path: root/ax25ipd/io.c

/* io.c 		All base I/O routines live here
 *
 * Copyright 1991, Michael Westerhof, Sun Microsystems, Inc.
 * This software may be freely used, distributed, or modified, providing
 * this header is not removed.
 *
 * This is the only module that knows about base level UNIX/SunOS I/O
 * This is also the key dispatching module, so it knows about a lot more
 * than just I/O stuff.
 */
#define _XOPEN_SOURCE
#define _XOPEN_SOURCE_EXTENDED

#include <errno.h>
#include <fcntl.h>
#include <memory.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <termio.h>
#include <time.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>

#include "ax25ipd.h"

static struct termio nterm;

int ttyfd = -1;
static int udpsock = -1;
static int sock = -1;
static struct sockaddr_in udpbind;
static struct sockaddr_in to;
static struct sockaddr_in from;
static socklen_t fromlen;

static time_t last_bc_time;

int ttyfd_bpq = 0;

/*
 * I/O modes for the io_error routine
 */
#define READ_MSG	0x00
#define SEND_MSG	0x01

#define IP_MODE		0x10
#define UDP_MODE	0x20
#define TTY_MODE	0x30

#ifndef FNDELAY
#define FNDELAY O_NDELAY
#endif

/*
 * process an I/O error; return true if a retry is needed
 *
 * oops		- the error flag; < 0 indicates a problem
 * buf		- the data in question
 * bufsize	- the size of the data buffer
 * dir		- the direction; input or output
 * mode		- the fd on which we got the error
 * where	- line in the code where this function was called
 */
static int io_error( int oops, unsigned char *buf, int bufsize, int dir,
	int mode, int where)
{

	/* if (oops >= 0)
		return 0; */	/* do we have an error ? */
	/* dl9sau: nobody has set fd's to O_NONBLOCK.
	 * thus EAGAIN (below) or EWOULDBLOCK are never be set.
	 * Has someone removed this behaviour previously?
	 * Anyway, in the current implementation, with blocking
	 * read/writes, a read or write of 0 bytes means EOF,
	 * for e.g. if the attached tty is closed.
	 * We have to exit then. We've currentlsy no mechanism
	 * for regulary reconnects.
	 */
	if (oops > 0)
		return 0;       /* do we have an error ? */

	if (oops == 0) {
		if (dir == READ_MSG && oops != TTY_MODE /* && != TCP_MODE, if we'd implement this */ )
			return 0;
		fprintf(stderr, "Close event on mode 0x%2.2x (during %s). LINE %d. Terminating normaly.\n", mode, (dir == READ_MSG ? "READ" : "WRITE"), where);
		exit(1);
	}

#ifdef EAGAIN
	if (errno == EAGAIN) {
#ifdef	notdef
		/* select() said that data is available, but recvfrom sais
		 * EAGAIN - i really do not know what's the sense in this.. */
		if (dir == READ_MSG && oops != TTY_MODE /* && != TCP_MODE, if we'd implement this */ )
			return 0;
		perror("System 5 I/O error!");
		fprintf(stderr, "A System 5 style I/O error was detected.  This rogram requires BSD 4.2\n");
		fprintf(stderr, "behaviour.  This is probably a result of compile-time environment.\n");
		fprintf(stderr, "Mode 0x%2.2x, LINE: %d. During %s\n", mode, where, (dir == READ_MSG ? "READ" : "WRITE"));
		exit(3);
#else
		int ret = 0;
		if (dir == READ_MSG) {
			LOGL4("read / recv returned -1 EAGAIN\n");
			ret = 0;
		} else if (dir == SEND_MSG) {
			LOGL4("write / send returned -1 EAGAIN, sleeping and retrying!\n");
			usleep(100000);
			ret = 1;
		}
		return ret;
#endif
	}
#endif

