p910nd ver. 0.95

[tomato.git] / release / src / router / p910nd / p910nd.c

/*
 *      Port 9100+n daemon
 *      Accepts a connection from port 9100+n and copy stream to
 *      /dev/lpn, where n = 0,1,2.
 *
 *      GPLv2 license, read COPYING
 *
 *      Run standalone as: p910nd [0|1|2]
 *
 *      Run under inetd as:
 *      p910n stream tcp nowait root /usr/sbin/tcpd p910nd [0|1|2]
 *       where p910n is an /etc/services entry for
 *       port 9100, 9101 or 9102 as the case may be.
 *       root can be replaced by any uid with rw permission on /dev/lpn
 *
 *      Port 9100+n will then be passively opened
 *      n defaults to 0
 *
 *      Version 0.95
 *      Patch by Mario Izquierdo
 *      Fix incomplete conversion to manipulate new ip_addr structure
 *      when LIBWRAP is selected
 *
 *      Version 0.94
 *      Patch by Guenther Niess:
 *      Support IPv6
 *      Patch by Philip Prindeville:
 *      Increase socket buffer size
 *      Use %hu for printing port
 *      Makefile fixes for LIBWRAP
 *
 *      Version 0.93
 *      Fix open call to include mode, required for O_CREAT
 *
 *      Version 0.92
 *      Patches by Dave Brown.  Use raw I/O syscalls instead of
 *      stdio buffering.  Buffer system to handle talkative bidi
 *      devices better on low-powered hosts.
 *
 *      Version 0.91
 *      Patch by Hans Harder.  Close printer device after each use to
 *      avoid crashing when hotpluggable devices going away.
 *      Don't wait 10 seconds after successful open.
 *
 *      Version 0.9
 *      Patch by Kostas Liakakis to keep retrying every 10 seconds
 *      if EBUSY is returned by open_printer, apparently NetBSD
 *      does this if the printer is not on.
 *      Patch by Albert Bartoszko (al_bin@vp_pl), August 2006
 *      Work with hotpluggable devices
 *      Improve Makefile
 *
 *      (The last two patches conflict somewhat, Liakakis's patch
 *      retries opening the device every 10 seconds until successful,
 *      whereas Bartoszko's patch exits if the printer device cannot be opened.
 *      The problem is with a hotpluggable device, that device node may
 *      not appear again.
 *
 *      I have opted for Liakakis's behaviour. Let me know if this can
 *      be improved. Perhaps we need another option that chooses the
 *      behaviour. - Ken)
 *
 *      Version 0.8
 *      Allow specifying address to bind to
 *
 *      Version 0.7
 *      Bidirectional data transfer
 *
 *      Version 0.6
 *      Arne Bernin fixed some cast warnings, corrected the version number
 *      and added a -v option to print the version.
 *
 *      Version 0.5
 *      -DUSE_LIBWRAP and -lwrap enables hosts_access (tcpwrappers) checking.
 *
 *      Version 0.4
 *      Ken Yap (greenpossum@users.sourceforge.net), April 2001
 *      Placed under GPL.
 *
 *      Added -f switch to specify device which overrides /dev/lpn.
 *      But number is still required get distinct ports and locks.
 *
 *      Added locking so that two invocations of the daemon under inetd
 *      don't try to open the printer at the same time. This can happen
 *      even if there is one host running clients because the previous
 *      client can exit after it has sent all data but the printer has not
 *      finished printing and inetd starts up a new daemon when the next
 *      request comes in too soon.
 *
 *      Various things could be Linux specific. I don't
 *      think there is much demand for this program outside of PCs,
 *      but if you port it to other distributions or platforms,
 *      I'd be happy to receive your patches.
 */

#include        <unistd.h>
#include        <stdlib.h>
#include        <stdio.h>
#include        <getopt.h>
#include        <ctype.h>
#include        <string.h>
#include        <fcntl.h>
#include        <netdb.h>
#include        <syslog.h>
#include        <errno.h>
#include        <sys/types.h>
#include        <sys/time.h>
#include        <sys/resource.h>
#include        <sys/stat.h>
#include        <sys/socket.h>
#include        <netinet/in.h>
#include        <arpa/inet.h>

