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freebsd-skq/usr.sbin/ppp/datalink.h
brian 659744dd68 Rewrite the link descriptor transfer code in MP mode. 
Previously, ppp attempted to bind() to a local domain tcp socket
based on the peer authname & enddisc.  If it succeeded, it listen()ed
and became MP server.  If it failed, it connect()ed and became MP
client.  The server then select()ed on the descriptor, accept()ed
it and wrote its pid to it then read the link data & link file descriptor,
and finally sent an ack (``!'').  The client would read() the server
pid, transfer the link lock to that pid, send the link data & descriptor
and read the ack.  It would then close the descriptor and clean up.

There was a race between the bind() and listen() where someone could
attempt to connect() and fail.

This change removes the race.  Now ppp makes the RCVBUF big enough on a
socket descriptor and attempts to bind() to a local domain *udp* socket
(same name as before).  If it succeeds, it becomes MP server.  If it
fails, it sets the SNDBUF and connect()s, becoming MP client.  The server
select()s on the descriptor and recvmsg()s the message, insisting on at
least two descriptors (plus the link data).  It uses the second descriptor
to write() its pid then read()s an ack (``!'').  The client creates a
socketpair() and sendmsg()s the link data, link descriptor and one of
the socketpair descriptors.  It then read()s the server pid from the
other socketpair descriptor, transfers any locks and write()s an ack.

Now, there can be no race, and a connect() failure indicates a stale
socket file.

This also fixes MP ppp over ethernet, where the struct msghdr was being
misconstructed when transferring the control socket descriptor.

Also, if we fail to send the link, don't hang around in a ``session
owner'' state, just do the setsid() and fork() if it's required to
disown a tty.

UDP idea suggested by: Chris Bennet from Mindspring at FreeBSDCon
1999-11-25 02:47:04 +00:00

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/*-
* Copyright (c) 1998 Brian Somers <brian@Awfulhak.org>
* 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*
* $FreeBSD$
*/
#define DATALINK_CLOSED (0)
#define DATALINK_OPENING (1)
#define DATALINK_HANGUP (2)
#define DATALINK_DIAL (3)
#define DATALINK_CARRIER (4)
#define DATALINK_LOGOUT (5)
#define DATALINK_LOGIN (6)
#define DATALINK_READY (7)
#define DATALINK_LCP (8)
#define DATALINK_AUTH (9)
#define DATALINK_CBCP (10)
#define DATALINK_OPEN (11)
#define DATALINK_MAXNAME (20) /* Maximum datalink::name length */
/* How to close the link */
#define CLOSE_NORMAL 0
#define CLOSE_STAYDOWN 1
#define CLOSE_LCP 2
struct iovec;
struct prompt;
struct physical;
struct bundle;
struct datalink {
struct descriptor desc; /* We play either a physical or a chat */
int state; /* Our DATALINK_* state */
struct physical *physical; /* Our link */
struct chat chat; /* For bringing the link up & down */
unsigned stayonline : 1; /* stay online when LCP is closed ? */
struct {
unsigned run : 1; /* run scripts ? */
unsigned packetmode : 1; /* Go into packet mode after login ? */
} script;
struct {
struct {
char dial[SCRIPT_LEN];
char login[SCRIPT_LEN];
char logout[SCRIPT_LEN];
char hangup[SCRIPT_LEN];
} script; /* various chat scripts */
struct {
char list[SCRIPT_LEN]; /* Telephone Numbers */
} phone;
struct {
int max; /* initially try again this number of times */
int next_timeout; /* Redial next timeout value */
int inc; /* Increment timeout by `inc' each time read */
int maxinc; /* Maximum number of increments */
int timeout; /* Redial timeout value (end of phone list) */
} dial;
struct {
int max; /* initially try again this number of times */
int timeout; /* Timeout before reconnect on carrier loss */
} reconnect;
struct callback callback; /* Direction depends on physical type */
struct cbcpcfg cbcp; /* Direction depends on phys type & callback */
} cfg; /* All our config data is in here */
struct {
char list[SCRIPT_LEN]; /* copy of cfg.list for strsep() */
char *next; /* Next phone from the list */
char *alt; /* Alternate (after fail) phone from the list */
const char *chosen; /* Chosen phone number after DIAL */
} phone;
struct cbcp cbcp;
struct {
struct pppTimer timer; /* For timing between close & open */
int tries; /* currently try again this number of times */
int incs; /* # times our timeout has been incremented */
} dial;
unsigned reconnect_tries; /* currently try again this number of times */
char *name; /* Our name */
struct peerid peer; /* Peer identification */
struct fsm_parent fsmp; /* Our callback functions */
const struct fsm_parent *parent; /* Our parent */
struct authinfo pap; /* Authentication using pap */
struct chap chap; /* Authentication using chap */
struct mp_link mp; /* multilink data */
struct bundle *bundle; /* for the moment */
struct datalink *next; /* Next in the list */
};
#define descriptor2datalink(d) \
((d)->type == DATALINK_DESCRIPTOR ? (struct datalink *)(d) : NULL)
extern struct datalink *datalink_Create(const char *name, struct bundle *, int);
extern struct datalink *datalink_Clone(struct datalink *, const char *);
extern struct datalink *iov2datalink(struct bundle *, struct iovec *, int *,
int, int, int *, int *);
extern int datalink2iov(struct datalink *, struct iovec *, int *, int, int *,
int *);
extern struct datalink *datalink_Destroy(struct datalink *);
extern void datalink_GotAuthname(struct datalink *, const char *);
extern void datalink_Up(struct datalink *, int, int);
extern void datalink_Close(struct datalink *, int);
extern void datalink_Down(struct datalink *, int);
extern void datalink_StayDown(struct datalink *);
extern void datalink_DontHangup(struct datalink *);
extern void datalink_AuthOk(struct datalink *);
extern void datalink_AuthNotOk(struct datalink *);
extern void datalink_NCPUp(struct datalink *);
extern void datalink_CBCPComplete(struct datalink *);
extern void datalink_CBCPFailed(struct datalink *);
extern int datalink_Show(struct cmdargs const *);
extern int datalink_SetRedial(struct cmdargs const *);
extern int datalink_SetReconnect(struct cmdargs const *);
extern const char *datalink_State(struct datalink *);
extern void datalink_Rename(struct datalink *, const char *);
extern char *datalink_NextName(struct datalink *);
extern int datalink_RemoveFromSet(struct datalink *, fd_set *, fd_set *,
fd_set *);
extern int datalink_SetMode(struct datalink *, int);
extern int datalink_GetDialTimeout(struct datalink *);
extern const char *datalink_ChoosePhoneNumber(struct datalink *);
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