4.4BSD snapshot (revision 8.1); add 1993 to copyright

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

diff --git a/usr/src/libexec/tftpd/tftpd.c b/usr/src/libexec/tftpd/tftpd.c
index 4b26edc..3e9c0f7 100644 (file)
--- a/usr/src/libexec/tftpd/tftpd.c
+++ b/usr/src/libexec/tftpd/tftpd.c
@@ -1,118 +1,233 @@
-/*     tftpd.c 4.8     83/05/03        */
+/*
+ * Copyright (c) 1983, 1993
+ *     The Regents of the University of California.  All rights reserved.
+ *
+ * %sccs.include.redist.c%
+ */
+
+#ifndef lint
+static char copyright[] =
+"@(#) Copyright (c) 1983, 1993\n\
+       The Regents of the University of California.  All rights reserved.\n";
+#endif /* not lint */
+
+#ifndef lint
+static char sccsid[] = "@(#)tftpd.c    8.1 (Berkeley) %G%";
+#endif /* not lint */

 
 /*
  * Trivial file transfer protocol server.
 
 /*
  * Trivial file transfer protocol server.

+ *
+ * This version includes many modifications by Jim Guyton
+ * <guyton@rand-unix>.

  */
  */

-#include <sys/types.h>
-#include <sys/socket.h>
+
+#include <sys/param.h>

 #include <sys/ioctl.h>
 #include <sys/ioctl.h>

+#include <sys/stat.h>
+#include <sys/socket.h>

 
 #include <netinet/in.h>
 
 #include <netinet/in.h>

-

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

+#include <arpa/inet.h>

 
 

-#include <signal.h>
-#include <stat.h>
-#include <stdio.h>
-#include <wait.h>
-#include <errno.h>

 #include <ctype.h>
 #include <ctype.h>

+#include <errno.h>
+#include <fcntl.h>

 #include <netdb.h>
 #include <netdb.h>

+#include <setjmp.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+#include <unistd.h>
+
+#include "tftpsubs.h"
+
+#define        TIMEOUT         5
+
+int    peer;
+int    rexmtval = TIMEOUT;
+int    maxtimeout = 5*TIMEOUT;
+
+#define        PKTSIZE SEGSIZE+4
+char   buf[PKTSIZE];
+char   ackbuf[PKTSIZE];
+struct sockaddr_in from;
+int    fromlen;
+
+void   tftp __P((struct tftphdr *, int));

 
 

-extern int errno;
-struct sockaddr_in sin = { AF_INET };
-int    f;
-char   buf[BUFSIZ];
+/*
+ * Null-terminated directory prefix list for absolute pathname requests and
+ * search list for relative pathname requests.
+ *
+ * MAXDIRS should be at least as large as the number of arguments that
+ * inetd allows (currently 20).
+ */
+#define MAXDIRS        20
+static struct dirlist {
+       char    *name;
+       int     len;
+} dirs[MAXDIRS+1];
+static int     suppress_naks;
+static int     logging;
+
+static char *errtomsg __P((int));
+static void  nak __P((int));
+static char *verifyhost __P((struct sockaddr_in *));

 
 

+int

 main(argc, argv)
 main(argc, argv)

+       int argc;

        char *argv[];
 {
        char *argv[];
 {

-       union wait status;
-       struct sockaddr_in from;

        register struct tftphdr *tp;
        register int n;
        register struct tftphdr *tp;
        register int n;

-       struct servent *sp;
+       int ch, on;
+       struct sockaddr_in sin;
+
+       openlog("tftpd", LOG_PID, LOG_FTP);
+       while ((ch = getopt(argc, argv, "ln")) != EOF) {
+               switch (ch) {
+               case 'l':
+                       logging = 1;
+                       break;
+               case 'n':
+                       suppress_naks = 1;
+                       break;
+               default:
+                       syslog(LOG_WARNING, "ignoring unknown option -%c", ch);
+               }
+       }
+       if (optind < argc) {
+               struct dirlist *dirp;

 
 