#ifdef  USE_LIBWRAP
#include        "tcpd.h"
int allow_severity, deny_severity;
extern int hosts_ctl(char *daemon, char *client_name, char *client_addr, char *client_user);
#endif

#define         BASEPORT        9100
#define         PIDFILE         "/var/run/p910%cd.pid"
#ifdef          LOCKFILE_DIR
#define         LOCKFILE        LOCKFILE_DIR "/p910%cd"
#else
#define         LOCKFILE        "/var/lock/subsys/p910%cd"
#endif
#ifndef         PRINTERFILE
#define         PRINTERFILE     "/dev/lp%c"
#endif
#define         LOGOPTS         LOG_ERR

#define         BUFFER_SIZE     8192

/* Circular buffer used for each direction. */
typedef struct {
        int detectEof;          /* If nonzero, EOF is marked when read returns 0 bytes. */
        int infd;               /* Input file descriptor. */
        int outfd;              /* Output file descriptor. */
        int startidx;           /* Index of the start of valid data. */
        int endidx;             /* Index of the end of valid data. */
        int bytes;              /* The number of bytes currently buffered. */
        int totalin;            /* Total bytes that have been read. */
        int totalout;           /* Total bytes that have been written. */
        int eof;                /* Nonzero indicates the input file has reached EOF. */
        int err;                /* Nonzero indicates an error detected on the output file. */
        char buffer[BUFFER_SIZE];       /* Buffered data goes here. */
} Buffer_t;

static char *progname;
static char version[] = "Version 0.94";
static char copyright[] = "Copyright (c) 2008 Ken Yap, GPLv2";
static int lockfd = -1;
static char *device = 0;
static int bidir = 0;
static char *bindaddr = 0;


/* Helper function: convert a struct sockaddr address (IPv4 and IPv6) to a string */
char *get_ip_str(const struct sockaddr *sa, char *s, size_t maxlen)
{
        switch(sa->sa_family) {
                case AF_INET:
                        inet_ntop(AF_INET, &(((struct sockaddr_in *)sa)->sin_addr), s, maxlen);
                        break;
                case AF_INET6:
                        inet_ntop(AF_INET6, &(((struct sockaddr_in6 *)sa)->sin6_addr), s, maxlen);
                        break;
                default:
                        strncpy(s, "Unknown AF", maxlen);
                return NULL;
        }
        return s;
}

uint16_t get_port(const struct sockaddr *sa)
{
        uint16_t port;
        switch(sa->sa_family) {
                case AF_INET:
                        port = ntohs(((struct sockaddr_in *)sa)->sin_port);
                        break;
                case AF_INET6:
                        port = ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
                        break;
                default:
                        return 0;
        }
        return port;
}

void usage(void)
{
        fprintf(stderr, "%s %s %s\n", progname, version, copyright);
        fprintf(stderr, "Usage: %s [-f device] [-i bindaddr] [-bv] [0|1|2]\n", progname);
        exit(1);
}

void show_version(void)
{
        fprintf(stdout, "%s %s\n", progname, version);
}

int open_printer(int lpnumber)
{
        int lp;
        char lpname[sizeof(PRINTERFILE)];

#ifdef  TESTING
        (void)snprintf(lpname, sizeof(lpname), "/dev/tty");
#else
        (void)snprintf(lpname, sizeof(lpname), PRINTERFILE, lpnumber);
#endif
        if (device == 0)
                device = lpname;
        if ((lp = open(device, bidir ? O_RDWR : O_WRONLY)) == -1) {
                if (errno != EBUSY)
                        syslog(LOGOPTS, "%s: %m\n", device);
                syslog(LOGOPTS, "%s: %m, will try opening later\n", device);
        }
        return (lp);
}

int get_lock(int lpnumber)
{
        char lockname[sizeof(LOCKFILE)];
        struct flock lplock;

