text: /***************************************************************************
   *                                  _   _ ____  _
   *  Project                     ___| | | |  _ \| |
   *                             / __| | | | |_) | |
   *                            | (__| |_| |  _ <| |___
   *                             \___|\___/|_| \_\_____|
   *
   *
   * Trivial file transfer protocol server.
   *
   * This code includes many modifications by Jim Guyton <guyton@rand-unix>
   *
   * This source file was started based on netkit-tftpd 0.17
   * Heavily modified for curl's test suite
   */
  
  /*
   * Copyright (c) 1983 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. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *      This product includes software developed by the University of
   *      California, Berkeley and its contributors.
   * 4. 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 "server_setup.h"
  
  #ifdef HAVE_SYS_IOCTL_H
  #include <sys/ioctl.h>
  #endif
  #ifdef HAVE_SIGNAL_H
  #include <signal.h>
  #endif
  #ifdef HAVE_FCNTL_H
  #include <fcntl.h>
  #endif
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  #ifdef HAVE_ARPA_INET_H
  #include <arpa/inet.h>
  #endif
  #ifdef HAVE_ARPA_TFTP_H
  #include <arpa/tftp.h>
  #else
  #include "tftp.h"
  #endif
  #ifdef HAVE_NETDB_H
  #include <netdb.h>
  #endif
  #ifdef HAVE_SYS_FILIO_H
  /* FIONREAD on Solaris 7 */
  #include <sys/filio.h>
  #endif
  
  #include <setjmp.h>
  
  #ifdef HAVE_PWD_H
  #include <pwd.h>
  #endif
  
  #define ENABLE_CURLX_PRINTF
  /* make the curlx header define all printf() functions to use the curlx_*
     versions instead */
  #include "curlx.h" /* from the private lib dir */
  #include "getpart.h"
  #include "util.h"
  #include "server_sockaddr.h"
  
  /* include memdebug.h last */
  #include "memdebug.h"
  
  /*****************************************************************************
  *                      STRUCT DECLARATIONS AND DEFINES                       *
  *****************************************************************************/
  
  #ifndef PKTSIZE
  #define PKTSIZE (SEGSIZE + 4)  /* SEGSIZE defined in arpa/tftp.h */
  #endif
  
  struct testcase {
    char *buffer;   /* holds the file data to send to the client */
    size_t bufsize; /* size of the data in buffer */
    char *rptr;     /* read pointer into the buffer */
    size_t rcount;  /* amount of data left to read of the file */
    long testno;    /* test case number */
    int ofile;      /* file descriptor for output file when uploading to us */
  
    int writedelay; /* number of seconds between each packet */
  };
  
  struct formats {
    const char *f_mode;
    int f_convert;
  };
  
  struct errmsg {
    int e_code;
    const char *e_msg;
  };
  
  typedef union {
    struct tftphdr hdr;
    char storage[PKTSIZE];
  } tftphdr_storage_t;
  
  /*
   * bf.counter values in range [-1 .. SEGSIZE] represents size of data in the
   * bf.buf buffer. Additionally it can also hold flags BF_ALLOC or BF_FREE.
   */
  
  struct bf {
    int counter;            /* size of data in buffer, or flag */
    tftphdr_storage_t buf;  /* room for data packet */
  };
  
  #define BF_ALLOC -3       /* alloc'd but not yet filled */
  #define BF_FREE  -2       /* free */
  
  #define opcode_RRQ   1
  #define opcode_WRQ   2
  #define opcode_DATA  3
  #define opcode_ACK   4
  #define opcode_ERROR 5
  
  #define TIMEOUT      5
  
  #undef MIN
  #define MIN(x,y) ((x)<(y)?(x):(y))
  
  #ifndef DEFAULT_LOGFILE
  #define DEFAULT_LOGFILE "log/tftpd.log"
  #endif
  
  #define REQUEST_DUMP  "log/server.input"
  
  #define DEFAULT_PORT 8999 /* UDP */
  
  /*****************************************************************************
  *                              GLOBAL VARIABLES                              *
  *****************************************************************************/
  
  static struct errmsg 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 }
  };
  
  static struct formats formata[] = {
    { "netascii",   1 },
    { "octet",      0 },
    { NULL,         0 }
  };
  
  static struct bf bfs[2];
  
  static int nextone;     /* index of next buffer to use */
  static int current;     /* index of buffer in use */
  
                             /* control flags for crlf conversions */
  static int newline = 0;    /* fillbuf: in middle of newline expansion */
  static int prevchar = -1;  /* putbuf: previous char (cr check) */
  
  static tftphdr_storage_t buf;
  static tftphdr_storage_t ackbuf;
  
  static srvr_sockaddr_union_t from;
  static curl_socklen_t fromlen;
  
  static curl_socket_t peer = CURL_SOCKET_BAD;
  
  static unsigned int timeout;
  static unsigned int maxtimeout = 5 * TIMEOUT;
  