-       sp = getservbyname("tftp", "udp");
-       if (sp == 0) {
-               fprintf(stderr, "tftpd: udp/tftp: unknown service\n");
+               /* Get list of directory prefixes. Skip relative pathnames. */
+               for (dirp = dirs; optind < argc && dirp < &dirs[MAXDIRS];
+                    optind++) {
+                       if (argv[optind][0] == '/') {
+                               dirp->name = argv[optind];
+                               dirp->len  = strlen(dirp->name);
+                               dirp++;
+                       }
+               }
+       }
+
+       on = 1;
+       if (ioctl(0, FIONBIO, &on) < 0) {
+               syslog(LOG_ERR, "ioctl(FIONBIO): %m\n");

                exit(1);
        }
                exit(1);
        }

-       sin.sin_port = sp->s_port;
-#ifndef DEBUG
-       if (fork())
-               exit(0);
-       for (f = 0; f < 10; f++)
-               (void) close(f);
-       (void) open("/", 0);
-       (void) dup2(0, 1);
-       (void) dup2(0, 2);
-       { int t = open("/dev/tty", 2);
-         if (t >= 0) {
-               ioctl(t, TIOCNOTTY, (char *)0);
-               (void) close(t);
-         }
+       fromlen = sizeof (from);
+       n = recvfrom(0, buf, sizeof (buf), 0,
+           (struct sockaddr *)&from, &fromlen);
+       if (n < 0) {
+               syslog(LOG_ERR, "recvfrom: %m\n");
+               exit(1);

        }
        }

-#endif
-       for (;;) {
-               int fromlen;
-
-               f = socket(AF_INET, SOCK_DGRAM, 0, 0);
-               if (f < 0) {
-                       perror("tftpd: socket");
-                       close(f);
-                       sleep(5);
-                       continue;
-               }
-               while (bind(f, (caddr_t)&sin, sizeof (sin), 0) < 0) {
-                       perror("tftpd: bind");
-                       close(f);
-                       sleep(5);
-                       continue;
+       /*
+        * Now that we have read the message out of the UDP
+        * socket, we fork and exit.  Thus, inetd will go back
+        * to listening to the tftp port, and the next request
+        * to come in will start up a new instance of tftpd.
+        *
+        * We do this so that inetd can run tftpd in "wait" mode.
+        * The problem with tftpd running in "nowait" mode is that
+        * inetd may get one or more successful "selects" on the
+        * tftp port before we do our receive, so more than one
+        * instance of tftpd may be started up.  Worse, if tftpd
+        * break before doing the above "recvfrom", inetd would
+        * spawn endless instances, clogging the system.
+        */
+       {
+               int pid;
+               int i, j;
+
+               for (i = 1; i < 20; i++) {
+                   pid = fork();
+                   if (pid < 0) {
+                               sleep(i);
+                               /*
+                                * flush out to most recently sent request.
+                                *
+                                * This may drop some request, but those
+                                * will be resent by the clients when
+                                * they timeout.  The positive effect of
+                                * this flush is to (try to) prevent more
+                                * than one tftpd being started up to service
+                                * a single request from a single client.
+                                */
+                               j = sizeof from;
+                               i = recvfrom(0, buf, sizeof (buf), 0,
+                                   (struct sockaddr *)&from, &j);
+                               if (i > 0) {
+                                       n = i;
+                                       fromlen = j;
+                               }
+                   } else {
+                               break;
+                   }

                }
                }

-again:
-               fromlen = sizeof (from);
-               n = recvfrom(f, buf, sizeof (buf), 0, (caddr_t)&from, &fromlen);
-               if (n <= 0) {
-                       if (n < 0)
-                               perror("tftpd: recvfrom");
-                       goto again;
+               if (pid < 0) {
+                       syslog(LOG_ERR, "fork: %m\n");
+                       exit(1);
+               } else if (pid != 0) {
+                       exit(0);

                }
                }

-               tp = (struct tftphdr *)buf;
-               tp->th_opcode = ntohs(tp->th_opcode);
-               if (tp->th_opcode == RRQ || tp->th_opcode == WRQ)
-                       if (fork() == 0)
-                               tftp(&from, tp, n);
-               (void) close(f);
-               while (wait3(status, WNOHANG, 0) > 0)
-                       continue;

        }
        }

+       from.sin_family = AF_INET;
+       alarm(0);
+       close(0);
+       close(1);
+       peer = socket(AF_INET, SOCK_DGRAM, 0);
+       if (peer < 0) {
+               syslog(LOG_ERR, "socket: %m\n");
+               exit(1);
+       }
+       memset(&sin, 0, sizeof(sin));
+       sin.sin_family = AF_INET;
+       if (bind(peer, (struct sockaddr *)&sin, sizeof (sin)) < 0) {
+               syslog(LOG_ERR, "bind: %m\n");
+               exit(1);
+       }
+       if (connect(peer, (struct sockaddr *)&from, sizeof(from)) < 0) {
+               syslog(LOG_ERR, "connect: %m\n");
+               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;
+int    validate_access __P((char **, int));
+void   sendfile __P((struct formats *));
+void   recvfile __P((struct formats *));

 
 struct formats {
        char    *f_mode;
 
 struct formats {
        char    *f_mode;

