		 */
		sprintf(pppoe_node_name, "%s:%s",
			source_ID, NG_ETHER_HOOK_ORPHAN);
	}
	/*
	 * We now have a PPPoE node attached to the Ethernet
	 * card. The Ethernet is addressed as ethername: The PPPoE
	 * node is addressed as pppoe_node_name: attach to it.
	 * Connect socket node to specified node Use the same hook
	 * name on both ends of the link.
	 */
	snprintf(ngc.path, sizeof(ngc.path), "%s", pppoe_node_name);
	snprintf(ngc.ourhook, sizeof(ngc.ourhook), "%s", sessname);
	snprintf(ngc.peerhook, sizeof(ngc.peerhook), "%s", sessname);

	if (NgSendMsg(*cfd, ".:", NGM_GENERIC_COOKIE,
		      NGM_CONNECT, &ngc, sizeof(ngc)) < 0) {
		return (errno);
	}
	/*
	 * Send it a message telling it to start up.
	 */
	bzero(&message, sizeof(message));
	snprintf(message.idata.hook, sizeof(message.idata.hook),
				"%s", sessname);
	if (service == NULL) {
		message.idata.data_len = 0;
	} else {
		snprintf(message.idata.data,
			 sizeof(message.idata.data), "%s", service);
		message.idata.data_len = strlen(service);
	}
	/* Tell session/hook to start up as a client */
	if (NgSendMsg(*cfd, ngc.path,
		      NGM_PPPOE_COOKIE, NGM_PPPOE_CONNECT, &message.idata,
		      sizeof(message.idata) + message.idata.data_len) < 0) {
		return (errno);
	}
	return (0);
}
.Ed
.Sh SEE ALSO
.Xr netgraph 3 ,
.Xr netgraph 4 ,
.Xr ng_ppp 4 ,
.Xr ng_socket 4 ,
.Xr ngctl 8
.Rs
.%A L. Mamakos
.%A K. Lidl
.%A J. Evarts
.%A D. Carrel
.%A D. Simone
.%A R. Wheeler
.%T "A Method for transmitting PPP over Ethernet (PPPoE)"
.%O RFC 2516
.Re
.Sh HISTORY
The
.Nm
node type was implemented in
.Fx 4.0 .
.Sh AUTHORS
.An Julian Elischer Aq julian@FreeBSD.org