        (void)snprintf(lockname, sizeof(lockname), LOCKFILE, lpnumber);
        if ((lockfd = open(lockname, O_CREAT | O_RDWR, 0666)) < 0) {
                syslog(LOGOPTS, "%s: %m\n", lockname);
                return (0);
        }
        memset(&lplock, 0, sizeof(lplock));
        lplock.l_type = F_WRLCK;
        lplock.l_pid = getpid();
        if (fcntl(lockfd, F_SETLKW, &lplock) < 0) {
                syslog(LOGOPTS, "%s: %m\n", lockname);
                return (0);
        }
        return (1);
}

void free_lock(void)
{
        if (lockfd >= 0)
                (void)close(lockfd);
}

/* Initializes the buffer, at the start. */
void initBuffer(Buffer_t * b, int infd, int outfd, int detectEof)
{
        b->detectEof = detectEof;
        b->infd = infd;
        b->outfd = outfd;
        b->startidx = 0;
        b->endidx = 0;
        b->bytes = 0;
        b->totalin = 0;
        b->totalout = 0;
        b->eof = 0;
        b->err = 0;
}

/* Sets the readfds and writefds (used by select) based on current buffer state. */
void prepBuffer(Buffer_t * b, fd_set * readfds, fd_set * writefds)
{
        if (!b->err && b->bytes != 0) {
                FD_SET(b->outfd, writefds);
        }
        if (!b->eof && b->bytes < sizeof(b->buffer)) {
                FD_SET(b->infd, readfds);
        }
}

/* Reads data into a buffer from its input file. */
ssize_t readBuffer(Buffer_t * b)
{
        int avail;
        ssize_t result = 1;
        /* If err, the data will not be written, so no need to store it. */
        if (b->bytes == 0 || b->err) {
                /* The buffer is empty. */
                b->startidx = b->endidx = 0;
                avail = sizeof(b->buffer);
        } else if (b->bytes == sizeof(b->buffer)) {
                /* The buffer is full. */
                avail = 0;
        } else if (b->endidx > b->startidx) {
                /* The buffer is not wrapped: from endidx to end of buffer is free. */
                avail = sizeof(b->buffer) - b->endidx;
        } else {
                /* The buffer is wrapped: gap between endidx and startidx is free. */
                avail = b->startidx - b->endidx;
        }
        if (avail) {
                result = read(b->infd, b->buffer + b->endidx, avail);
                if (result > 0) {
                        /* Some data was read. Update accordingly. */
                        b->endidx += result;
                        b->totalin += result;
                        b->bytes += result;
                        if (b->endidx == sizeof(b->buffer)) {
                                /* Time to wrap the buffer. */
                                b->endidx = 0;
                        }
                } else if (result < 0 || b->detectEof) {
                        /* Mark end-of-file on input error, or on zero return if detectEof. */
                        b->eof = 1;
                }
        }
        /* Return the value returned by read(), which is -1, 0, or #bytes read. */
        return result;
}

/* Writes data from a buffer to the output file. */
ssize_t writeBuffer(Buffer_t * b)
{
        int avail;
        ssize_t result = 1;
        if (b->bytes == 0 || b->err) {
                /* Buffer is empty. */
                avail = 0;
        } else if (b->endidx > b->startidx) {
                /* Buffer is not wrapped. Can write all the data. */
                avail = b->endidx - b->startidx;
        } else {
                /* Buffer is wrapped. Can only write the top (first) part. */
                avail = sizeof(b->buffer) - b->startidx;
        }
        if (avail) {
                result = write(b->outfd, b->buffer + b->startidx, avail);
                if (result < 0) {
                        /* Mark the output file in an error condition. */
                        syslog(LOGOPTS, "write: %m\n");
                        b->err = 1;
                } else {
                        /* Zero or more bytes were written. */
                        b->startidx += result;
                        b->totalout += result;
                        b->bytes -= result;
                        if (b->startidx == sizeof(b->buffer)) {
                                /* Unwrap the buffer. */
                                b->startidx = 0;
                        }
                }
        }
        /* Return the write() result, -1 (error), or #bytes written. */
        return result;
}

