/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

/*
 * TFTP User Program -- Protocol Machines
 */
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/stat.h>

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stddef.h>
#include <inttypes.h>

#include "tftpcommon.h"
#include "tftpprivate.h"

static char     *blksize_str(void);
static char     *timeout_str(void);
static char     *tsize_str(void);
static int      blksize_handler(char *);
static int      timeout_handler(char *);
static int      tsize_handler(char *);
static int      add_options(char *, char *);
static int      process_oack(tftpbuf *, int);
static void     nak(int);
static void     startclock(void);
static void     stopclock(void);
static void     printstats(char *, off_t);
static int      makerequest(int, char *, struct tftphdr *, char *);
static void     tpacket(char *, struct tftphdr *, int);

static struct options {
        char    *opt_name;
        char    *(*opt_str)(void);
        int     (*opt_handler)(char *);
} options[] = {
        { "blksize",    blksize_str, blksize_handler },
        { "timeout",    timeout_str, timeout_handler },
        { "tsize",      tsize_str, tsize_handler },
        { NULL }
};

static char     optbuf[MAX_OPTVAL_LEN];
static bool     tsize_set;

static tftpbuf  ackbuf;
static int      timeout;
static off_t    tsize;
static jmp_buf  timeoutbuf;

int     blocksize = SEGSIZE;    /* Number of data bytes in a DATA packet */

/*ARGSUSED*/
static void
timer(int signum)
{
        timeout += rexmtval;
        if (timeout >= maxtimeout) {
                (void) fputs("Transfer timed out.\n", stderr);
                longjmp(toplevel, -1);
        }
        (void) signal(SIGALRM, timer);
        longjmp(timeoutbuf, 1);
}

/*
 * Send the requested file.
 */
void
tftp_sendfile(int fd, char *name, char *mode)
{
        struct tftphdr *ap;     /* data and ack packets */
        struct tftphdr *dp;
        int n;
        volatile int count = 0, size;
        volatile ushort_t block = 0;
        volatile off_t amount = 0;
        struct sockaddr_in6 from;
        socklen_t fromlen;
        int convert;    /* true if doing nl->crlf conversion */
        FILE *file;
        struct stat statb;
        int errcode;

        startclock();   /* start stat's clock */
        dp = r_init();  /* reset fillbuf/read-ahead code */
        ap = &ackbuf.tb_hdr;
        file = fdopen(fd, "r");
        convert = (strcmp(mode, "netascii") == 0);

        tsize_set = ((tsize_opt != 0) && !convert && (fstat(fd, &statb) == 0));
        if (tsize_set)
                tsize = statb.st_size;