-       int     (*f_validate)();
-       int     (*f_send)();
-       int     (*f_recv)();
+       int     (*f_validate) __P((char **, int));
+       void    (*f_send) __P((struct formats *));
+       void    (*f_recv) __P((struct formats *));
+       int     f_convert;

 } formats[] = {
 } formats[] = {

-       { "netascii",   validate_access,        sendfile,       recvfile },
-       { "octet",      validate_access,        sendfile,       recvfile },
+       { "netascii",   validate_access,        sendfile,       recvfile, 1 },
+       { "octet",      validate_access,        sendfile,       recvfile, 0 },

 #ifdef notdef
 #ifdef notdef

-       { "mail",       validate_user,          sendmail,       recvmail },
+       { "mail",       validate_user,          sendmail,       recvmail, 1 },

 #endif
        { 0 }
 };
 
 #endif
        { 0 }
 };
 

-int    fd;                     /* file being transferred */
-

 /*
  * Handle initial connection protocol.
  */
 /*
  * Handle initial connection protocol.
  */

-tftp(client, tp, size)
-       struct sockaddr_in *client;
+void
+tftp(tp, size)

        struct tftphdr *tp;
        int size;
 {
        struct tftphdr *tp;
        int size;
 {


@@ -121,10 +236,6 @@ tftp(client, tp, size)
        register struct formats *pf;
        char *filename, *mode;
 
        register struct formats *pf;
        char *filename, *mode;
 

-       if (connect(f, (caddr_t)client, sizeof (*client), 0) < 0) {
-               perror("connect");
-               exit(1);
-       }

        filename = cp = tp->th_stuff;
 again:
        while (cp < buf + size) {
        filename = cp = tp->th_stuff;
 again:
        while (cp < buf + size) {


@@ -151,8 +262,20 @@ again:
                nak(EBADOP);
                exit(1);
        }
                nak(EBADOP);
                exit(1);
        }

-       ecode = (*pf->f_validate)(filename, client, tp->th_opcode);
+       ecode = (*pf->f_validate)(&filename, tp->th_opcode);
+       if (logging) {
+               syslog(LOG_INFO, "%s: %s request for %s: %s",
+                       verifyhost(&from),
+                       tp->th_opcode == WRQ ? "write" : "read",
+                       filename, errtomsg(ecode));
+       }

        if (ecode) {
        if (ecode) {

+               /*
+                * Avoid storms of naks to a RRQ broadcast for a relative
+                * bootfile pathname from a diskless Sun.
+                */
+               if (suppress_naks && *filename != '/' && ecode == ENOTFOUND)
+                       exit(0);

                nak(ecode);
                exit(1);
        }
                nak(ecode);
                exit(1);
        }


@@ -163,151 +286,265 @@ again:
        exit(0);
 }
 
        exit(0);
 }
 

+
+FILE *file;
+

 /*
  * Validate file access.  Since we
  * have no uid or gid, for now require
  * file to exist and be publicly
  * readable/writable.
 /*
  * Validate file access.  Since we
  * have no uid or gid, for now require
  * file to exist and be publicly
  * readable/writable.

+ * If we were invoked with arguments
+ * from inetd then the file must also be
+ * in one of the given directory prefixes.

  * Note also, full path name must be
  * given as we have no login directory.
  */
  * Note also, full path name must be
  * given as we have no login directory.
  */

-validate_access(file, client, mode)
-       char *file;
-       struct sockaddr_in *client;
+int
+validate_access(filep, mode)
+       char **filep;

        int mode;
 {
        struct stat stbuf;
        int mode;
 {
        struct stat stbuf;

+       int     fd;
+       struct dirlist *dirp;
+       static char pathname[MAXPATHLEN];
+       char *filename = *filep;

 
 

-       if (*file != '/')
+       /*
+        * Prevent tricksters from getting around the directory restrictions
+        */
+       if (strstr(filename, "/../"))

                return (EACCESS);
                return (EACCESS);