/* Copy network data from file descriptor fd (network) to lp (printer) until EOS */
/* If bidir, also copy data from printer (lp) to network (fd). */
int copy_stream(int fd, int lp)
{
        int result;
        Buffer_t networkToPrinterBuffer;
        initBuffer(&networkToPrinterBuffer, fd, lp, 1);

        if (bidir) {
                struct timeval now;
                struct timeval then;
                struct timeval timeout;
                int timer = 0;
                Buffer_t printerToNetworkBuffer;
                initBuffer(&printerToNetworkBuffer, lp, fd, 0);
                fd_set readfds;
                fd_set writefds;
                /* Initially read from both streams, don't write to either. */
                FD_ZERO(&readfds);
                FD_ZERO(&writefds);
                FD_SET(lp, &readfds);
                FD_SET(fd, &readfds);
                /* Finish when no longer reading fd, and no longer writing to lp. */
                /* Although the printer to network stream may not be finished, that does not matter. */
                while ((FD_ISSET(fd, &readfds)) || (FD_ISSET(lp, &writefds))) {
                        int maxfd = lp > fd ? lp : fd;
                        if (timer) {
                                /* Delay after reading from the printer, so the */
                                /* return stream cannot dominate. */
                                /* Don't read from the printer until the timer expires. */
                                gettimeofday(&now, 0);
                                if ((now.tv_sec > then.tv_sec) || (now.tv_sec == then.tv_sec && now.tv_usec > then.tv_usec)) {
                                        timer = 0;
                                } else {
                                        timeout.tv_sec = then.tv_sec;
                                        timeout.tv_usec = then.tv_usec;
                                        FD_CLR(lp, &readfds);
                                }
                        }
                        if (timer) {
                                result = select(maxfd + 1, &readfds, &writefds, 0, &timeout);
                        } else {
                                result = select(maxfd + 1, &readfds, &writefds, 0, 0);
                        }
                        if (result < 0)
                                return (result);
                        if (FD_ISSET(fd, &readfds)) {
                                /* Read network data. */
                                result = readBuffer(&networkToPrinterBuffer);
                        }
                        if (FD_ISSET(lp, &readfds)) {
                                /* Read printer data, but pace it more slowly. */
                                result = readBuffer(&printerToNetworkBuffer);
                                if (result >= 0) {
                                        gettimeofday(&then, 0);
                                        // wait 100 msec before reading again.
                                        then.tv_usec += 100000;
                                        if (then.tv_usec > 1000000) {
                                                then.tv_usec -= 1000000;
                                                then.tv_sec++;
                                        }
                                        timer = 1;
                                }
                        }
                        if (FD_ISSET(lp, &writefds)) {
                                /* Write data to printer. */
                                result = writeBuffer(&networkToPrinterBuffer);
                        }
                        if (FD_ISSET(fd, &writefds)) {
                                /* Write data to network. */
                                result = writeBuffer(&printerToNetworkBuffer);
                                /* If socket write error, stop reading from printer */
                                if (result < 0)
                                        networkToPrinterBuffer.eof = 1;
                        }
                        /* Prepare for next iteration. */
                        FD_ZERO(&readfds);
                        FD_ZERO(&writefds);
                        prepBuffer(&networkToPrinterBuffer, &readfds, &writefds);
                        prepBuffer(&printerToNetworkBuffer, &readfds, &writefds);
                }
                syslog(LOG_NOTICE,
                       "Finished job: %d bytes received, %d bytes sent\n",
                       networkToPrinterBuffer.totalout, printerToNetworkBuffer.totalout);
                return (0);
        } else {
                /* Unidirectional: simply read from network, and write to printer. */
                while ((result = readBuffer(&networkToPrinterBuffer)) > 0) {
                        (void)writeBuffer(&networkToPrinterBuffer);
                }
                syslog(LOG_NOTICE, "Finished job: %d bytes received\n", networkToPrinterBuffer.totalout);
                return (result);
        }
}

void one_job(int lpnumber)
{
        int lp;
        struct sockaddr_storage client;
        socklen_t clientlen = sizeof(client);