        do {
                (void) signal(SIGALRM, timer);
                if (count == 0) {
                        if ((size = makerequest(WRQ, name, dp, mode)) == -1) {
                                (void) fprintf(stderr,
                                    "tftp: Error: Write request packet too "
                                    "big\n");
                                (void) fclose(file);
                                return;
                        }
                        size -= 4;
                } else {
                        size = readit(file, &dp, convert);
                        if (size < 0) {
                                nak(errno + 100);
                                break;
                        }
                        dp->th_opcode = htons((ushort_t)DATA);
                        dp->th_block = htons((ushort_t)block);
                }
                timeout = 0;
                (void) setjmp(timeoutbuf);
                if (trace)
                        tpacket("sent", dp, size + 4);
                n = sendto(f, dp, size + 4, 0,
                    (struct sockaddr *)&sin6, sizeof (sin6));
                if (n != size + 4) {
                        perror("tftp: sendto");
                        goto abort;
                }
                /* Can't read-ahead first block as OACK may change blocksize */
                if (count != 0)
                        read_ahead(file, convert);
                (void) alarm(rexmtval);
                for (; ; ) {
                        (void) sigrelse(SIGALRM);
                        do {
                                fromlen = (socklen_t)sizeof (from);
                                n = recvfrom(f, ackbuf.tb_data,
                                    sizeof (ackbuf.tb_data), 0,
                                    (struct sockaddr *)&from, &fromlen);
                                if (n < 0) {
                                        perror("tftp: recvfrom");
                                        goto abort;
                                }
                        } while (n < offsetof(struct tftphdr, th_data));
                        (void) sighold(SIGALRM);
                        sin6.sin6_port = from.sin6_port;   /* added */
                        if (trace)
                                tpacket("received", ap, n);
                        /* should verify packet came from server */
                        ap->th_opcode = ntohs(ap->th_opcode);
                        if (ap->th_opcode == ERROR) {
                                ap->th_code = ntohs(ap->th_code);
                                (void) fprintf(stderr,
                                    "Error code %d", ap->th_code);
                                if (n > offsetof(struct tftphdr, th_data))
                                        (void) fprintf(stderr, ": %.*s", n -
                                            offsetof(struct tftphdr, th_data),
                                            ap->th_msg);
                                (void) fputc('\n', stderr);
                                goto abort;
                        }
                        if ((count == 0) && (ap->th_opcode == OACK)) {
                                errcode = process_oack(&ackbuf, n);
                                if (errcode >= 0) {
                                        nak(errcode);
                                        (void) fputs("Rejected OACK\n",
                                            stderr);
                                        goto abort;
                                }
                                break;
                        }
                        if (ap->th_opcode == ACK) {
                                ap->th_block = ntohs(ap->th_block);
                                if (ap->th_block == block) {
                                        break;
                                }
                                /*
                                 * Never resend the current DATA packet on
                                 * receipt of a duplicate ACK, doing so would
                                 * cause the "Sorcerer's Apprentice Syndrome".
                                 */
                        }
                }
                cancel_alarm();
                if (count > 0)
                        amount += size;
                block++;
                count++;
        } while (size == blocksize || count == 1);
abort:
        cancel_alarm();
        (void) fclose(file);
        stopclock();
        if (amount > 0)
                printstats("Sent", amount);
}

/*
 * Receive a file.
 */
void
tftp_recvfile(int fd, char *name, char *mode)
{
        struct tftphdr *ap;
        struct tftphdr *dp;
        volatile ushort_t block = 1;
        int n;
        volatile int size;
        volatile unsigned long amount = 0;
        struct sockaddr_in6 from;
        socklen_t fromlen;
        volatile bool firsttrip = true;
        FILE *file;
        int convert;    /* true if converting crlf -> lf */
        int errcode;

        startclock();
        dp = w_init();
        ap = &ackbuf.tb_hdr;
        file = fdopen(fd, "w");
        convert = (strcmp(mode, "netascii") == 0);

        tsize_set = (tsize_opt != 0);
        if (tsize_set)
                tsize = 0;

        if ((size = makerequest(RRQ, name, ap, mode)) == -1) {
                (void) fprintf(stderr,
                    "tftp: Error: Read request packet too big\n");
                (void) fclose(file);
                return;
        }

        do {
                (void) signal(SIGALRM, timer);
                if (firsttrip) {
                        firsttrip = false;
                } else {
                        ap->th_opcode = htons((ushort_t)ACK);
                        ap->th_block = htons((ushort_t)(block));
                        size = 4;
                        block++;
                }