  #ifdef ENABLE_IPV6
  static bool use_ipv6 = FALSE;
  #endif
  static const char *ipv_inuse = "IPv4";
  
  const  char *serverlogfile = DEFAULT_LOGFILE;
  static const char *pidname = ".tftpd.pid";
  static int serverlogslocked = 0;
  static int wrotepidfile = 0;
  
  #ifdef HAVE_SIGSETJMP
  static sigjmp_buf timeoutbuf;
  #endif
  
  #if defined(HAVE_ALARM) && defined(SIGALRM)
  static const unsigned int rexmtval = TIMEOUT;
  #endif
  
  /* do-nothing macro replacement for systems which lack siginterrupt() */
  
  #ifndef HAVE_SIGINTERRUPT
  #define siginterrupt(x,y) do {} while(0)
  #endif
  
  /* vars used to keep around previous signal handlers */
  
  typedef RETSIGTYPE (*SIGHANDLER_T)(int);
  
  #ifdef SIGHUP
  static SIGHANDLER_T old_sighup_handler  = SIG_ERR;
  #endif
  
  #ifdef SIGPIPE
  static SIGHANDLER_T old_sigpipe_handler = SIG_ERR;
  #endif
  
  #ifdef SIGINT
  static SIGHANDLER_T old_sigint_handler  = SIG_ERR;
  #endif
  
  #ifdef SIGTERM
  static SIGHANDLER_T old_sigterm_handler = SIG_ERR;
  #endif
  
  #if defined(SIGBREAK) && defined(WIN32)
  static SIGHANDLER_T old_sigbreak_handler = SIG_ERR;
  #endif
  
  /* var which if set indicates that the program should finish execution */
  
  SIG_ATOMIC_T got_exit_signal = 0;
  
  /* if next is set indicates the first signal handled in exit_signal_handler */
  
  static volatile int exit_signal = 0;
  
  /*****************************************************************************
  *                            FUNCTION PROTOTYPES                             *
  *****************************************************************************/
  
  static struct tftphdr *rw_init(int);
  
  static struct tftphdr *w_init(void);
  
  static struct tftphdr *r_init(void);
  
  static void read_ahead(struct testcase *test, int convert);
  
  static ssize_t write_behind(struct testcase *test, int convert);
  
  static int synchnet(curl_socket_t);
  
  static int do_tftp(struct testcase *test, struct tftphdr *tp, ssize_t size);
  
  static int validate_access(struct testcase *test, const char *fname, int mode);
  
  static void sendtftp(struct testcase *test, struct formats *pf);
  
  static void recvtftp(struct testcase *test, struct formats *pf);
  
  static void nak(int error);
  
  #if defined(HAVE_ALARM) && defined(SIGALRM)
  
  static void mysignal(int sig, void (*handler)(int));
  
  static void timer(int signum);
  
  static void justtimeout(int signum);
  
  #endif /* HAVE_ALARM && SIGALRM */
  
  static RETSIGTYPE exit_signal_handler(int signum);
  
  static void install_signal_handlers(void);
  
  static void restore_signal_handlers(void);
  
  /*****************************************************************************
  *                          FUNCTION IMPLEMENTATIONS                          *
  *****************************************************************************/
  
  #if defined(HAVE_ALARM) && defined(SIGALRM)
  
  /*
   * Like signal(), but with well-defined semantics.
   */
  static void mysignal(int sig, void (*handler)(int))
  {
    struct sigaction sa;
    memset(&sa, 0, sizeof(sa));
    sa.sa_handler = handler;
    sigaction(sig, &sa, NULL);
  }
  
  static void timer(int signum)
  {
    (void)signum;
  
    logmsg("alarm!");
  
    timeout += rexmtval;
    if(timeout >= maxtimeout) {
      if(wrotepidfile) {
        wrotepidfile = 0;
        unlink(pidname);
      }
      if(serverlogslocked) {
        serverlogslocked = 0;
        clear_advisor_read_lock(SERVERLOGS_LOCK);
      }
      exit(1);
    }
  #ifdef HAVE_SIGSETJMP
    siglongjmp(timeoutbuf, 1);
  #endif
  }
  
  static void justtimeout(int signum)
  {
    (void)signum;
  }
  
  #endif /* HAVE_ALARM && SIGALRM */
  
  /* signal handler that will be triggered to indicate that the program
    should finish its execution in a controlled manner as soon as possible.
    The first time this is called it will set got_exit_signal to one and
    store in exit_signal the signal that triggered its execution. */
  
