sys-linux.c

自己精简过的PPPD代码。在嵌入中应用可以更好的发挥。比原先的小了很多

/*
 * add_fd - add an fd to the set that wait_input waits for.
 */
void add_fd(int fd)
{
    if (fd >= FD_SETSIZE)
	fatal("internal error: file descriptor too large (%d)", fd);
    FD_SET(fd, &in_fds);
    if (fd > max_in_fd)
	max_in_fd = fd;
}

/*
 * remove_fd - remove an fd from the set that wait_input waits for.
 */
void remove_fd(int fd)
{
    FD_CLR(fd, &in_fds);
}


/********************************************************************
 *
 * read_packet - get a PPP packet from the serial device.
 */

int read_packet (unsigned char *buf)
{
    int len, nr;

    len = PPP_MRU + PPP_HDRLEN;
    if (new_style_driver) {
	*buf++ = PPP_ALLSTATIONS;
	*buf++ = PPP_UI;
	len -= 2;
    }
    nr = -1;
    if (ppp_fd >= 0) {
	nr = read(ppp_fd, buf, len);
	if (nr < 0 && errno != EWOULDBLOCK && errno != EAGAIN
	    && errno != EIO && errno != EINTR)
	    error("read: %m");
	if (nr < 0 && errno == ENXIO)
	    return 0;
    }
    if (nr < 0 && new_style_driver && ppp_dev_fd >= 0 && !bundle_eof) {
	/* N.B. we read ppp_fd first since LCP packets come in there. */
	nr = read(ppp_dev_fd, buf, len);
	if (nr < 0 && errno != EWOULDBLOCK && errno != EAGAIN
	    && errno != EIO && errno != EINTR)
	    error("read /dev/ppp: %m");
	if (nr < 0 && errno == ENXIO)
	    nr = 0;
	if (nr == 0 && doing_multilink) {
	    remove_fd(ppp_dev_fd);
	    bundle_eof = 1;
	}
    }
    if (new_style_driver && ppp_fd < 0 && ppp_dev_fd < 0)
	nr = 0;
    return (new_style_driver && nr > 0)? nr+2: nr;
}

/********************************************************************
 *
 * get_loop_output - get outgoing packets from the ppp device,
 * and detect when we want to bring the real link up.
 * Return value is 1 if we need to bring up the link, 0 otherwise.
 */
int
get_loop_output(void)
{
    int rv = 0;
    int n;

    if (new_style_driver) {
	while ((n = read_packet(inpacket_buf)) > 0)
	    if (loop_frame(inpacket_buf, n))
		rv = 1;
	return rv;
    }

    while ((n = read(master_fd, inbuf, sizeof(inbuf))) > 0)
	if (loop_chars(inbuf, n))
	    rv = 1;

    if (n == 0)
	fatal("eof on loopback");

    if (errno != EWOULDBLOCK && errno != EAGAIN)
	fatal("read from loopback: %m(%d)", errno);

    return rv;
}

/*
 * netif_set_mtu - set the MTU on the PPP network interface.
 */
void
netif_set_mtu(int unit, int mtu)
{
    struct ifreq ifr;

    memset (&ifr, '\0', sizeof (ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
    ifr.ifr_mtu = mtu;

    if (ifunit >= 0 && ioctl(sock_fd, SIOCSIFMTU, (caddr_t) &ifr) < 0)
	error("ioctl(SIOCSIFMTU): %m (line %d)", __LINE__);
}

/*
 * netif_get_mtu - get the MTU on the PPP network interface.
 */
int
netif_get_mtu(int unit)
{
    struct ifreq ifr;

    memset (&ifr, '\0', sizeof (ifr));
    strlcpy(ifr.ifr_name, ifname, sizeof (ifr.ifr_name));

    if (ifunit >= 0 && ioctl(sock_fd, SIOCGIFMTU, (caddr_t) &ifr) < 0) {
	error("ioctl(SIOCGIFMTU): %m (line %d)", __LINE__);
	return 0;
    }
    return ifr.ifr_mtu;
}

