/*      $NetBSD: tftp.c,v 1.37 2023/01/06 17:18:56 christos Exp $       */

/*
 * Copyright (c) 1983, 1993
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)tftp.c      8.1 (Berkeley) 6/6/93";
#else
__RCSID("$NetBSD: tftp.c,v 1.37 2023/01/06 17:18:56 christos Exp $");
#endif
#endif /* not lint */

/* Many bug fixes are from Jim Guyton <guyton@rand-unix> */

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

#include <netinet/in.h>

#include <arpa/tftp.h>
#include <arpa/inet.h>

#include <err.h>
#include <errno.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>

#include "extern.h"
#include "tftpsubs.h"

extern jmp_buf  toplevel;

char    ackbuf[PKTSIZE];
int     timeout;
jmp_buf timeoutbuf;

static void nak(int, struct sockaddr *);
static int makerequest(int, const char *, struct tftphdr *, const char *, off_t);
static void printstats(const char *, unsigned long);
static void startclock(void);
static void stopclock(void);
static __dead void timer(int);
static void tpacket(const char *, struct tftphdr *, int);
static int cmpport(struct sockaddr *, struct sockaddr *);

static void get_options(struct tftphdr *, int);
static int tftp_igmp_join(void);
static void tftp_igmp_leave(int);

static void
get_options(struct tftphdr *ap, int size)
{
        unsigned long val;
        char *opt, *endp, *nextopt, *valp;
        int l;

        size -= 2;      /* skip over opcode */
        opt = ap->th_stuff;
        endp = opt + size - 1;
        *endp = '\0';

        while (opt < endp) {
                int ismulticast;
                l = strlen(opt) + 1;
                valp = opt + l;
                ismulticast = !strcasecmp(opt, "multicast");
                if (valp < endp) {
                        val = strtoul(valp, NULL, 10);
                        l = strlen(valp) + 1;
                        nextopt = valp + l;
                        if (!ismulticast) {
                                if (val == ULONG_MAX && errno == ERANGE) {
                                        /* Report illegal value */
                                        opt = nextopt;
                                        continue;
                                }
                        }
                } else {
                        /* Badly formed OACK */
                        break;
                }
                if (strcmp(opt, "tsize") == 0) {
                        /* cool, but we'll ignore it */
                } else if (strcmp(opt, "timeout") == 0) {
                        if (val >= 1 && val <= 255) {
                                rexmtval = val;
                        } else {
                                /* Report error? */
                        }
                } else if (strcmp(opt, "blksize") == 0) {
                        if (val >= 8 && val <= MAXSEGSIZE) {
                                blksize = val;
                        } else {
                                /* Report error? */
                        }
                } else if (ismulticast) {
                        char multicast[24];
                        char *pmulticast;
                        char *addr;

                        strlcpy(multicast, valp, sizeof(multicast));
                        pmulticast = multicast;
                        addr = strsep(&pmulticast, ",");
                        if (pmulticast == NULL)
                                continue; /* Report error? */
                        mcport = atoi(strsep(&pmulticast, ","));
                        if (pmulticast == NULL)
                                continue; /* Report error? */
                        mcmasterslave = atoi(pmulticast);
                        mcaddr = inet_addr(addr);
                        if (mcaddr == INADDR_NONE)
                                continue; /* Report error? */
                } else {
                        /* unknown option */
                }
                opt = nextopt;
        }
}

static int
tftp_igmp_join(void)
{
        struct ip_mreq req;
        struct sockaddr_in s;
        int fd, rv;

        memset(&req, 0, sizeof(struct ip_mreq));
        req.imr_multiaddr.s_addr = mcaddr;
        req.imr_interface.s_addr = INADDR_ANY;

        fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
        if (fd < 0) {
                perror("socket");
                return fd;
        }

        memset(&s, 0, sizeof(struct sockaddr_in));
        s.sin_family = AF_INET;
        s.sin_port = htons(mcport);
        s.sin_len = sizeof(struct sockaddr_in);
        rv = bind(fd, (struct sockaddr *)&s, sizeof(struct sockaddr_in));
        if (rv < 0) {
                perror("bind");
                close(fd);
                return rv;
        }

        rv = setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &req,
            sizeof(struct ip_mreq));
        if (rv < 0) {
                perror("setsockopt");
                close(fd);
                return rv;
        }