  static RETSIGTYPE exit_signal_handler(int signum)
  {
    int old_errno = errno;
    if(got_exit_signal == 0) {
      got_exit_signal = 1;
      exit_signal = signum;
    }
    (void)signal(signum, exit_signal_handler);
    errno = old_errno;
  }
  
  static void install_signal_handlers(void)
  {
  #ifdef SIGHUP
    /* ignore SIGHUP signal */
    old_sighup_handler = signal(SIGHUP, SIG_IGN);
    if(old_sighup_handler == SIG_ERR)
      logmsg("cannot install SIGHUP handler: %s", strerror(errno));
  #endif
  #ifdef SIGPIPE
    /* ignore SIGPIPE signal */
    old_sigpipe_handler = signal(SIGPIPE, SIG_IGN);
    if(old_sigpipe_handler == SIG_ERR)
      logmsg("cannot install SIGPIPE handler: %s", strerror(errno));
  #endif
  #ifdef SIGINT
    /* handle SIGINT signal with our exit_signal_handler */
    old_sigint_handler = signal(SIGINT, exit_signal_handler);
    if(old_sigint_handler == SIG_ERR)
      logmsg("cannot install SIGINT handler: %s", strerror(errno));
    else
      siginterrupt(SIGINT, 1);
  #endif
  #ifdef SIGTERM
    /* handle SIGTERM signal with our exit_signal_handler */
    old_sigterm_handler = signal(SIGTERM, exit_signal_handler);
    if(old_sigterm_handler == SIG_ERR)
      logmsg("cannot install SIGTERM handler: %s", strerror(errno));
    else
      siginterrupt(SIGTERM, 1);
  #endif
  #if defined(SIGBREAK) && defined(WIN32)
    /* handle SIGBREAK signal with our exit_signal_handler */
    old_sigbreak_handler = signal(SIGBREAK, exit_signal_handler);
    if(old_sigbreak_handler == SIG_ERR)
      logmsg("cannot install SIGBREAK handler: %s", strerror(errno));
    else
      siginterrupt(SIGBREAK, 1);
  #endif
  }
  
  static void restore_signal_handlers(void)
  {
  #ifdef SIGHUP
    if(SIG_ERR != old_sighup_handler)
      (void)signal(SIGHUP, old_sighup_handler);
  #endif
  #ifdef SIGPIPE
    if(SIG_ERR != old_sigpipe_handler)
      (void)signal(SIGPIPE, old_sigpipe_handler);
  #endif
  #ifdef SIGINT
    if(SIG_ERR != old_sigint_handler)
      (void)signal(SIGINT, old_sigint_handler);
  #endif
  #ifdef SIGTERM
    if(SIG_ERR != old_sigterm_handler)
      (void)signal(SIGTERM, old_sigterm_handler);
  #endif
  #if defined(SIGBREAK) && defined(WIN32)
    if(SIG_ERR != old_sigbreak_handler)
      (void)signal(SIGBREAK, old_sigbreak_handler);
  #endif
  }
  
  /*
   * init for either read-ahead or write-behind.
   * zero for write-behind, one for read-head.
   */
  static struct tftphdr *rw_init(int x)
  {
    newline = 0;                    /* init crlf flag */
    prevchar = -1;
    bfs[0].counter =  BF_ALLOC;     /* pass out the first buffer */
    current = 0;
    bfs[1].counter = BF_FREE;
    nextone = x;                    /* ahead or behind? */
    return &bfs[0].buf.hdr;
  }
  
  static struct tftphdr *w_init(void)
  {
    return rw_init(0); /* write-behind */
  }
  
  static struct tftphdr *r_init(void)
  {
    return rw_init(1); /* read-ahead */
  }
  
  /* Have emptied current buffer by sending to net and getting ack.
     Free it and return next buffer filled with data.
   */
  static int readit(struct testcase *test, struct tftphdr **dpp,
                    int convert /* if true, convert to ascii */)
  {
    struct bf *b;
  
    bfs[current].counter = BF_FREE; /* free old one */
    current = !current;             /* "incr" current */
  
    b = &bfs[current];              /* look at new buffer */
    if(b->counter == BF_FREE)      /* if it's empty */
      read_ahead(test, convert);    /* fill it */
  
    *dpp = &b->buf.hdr;             /* set caller's ptr */
    return b->counter;
  }
  
  /*
   * fill the input buffer, doing ascii conversions if requested
   * conversions are  lf -> cr, lf  and cr -> cr, nul
   */
  static void read_ahead(struct testcase *test,
                         int convert /* if true, convert to ascii */)
  {
    int i;
    char *p;
    int c;
    struct bf *b;
    struct tftphdr *dp;
  
    b = &bfs[nextone];              /* look at "next" buffer */
    if(b->counter != BF_FREE)      /* nop if not free */
      return;
    nextone = !nextone;             /* "incr" next buffer ptr */
  
    dp = &b->buf.hdr;
  
    if(convert == 0) {
      /* The former file reading code did this:
         b->counter = read(fileno(file), dp->th_data, SEGSIZE); */
      size_t copy_n = MIN(SEGSIZE, test->rcount);
      memcpy(dp->th_data, test->rptr, copy_n);
  