/********************************************************************
 *
 * tty_send_config - configure the transmit characteristics of
 * the ppp interface.
 */

void tty_send_config(int mtu, u_int32_t asyncmap, int pcomp, int accomp)
{
	int x;

	if (!still_ppp())
		return;
	link_mtu = mtu;
	if (ioctl(ppp_fd, PPPIOCSASYNCMAP, (caddr_t) &asyncmap) < 0) {
		if (errno != EIO && errno != ENOTTY)
			error("Couldn't set transmit async character map: %m");
		++error_count;
		return;
	}

	x = (pcomp? SC_COMP_PROT: 0) | (accomp? SC_COMP_AC: 0)
	    | (sync_serial? SC_SYNC: 0);
	modify_flags(ppp_fd, SC_COMP_PROT|SC_COMP_AC|SC_SYNC, x);
}

/********************************************************************
 *
 * tty_set_xaccm - set the extended transmit ACCM for the interface.
 */

void tty_set_xaccm (ext_accm accm)
{
    if (!still_ppp())
	return;
    if (ioctl(ppp_fd, PPPIOCSXASYNCMAP, accm) < 0 && errno != ENOTTY) {
	if ( ! ok_error (errno))
	    warn("ioctl(set extended ACCM): %m (line %d)", __LINE__);
    }
}

/********************************************************************
 *
 * tty_recv_config - configure the receive-side characteristics of
 * the ppp interface.
 */

void tty_recv_config(int mru, u_int32_t asyncmap, int pcomp, int accomp)
{
/*
 * If we were called because the link has gone down then there is nothing
 * which may be done. Just return without incident.
 */
	if (!still_ppp())
		return;
/*
 * Set the receiver parameters
 */
	if (ioctl(ppp_fd, PPPIOCSMRU, (caddr_t) &mru) < 0) {
		if (errno != EIO && errno != ENOTTY)
			error("Couldn't set channel receive MRU: %m");
	}
	if (new_style_driver && ppp_dev_fd >= 0
	    && ioctl(ppp_dev_fd, PPPIOCSMRU, (caddr_t) &mru) < 0)
		error("Couldn't set MRU in generic PPP layer: %m");

	if (ioctl(ppp_fd, PPPIOCSRASYNCMAP, (caddr_t) &asyncmap) < 0) {
		if (errno != EIO && errno != ENOTTY)
			error("Couldn't set channel receive asyncmap: %m");
	}
}

/********************************************************************
 *
 * ccp_test - ask kernel whether a given compression method
 * is acceptable for use.
 */

int
ccp_test(int unit, u_char *opt_ptr, int opt_len, int for_transmit)
{
    struct ppp_option_data data;

    memset (&data, '\0', sizeof (data));
    data.ptr      = opt_ptr;
    data.length   = opt_len;
    data.transmit = for_transmit;

    if (ioctl(ppp_dev_fd, PPPIOCSCOMPRESS, (caddr_t) &data) >= 0)
	return 1;

    return (errno == ENOBUFS)? 0: -1;
}

/********************************************************************
 *
 * ccp_flags_set - inform kernel about the current state of CCP.
 */

void ccp_flags_set (int unit, int isopen, int isup)
{
	int x;

	x = (isopen? SC_CCP_OPEN: 0) | (isup? SC_CCP_UP: 0);
	if (still_ppp() && ppp_dev_fd >= 0)
		modify_flags(ppp_dev_fd, SC_CCP_OPEN|SC_CCP_UP, x);
}