	if (dir == READ_MSG) {
		if (errno == EINTR)
			return 0;	/* never retry read */
		if (errno == EWOULDBLOCK) {
			LOGL4("READ would block (?!), sleeping and retrying!\n");
			usleep(100000);	/* sleep a bit */
			return 1;	/* and retry */
		}
		if (mode == IP_MODE) {
			perror("reading from raw ip socket");
			exit(2);
		} else if (mode == UDP_MODE) {
			perror("reading from udp socket");
			exit(2);
		} else if (mode == TTY_MODE) {
			perror("reading from tty device");
			exit(2);
		} else {
			perror("reading from unknown I/O");
			exit(2);
		}
	} else if (dir == SEND_MSG) {
		if (errno == EINTR)
			return 1;	/* always retry on writes */
		if (mode == IP_MODE) {
			if (errno == EMSGSIZE) {	/* msg too big, drop it */
				perror("message dropped on raw ip socket");
				fprintf (stderr, "message was %d bytes long.\n", bufsize);
				return 0;
			}
			if (errno == ENETDOWN || errno == ENETRESET ||
			    errno == ENETUNREACH || errno == EHOSTDOWN ||
			    errno == EHOSTUNREACH || errno == ENONET ||
			    errno == EPERM) {
				/* host closed his axip receiver or dropped the line */
				perror("error after sending on to axip partner. ignoring.");
				LOGL4("error after sending on to axip partner: %s; ignoring!\n", strerror(errno));

				return 0;
			}
			if (errno == ENOBUFS) {	/* congestion; sleep + retry */
				LOGL4("send congestion on raw ip, sleeping and retrying!\n");
				usleep(100000);
				return 1;
			}
			if (errno == EWOULDBLOCK) {
				LOGL4("send on raw ip would block, sleeping and retrying!\n");
				usleep(100000);	/* sleep a bit */
				return 1;	/* and retry */
			}
			perror("writing to raw ip socket");
			exit(2);
		} else if (mode == UDP_MODE) {
			if (errno == EMSGSIZE) {	/* msg too big, drop it */
				perror("message dropped on udp socket");
				fprintf(stderr, "message was %d bytes long.\n", bufsize);
				return 0;
			}
			if (errno == ENETDOWN || errno == ENETRESET ||
			    errno == ENETUNREACH || errno == EHOSTDOWN ||
			    errno == EHOSTUNREACH || errno == ENONET ||
			    errno == EPERM) {
				/* host closed his axudp receiver or dropped the line */
				perror("error after sending to axudp partner. ignoring.");
				LOGL4("error after sending to axudp partner: %s; ignoring!\n", strerror(errno));

				return 0;
			}
			if (errno == ENOBUFS) {	/* congestion; sleep + retry */
				LOGL4("send congestion on udp, sleeping and retrying!\n");
				usleep(100000);
				return 1;
			}
			if (errno == EWOULDBLOCK) {
				LOGL4("send on udp would block, sleeping and retrying!\n");
				usleep(100000);	/* sleep a bit */
				return 1;	/* and retry */
			}
			perror("writing to udp socket");
			exit(2);
		} else if (mode == TTY_MODE) {
			if (errno == EWOULDBLOCK) {
				LOGL4("write to tty would block, sleeping and retrying!\n");
				usleep(100000);	/* sleep a bit */
				return 1;	/* and retry */
			}
			perror("writing to tty device");
			exit(2);
		} else {
			perror("writing to unknown I/O");
			exit(2);
		}
	} else {
		perror("Unknown direction and I/O");
		exit(2);
	}
	return 0;
}

/*
 * Initialize the io variables
 */

void io_init(void)
{

/*
 * Close the file descriptors if they are open.  The idea is that we
 * will be able to support a re-initialization if sent a SIGHUP.
 */

	if (ttyfd >= 0) {
		close(ttyfd);
		ttyfd = -1;
	}

	if (sock >= 0) {
		close(sock);
		sock = -1;
	}

	if (udpsock >= 0) {
		close(udpsock);
		udpsock = -1;
	}

/*
 * The memset is not strictly required - it simply zeros out the
 * address structure.  Since both to and from are static, they are
 * already clear.
 */
	memset(&to, 0, sizeof(struct sockaddr));
	to.sin_family = AF_INET;

	memset(&from, 0, sizeof(struct sockaddr));
	from.sin_family = AF_INET;

	memset(&udpbind, 0, sizeof(struct sockaddr));
	udpbind.sin_family = AF_INET;
}

/*
 * open and initialize the IO interfaces
 */

void io_open(void)
{
	int baudrate;
	int i_am_unix98_pty_master = 0; /* unix98 ptmx support */
	char *namepts = NULL;           /* name of the unix98 pts slave, which
					 * the client has to use */