      /* decrease amount, advance pointer */
      test->rcount -= copy_n;
      test->rptr += copy_n;
      b->counter = (int)copy_n;
      return;
    }
  
    p = dp->th_data;
    for(i = 0 ; i < SEGSIZE; i++) {
      if(newline) {
        if(prevchar == '\n')
          c = '\n';       /* lf to cr,lf */
        else
          c = '\0';       /* cr to cr,nul */
        newline = 0;
      }
      else {
        if(test->rcount) {
          c = test->rptr[0];
          test->rptr++;
          test->rcount--;
        }
        else
          break;
        if(c == '\n' || c == '\r') {
          prevchar = c;
          c = '\r';
          newline = 1;
        }
      }
      *p++ = (char)c;
    }
    b->counter = (int)(p - dp->th_data);
  }
  
  /* Update count associated with the buffer, get new buffer from the queue.
     Calls write_behind only if next buffer not available.
   */
  static int writeit(struct testcase *test, struct tftphdr * volatile *dpp,
                     int ct, int convert)
  {
    bfs[current].counter = ct;      /* set size of data to write */
    current = !current;             /* switch to other buffer */
    if(bfs[current].counter != BF_FREE)     /* if not free */
      write_behind(test, convert);     /* flush it */
    bfs[current].counter = BF_ALLOC;        /* mark as alloc'd */
    *dpp =  &bfs[current].buf.hdr;
    return ct;                      /* this is a lie of course */
  }
  
  /*
   * Output a buffer to a file, converting from netascii if requested.
   * CR, NUL -> CR  and CR, LF => LF.
   * Note spec is undefined if we get CR as last byte of file or a
   * CR followed by anything else.  In this case we leave it alone.
   */
  static ssize_t write_behind(struct testcase *test, int convert)
  {
    char *writebuf;
    int count;
    int ct;
    char *p;
    int c;                          /* current character */
    struct bf *b;
    struct tftphdr *dp;
  
    b = &bfs[nextone];
    if(b->counter < -1)            /* anything to flush? */
      return 0;                     /* just nop if nothing to do */
  
    if(!test->ofile) {
      char outfile[256];
      msnprintf(outfile, sizeof(outfile), "log/upload.%ld", test->testno);
  #ifdef WIN32
      test->ofile = open(outfile, O_CREAT|O_RDWR|O_BINARY, 0777);
  #else
      test->ofile = open(outfile, O_CREAT|O_RDWR, 0777);
  #endif
      if(test->ofile == -1) {
        logmsg("Couldn't create and/or open file %s for upload!", outfile);
        return -1; /* failure! */
      }
    }
  
    count = b->counter;             /* remember byte count */
    b->counter = BF_FREE;           /* reset flag */
    dp = &b->buf.hdr;
    nextone = !nextone;             /* incr for next time */
    writebuf = dp->th_data;
  
    if(count <= 0)
      return -1;                    /* nak logic? */
  
    if(convert == 0)
      return write(test->ofile, writebuf, count);
  
    p = writebuf;
    ct = count;
    while(ct--) {                   /* loop over the buffer */
      c = *p++;                     /* pick up a character */
      if(prevchar == '\r') {        /* if prev char was cr */
        if(c == '\n')               /* if have cr,lf then just */
          lseek(test->ofile, -1, SEEK_CUR); /* smash lf on top of the cr */
        else
          if(c == '\0')             /* if have cr,nul then */
            goto skipit;            /* just skip over the putc */
        /* else just fall through and allow it */
      }
      /* formerly
         putc(c, file); */
      if(1 != write(test->ofile, &c, 1))
        break;
      skipit:
      prevchar = c;
    }
    return count;
  }
  