        return fd;
}

static void
tftp_igmp_leave(int fd)
{
        struct ip_mreq req;
        int rv;

        memset(&req, 0, sizeof(struct ip_mreq));
        req.imr_multiaddr.s_addr = mcaddr;
        req.imr_interface.s_addr = INADDR_ANY;

        rv = setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &req,
            sizeof(struct ip_mreq));
        if (rv < 0)
                perror("setsockopt");

        close(fd);

        return;
}

/*
 * Send the requested file.
 */
void
sendfile(int fd, const char *name, const char *mode)
{
        struct tftphdr *ap;        /* data and ack packets */
        struct tftphdr *dp;
        int j, n;
        volatile unsigned int block;
        volatile int size, convert;
        volatile unsigned long amount;
        struct sockaddr_storage from;
        struct stat sbuf;
        volatile off_t filesize = 0;
        socklen_t fromlen;
        FILE *file;
        struct sockaddr_storage peer;
        struct sockaddr_storage serv;   /* valid server port number */

        startclock();           /* start stat's clock */
        dp = r_init();          /* reset fillbuf/read-ahead code */
        ap = (struct tftphdr *)(void *)ackbuf;
        if (tsize) {
                if (fstat(fd, &sbuf) == 0) {
                        filesize = sbuf.st_size;
                } else {
                        filesize = -1ULL;
                }
        }
        file = fdopen(fd, "r");
        convert = !strcmp(mode, "netascii");
        block = 0;
        amount = 0;
        (void)memcpy(&peer, &peeraddr, (size_t)peeraddr.ss_len);
        (void)memset(&serv, 0, sizeof(serv));

        (void)signal(SIGALRM, timer);
        do {
                if (block == 0)
                        size = makerequest(WRQ, name, dp, mode, filesize) - 4;
                else {
                /*      size = read(fd, dp->th_data, SEGSIZE);   */
                        size = readit(file, &dp, blksize, convert);
                        if (size < 0) {
                                nak(errno + 100,
                                    (struct sockaddr *)(void *)&peer);
                                break;
                        }
                        dp->th_opcode = htons((u_short)DATA);
                        dp->th_block = htons((u_short)block);
                }
                timeout = 0;
                (void) setjmp(timeoutbuf);
send_data:
                if (trace)
                        tpacket("sent", dp, size + 4);
                n = sendto(f, dp, (socklen_t)(size + 4), 0,
                    (struct sockaddr *)(void *)&peer, (socklen_t)peer.ss_len);
                if (n != size + 4) {
                        warn("sendto");
                        goto abort;
                }
                if (block)
                        read_ahead(file, blksize, convert);
                for ( ; ; ) {
                        (void)alarm(rexmtval);
                        do {
                                int curf;
                                fromlen = sizeof(from);
                                if (mcaddr != INADDR_NONE)
                                        curf = mf;
                                else
                                        curf = f;
                                n = recvfrom(curf, ackbuf, sizeof(ackbuf), 0,
                                    (struct sockaddr *)(void *)&from, &fromlen);
                        } while (n <= 0);
                        (void)alarm(0);
                        if (n < 0) {
                                warn("recvfrom");
                                goto abort;
                        }
                        if (!serv.ss_family)
                                serv = from;
                        else if (!cmpport((struct sockaddr *)(void *)&serv,
                            (struct sockaddr *)(void *)&from)) {
                                warn("server port mismatch");
                                goto abort;
                        }
                        peer = from;
                        if (trace)
                                tpacket("received", ap, n);
                        /* should verify packet came from server */
                        ap->th_opcode = ntohs(ap->th_opcode);
                        if (ap->th_opcode == ERROR) {
                                (void)printf("Error code %d: %s\n", 
                                    ntohs(ap->th_code), ap->th_msg);
                                goto abort;
                        }
                        if (ap->th_opcode == ACK) {
                                ap->th_block = ntohs(ap->th_block);