send_oack_ack:
                timeout = 0;
                (void) setjmp(timeoutbuf);
send_ack:
                if (trace)
                        tpacket("sent", ap, size);
                if (sendto(f, ackbuf.tb_data, size, 0, (struct sockaddr *)&sin6,
                    sizeof (sin6)) != size) {
                        (void) alarm(0);
                        perror("tftp: sendto");
                        goto abort;
                }
                if (write_behind(file, convert) < 0) {
                        nak(errno + 100);
                        goto abort;
                }
                (void) alarm(rexmtval);
                for (; ; ) {
                        (void) sigrelse(SIGALRM);
                        do  {
                                fromlen = (socklen_t)sizeof (from);
                                n = recvfrom(f, dp, blocksize + 4, 0,
                                    (struct sockaddr *)&from, &fromlen);
                                if (n < 0) {
                                        perror("tftp: recvfrom");
                                        goto abort;
                                }
                        } while (n < offsetof(struct tftphdr, th_data));
                        (void) sighold(SIGALRM);
                        sin6.sin6_port = from.sin6_port;   /* added */
                        if (trace)
                                tpacket("received", dp, n);
                        /* should verify client address */
                        dp->th_opcode = ntohs(dp->th_opcode);
                        if (dp->th_opcode == ERROR) {
                                dp->th_code = ntohs(dp->th_code);
                                (void) fprintf(stderr, "Error code %d",
                                    dp->th_code);
                                if (n > offsetof(struct tftphdr, th_data))
                                        (void) fprintf(stderr, ": %.*s", n -
                                            offsetof(struct tftphdr, th_data),
                                            dp->th_msg);
                                (void) fputc('\n', stderr);
                                goto abort;
                        }
                        if ((block == 1) && (dp->th_opcode == OACK)) {
                                errcode = process_oack((tftpbuf *)dp, n);
                                if (errcode >= 0) {
                                        cancel_alarm();
                                        nak(errcode);
                                        (void) fputs("Rejected OACK\n",
                                            stderr);
                                        (void) fclose(file);
                                        return;
                                }
                                ap->th_opcode = htons((ushort_t)ACK);
                                ap->th_block = htons(0);
                                size = 4;
                                goto send_oack_ack;
                        }
                        if (dp->th_opcode == DATA) {
                                int j;

                                dp->th_block = ntohs(dp->th_block);
                                if (dp->th_block == block) {
                                        break;  /* have next packet */
                                }
                                /*
                                 * On an error, try to synchronize
                                 * both sides.
                                 */
                                j = synchnet(f);
                                if (j < 0) {
                                        perror("tftp: recvfrom");
                                        goto abort;
                                }
                                if ((j > 0) && trace) {
                                        (void) printf("discarded %d packets\n",
                                            j);
                                }
                                if (dp->th_block == (block-1)) {
                                        goto send_ack;  /* resend ack */
                                }
                        }
                }
                cancel_alarm();
                size = writeit(file, &dp, n - 4, convert);
                if (size < 0) {
                        nak(errno + 100);
                        goto abort;
                }
                amount += size;
        } while (size == blocksize);

        cancel_alarm();
        if (write_behind(file, convert) < 0) {  /* flush last buffer */
                nak(errno + 100);
                goto abort;
        }
        n = fclose(file);
        file = NULL;
        if (n == EOF) {
                nak(errno + 100);
                goto abort;
        }

        /* ok to ack, since user has seen err msg */
        ap->th_opcode = htons((ushort_t)ACK);
        ap->th_block = htons((ushort_t)block);
        if (trace)
                tpacket("sent", ap, 4);
        if (sendto(f, ackbuf.tb_data, 4, 0,
            (struct sockaddr *)&sin6, sizeof (sin6)) != 4)
                perror("tftp: sendto");

abort:
        cancel_alarm();
        if (file != NULL)
                (void) fclose(file);
        stopclock();
        if (amount > 0)
                printstats("Received", amount);
}

static int
makerequest(int request, char *name, struct tftphdr *tp, char *mode)
{
        char *cp, *cpend;
        int len;

        tp->th_opcode = htons((ushort_t)request);
        cp = (char *)&tp->th_stuff;

        /* Maximum size of a request packet is 512 bytes (RFC 2347) */
        cpend = (char *)tp + SEGSIZE;

        len = strlcpy(cp, name, cpend - cp) + 1;
        cp += len;
        if (cp > cpend)
                return (-1);

        len = strlcpy(cp, mode, cpend - cp) + 1;
        cp += len;
        if (cp > cpend)
                return (-1);

        len = add_options(cp, cpend);
        if (len == -1)
                return (-1);
        cp += len;

        return (cp - (char *)tp);
}

/*
 * Return the blksize option value string to include in the request packet.
 */
static char *
blksize_str(void)
{
        blocksize = SEGSIZE;
        if (blksize == 0)
                return (NULL);