  /* When an error has occurred, it is possible that the two sides are out of
   * synch.  Ie: that what I think is the other side's response to packet N is
   * really their response to packet N-1.
   *
   * So, to try to prevent that, we flush all the input queued up for us on the
   * network connection on our host.
   *
   * We return the number of packets we flushed (mostly for reporting when trace
   * is active).
   */
  
  static int synchnet(curl_socket_t f /* socket to flush */)
  {
  
  #if defined(HAVE_IOCTLSOCKET)
    unsigned long i;
  #else
    int i;
  #endif
    int j = 0;
    char rbuf[PKTSIZE];
    srvr_sockaddr_union_t fromaddr;
    curl_socklen_t fromaddrlen;
  
    for(;;) {
  #if defined(HAVE_IOCTLSOCKET)
      (void) ioctlsocket(f, FIONREAD, &i);
  #else
      (void) ioctl(f, FIONREAD, &i);
  #endif
      if(i) {
        j++;
  #ifdef ENABLE_IPV6
        if(!use_ipv6)
  #endif
          fromaddrlen = sizeof(fromaddr.sa4);
  #ifdef ENABLE_IPV6
        else
          fromaddrlen = sizeof(fromaddr.sa6);
  #endif
        (void) recvfrom(f, rbuf, sizeof(rbuf), 0,
                        &fromaddr.sa, &fromaddrlen);
      }
      else
        break;
    }
    return j;
  }
  
  int main(int argc, char **argv)
  {
    srvr_sockaddr_union_t me;
    struct tftphdr *tp;
    ssize_t n = 0;
    int arg = 1;
    unsigned short port = DEFAULT_PORT;
    curl_socket_t sock = CURL_SOCKET_BAD;
    int flag;
    int rc;
    int error;
    long pid;
    struct testcase test;
    int result = 0;
  
    memset(&test, 0, sizeof(test));
  
    while(argc>arg) {
      if(!strcmp("--version", argv[arg])) {
        printf("tftpd IPv4%s\n",
  #ifdef ENABLE_IPV6
               "/IPv6"
  #else
               ""
  #endif
               );
        return 0;
      }
      else if(!strcmp("--pidfile", argv[arg])) {
        arg++;
        if(argc>arg)
          pidname = argv[arg++];
      }
      else if(!strcmp("--logfile", argv[arg])) {
        arg++;
        if(argc>arg)
          serverlogfile = argv[arg++];
      }
      else if(!strcmp("--ipv4", argv[arg])) {
  #ifdef ENABLE_IPV6
        ipv_inuse = "IPv4";
        use_ipv6 = FALSE;
  #endif
        arg++;
      }
      else if(!strcmp("--ipv6", argv[arg])) {
  #ifdef ENABLE_IPV6
        ipv_inuse = "IPv6";
        use_ipv6 = TRUE;
  #endif
        arg++;
      }
      else if(!strcmp("--port", argv[arg])) {
        arg++;
        if(argc>arg) {
          char *endptr;
          unsigned long ulnum = strtoul(argv[arg], &endptr, 10);
          if((endptr != argv[arg] + strlen(argv[arg])) ||
             (ulnum < 1025UL) || (ulnum > 65535UL)) {
            fprintf(stderr, "tftpd: invalid --port argument (%s)\n",
                    argv[arg]);
            return 0;
          }
          port = curlx_ultous(ulnum);
          arg++;
        }
      }
      else if(!strcmp("--srcdir", argv[arg])) {
        arg++;
        if(argc>arg) {
          path = argv[arg];
          arg++;
        }
      }
      else {
        puts("Usage: tftpd [option]\n"
             " --version\n"
             " --logfile [file]\n"
             " --pidfile [file]\n"
             " --ipv4\n"
             " --ipv6\n"
             " --port [port]\n"
             " --srcdir [path]");
        return 0;
      }
    }
  
  #ifdef WIN32
    win32_init();
    atexit(win32_cleanup);
  #endif
  
    install_signal_handlers();
  
    pid = (long)getpid();
  
  #ifdef ENABLE_IPV6
    if(!use_ipv6)
  #endif
      sock = socket(AF_INET, SOCK_DGRAM, 0);
  #ifdef ENABLE_IPV6
    else
      sock = socket(AF_INET6, SOCK_DGRAM, 0);
  #endif
  
    if(CURL_SOCKET_BAD == sock) {
      error = SOCKERRNO;
      logmsg("Error creating socket: (%d) %s",
             error, strerror(error));
      result = 1;
      goto tftpd_cleanup;
    }
  
    flag = 1;
    if(0 != setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
              (void *)&flag, sizeof(flag))) {
      error = SOCKERRNO;
      logmsg("setsockopt(SO_REUSEADDR) failed with error: (%d) %s",
             error, strerror(error));
      result = 1;
      goto tftpd_cleanup;
    }
  