-       if (stat(file, &stbuf) < 0)
-               return (errno == ENOENT ? ENOTFOUND : EACCESS);
-       if (mode == RRQ) {
-               if ((stbuf.st_mode&(S_IREAD >> 6)) == 0)
+
+       if (*filename == '/') {
+               /*
+                * Allow the request if it's in one of the approved locations.
+                * Special case: check the null prefix ("/") by looking
+                * for length = 1 and relying on the arg. processing that
+                * it's a /.
+                */
+               for (dirp = dirs; dirp->name != NULL; dirp++) {
+                       if (dirp->len == 1 ||
+                           (!strncmp(filename, dirp->name, dirp->len) &&
+                            filename[dirp->len] == '/'))
+                                   break;
+               }
+               /* If directory list is empty, allow access to any file */
+               if (dirp->name == NULL && dirp != dirs)

                        return (EACCESS);
                        return (EACCESS);

+               if (stat(filename, &stbuf) < 0)
+                       return (errno == ENOENT ? ENOTFOUND : EACCESS);
+               if ((stbuf.st_mode & S_IFMT) != S_IFREG)
+                       return (ENOTFOUND);
+               if (mode == RRQ) {
+                       if ((stbuf.st_mode & S_IROTH) == 0)
+                               return (EACCESS);
+               } else {
+                       if ((stbuf.st_mode & S_IWOTH) == 0)
+                               return (EACCESS);
+               }

        } else {
        } else {

-               if ((stbuf.st_mode&(S_IWRITE >> 6)) == 0)
+               int err;
+
+               /*
+                * Relative file name: search the approved locations for it.
+                * Don't allow write requests or ones that avoid directory
+                * restrictions.
+                */
+
+               if (mode != RRQ || !strncmp(filename, "../", 3))

                        return (EACCESS);
                        return (EACCESS);

+
+               /*
+                * If the file exists in one of the directories and isn't
+                * readable, continue looking. However, change the error code
+                * to give an indication that the file exists.
+                */
+               err = ENOTFOUND;
+               for (dirp = dirs; dirp->name != NULL; dirp++) {
+                       sprintf(pathname, "%s/%s", dirp->name, filename);
+                       if (stat(pathname, &stbuf) == 0 &&
+                           (stbuf.st_mode & S_IFMT) == S_IFREG) {
+                               if ((stbuf.st_mode & S_IROTH) != 0) {
+                                       break;
+                               }
+                               err = EACCESS;
+                       }
+               }
+               if (dirp->name == NULL)
+                       return (err);
+               *filep = filename = pathname;

        }
        }

-       fd = open(file, mode == RRQ ? 0 : 1);
+       fd = open(filename, mode == RRQ ? 0 : 1);

        if (fd < 0)
                return (errno + 100);
        if (fd < 0)
                return (errno + 100);

+       file = fdopen(fd, (mode == RRQ)? "r":"w");
+       if (file == NULL) {
+               return errno+100;
+       }

        return (0);
 }
 
        return (0);
 }
 

-int timeout;
+int    timeout;
+jmp_buf        timeoutbuf;

 
 

+void

 timer()
 {
 timer()
 {

-       timeout += TIMEOUT;
-       if (timeout >= MAXTIMEOUT)
+
+       timeout += rexmtval;
+       if (timeout >= maxtimeout)

                exit(1);
                exit(1);

-       alarm(TIMEOUT);
+       longjmp(timeoutbuf, 1);

 }
 
 /*
  * Send the requested file.
  */
 }
 
 /*
  * Send the requested file.
  */

+void

 sendfile(pf)
 sendfile(pf)

-       struct format *pf;
+       struct formats *pf;

 {
 {

-       register struct tftphdr *tp;
-       register int block = 1, size, n;
+       struct tftphdr *dp, *r_init();
+       register struct tftphdr *ap;    /* ack packet */
+       register int size, n;
+       volatile int block;

 
 

-       sigset(SIGALRM, timer);
-       tp = (struct tftphdr *)buf;
+       signal(SIGALRM, timer);
+       dp = r_init();
+       ap = (struct tftphdr *)ackbuf;
+       block = 1;

        do {
        do {

-               size = read(fd, tp->th_data, SEGSIZE);
+               size = readit(file, &dp, pf->f_convert);

                if (size < 0) {
                        nak(errno + 100);
                if (size < 0) {
                        nak(errno + 100);

-                       break;
+                       goto abort;

                }
                }

-               tp->th_opcode = htons((u_short)DATA);
-               tp->th_block = htons((u_short)block);
+               dp->th_opcode = htons((u_short)DATA);
+               dp->th_block = htons((u_short)block);

                timeout = 0;
                timeout = 0;