	if (ip_mode) {
		sock = socket(AF_INET, SOCK_RAW, IPPROTO_AX25);
		if (sock < 0) {
			perror("opening raw socket");
			exit(1);
		}
		if (fcntl(sock, F_SETFL, FNDELAY) < 0) {
			perror("setting non-blocking I/O on raw socket");
			exit(1);
		}
	}

	if (udp_mode) {
		udpsock = socket(AF_INET, SOCK_DGRAM, 0);
		if (udpsock < 0) {
			perror("opening udp socket");
			exit(1);
		}
		if (fcntl(udpsock, F_SETFL, FNDELAY) < 0) {
			perror("setting non-blocking I/O on UDP socket");
			exit(1);
		}
/*
 * Ok, the udp socket is open.  Now express our interest in receiving
 * data destined for a particular socket.
 */
		udpbind.sin_addr.s_addr = INADDR_ANY;
		udpbind.sin_port = my_udp;
		if (bind(udpsock, (struct sockaddr *) &udpbind, sizeof udpbind) < 0) {
			perror("binding udp socket");
			exit(1);
		}
	}

	if (!strcmp("/dev/ptmx", ttydevice))
		i_am_unix98_pty_master = 1;

	ttyfd = ((ttyfd_bpq = (strchr(ttydevice, '/') ? 0 : 1)) ? open_ethertap(ttydevice) : open(ttydevice, O_RDWR, 0));
	if (ttyfd < 0) {
		perror("opening tty device");
		exit(1);
	}
	if (fcntl(ttyfd, F_SETFL, FNDELAY) < 0) {
		perror("setting non-blocking I/O on tty device");
		exit(1);
	}

	if (i_am_unix98_pty_master) {
		/* get name of pts-device */
		namepts = ptsname(ttyfd);
		if (namepts == NULL) {
			perror("Cannot get name of pts-device.");
			exit(1);
		}
		/* unlock pts-device */
		if (unlockpt(ttyfd) == -1) {
			perror("Cannot unlock pts-device.");
			exit(1);
		}
	}

	if (ttyfd_bpq) {
		set_bpq_dev_call_and_up(ttydevice);
		goto behind_normal_tty;
	}
	if (ioctl(ttyfd, TCGETA, &nterm) < 0) {
		perror("fetching tty device parameters");
		exit(1);
	}

	if (ttyspeed == 50)
		baudrate = B50;
	else if (ttyspeed == 50)
		baudrate = B50;
	else if (ttyspeed == 75)
		baudrate = B75;
	else if (ttyspeed == 110)
		baudrate = B110;
	else if (ttyspeed == 134)
		baudrate = B134;
	else if (ttyspeed == 150)
		baudrate = B150;
	else if (ttyspeed == 200)
		baudrate = B200;
	else if (ttyspeed == 300)
		baudrate = B300;
	else if (ttyspeed == 600)
		baudrate = B600;
	else if (ttyspeed == 1200)
		baudrate = B1200;
	else if (ttyspeed == 1800)
		baudrate = B1800;
	else if (ttyspeed == 2400)
		baudrate = B2400;
	else if (ttyspeed == 4800)
		baudrate = B4800;
	else if (ttyspeed == 9600)
		baudrate = B9600;
#ifdef B19200
	else if (ttyspeed == 19200)
		baudrate = B19200;
#else
#ifdef EXTA
	else if (ttyspeed == 19200)
		baudrate = EXTA;
#endif	/* EXTA */
#endif	/* B19200 */
#ifdef B38400
	else if (ttyspeed == 38400)
		baudrate = B38400;
#else
#ifdef EXTB
	else if (ttyspeed == 38400)
		baudrate = EXTB;
#endif /* EXTB */
#endif /* B38400 */
#ifdef B57600
	 else if (ttyspeed == 57600)
		baudrate = B57600;
#endif /* B57600  */
#ifdef B76800					/* SPARC-specific  */
	 else if (ttyspeed == 76800)
		baudrate = B76800;
#endif /* B76800  */
#ifdef B115200
	 else if (ttyspeed == 115200)
		baudrate = B115200;
#endif /* B115200  */
#ifdef B153600					/* SPARC-specific  */
	 else if (ttyspeed == 153600)
		baudrate = B153600;
#endif /* B153600  */
#ifdef B230400
	 else if (ttyspeed == 230400)
		baudrate = B230400;
#endif /* B230400  */
#ifdef B307200					/* SPARC-specific  */
	 else if (ttyspeed == 307200)
		baudrate = B307200;
#endif /* B307200  */
#ifdef B460800
	 else if (ttyspeed == 460800)
		baudrate = B460800;
#endif /* B460800  */
#ifdef B500000
	 else if (ttyspeed == 500000)
		baudrate = B500000;
#endif /* B500000  */
#ifdef B576000
	 else if (ttyspeed == 576000)
		baudrate = B576000;
#endif /* B576000  */
#ifdef B614400					/* SPARC-specific  */
	 else if (ttyspeed == 614400)
		baudrate = B614400;
#endif /* B614400  */
#ifdef B921600					/* SPARC-specific  */
	 else if (ttyspeed == 921600)
		baudrate = B921600;
#endif /* B921600  */
#ifdef B1000000
	 else if (ttyspeed == 1000000)
		baudrate = B1000000;
#endif /* B1000000  */
#ifdef B1152000
	 else if (ttyspeed == 1152000)
		baudrate = B1152000;
#endif /* B1152000  */
#ifdef B1500000
	 else if (ttyspeed == 1500000)
		baudrate = B1500000;
#endif /* B1500000  */
#ifdef B2000000
	 else if (ttyspeed == 2000000)
		baudrate = B2000000;
#endif /* B2000000  */
#ifdef B2500000
	 else if (ttyspeed == 2500000)
		baudrate = B2500000;
#endif /* B2500000  */
#ifdef B3000000
	 else if (ttyspeed == 3000000)
		baudrate = B3000000;
#endif /* B3000000  */
#ifdef B3500000
	 else if (ttyspeed == 3500000)
		baudrate = B3500000;
#endif /* B3500000  */
#ifdef B4000000
	 else if (ttyspeed == 4000000)
		baudrate = B4000000;
#endif /* B4000000  */
	else
		baudrate = B9600;