  #ifdef ENABLE_IPV6
    if(!use_ipv6) {
  #endif
      memset(&me.sa4, 0, sizeof(me.sa4));
      me.sa4.sin_family = AF_INET;
      me.sa4.sin_addr.s_addr = INADDR_ANY;
      me.sa4.sin_port = htons(port);
      rc = bind(sock, &me.sa, sizeof(me.sa4));
  #ifdef ENABLE_IPV6
    }
    else {
      memset(&me.sa6, 0, sizeof(me.sa6));
      me.sa6.sin6_family = AF_INET6;
      me.sa6.sin6_addr = in6addr_any;
      me.sa6.sin6_port = htons(port);
      rc = bind(sock, &me.sa, sizeof(me.sa6));
    }
  #endif /* ENABLE_IPV6 */
    if(0 != rc) {
      error = SOCKERRNO;
      logmsg("Error binding socket on port %hu: (%d) %s",
             port, error, strerror(error));
      result = 1;
      goto tftpd_cleanup;
    }
  
    wrotepidfile = write_pidfile(pidname);
    if(!wrotepidfile) {
      result = 1;
      goto tftpd_cleanup;
    }
  
    logmsg("Running %s version on port UDP/%d", ipv_inuse, (int)port);
  
    for(;;) {
      fromlen = sizeof(from);
  #ifdef ENABLE_IPV6
      if(!use_ipv6)
  #endif
        fromlen = sizeof(from.sa4);
  #ifdef ENABLE_IPV6
      else
        fromlen = sizeof(from.sa6);
  #endif
      n = (ssize_t)recvfrom(sock, &buf.storage[0], sizeof(buf.storage), 0,
                            &from.sa, &fromlen);
      if(got_exit_signal)
        break;
      if(n < 0) {
        logmsg("recvfrom");
        result = 3;
        break;
      }
  
      set_advisor_read_lock(SERVERLOGS_LOCK);
      serverlogslocked = 1;
  
  #ifdef ENABLE_IPV6
      if(!use_ipv6) {
  #endif
        from.sa4.sin_family = AF_INET;
        peer = socket(AF_INET, SOCK_DGRAM, 0);
        if(CURL_SOCKET_BAD == peer) {
          logmsg("socket");
          result = 2;
          break;
        }
        if(connect(peer, &from.sa, sizeof(from.sa4)) < 0) {
          logmsg("connect: fail");
          result = 1;
          break;
        }
  #ifdef ENABLE_IPV6
      }
      else {
        from.sa6.sin6_family = AF_INET6;
        peer = socket(AF_INET6, SOCK_DGRAM, 0);
        if(CURL_SOCKET_BAD == peer) {
          logmsg("socket");
          result = 2;
          break;
        }
        if(connect(peer, &from.sa, sizeof(from.sa6)) < 0) {
          logmsg("connect: fail");
          result = 1;
          break;
        }
      }
  #endif
  
      maxtimeout = 5*TIMEOUT;
  
      tp = &buf.hdr;
      tp->th_opcode = ntohs(tp->th_opcode);
      if(tp->th_opcode == opcode_RRQ || tp->th_opcode == opcode_WRQ) {
        memset(&test, 0, sizeof(test));
        if(do_tftp(&test, tp, n) < 0)
          break;
        free(test.buffer);
      }
      sclose(peer);
      peer = CURL_SOCKET_BAD;
  
      if(test.ofile > 0) {
        close(test.ofile);
        test.ofile = 0;
      }
  
      if(got_exit_signal)
        break;
  
      if(serverlogslocked) {
        serverlogslocked = 0;
        clear_advisor_read_lock(SERVERLOGS_LOCK);
      }
  
      logmsg("end of one transfer");
  
    }
  
  tftpd_cleanup:
  
    if(test.ofile > 0)
      close(test.ofile);
  
    if((peer != sock) && (peer != CURL_SOCKET_BAD))
      sclose(peer);
  
    if(sock != CURL_SOCKET_BAD)
      sclose(sock);
  
    if(got_exit_signal)
      logmsg("signalled to die");
  
    if(wrotepidfile)
      unlink(pidname);
  
    if(serverlogslocked) {
      serverlogslocked = 0;
      clear_advisor_read_lock(SERVERLOGS_LOCK);
    }
  
    restore_signal_handlers();
  
    if(got_exit_signal) {
      logmsg("========> %s tftpd (port: %d pid: %ld) exits with signal (%d)",
             ipv_inuse, (int)port, pid, exit_signal);
      /*
       * To properly set the return status of the process we
       * must raise the same signal SIGINT or SIGTERM that we
       * caught and let the old handler take care of it.
       */
      raise(exit_signal);
    }
  
    logmsg("========> tftpd quits");
    return result;
  }
  
  /*
   * Handle initial connection protocol.
   */
  static int do_tftp(struct testcase *test, struct tftphdr *tp, ssize_t size)
  {
    char *cp;
    int first = 1, ecode;
    struct formats *pf;
    char *filename, *mode = NULL;
  #ifdef USE_WINSOCK
    DWORD recvtimeout, recvtimeoutbak;
  #endif
    const char *option = "mode"; /* mode is implicit */
    int toggle = 1;
  