        (void) snprintf(optbuf, sizeof (optbuf), "%d", blksize);
        return (optbuf);
}

/*
 * Return the timeout option value string to include in the request packet.
 */
static char *
timeout_str(void)
{
        if (srexmtval == 0)
                return (NULL);

        (void) snprintf(optbuf, sizeof (optbuf), "%d", srexmtval);
        return (optbuf);
}

/*
 * Return the tsize option value string to include in the request packet.
 */
static char *
tsize_str(void)
{
        if (tsize_set == false)
                return (NULL);

        (void) snprintf(optbuf, sizeof (optbuf), OFF_T_FMT, tsize);
        return (optbuf);
}

/*
 * Validate and action the blksize option value string from the OACK packet.
 * Returns -1 on success or an error code on failure.
 */
static int
blksize_handler(char *optstr)
{
        char *endp;
        int value;

        /* Make sure the option was requested */
        if (blksize == 0)
                return (EOPTNEG);
        errno = 0;
        value = (int)strtol(optstr, &endp, 10);
        if (errno != 0 || value < MIN_BLKSIZE || value > blksize ||
            *endp != '\0')
                return (EOPTNEG);
        blocksize = value;
        return (-1);
}

/*
 * Validate and action the timeout option value string from the OACK packet.
 * Returns -1 on success or an error code on failure.
 */
static int
timeout_handler(char *optstr)
{
        char *endp;
        int value;

        /* Make sure the option was requested */
        if (srexmtval == 0)
                return (EOPTNEG);
        errno = 0;
        value = (int)strtol(optstr, &endp, 10);
        if (errno != 0 || value != srexmtval || *endp != '\0')
                return (EOPTNEG);
        /*
         * Nothing to set, client and server retransmission intervals are
         * set separately in the client.
         */
        return (-1);
}

/*
 * Validate and action the tsize option value string from the OACK packet.
 * Returns -1 on success or an error code on failure.
 */
static int
tsize_handler(char *optstr)
{
        char *endp;
        longlong_t value;

        /* Make sure the option was requested */
        if (tsize_set == false)
                return (EOPTNEG);
        errno = 0;
        value = strtoll(optstr, &endp, 10);
        if (errno != 0 || value < 0 || *endp != '\0')
                return (EOPTNEG);
#if _FILE_OFFSET_BITS == 32
        if (value > MAXOFF_T)
                return (ENOSPACE);
#endif
        /*
         * Don't bother checking the tsize value we specified in a write
         * request is echoed back in the OACK.
         */
        if (tsize == 0)
                tsize = value;
        return (-1);
}

/*
 * Add TFTP options to a request packet.
 */
static int
add_options(char *obuf, char *obufend)
{
        int i;
        char *cp, *ostr;

        cp = obuf;
        for (i = 0; options[i].opt_name != NULL; i++) {
                ostr = options[i].opt_str();
                if (ostr != NULL) {
                        cp += strlcpy(cp, options[i].opt_name, obufend - cp)
                            + 1;
                        if (cp > obufend)
                                return (-1);

                        cp += strlcpy(cp, ostr, obufend - cp) + 1;
                        if (cp > obufend)
                                return (-1);
                }
        }
        return (cp - obuf);
}

/*
 * Process OACK packet sent by server in response to options in the request
 * packet. Returns -1 on success or an error code on failure.
 */
static int
process_oack(tftpbuf *oackbuf, int n)
{
        char *cp, *oackend, *optname, *optval;
        struct tftphdr *oackp;
        int i, errcode;

        oackp = &oackbuf->tb_hdr;
        cp = (char *)&oackp->th_stuff;
        oackend = (char *)oackbuf + n;

        while (cp < oackend) {
                optname = cp;
                if ((optval = next_field(optname, oackend)) == NULL)
                        return (EOPTNEG);
                if ((cp = next_field(optval, oackend)) == NULL)
                        return (EOPTNEG);
                for (i = 0; options[i].opt_name != NULL; i++) {
                        if (strcasecmp(optname, options[i].opt_name) == 0)
                                break;
                }
                if (options[i].opt_name == NULL)
                        return (EOPTNEG);
                errcode = options[i].opt_handler(optval);
                if (errcode >= 0)
                        return (errcode);
        }
        return (-1);
}