                                if (ap->th_block == 0) {
                                        /*
                                         * If the extended options are enabled,
                                         * the server just refused 'em all.
                                         * The only one that _really_
                                         * matters is blksize, but we'll
                                         * clear timeout and mcaddr, too.
                                         */
                                        blksize = def_blksize;
                                        rexmtval = def_rexmtval;
                                        mcaddr = INADDR_NONE;
                                }
                                if (ap->th_block == block) {
                                        break;
                                }
                                /* On an error, try to synchronize
                                 * both sides.
                                 */
                                j = synchnet(f, blksize+4);
                                if (j && trace) {
                                        (void)printf("discarded %d packets\n",
                                                        j);
                                }
                                if (ap->th_block == (block-1)) {
                                        goto send_data;
                                }
                        }
                        if (ap->th_opcode == OACK) {
                                if (block == 0) {
                                        blksize = def_blksize;
                                        rexmtval = def_rexmtval;
                                        mcaddr = INADDR_NONE;
                                        get_options(ap, n);
                                        break;
                                }
                        }
                }
                if (block > 0)
                        amount += size;
                block++;
        } while ((size_t)size == blksize || block == 1);
abort:
        (void)fclose(file);
        stopclock();
        if (amount > 0)
                printstats("Sent", amount);
}

/*
 * Receive a file.
 */
void
recvfile(int fd, const char *name, const char *mode)
{
        struct tftphdr *ap;
        struct tftphdr *dp;
        int j, n;
        volatile int oack = 0;
        volatile unsigned int block;
        volatile int size, firsttrip;
        volatile unsigned long amount;
        struct sockaddr_storage from;
        socklen_t fromlen;
        volatile size_t readlen;
        FILE *file;
        volatile int convert;           /* true if converting crlf -> lf */
        struct sockaddr_storage peer;
        struct sockaddr_storage serv;   /* valid server port number */

        startclock();
        dp = w_init();
        ap = (struct tftphdr *)(void *)ackbuf;
        file = fdopen(fd, "w");
        convert = !strcmp(mode, "netascii");
        block = 1;
        firsttrip = 1;
        amount = 0;
        (void)memcpy(&peer, &peeraddr, (size_t)peeraddr.ss_len);
        (void)memset(&serv, 0, sizeof(serv));

        (void)signal(SIGALRM, timer);
        do {
                if (firsttrip) {
                        size = makerequest(RRQ, name, ap, mode, (off_t)0);
                        readlen = PKTSIZE;
                        firsttrip = 0;
                } else {
                        ap->th_opcode = htons((u_short)ACK);
                        ap->th_block = htons((u_short)(block));
                        readlen = blksize+4;
                        size = 4;
                        block++;
                }
                timeout = 0;
                (void) setjmp(timeoutbuf);
send_ack:
                if (trace)
                        tpacket("sent", ap, size);
                if (sendto(f, ackbuf, (socklen_t)size, 0,
                    (struct sockaddr *)(void *)&peer,
                    (socklen_t)peer.ss_len) != size) {
                        (void)alarm(0);
                        warn("sendto");
                        goto abort;
                }
skip_ack:
                if (write_behind(file, convert) == -1)
                        goto abort;
                for ( ; ; ) {
                        (void)alarm(rexmtval);
                        do  {
                                int readfd;
                                if (mf > 0)
                                        readfd = mf;
                                else
                                        readfd = f;
                                fromlen = sizeof(from);
                                n = recvfrom(readfd, dp, readlen, 0,
                                    (struct sockaddr *)(void *)&from, &fromlen);
                        } while (n <= 0);
                        (void)alarm(0);
                        if (n < 0) {
                                warn("recvfrom");
                                goto abort;
                        }
                        if (!serv.ss_family)
                                serv = from;
                        else if (!cmpport((struct sockaddr *)(void *)&serv,
                            (struct sockaddr *)(void *)&from)) {
                                warn("server port mismatch");
                                goto abort;
                        }
                        peer = from;
                        if (trace)
                                tpacket("received", dp, n);
                        /* should verify client address */
                        dp->th_opcode = ntohs(dp->th_opcode);
                        if (dp->th_opcode == ERROR) {
                                (void)printf("Error code %d: %s\n",
                                    ntohs(dp->th_code), dp->th_msg);
                                goto abort;
                        }
                        if (dp->th_opcode == DATA) {
                                dp->th_block = ntohs(dp->th_block);