-               alarm(TIMEOUT);
-rexmt:
-               if (write(f, buf, size + 4) != size + 4) {
-                       perror("send");
-                       break;
+               (void)setjmp(timeoutbuf);
+
+send_data:
+               if (send(peer, dp, size + 4, 0) != size + 4) {
+                       syslog(LOG_ERR, "tftpd: write: %m\n");
+                       goto abort;

                }
                }

-again:
-               n = read(f, buf, sizeof (buf));
-               if (n <= 0) {
-                       if (n == 0)
-                               goto again;
-                       if (errno == EINTR)
-                               goto rexmt;
+               read_ahead(file, pf->f_convert);
+               for ( ; ; ) {
+                       alarm(rexmtval);        /* read the ack */
+                       n = recv(peer, ackbuf, sizeof (ackbuf), 0);

                        alarm(0);
                        alarm(0);

-                       perror("receive");
-                       break;
+                       if (n < 0) {
+                               syslog(LOG_ERR, "tftpd: read: %m\n");
+                               goto abort;
+                       }
+                       ap->th_opcode = ntohs((u_short)ap->th_opcode);
+                       ap->th_block = ntohs((u_short)ap->th_block);
+
+                       if (ap->th_opcode == ERROR)
+                               goto abort;
+
+                       if (ap->th_opcode == ACK) {
+                               if (ap->th_block == block)
+                                       break;
+                               /* Re-synchronize with the other side */
+                               (void) synchnet(peer);
+                               if (ap->th_block == (block -1))
+                                       goto send_data;
+                       }
+

                }
                }

-               alarm(0);
-#if vax || pdp11
-               tp->th_opcode = ntohs((u_short)tp->th_opcode);
-               tp->th_block = ntohs((u_short)tp->th_block);
-#endif
-               if (tp->th_opcode == ERROR)
-                       break;
-               if (tp->th_opcode != ACK || tp->th_block != block)
-                       goto again;

                block++;
        } while (size == SEGSIZE);
                block++;
        } while (size == SEGSIZE);

-       (void) close(fd);
+abort:
+       (void) fclose(file);

 }
 
 }
 

+void
+justquit()
+{
+       exit(0);
+}
+
+

 /*
  * Receive a file.
  */
 /*
  * Receive a file.
  */

+void

 recvfile(pf)
 recvfile(pf)

-       struct format *pf;
+       struct formats *pf;

 {
 {

-       register struct tftphdr *tp;
-       register int block = 0, n, size;
+       struct tftphdr *dp, *w_init();
+       register struct tftphdr *ap;    /* ack buffer */
+       register int n, size;
+       volatile int block;

 
 

-       sigset(SIGALRM, timer);
-       tp = (struct tftphdr *)buf;
+       signal(SIGALRM, timer);
+       dp = w_init();
+       ap = (struct tftphdr *)ackbuf;
+       block = 0;

        do {
                timeout = 0;
        do {
                timeout = 0;

-               alarm(TIMEOUT);
-               tp->th_opcode = htons((u_short)ACK);
-               tp->th_block = htons((u_short)block);
+               ap->th_opcode = htons((u_short)ACK);
+               ap->th_block = htons((u_short)block);

                block++;
                block++;

-rexmt:
-               if (write(f, buf, 4) != 4) {
-                       perror("ack");
-                       break;
+               (void) setjmp(timeoutbuf);
+send_ack:
+               if (send(peer, ackbuf, 4, 0) != 4) {
+                       syslog(LOG_ERR, "tftpd: write: %m\n");
+                       goto abort;

                }
                }

-again:
-               n = read(f, buf, sizeof (buf));
-               if (n <= 0) {
-                       if (n == 0)
-                               goto again;
-                       if (errno == EINTR)
-                               goto rexmt;
+               write_behind(file, pf->f_convert);
+               for ( ; ; ) {
+                       alarm(rexmtval);
+                       n = recv(peer, dp, PKTSIZE, 0);

                        alarm(0);
                        alarm(0);