    /* Open request dump file. */
    FILE *server = fopen(REQUEST_DUMP, "ab");
    if(!server) {
      int error = errno;
      logmsg("fopen() failed with error: %d %s", error, strerror(error));
      logmsg("Error opening file: %s", REQUEST_DUMP);
      return -1;
    }
  
    /* store input protocol */
    fprintf(server, "opcode: %x\n", tp->th_opcode);
  
    cp = (char *)&tp->th_stuff;
    filename = cp;
    do {
      bool endofit = true;
      while(cp < &buf.storage[size]) {
        if(*cp == '\0') {
          endofit = false;
          break;
        }
        cp++;
      }
      if(endofit)
        /* no more options */
        break;
  
      /* before increasing pointer, make sure it is still within the legal
         space */
      if((cp + 1) < &buf.storage[size]) {
        ++cp;
        if(first) {
          /* store the mode since we need it later */
          mode = cp;
          first = 0;
        }
        if(toggle)
          /* name/value pair: */
          fprintf(server, "%s: %s\n", option, cp);
        else {
          /* store the name pointer */
          option = cp;
        }
        toggle ^= 1;
      }
      else
        /* No more options */
        break;
    } while(1);
  
    if(*cp) {
      nak(EBADOP);
      fclose(server);
      return 3;
    }
  
    /* store input protocol */
    fprintf(server, "filename: %s\n", filename);
  
    for(cp = mode; cp && *cp; cp++)
      if(ISUPPER(*cp))
        *cp = (char)tolower((int)*cp);
  
    /* store input protocol */
    fclose(server);
  
    for(pf = formata; pf->f_mode; pf++)
      if(strcmp(pf->f_mode, mode) == 0)
        break;
    if(!pf->f_mode) {
      nak(EBADOP);
      return 2;
    }
    ecode = validate_access(test, filename, tp->th_opcode);
    if(ecode) {
      nak(ecode);
      return 1;
    }
  
  #ifdef USE_WINSOCK
    recvtimeout = sizeof(recvtimeoutbak);
    getsockopt(peer, SOL_SOCKET, SO_RCVTIMEO,
               (char *)&recvtimeoutbak, (int *)&recvtimeout);
    recvtimeout = TIMEOUT*1000;
    setsockopt(peer, SOL_SOCKET, SO_RCVTIMEO,
               (const char *)&recvtimeout, sizeof(recvtimeout));
  #endif
  
    if(tp->th_opcode == opcode_WRQ)
      recvtftp(test, pf);
    else
      sendtftp(test, pf);
  
  #ifdef USE_WINSOCK
    recvtimeout = recvtimeoutbak;
    setsockopt(peer, SOL_SOCKET, SO_RCVTIMEO,
               (const char *)&recvtimeout, sizeof(recvtimeout));
  #endif
  
    return 0;
  }
  
  /* Based on the testno, parse the correct server commands. */
  static int parse_servercmd(struct testcase *req)
  {
    FILE *stream;
    char *filename;
    int error;
  
    filename = test2file(req->testno);
  
    stream = fopen(filename, "rb");
    if(!stream) {
      error = errno;
      logmsg("fopen() failed with error: %d %s", error, strerror(error));
      logmsg("  [1] Error opening file: %s", filename);
      logmsg("  Couldn't open test file %ld", req->testno);
      return 1; /* done */
    }
    else {
      char *orgcmd = NULL;
      char *cmd = NULL;
      size_t cmdsize = 0;
      int num = 0;
  
      /* get the custom server control "commands" */
      error = getpart(&orgcmd, &cmdsize, "reply", "servercmd", stream);
      fclose(stream);
      if(error) {
        logmsg("getpart() failed with error: %d", error);
        return 1; /* done */
      }
  
      cmd = orgcmd;
      while(cmd && cmdsize) {
        char *check;
        if(1 == sscanf(cmd, "writedelay: %d", &num)) {
          logmsg("instructed to delay %d secs between packets", num);
          req->writedelay = num;
        }
        else {
          logmsg("Unknown <servercmd> instruction found: %s", cmd);
        }
        /* try to deal with CRLF or just LF */
        check = strchr(cmd, '\r');
        if(!check)
          check = strchr(cmd, '\n');
  
        if(check) {
          /* get to the letter following the newline */
          while((*check == '\r') || (*check == '\n'))
            check++;
  
          if(!*check)
            /* if we reached a zero, get out */
            break;
          cmd = check;
        }
        else
          break;
      }
      free(orgcmd);
    }
  
    return 0; /* OK! */
  }
  
  
  /*
   * Validate file access.
   */
  static int validate_access(struct testcase *test,
                             const char *filename, int mode)
  {
    char *ptr;
  
    logmsg("trying to get file: %s mode %x", filename, mode);
  
    if(!strncmp("verifiedserver", filename, 14)) {
      char weare[128];
      size_t count = msnprintf(weare, sizeof(weare),
                               "WE ROOLZ: %ld\r\n", (long)getpid());
  
      logmsg("Are-we-friendly question received");
      test->buffer = strdup(weare);
      test->rptr = test->buffer; /* set read pointer */
      test->bufsize = count;    /* set total count */
      test->rcount = count;     /* set data left to read */
      return 0; /* fine */
    }
  
