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[unix-history] / usr / src / libexec / tftpd / tftpd.c

/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1983 Regents of the University of California.\n\
All rights reserved.\n";
#endif not lint

#ifndef lint
static char sccsid[] = "@(#)tftpd.c     5.1 (Berkeley) %G%";
#endif not lint

/*
* Trivial file transfer protocol server.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <sys/stat.h>

#include <netinet/in.h>

#include <arpa/tftp.h>

#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <netdb.h>
#include <setjmp.h>
#include <syslog.h>

#define TIMEOUT         5

extern  int errno;
struct  sockaddr_in sin = { AF_INET };
int     peer;
int     rexmtval = TIMEOUT;
int     maxtimeout = 5*TIMEOUT;
char    buf[BUFSIZ];
struct  sockaddr_in from;
int     fromlen;

main()
{
       register struct tftphdr *tp;
       register int n;

       alarm(10);
       fromlen = sizeof (from);
       n = recvfrom(0, buf, sizeof (buf), 0,
           (caddr_t)&from, &fromlen);
       if (n < 0) {
               perror("tftpd: recvfrom");
               exit(1);
       }
       from.sin_family = AF_INET;
       alarm(0);
       close(0);
       close(1);
       peer = socket(AF_INET, SOCK_DGRAM, 0);
       if (peer < 0) {
               openlog("tftpd", LOG_PID, 0);
               syslog(LOG_ERR, "socket: %m");
               exit(1);
       }
       if (bind(peer, (caddr_t)&sin, sizeof (sin)) < 0) {
               openlog("tftpd", LOG_PID, 0);
               syslog(LOG_ERR, "bind: %m");
               exit(1);
       }
       if (connect(peer, (caddr_t)&from, sizeof(from)) < 0) {
               openlog("tftpd", LOG_PID, 0);
               syslog(LOG_ERR, "connect: %m");
               exit(1);
       }
       tp = (struct tftphdr *)buf;
       tp->th_opcode = ntohs(tp->th_opcode);
       if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
               tftp(tp, n);
       exit(1);
}

int     validate_access();
int     sendfile(), recvfile();

struct formats {
       char    *f_mode;
       int     (*f_validate)();
       int     (*f_send)();
       int     (*f_recv)();
} formats[] = {
       { "netascii",   validate_access,        sendfile,       recvfile },
       { "octet",      validate_access,        sendfile,       recvfile },
#ifdef notdef
       { "mail",       validate_user,          sendmail,       recvmail },
#endif
       { 0 }
};

/*
* Handle initial connection protocol.
*/
tftp(tp, size)
       struct tftphdr *tp;
       int size;
{
       register char *cp;
       int first = 1, ecode;
       register struct formats *pf;
       char *filename, *mode;

       filename = cp = tp->th_stuff;
again:
       while (cp < buf + size) {
               if (*cp == '\0')
                       break;
               cp++;
       }
       if (*cp != '\0') {
               nak(EBADOP);
               exit(1);
       }
       if (first) {
               mode = ++cp;
               first = 0;
               goto again;
       }
       for (cp = mode; *cp; cp++)
               if (isupper(*cp))
                       *cp = tolower(*cp);
       for (pf = formats; pf->f_mode; pf++)
               if (strcmp(pf->f_mode, mode) == 0)
                       break;
       if (pf->f_mode == 0) {
               nak(EBADOP);
               exit(1);
       }
       ecode = (*pf->f_validate)(filename, tp->th_opcode);
       if (ecode) {
               nak(ecode);
               exit(1);
       }
       if (tp->th_opcode == WRQ)
               (*pf->f_recv)(pf);
       else
               (*pf->f_send)(pf);
       exit(0);
}

int     fd;