                                if (dp->th_block == 1 && !oack) {
                                        /* no OACK, revert to defaults */
                                        blksize = def_blksize;
                                        rexmtval = def_rexmtval;
                                }
                                if (dp->th_block == block) {
                                        break;          /* have next packet */
                                }
                                /* On an error, try to synchronize
                                 * both sides.
                                 */
                                j = synchnet(f, blksize);
                                if (j && trace) {
                                        (void)printf("discarded %d packets\n",
                                            j);
                                }
                                if (dp->th_block == (block-1)) {
                                        goto send_ack;  /* resend ack */
                                }
                        }
                        if (dp->th_opcode == OACK) {
                                if (block == 1) {
                                        oack = 1;
                                        blksize = def_blksize;
                                        rexmtval = def_rexmtval;
                                        get_options(dp, n);
                                        ap->th_opcode = htons(ACK);
                                        ap->th_block = 0;
                                        readlen = blksize+4;
                                        size = 4;
                                        if (mcaddr != INADDR_NONE) {
                                                mf = tftp_igmp_join();
                                                if (mf < 0) 
                                                        goto abort;
                                                if (mcmasterslave == 0)
                                                        goto skip_ack;
                                        }
                                        goto send_ack;
                                }
                        }
                }
        /*      size = write(fd, dp->th_data, n - 4); */
                size = writeit(file, &dp, n - 4, convert);
                if (size < 0) {
                        nak(errno + 100, (struct sockaddr *)(void *)&peer);
                        break;
                }
                amount += size;
        } while ((size_t)size == blksize);
abort:                                          /* ok to ack, since user */
        ap->th_opcode = htons((u_short)ACK);    /* has seen err msg */
        ap->th_block = htons((u_short)block);
        if (mcaddr != INADDR_NONE && mf >= 0) {
                tftp_igmp_leave(mf);
                mf = -1;
        }
        (void) sendto(f, ackbuf, 4, 0, (struct sockaddr *)(void *)&peer,
            (socklen_t)peer.ss_len);
        /*
         * flush last buffer
         * We do not check for failure because last buffer
         * can be empty, thus returning an error.
         * XXX maybe we should fix 'write_behind' instead.
         */
        (void)write_behind(file, convert);
        (void)fclose(file);
        stopclock();
        if (amount > 0)
                printstats("Received", amount);
}

static int
makerequest(int request, const char *name, struct tftphdr *tp, const char *mode,
        off_t filesize)
{
        char *cp;

        tp->th_opcode = htons((u_short)request);
#ifndef __SVR4
        cp = tp->th_stuff;
#else
        cp = (void *)&tp->th_stuff;
#endif
        (void)strcpy(cp, name);
        cp += strlen(name);
        *cp++ = '\0';
        (void)strcpy(cp, mode);
        cp += strlen(mode);
        *cp++ = '\0';
        if (tsize) {
                (void)strcpy(cp, "tsize");
                cp += strlen(cp);
                *cp++ = '\0';
                (void)sprintf(cp, "%lu", (unsigned long) filesize);
                cp += strlen(cp);
                *cp++ = '\0';
        }
        if (tout) {
                (void)strcpy(cp, "timeout");
                cp += strlen(cp);
                *cp++ = '\0';
                (void)sprintf(cp, "%d", rexmtval);
                cp += strlen(cp);
                *cp++ = '\0';
        }
        if (blksize != SEGSIZE) {
                (void)strcpy(cp, "blksize");
                cp += strlen(cp);
                *cp++ = '\0';
                (void)sprintf(cp, "%zd", blksize);
                cp += strlen(cp);
                *cp++ = '\0';
        }
        return (cp - (char *)(void *)tp);
}

const struct errmsg {
        int     e_code;
        const char *e_msg;
} errmsgs[] = {
        { EUNDEF,       "Undefined error code" },
        { ENOTFOUND,    "File not found" },
        { EACCESS,      "Access violation" },
        { ENOSPACE,     "Disk full or allocation exceeded" },
        { EBADOP,       "Illegal TFTP operation" },
        { EBADID,       "Unknown transfer ID" },
        { EEXISTS,      "File already exists" },
        { ENOUSER,      "No such user" },
        { EOPTNEG,      "Option negotiation failed" },
        { -1,           0 }
};