/*
 * Send a nak packet (error message).
 * Error code passed in is one of the
 * standard TFTP codes, or a UNIX errno
 * offset by 100.
 */
static void
nak(int error)
{
        struct tftphdr *tp;
        int length;
        struct errmsg *pe;

        tp = &ackbuf.tb_hdr;
        tp->th_opcode = htons((ushort_t)ERROR);
        tp->th_code = htons((ushort_t)error);
        for (pe = errmsgs; pe->e_code >= 0; pe++)
                if (pe->e_code == error)
                        break;
        if (pe->e_code < 0) {
                pe->e_msg = strerror(error - 100);
                tp->th_code = EUNDEF;
        }
        (void) strlcpy(tp->th_msg, pe->e_msg,
            sizeof (ackbuf) - sizeof (struct tftphdr));
        length = strlen(pe->e_msg) + 4;
        if (trace)
                tpacket("sent", tp, length);
        if (sendto(f, ackbuf.tb_data, length, 0,
            (struct sockaddr *)&sin6, sizeof (sin6)) != length)
                perror("nak");
}

static void
tpacket(char *s, struct tftphdr *tp, int n)
{
        static char *opcodes[] = {
            "#0", "RRQ", "WRQ", "DATA", "ACK", "ERROR", "OACK"
        };
        char *cp, *file, *mode;
        ushort_t op = ntohs(tp->th_opcode);
        char *tpend;

        if (op < RRQ || op > OACK)
                (void) printf("%s opcode=%x ", s, op);
        else
                (void) printf("%s %s ", s, opcodes[op]);

        switch (op) {
        case RRQ:
        case WRQ:
                tpend = (char *)tp + n;
                n -= sizeof (tp->th_opcode);
                file = (char *)&tp->th_stuff;
                if ((mode = next_field(file, tpend)) == NULL) {
                        (void) printf("<file=%.*s>\n", n, file);
                        break;
                }
                n -= mode - file;
                if ((cp = next_field(mode, tpend)) == NULL) {
                        (void) printf("<file=%s, mode=%.*s>\n", file, n, mode);
                        break;
                }
                (void) printf("<file=%s, mode=%s", file, mode);
                n -= cp - mode;
                if (n > 0) {
                        (void) printf(", options: ");
                        print_options(stdout, cp, n);
                }
                (void) puts(">");
                break;

        case DATA:
                (void) printf("<block=%d, %d bytes>\n", ntohs(tp->th_block),
                    n - sizeof (tp->th_opcode) - sizeof (tp->th_block));
                break;

        case ACK:
                (void) printf("<block=%d>\n", ntohs(tp->th_block));
                break;

        case OACK:
                (void) printf("<options: ");
                print_options(stdout, (char *)&tp->th_stuff,
                    n - sizeof (tp->th_opcode));
                (void) puts(">");
                break;

        case ERROR:
                (void) printf("<code=%d", ntohs(tp->th_code));
                n = n - sizeof (tp->th_opcode) - sizeof (tp->th_code);
                if (n > 0)
                        (void) printf(", msg=%.*s", n, tp->th_msg);
                (void) puts(">");
                break;
        }
}

static hrtime_t tstart, tstop;

static void
startclock(void)
{
        tstart = gethrtime();
}

static void
stopclock(void)
{
        tstop = gethrtime();
}

static void
printstats(char *direction, off_t amount)
{
        hrtime_t        delta, tenths;

        delta = tstop - tstart;
        tenths = delta / (NANOSEC / 10);
        (void) printf("%s " OFF_T_FMT " bytes in %" PRId64 ".%" PRId64
            " seconds", direction, amount, tenths / 10, tenths % 10);
        if (verbose)
                (void) printf(" [%" PRId64 " bits/sec]\n",
                    ((hrtime_t)amount * 8 * NANOSEC) / delta);
        else
                (void) putchar('\n');
}