        if (getpeername(0, (struct sockaddr *)&client, &clientlen) >= 0) {
                char host[INET6_ADDRSTRLEN];
                syslog(LOG_NOTICE, "Connection from %s port %hu\n", get_ip_str((struct sockaddr *)&client, host, sizeof(host)), get_port((struct sockaddr *)&client));
        }
        if (get_lock(lpnumber) == 0)
                return;
        /* Make sure lp device is open... */
        while ((lp = open_printer(lpnumber)) == -1)
                sleep(10);
        if (copy_stream(0, lp) < 0)
                syslog(LOGOPTS, "copy_stream: %m\n");
        close(lp);
        free_lock();
}

void server(int lpnumber)
{
        struct rlimit resourcelimit;
#ifdef  USE_GETPROTOBYNAME
        struct protoent *proto;
#endif
        int netfd = -1, fd, lp, one = 1;
        socklen_t clientlen;
        struct sockaddr_storage client;
        struct addrinfo hints, *res, *ressave;
        char pidfilename[sizeof(PIDFILE)];
        char service[sizeof(BASEPORT+lpnumber-'0')+1];
        FILE *f;
        const int bufsiz = 65536;

#ifndef TESTING
        switch (fork()) {
        case -1:
                syslog(LOGOPTS, "fork: %m\n");
                exit(1);
        case 0:         /* child */
                break;
        default:                /* parent */
                exit(0);
        }
        /* Now in child process */
        resourcelimit.rlim_max = 0;
        if (getrlimit(RLIMIT_NOFILE, &resourcelimit) < 0) {
                syslog(LOGOPTS, "getrlimit: %m\n");
                exit(1);
        }
        for (fd = 0; fd < resourcelimit.rlim_max; ++fd)
                (void)close(fd);
        if (setsid() < 0) {
                syslog(LOGOPTS, "setsid: %m\n");
                exit(1);
        }
        (void)chdir("/");
        (void)umask(022);
        fd = open("/dev/null", O_RDWR); /* stdin */
        (void)dup(fd);          /* stdout */
        (void)dup(fd);          /* stderr */
        (void)snprintf(pidfilename, sizeof(pidfilename), PIDFILE, lpnumber);
        if ((f = fopen(pidfilename, "w")) == NULL) {
                syslog(LOGOPTS, "%s: %m\n", pidfilename);
                exit(1);
        }
        (void)fprintf(f, "%d\n", getpid());
        (void)fclose(f);
        if (get_lock(lpnumber) == 0)
                exit(1);
#endif
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = PF_UNSPEC;
        hints.ai_flags = AI_PASSIVE;
        hints.ai_socktype = SOCK_STREAM;
        (void)snprintf(service, sizeof(service), "%hu", (BASEPORT + lpnumber - '0'));
        if (getaddrinfo(bindaddr, service, &hints, &res) != 0) {
                syslog(LOGOPTS, "getaddr: %m\n");
                exit(1);
        }
        ressave = res;
        while (res) {
#ifdef  USE_GETPROTOBYNAME
                if ((proto = getprotobyname("tcp6")) == NULL) {
                        if ((proto = getprotobyname("tcp")) == NULL) {
                                syslog(LOGOPTS, "Cannot find protocol for TCP!\n");
                                exit(1);
                        }
                }
                if ((netfd = socket(res->ai_family, res->ai_socktype, proto->p_proto)) < 0)
#else
                if ((netfd = socket(res->ai_family, res->ai_socktype, IPPROTO_IP)) < 0)
#endif
        {
                syslog(LOGOPTS, "socket: %m\n");
                        close(netfd);
                        res = res->ai_next;
                        continue;
                }
                if (setsockopt(netfd, SOL_SOCKET, SO_RCVBUF, &bufsiz, sizeof(bufsiz)) < 0) {
                        syslog(LOGOPTS, "setsocketopt: SO_RCVBUF: %m\n");
                        /* not fatal if it fails */
                }
                if (setsockopt(netfd, SOL_SOCKET, SO_SNDBUF, &bufsiz, sizeof(bufsiz)) < 0) {
                        syslog(LOGOPTS, "setsocketopt: SO_SNDBUF: %m\n");
                        /* not fatal if it fails */
                }
                if (setsockopt(netfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0) {
                        syslog(LOGOPTS, "setsocketopt: SO_REUSEADDR: %m\n");
                        close(netfd);
                        res = res->ai_next;
                        continue;
                }
                if (bind(netfd, res->ai_addr, res->ai_addrlen) < 0) {
                        syslog(LOGOPTS, "bind: %m\n");
                        close(netfd);
                        res = res->ai_next;
                        continue;
                }
                if (listen(netfd, 5) < 0) {
                        syslog(LOGOPTS, "listen: %m\n");
                        close(netfd);
                        res = res->ai_next;
                        continue;
                }
                break;
        }
        freeaddrinfo(ressave);
        clientlen = sizeof(client);
        memset(&client, 0, sizeof(client));
        while ((fd = accept(netfd, (struct sockaddr *)&client, &clientlen)) >= 0) {
                char host[INET6_ADDRSTRLEN];
#ifdef  USE_LIBWRAP
                if (hosts_ctl("p910nd", STRING_UNKNOWN, get_ip_str((struct sockaddr *)&client, host, sizeof(host)), STRING_UNKNOWN) == 0) {
                        syslog(LOGOPTS,
                               "Connection from %s port %hu rejected\n", get_ip_str((struct sockaddr *)&client, host, sizeof(host)), get_port((struct sockaddr *)&client));
                        close(fd);
                        continue;
                }
#endif
                syslog(LOG_NOTICE, "Connection from %s port %hu accepted\n", get_ip_str((struct sockaddr *)&client, host, sizeof(host)), get_port((struct sockaddr *)&client));
                /*write(fd, "Printing", 8); */