-                       perror("receive");
-                       break;
+                       if (n < 0) {            /* really? */
+                               syslog(LOG_ERR, "tftpd: read: %m\n");
+                               goto abort;
+                       }
+                       dp->th_opcode = ntohs((u_short)dp->th_opcode);
+                       dp->th_block = ntohs((u_short)dp->th_block);
+                       if (dp->th_opcode == ERROR)
+                               goto abort;
+                       if (dp->th_opcode == DATA) {
+                               if (dp->th_block == block) {
+                                       break;   /* normal */
+                               }
+                               /* Re-synchronize with the other side */
+                               (void) synchnet(peer);
+                               if (dp->th_block == (block-1))
+                                       goto send_ack;          /* rexmit */
+                       }

                }
                }

-               alarm(0);
-#if vax || pdp11
-               tp->th_opcode = ntohs((u_short)tp->th_opcode);
-               tp->th_block = ntohs((u_short)tp->th_block);
-#endif
-               if (tp->th_opcode == ERROR)
-                       break;
-               if (tp->th_opcode != DATA || block != tp->th_block)
-                       goto again;
-               size = write(fd, tp->th_data, n - 4);
-               if (size < 0) {
-                       nak(errno + 100);
-                       break;
+               /*  size = write(file, dp->th_data, n - 4); */
+               size = writeit(file, &dp, n - 4, pf->f_convert);
+               if (size != (n-4)) {                    /* ahem */
+                       if (size < 0) nak(errno + 100);
+                       else nak(ENOSPACE);
+                       goto abort;

                }
        } while (size == SEGSIZE);
                }
        } while (size == SEGSIZE);

-       tp->th_opcode = htons((u_short)ACK);
-       tp->th_block = htons((u_short)(block));
-       (void) write(f, buf, 4);
-       (void) close(fd);
+       write_behind(file, pf->f_convert);
+       (void) fclose(file);            /* close data file */
+
+       ap->th_opcode = htons((u_short)ACK);    /* send the "final" ack */
+       ap->th_block = htons((u_short)(block));
+       (void) send(peer, ackbuf, 4, 0);
+
+       signal(SIGALRM, justquit);      /* just quit on timeout */
+       alarm(rexmtval);
+       n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
+       alarm(0);
+       if (n >= 4 &&                   /* if read some data */
+           dp->th_opcode == DATA &&    /* and got a data block */
+           block == dp->th_block) {    /* then my last ack was lost */
+               (void) send(peer, ackbuf, 4, 0);     /* resend final ack */
+       }
+abort:
+       return;

 }
 
 struct errmsg {
 }
 
 struct errmsg {


@@ -325,19 +562,34 @@ struct errmsg {
        { -1,           0 }
 };
 
        { -1,           0 }
 };
 

+static char *
+errtomsg(error)
+       int error;
+{
+       static char buf[20];
+       register struct errmsg *pe;
+       if (error == 0)
+               return "success";
+       for (pe = errmsgs; pe->e_code >= 0; pe++)
+               if (pe->e_code == error)
+                       return pe->e_msg;
+       sprintf(buf, "error %d", error);
+       return buf;
+}
+

 /*
  * Send a nak packet (error message).
  * Error code passed in is one of the
  * standard TFTP codes, or a UNIX errno
  * offset by 100.
  */
 /*
  * 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(error)
        int error;
 {
        register struct tftphdr *tp;
        int length;
        register struct errmsg *pe;
 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 = (struct tftphdr *)buf;
        tp->th_opcode = htons((u_short)ERROR);


@@ -345,12 +597,28 @@ nak(error)
        for (pe = errmsgs; pe->e_code >= 0; pe++)
                if (pe->e_code == error)
                        break;
        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];
+       if (pe->e_code < 0) {
+               pe->e_msg = strerror(error - 100);
+               tp->th_code = EUNDEF;   /* set 'undef' errorcode */
+       }

        strcpy(tp->th_msg, pe->e_msg);
        length = strlen(pe->e_msg);
        tp->th_msg[length] = '\0';
        length += 5;
        strcpy(tp->th_msg, pe->e_msg);
        length = strlen(pe->e_msg);
        tp->th_msg[length] = '\0';
        length += 5;

-       if (write(f, buf, length) != length)
-               perror("nak");
+       if (send(peer, buf, length, 0) != length)
+               syslog(LOG_ERR, "nak: %m\n");
+}
+
+static char *
+verifyhost(fromp)
+       struct sockaddr_in *fromp;
+{
+       struct hostent *hp;
+
+       hp = gethostbyaddr((char *)&fromp->sin_addr, sizeof (fromp->sin_addr),
+                           fromp->sin_family);
+       if (hp)
+               return hp->h_name;
+       else
+               return inet_ntoa(fromp->sin_addr);

 }
 }