#ifdef PPP_FILTER
/*
 * set_filters - set the active and pass filters in the kernel driver.
 */
int set_filters(struct bpf_program *pass, struct bpf_program *active)
{
	struct sock_fprog fp;

	fp.len = pass->bf_len;
	fp.filter = (struct sock_filter *) pass->bf_insns;
	if (ioctl(ppp_dev_fd, PPPIOCSPASS, &fp) < 0) {
		if (errno == ENOTTY)
			warn("kernel does not support PPP filtering");
		else
			error("Couldn't set pass-filter in kernel: %m");
		return 0;
	}
	fp.len = active->bf_len;
	fp.filter = (struct sock_filter *) active->bf_insns;
	if (ioctl(ppp_dev_fd, PPPIOCSACTIVE, &fp) < 0) {
		error("Couldn't set active-filter in kernel: %m");
		return 0;
	}
	return 1;
}
#endif /* PPP_FILTER */

/********************************************************************
 *
 * get_idle_time - return how long the link has been idle.
 */
int
get_idle_time(u, ip)
    int u;
    struct ppp_idle *ip;
{
    return ioctl(ppp_dev_fd, PPPIOCGIDLE, ip) >= 0;
}

/********************************************************************
 *
 * get_ppp_stats - return statistics for the link.
 */
int
get_ppp_stats(u, stats)
    int u;
    struct pppd_stats *stats;
{
    struct ifpppstatsreq req;

    memset (&req, 0, sizeof (req));

    req.stats_ptr = (caddr_t) &req.stats;
    strlcpy(req.ifr__name, ifname, sizeof(req.ifr__name));
    if (ioctl(sock_fd, SIOCGPPPSTATS, &req) < 0) {
	error("Couldn't get PPP statistics: %m");
	return 0;
    }
    stats->bytes_in = req.stats.p.ppp_ibytes;
    stats->bytes_out = req.stats.p.ppp_obytes;
    stats->pkts_in = req.stats.p.ppp_ipackets;
    stats->pkts_out = req.stats.p.ppp_opackets;
    return 1;
}

/********************************************************************
 *
 * ccp_fatal_error - returns 1 if decompression was disabled as a
 * result of an error detected after decompression of a packet,
 * 0 otherwise.  This is necessary because of patent nonsense.
 */

int ccp_fatal_error (int unit)
{
	int flags;

	if (ioctl(ppp_dev_fd, PPPIOCGFLAGS, &flags) < 0) {
		error("Couldn't read compression error flags: %m");
		flags = 0;
	}
	return flags & SC_DC_FERROR;
}

/********************************************************************
 *
 * path_to_procfs - find the path to the proc file system mount point
 */
static char proc_path[MAXPATHLEN];
static int proc_path_len;

static char *path_to_procfs(const char *tail)
{
    struct mntent *mntent;
    FILE *fp;

    if (proc_path_len == 0) {
	/* Default the mount location of /proc */
	strlcpy (proc_path, "/proc", sizeof(proc_path));
	proc_path_len = 5;
	fp = fopen(MOUNTED, "r");
	if (fp != NULL) {
	    while ((mntent = getmntent(fp)) != NULL) {
		if (strcmp(mntent->mnt_type, MNTTYPE_IGNORE) == 0)
		    continue;
		if (strcmp(mntent->mnt_type, "proc") == 0) {
		    strlcpy(proc_path, mntent->mnt_dir, sizeof(proc_path));
		    proc_path_len = strlen(proc_path);
		    break;
		}
	    }
	    fclose (fp);
	}
    }

    strlcpy(proc_path + proc_path_len, tail,
	    sizeof(proc_path) - proc_path_len);
    return proc_path;
}

/*
 * /proc/net/route parsing stuff.
 */
#define ROUTE_MAX_COLS	12
FILE *route_fd = (FILE *) 0;
static char route_buffer[512];
static int route_dev_col, route_dest_col, route_gw_col;
static int route_flags_col, route_mask_col;
static int route_num_cols;

static int open_route_table (void);
static void close_route_table (void);
static int read_route_table (struct rtentry *rt);

/********************************************************************
 *
 * close_route_table - close the interface to the route table
 */

static void close_route_table (void)
{
    if (route_fd != (FILE *) 0) {
	fclose (route_fd);
	route_fd = (FILE *) 0;
    }
}