                /* Make sure lp device is open... */
                while ((lp = open_printer(lpnumber)) == -1)
                        sleep(10);

                if (copy_stream(fd, lp) < 0)
                        syslog(LOGOPTS, "copy_stream: %m\n");
                (void)close(fd);
                (void)close(lp);
        }
        syslog(LOGOPTS, "accept: %m\n");
        free_lock();
        exit(1);
}

int is_standalone(void)
{
        struct sockaddr_storage bind_addr;
        socklen_t ba_len;

        /*
         * Check to see if a socket was passed to us from (x)inetd.
         *
         * Use getsockname() to determine if descriptor 0 is indeed a socket
         * (and thus we are probably a child of (x)inetd) or if it is instead
         * something else and we are running standalone.
         */
        ba_len = sizeof(bind_addr);
        if (getsockname(0, (struct sockaddr *)&bind_addr, &ba_len) == 0)
                return (0);     /* under (x)inetd */
        if (errno != ENOTSOCK)  /* strange... */
                syslog(LOGOPTS, "getsockname: %m\n");
        return (1);
}

int main(int argc, char *argv[])
{
        int c, lpnumber;
        char *p;

        if (argc <= 0)          /* in case not provided in (x)inetd config */
                progname = "p910nd";
        else {
                progname = argv[0];
                if ((p = strrchr(progname, '/')) != 0)
                        progname = p + 1;
        }
        lpnumber = '0';
        while ((c = getopt(argc, argv, "bi:f:v")) != EOF) {
                switch (c) {
                case 'b':
                        bidir = 1;
                        break;
                case 'f':
                        device = optarg;
                        break;
                case 'i':
                        bindaddr = optarg;
                        break;
                case 'v':
                        show_version();
                        break;
                default:
                        usage();
                        break;
                }
        }
        argc -= optind;
        argv += optind;
        if (argc > 0) {
                if (isdigit(argv[0][0]))
                        lpnumber = argv[0][0];
        }
        /* change the n in argv[0] to match the port so ps will show that */
        if ((p = strstr(progname, "p910n")) != NULL)
                p[4] = lpnumber;

        /* We used to pass (LOG_PERROR|LOG_PID|LOG_LPR|LOG_ERR) to syslog, but
         * syslog ignored the LOG_PID and LOG_PERROR option.  I.e. the intention
         * was to add both options but the effect was to have neither.
         * I disagree with the intention to add PERROR.  --Stef  */
        openlog(p, LOG_PID, LOG_LPR);
        if (is_standalone())
                server(lpnumber);
        else
                one_job(lpnumber);
        return (0);
}