/*
 * 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 sockaddr *peer)
{
        const struct errmsg *pe;
        struct tftphdr *tp;
        int length;
        size_t msglen;

        tp = (struct tftphdr *)(void *)ackbuf;
        tp->th_opcode = htons((u_short)ERROR);
        msglen = sizeof(ackbuf) - (&tp->th_msg[0] - ackbuf);
        for (pe = errmsgs; pe->e_code >= 0; pe++)
                if (pe->e_code == error)
                        break;
        if (pe->e_code < 0) {
                tp->th_code = EUNDEF;
                (void)strlcpy(tp->th_msg, strerror(error - 100), msglen);
        } else {
                tp->th_code = htons((u_short)error);
                (void)strlcpy(tp->th_msg, pe->e_msg, msglen);
        }
        length = strlen(tp->th_msg);
        msglen = &tp->th_msg[length + 1] - ackbuf;
        if (trace)
                tpacket("sent", tp, (int)msglen);
        if ((size_t)sendto(f, ackbuf, msglen, 0, peer, (socklen_t)peer->sa_len) != msglen)
                warn("nak");
}

static void
tpacket(const char *s, struct tftphdr *tp, int n)
{
        static const char *opcodes[] =
           { "#0", "RRQ", "WRQ", "DATA", "ACK", "ERROR", "OACK" };
        char *cp, *file, *endp, *opt = NULL;
        const char *spc;
        u_short op = ntohs(tp->th_opcode);
        int i, o;

        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:
                n -= 2;
#ifndef __SVR4
                cp = tp->th_stuff;
#else
                cp = (void *) &tp->th_stuff;
#endif
                endp = cp + n - 1;
                if (*endp != '\0') {    /* Shouldn't happen, but... */
                        *endp = '\0';
                }
                file = cp;
                cp = strchr(cp, '\0') + 1;
                (void)printf("<file=%s, mode=%s", file, cp);
                cp = strchr(cp, '\0') + 1;
                o = 0;
                while (cp < endp) {
                        i = strlen(cp) + 1;
                        if (o) {
                                (void)printf(", %s=%s", opt, cp);
                        } else {
                                opt = cp;
                        }
                        o = (o+1) % 2;
                        cp += i;
                }
                (void)printf(">\n");
                break;

        case DATA:
                (void)printf("<block=%d, %d bytes>\n", ntohs(tp->th_block),
                    n - 4);
                break;

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

        case ERROR:
                (void)printf("<code=%d, msg=%s>\n", ntohs(tp->th_code),
                    tp->th_msg);
                break;

        case OACK:
                o = 0;
                n -= 2;
                cp = tp->th_stuff;
                endp = cp + n - 1;
                if (*endp != '\0') {    /* Shouldn't happen, but... */
                        *endp = '\0';
                }
                (void)printf("<");
                spc = "";
                while (cp < endp) {
                        i = strlen(cp) + 1;
                        if (o) {
                                (void)printf("%s%s=%s", spc, opt, cp);
                                spc = ", ";
                        } else {
                                opt = cp;
                        }
                        o = (o+1) % 2;
                        cp += i;
                }
                (void)printf(">\n");
                break;
        }
}

struct timeval tstart;
struct timeval tstop;

static void
startclock(void)
{

        (void)gettimeofday(&tstart, NULL);
}

static void
stopclock(void)
{

        (void)gettimeofday(&tstop, NULL);
}

static void
printstats(const char *direction, unsigned long amount)
{
        double delta;

        /* compute delta in 1/10's second units */
        delta = ((tstop.tv_sec*10.)+(tstop.tv_usec/100000)) -
                ((tstart.tv_sec*10.)+(tstart.tv_usec/100000));
        delta = delta/10.;      /* back to seconds */
        (void)printf("%s %ld bytes in %.1f seconds", direction, amount, delta);
        if (verbose)
                (void)printf(" [%.0f bits/sec]", (amount*8.)/delta);
        (void)putchar('\n');
}

static void
/*ARGSUSED*/
timer(int sig)
{

        timeout += rexmtval;
        if (timeout >= maxtimeout) {
                (void)printf("Transfer timed out.");
                longjmp(toplevel, -1);
        }
        longjmp(timeoutbuf, 1);
}

static int
cmpport(struct sockaddr *sa, struct sockaddr *sb)
{
        char a[NI_MAXSERV], b[NI_MAXSERV];

        if (getnameinfo(sa, (socklen_t)sa->sa_len, NULL, 0, a, sizeof(a),
            NI_NUMERICSERV))
                return 0;
        if (getnameinfo(sb, (socklen_t)sb->sa_len, NULL, 0, b, sizeof(b),
            NI_NUMERICSERV))
                return 0;
        if (strcmp(a, b) != 0)
                return 0;

        return 1;
}