	nterm.c_iflag = 0;
	nterm.c_oflag = 0;
	nterm.c_cflag = baudrate | CS8 | CREAD | CLOCAL;
	nterm.c_lflag = 0;
	nterm.c_cc[VMIN] = 0;
	nterm.c_cc[VTIME] = 0;

	if (ioctl(ttyfd, TCSETA, &nterm) < 0) {
		perror("setting tty device parameters");
		exit(1);
	}

	if (digi)
		send_params();

	if (i_am_unix98_pty_master) {
		/* Users await the slave pty to be referenced in the last line */
		printf("Awaiting client connects on\n%s\n", namepts);
		syslog(LOG_INFO, "Bound to master pty /dev/ptmx with slave pty %s\n", namepts);
	}

behind_normal_tty:

	last_bc_time = 0;	/* force immediate id */
}

/*
 * Start up and run the I/O mechanisms.
 *  run in a loop, using the select call to handle input.
 */

void io_start(void) {
	int n, nb, hdr_len;
	fd_set readfds;
	unsigned char buf[MAX_FRAME];
	struct timeval wait;
	struct iphdr *ipptr;
	time_t now;

	for (;;) {

		if ((bc_interval > 0) && digi) {
			now = time(NULL);
			if (last_bc_time + bc_interval < now) {
				last_bc_time = now;
				LOGL4("iostart: BEACON\n");
				do_beacon();
			}
		}

		wait.tv_sec = 10;	/* lets us keep the beacon going */
		wait.tv_usec = 0;

		FD_ZERO(&readfds);

		FD_SET(ttyfd, &readfds);

		if (ip_mode) {
			FD_SET(sock, &readfds);
		}

		if (udp_mode) {
			FD_SET(udpsock, &readfds);
		}

		nb = select(FD_SETSIZE, &readfds, (fd_set *) 0, (fd_set *) 0, &wait);

		if (nb < 0) {
			if (errno == EINTR)
				continue;	/* Ignore */
			perror("select");
			exit(1);
		}

		if (nb == 0) {
			fflush(stdout);
			fflush(stderr);
			/* just so we go back to the top of the loop! */
			continue;
		}

		if (FD_ISSET(ttyfd, &readfds)) {
			do {
				n = read(ttyfd, buf, MAX_FRAME);
			}
			while (io_error(n, buf, n, READ_MSG, TTY_MODE, __LINE__));
			LOGL4("ttydata l=%d\n", n);
			if (n > 0) {
				if (!ttyfd_bpq) {
					assemble_kiss(buf, n);
				} else {
					/* no crc but MAC header on bpqether */
					if (receive_bpq(buf, n) < 0) {
						goto out_ttyfd;
					}
				}
			}