/*
* Validate file access.  Since we
* have no uid or gid, for now require
* file to exist and be publicly
* readable/writable.
* Note also, full path name must be
* given as we have no login directory.
*/
validate_access(file, mode)
       char *file;
       int mode;
{
       struct stat stbuf;

       if (*file != '/')
               return (EACCESS);
       if (stat(file, &stbuf) < 0)
               return (errno == ENOENT ? ENOTFOUND : EACCESS);
       if (mode == RRQ) {
               if ((stbuf.st_mode&(S_IREAD >> 6)) == 0)
                       return (EACCESS);
       } else {
               if ((stbuf.st_mode&(S_IWRITE >> 6)) == 0)
                       return (EACCESS);
       }
       fd = open(file, mode == RRQ ? 0 : 1);
       if (fd < 0)
               return (errno + 100);
       return (0);
}

int     timeout;
jmp_buf timeoutbuf;

timer()
{

       timeout += rexmtval;
       if (timeout >= maxtimeout)
               exit(1);
       longjmp(timeoutbuf, 1);
}

/*
* Send the requested file.
*/
sendfile(pf)
       struct format *pf;
{
       register struct tftphdr *tp;
       register int block = 1, size, n;

       signal(SIGALRM, timer);
       tp = (struct tftphdr *)buf;
       do {
               size = read(fd, tp->th_data, SEGSIZE);
               if (size < 0) {
                       nak(errno + 100);
                       return;
               }
               tp->th_opcode = htons((u_short)DATA);
               tp->th_block = htons((u_short)block);
               timeout = 0;
               (void) setjmp(timeoutbuf);
               if (send(peer, buf, size + 4, 0) != size + 4) {
                       perror("tftpd: send");
                       return;
               }
               do {
                       alarm(rexmtval);
                       n = recv(peer, buf, sizeof (buf), 0);
                       alarm(0);
                       if (n < 0) {
                               perror("tftpd: recv");
                               return;
                       }
                       tp->th_opcode = ntohs((u_short)tp->th_opcode);
                       tp->th_block = ntohs((u_short)tp->th_block);
                       if (tp->th_opcode == ERROR)
                               return;
               } while (tp->th_opcode != ACK || tp->th_block != block);
               block++;
       } while (size == SEGSIZE);
}

/*
* Receive a file.
*/
recvfile(pf)
       struct format *pf;
{
       register struct tftphdr *tp;
       register int block = 0, n, size;

       signal(SIGALRM, timer);
       tp = (struct tftphdr *)buf;
       do {
               timeout = 0;
               tp->th_opcode = htons((u_short)ACK);
               tp->th_block = htons((u_short)block);
               block++;
               (void) setjmp(timeoutbuf);
               if (send(peer, buf, 4, 0) != 4) {
                       perror("tftpd: send");
                       goto abort;
               }
               do {
                       alarm(rexmtval);
                       n = recv(peer, buf, sizeof (buf), 0);
                       alarm(0);
                       if (n < 0) {
                               perror("tftpd: recv");
                               goto abort;
                       }
                       tp->th_opcode = ntohs((u_short)tp->th_opcode);
                       tp->th_block = ntohs((u_short)tp->th_block);
                       if (tp->th_opcode == ERROR)
                               goto abort;
               } while (tp->th_opcode != DATA || block != tp->th_block);
               size = write(fd, tp->th_data, n - 4);
               if (size < 0) {
                       nak(errno + 100);
                       goto abort;
               }
       } while (size == SEGSIZE);
abort:
       tp->th_opcode = htons((u_short)ACK);
       tp->th_block = htons((u_short)(block));
       (void) send(peer, buf, 4, 0);
}

struct errmsg {
       int     e_code;
       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.
*/
nak(error)
       int error;
{
       register struct tftphdr *tp;
       int length;
       register struct errmsg *pe;
       extern char *sys_errlist[];

       tp = (struct tftphdr *)buf;
       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 = sys_errlist[error - 100];
       strcpy(tp->th_msg, pe->e_msg);
       length = strlen(pe->e_msg);
       tp->th_msg[length] = '\0';
       length += 5;
       if (send(peer, buf, length, 0) != length)
               perror("nak");
       exit(1);
}