/*
 * 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.
 *
 * @(#)tftp.c   8.1 (Berkeley) 6/6/93
 * $FreeBSD: src/usr.bin/tftp/tftp.c,v 1.5.2.3 2002/05/14 22:08:07 bsd Exp $
 * $DragonFly: src/usr.bin/tftp/tftp.c,v 1.6 2008/10/16 01:52:33 swildner Exp $
 */

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

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

#include <netinet/in.h>

#include <arpa/tftp.h>

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

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

extern  struct sockaddr_storage peeraddr; /* filled in by main */
extern  int     f;                      /* the opened socket */
extern  int     tftp_trace;
extern  int     verbose;
extern  int     rexmtval;
extern  int     maxtimeout;
extern  volatile int txrx_error;

#define PKTSIZE    SEGSIZE+4
char    ackbuf[PKTSIZE];
int     timeout;
jmp_buf toplevel;
jmp_buf timeoutbuf;

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

/*
 * Send the requested file.
 */
void
xmitfile(int fd, char *name, char *mode)
{
        struct tftphdr *ap;             /* data and ack packets */
        struct tftphdr *dp;
        int n;
        volatile unsigned short block;
        volatile int size, convert;
        volatile unsigned long amount;
        struct sockaddr_storage from;
        int 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 *)ackbuf;
        file = fdopen(fd, "r");
        convert = !strcmp(mode, "netascii");
        block = 0;
        amount = 0;
        memcpy(&peer, &peeraddr, peeraddr.ss_len);
        memset(&serv, 0, sizeof(serv));

        signal(SIGALRM, timer);
        do {
                if (block == 0)
                        size = makerequest(WRQ, name, dp, mode) - 4;
                else {
                /*      size = read(fd, dp->th_data, SEGSIZE);   */
                        size = readit(file, &dp, convert);
                        if (size < 0) {
                                nak(errno + 100, (struct sockaddr *)&peer);
                                break;
                        }
                        dp->th_opcode = htons((u_short)DATA);
                        dp->th_block = htons((u_short)block);
                }
                timeout = 0;
                (void) setjmp(timeoutbuf);
send_data:
                if (tftp_trace)
                        tpacket("sent", dp, size + 4);
                n = sendto(f, dp, size + 4, 0,
                    (struct sockaddr *)&peer, peer.ss_len);
                if (n != size + 4) {
                        warn("sendto");
                        goto abort;
                }
                read_ahead(file, convert);
                for ( ; ; ) {
                        alarm(rexmtval);
                        do {
                                fromlen = sizeof(from);
                                n = recvfrom(f, ackbuf, sizeof(ackbuf), 0,
                                    (struct sockaddr *)&from, &fromlen);
                        } while (n <= 0);
                        alarm(0);
                        if (n < 0) {
                                warn("recvfrom");
                                goto abort;
                        }
                        if (!serv.ss_family)
                                serv = from;
                        else if (!cmpport((struct sockaddr *)&serv,
                            (struct sockaddr *)&from)) {
                                warn("server port mismatch");
                                goto abort;
                        }
                        peer = from;
                        if (tftp_trace)
                                tpacket("received", ap, n);
                        /* should verify packet came from server */
                        ap->th_opcode = ntohs(ap->th_opcode);
                        ap->th_block = ntohs(ap->th_block);
                        if (ap->th_opcode == ERROR) {
                                printf("Error code %d: %s\n", ap->th_code,
                                        ap->th_msg);
                                txrx_error = 1;
                                goto abort;
                        }
                        if (ap->th_opcode == ACK) {
                                int j;

                                if (ap->th_block == block) {
                                        break;
                                }
                                /* On an error, try to synchronize
                                 * both sides.
                                 */
                                j = synchnet(f);
                                if (j && tftp_trace) {
                                        printf("discarded %d packets\n",
                                                        j);
                                }
                                if (ap->th_block == (block-1)) {
                                        goto send_data;
                                }
                        }
                }
                if (block > 0)
                        amount += size;
                block++;
        } while (size == SEGSIZE || block == 1);
abort:
        fclose(file);
        stopclock();
        if (amount > 0)
                printstats("Sent", amount);
}

/*
 * Receive a file.
 */
void
recvfile(int fd, char *name, char *mode)
{
        struct tftphdr *ap;
        struct tftphdr *dp;
        int n;
        volatile unsigned short block;
        volatile int size, firsttrip;
        volatile unsigned long amount;
        struct sockaddr_storage from;
        int fromlen;
        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 *)ackbuf;
        file = fdopen(fd, "w");
        convert = !strcmp(mode, "netascii");
        block = 1;
        firsttrip = 1;
        amount = 0;
        memcpy(&peer, &peeraddr, peeraddr.ss_len);
        memset(&serv, 0, sizeof(serv));

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

                                if (dp->th_block == block) {
                                        break;          /* have next packet */
                                }
                                /* On an error, try to synchronize
                                 * both sides.
                                 */
                                j = synchnet(f);
                                if (j && tftp_trace) {
                                        printf("discarded %d packets\n", j);
                                }
                                if (dp->th_block == (block-1)) {
                                        goto send_ack;  /* resend ack */
                                }
                        }
                }
        /*      size = write(fd, dp->th_data, n - 4); */
                size = writeit(file, &dp, n - 4, convert);
                if (size < 0) {
                        nak(errno + 100, (struct sockaddr *)&peer);
                        break;
                }
                amount += size;
        } while (size == SEGSIZE);
abort:                                          /* ok to ack, since user */
        ap->th_opcode = htons((u_short)ACK);    /* has seen err msg */
        ap->th_block = htons((u_short)block);
        (void) sendto(f, ackbuf, 4, 0, (struct sockaddr *)&peer,
            peer.ss_len);
        write_behind(file, convert);            /* flush last buffer */
        fclose(file);
        stopclock();
        if (amount > 0)
                printstats("Received", amount);
}

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

        tp->th_opcode = htons((u_short)request);
        cp = tp->th_stuff;
        strcpy(cp, name);
        cp += strlen(name);
        *cp++ = '\0';
        strcpy(cp, mode);
        cp += strlen(mode);
        *cp++ = '\0';
        return (cp - (char *)tp);
}

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" },
        { -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)
{
        struct errmsg *pe;
        struct tftphdr *tp;
        int length;

        tp = (struct tftphdr *)ackbuf;
        tp->th_opcode = htons((u_short)ERROR);
        tp->th_code = htons((u_short)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;
        }
        strcpy(tp->th_msg, pe->e_msg);
        length = strlen(pe->e_msg) + 4;
        if (tftp_trace)
                tpacket("sent", tp, length);
        if (sendto(f, ackbuf, length, 0, peer, peer->sa_len) != length)
                warn("nak");
}

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

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

        case RRQ:
        case WRQ:
                n -= 2;
                file = cp = tp->th_stuff;
                cp = strchr(cp, '\0');
                printf("<file=%s, mode=%s>\n", file, cp + 1);
                break;

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

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

        case ERROR:
                printf("<code=%d, msg=%s>\n", ntohs(tp->th_code), tp->th_msg);
                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 */
        printf("%s %lu bytes in %.1f seconds", direction, amount, delta);
        if (verbose)
                printf(" [%.0f bits/sec]", (amount*8.)/delta);
        putchar('\n');
}

static void
timer(int sig __unused)
{

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

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

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

        return 1;
}