/********************************************************************
 *
 * open_route_table - open the interface to the route table
 */
static char route_delims[] = " \t\n";

static int open_route_table (void)
{
    char *path;

    close_route_table();

    path = path_to_procfs("/net/route");
    route_fd = fopen (path, "r");
    if (route_fd == NULL) {
	error("can't open routing table %s: %m", path);
	return 0;
    }

    route_dev_col = 0;		/* default to usual columns */
    route_dest_col = 1;
    route_gw_col = 2;
    route_flags_col = 3;
    route_mask_col = 7;
    route_num_cols = 8;

    /* parse header line */
    if (fgets(route_buffer, sizeof(route_buffer), route_fd) != 0) {
	char *p = route_buffer, *q;
	int col;
	for (col = 0; col < ROUTE_MAX_COLS; ++col) {
	    int used = 1;
	    if ((q = strtok(p, route_delims)) == 0)
		break;
	    if (strcasecmp(q, "iface") == 0)
		route_dev_col = col;
	    else if (strcasecmp(q, "destination") == 0)
		route_dest_col = col;
	    else if (strcasecmp(q, "gateway") == 0)
		route_gw_col = col;
	    else if (strcasecmp(q, "flags") == 0)
		route_flags_col = col;
	    else if (strcasecmp(q, "mask") == 0)
		route_mask_col = col;
	    else
		used = 0;
	    if (used && col >= route_num_cols)
		route_num_cols = col + 1;
	    p = NULL;
	}
    }

    return 1;
}

/********************************************************************
 *
 * read_route_table - read the next entry from the route table
 */

static int read_route_table(struct rtentry *rt)
{
    char *cols[ROUTE_MAX_COLS], *p;
    int col;

    memset (rt, '\0', sizeof (struct rtentry));

    if (fgets (route_buffer, sizeof (route_buffer), route_fd) == (char *) 0)
	return 0;

    p = route_buffer;
    for (col = 0; col < route_num_cols; ++col) {
	cols[col] = strtok(p, route_delims);
	if (cols[col] == NULL)
	    return 0;		/* didn't get enough columns */
	p = NULL;
    }

    SIN_ADDR(rt->rt_dst) = strtoul(cols[route_dest_col], NULL, 16);
    SIN_ADDR(rt->rt_gateway) = strtoul(cols[route_gw_col], NULL, 16);
    SIN_ADDR(rt->rt_genmask) = strtoul(cols[route_mask_col], NULL, 16);

    rt->rt_flags = (short) strtoul(cols[route_flags_col], NULL, 16);
    rt->rt_dev   = cols[route_dev_col];

    return 1;
}

/********************************************************************
 *
 * defaultroute_exists - determine if there is a default route
 */

static int defaultroute_exists (struct rtentry *rt)
{
    int result = 0;

    if (!open_route_table())
	return 0;

    while (read_route_table(rt) != 0) {
	if ((rt->rt_flags & RTF_UP) == 0)
	    continue;

	if (kernel_version > KVERSION(2,1,0) && SIN_ADDR(rt->rt_genmask) != 0)
	    continue;
	if (SIN_ADDR(rt->rt_dst) == 0L) {
	    result = 1;
	    break;
	}
    }

    close_route_table();
    return result;
}

/*
 * have_route_to - determine if the system has any route to
 * a given IP address.  `addr' is in network byte order.
 * Return value is 1 if yes, 0 if no, -1 if don't know.
 * For demand mode to work properly, we have to ignore routes
 * through our own interface.
 */
int have_route_to(u_int32_t addr)
{
    struct rtentry rt;
    int result = 0;

    if (!open_route_table())
	return -1;		/* don't know */

    while (read_route_table(&rt)) {
	if ((rt.rt_flags & RTF_UP) == 0 || strcmp(rt.rt_dev, ifname) == 0)
	    continue;
	if ((addr & SIN_ADDR(rt.rt_genmask)) == SIN_ADDR(rt.rt_dst)) {
	    result = 1;
	    break;
	}
    }

    close_route_table();
    return result;
}