/*
 * If we are in "beacon after" mode, reset the "last_bc_time" each time
 * we hear something on the channel.
 */
			if (!bc_every)
				last_bc_time = time(NULL);
		}
out_ttyfd:

		if (udp_mode) {
			if (FD_ISSET(udpsock, &readfds)) {
				do {
					fromlen = sizeof from;
					n = recvfrom(udpsock, buf, MAX_FRAME, 0, (struct sockaddr *) &from, &fromlen);
				}
				while (io_error(n, buf, n, READ_MSG, UDP_MODE, __LINE__));
				LOGL4("udpdata from=%s port=%d l=%d\n",
				      inet_ntoa(from.  sin_addr),
				      ntohs(from.  sin_port), n);
				stats.udp_in++;
				if (n > 0)
					from_ip(buf, n);
			}
		}
		/* if udp_mode */
		if (ip_mode) {
			if (FD_ISSET(sock, &readfds)) {
				do {
					fromlen = sizeof from;
					n = recvfrom(sock, buf, MAX_FRAME, 0, (struct sockaddr *) &from, &fromlen);
				}
				while (io_error(n, buf, n, READ_MSG, IP_MODE, __LINE__));
				ipptr = (struct iphdr *) buf;
				hdr_len = 4 * ipptr-> ihl;
				LOGL4("ipdata from=%s l=%d, hl=%d\n",
				      inet_ntoa(from.  sin_addr), n, hdr_len);
				stats.ip_in++;
				if (n > hdr_len)
					from_ip(buf + hdr_len, n - hdr_len);
			}
		}
		/* if ip_mode */
	}	/* for forever */
}

/* Send an IP frame */

void send_ip(unsigned char *buf, int l, unsigned char *targetip)
{
	int n;

	if (l <= 0)
		return;
	memcpy(&to.sin_addr, targetip, 4);
	memcpy(&to.sin_port, &targetip[4], 2);
	LOGL4("sendipdata to=%s %s %d l=%d\n", inet_ntoa(to.  sin_addr),
	      to.sin_port ? "udp" : "ip", ntohs(to.sin_port), l);
	if (to.sin_port) {
		if (udp_mode) {
			stats.udp_out++;
			do {
				n = sendto(udpsock, buf, l, 0, (struct sockaddr *) &to, sizeof to);
			}
			while (io_error(n, buf, l, SEND_MSG, UDP_MODE, __LINE__));
		}
	} else {
		if (ip_mode) {
			stats.ip_out++;
			do {
				n = sendto(sock, buf, l, 0, (struct sockaddr *) &to, sizeof to);
			}
			while (io_error(n, buf, l, SEND_MSG, IP_MODE, __LINE__));
		}
	}
}

/* Send a kiss frame */

void send_tty(unsigned char *buf, int l)
{
	int n;
	unsigned char *p;
	int nc;

	if (l <= 0)
		return;
	LOGL4("sendttydata l=%d\tsent: ", l);
	stats.kiss_out++;

	p = buf;
	nc = l;
	n = 0;

/*
 * we have to loop around here because each call to write may write a few
 * characters.  So we simply increment the buffer each time around.  If
 * we ever write no characters, we should get an error code, and io_error
 * will sleep for a fraction of a second.  Note that we are keyed to
 * the BSD 4.2 behaviour... the Sys 5 non-blocking I/O may or may not work
 * in this loop.  We may detect system 5 behaviour (this would result from
 * compile-time options) by having io_error barf when it detects an EAGAIN
 * error code.
 */
	do {
		if ((n > 0) && (n < nc)) {	/* did we put only write a bit? */
			p += n;	/* point to the new data */
			nc -= n;	/* drop the length */
		}
		n = write(ttyfd, p, nc);
		if (n > 0) {
			if (n != nc) {
				LOGL4("%d ", n);	/* no-one said loglevel 4 */
			} else {
				LOGL4("%d\n", n);	/* was efficient!!! */
			}
		}
	}
	while (((n > 0) && (n < nc)) || (io_error(n, p, nc, SEND_MSG, TTY_MODE, __LINE__)));
}