    /* find the last slash */
    ptr = strrchr(filename, '/');
  
    if(ptr) {
      char partbuf[80]="data";
      long partno;
      long testno;
      char *file;
  
      ptr++; /* skip the slash */
  
      /* skip all non-numericals following the slash */
      while(*ptr && !ISDIGIT(*ptr))
        ptr++;
  
      /* get the number */
      testno = strtol(ptr, &ptr, 10);
  
      if(testno > 10000) {
        partno = testno % 10000;
        testno /= 10000;
      }
      else
        partno = 0;
  
  
      logmsg("requested test number %ld part %ld", testno, partno);
  
      test->testno = testno;
  
      (void)parse_servercmd(test);
  
      file = test2file(testno);
  
      if(0 != partno)
        msnprintf(partbuf, sizeof(partbuf), "data%ld", partno);
  
      if(file) {
        FILE *stream = fopen(file, "rb");
        if(!stream) {
          int error = errno;
          logmsg("fopen() failed with error: %d %s", error, strerror(error));
          logmsg("Error opening file: %s", file);
          logmsg("Couldn't open test file: %s", file);
          return EACCESS;
        }
        else {
          size_t count;
          int error = getpart(&test->buffer, &count, "reply", partbuf, stream);
          fclose(stream);
          if(error) {
            logmsg("getpart() failed with error: %d", error);
            return EACCESS;
          }
          if(test->buffer) {
            test->rptr = test->buffer; /* set read pointer */
            test->bufsize = count;    /* set total count */
            test->rcount = count;     /* set data left to read */
          }
          else
            return EACCESS;
        }
  
      }
      else
        return EACCESS;
    }
    else {
      logmsg("no slash found in path");
      return EACCESS; /* failure */
    }
  
    logmsg("file opened and all is good");
    return 0;
  }
  
  /*
   * Send the requested file.
   */
  static void sendtftp(struct testcase *test, struct formats *pf)
  {
    int size;
    ssize_t n;
    /* These are volatile to live through a siglongjmp */
    volatile unsigned short sendblock; /* block count */
    struct tftphdr * volatile sdp = r_init(); /* data buffer */
    struct tftphdr * const sap = &ackbuf.hdr; /* ack buffer */
  
    sendblock = 1;
  #if defined(HAVE_ALARM) && defined(SIGALRM)
    mysignal(SIGALRM, timer);
  #endif
    do {
      size = readit(test, (struct tftphdr **)&sdp, pf->f_convert);
      if(size < 0) {
        nak(errno + 100);
        return;
      }
      sdp->th_opcode = htons((unsigned short)opcode_DATA);
      sdp->th_block = htons(sendblock);
      timeout = 0;
  #ifdef HAVE_SIGSETJMP
      (void) sigsetjmp(timeoutbuf, 1);
  #endif
      if(test->writedelay) {
        logmsg("Pausing %d seconds before %d bytes", test->writedelay,
               size);
        wait_ms(1000*test->writedelay);
      }
  
      send_data:
      if(swrite(peer, sdp, size + 4) != size + 4) {
        logmsg("write");
        return;
      }
      read_ahead(test, pf->f_convert);
      for(;;) {
  #ifdef HAVE_ALARM
        alarm(rexmtval);        /* read the ack */
  #endif
        n = sread(peer, &ackbuf.storage[0], sizeof(ackbuf.storage));
  #ifdef HAVE_ALARM
        alarm(0);
  #endif
        if(got_exit_signal)
          return;
        if(n < 0) {
          logmsg("read: fail");
          return;
        }
        sap->th_opcode = ntohs((unsigned short)sap->th_opcode);
        sap->th_block = ntohs(sap->th_block);
  
        if(sap->th_opcode == opcode_ERROR) {
          logmsg("got ERROR");
          return;
        }
  
        if(sap->th_opcode == opcode_ACK) {
          if(sap->th_block == sendblock) {
            break;
          }
          /* Re-synchronize with the other side */
          (void) synchnet(peer);
          if(sap->th_block == (sendblock-1)) {
            goto send_data;
          }
        }
  
      }
      sendblock++;
    } while(size == SEGSIZE);
  }
  
  /*
   * Receive a file.
   */
  static void recvtftp(struct testcase *test, struct formats *pf)
  {
    ssize_t n, size;
    /* These are volatile to live through a siglongjmp */
    volatile unsigned short recvblock; /* block count */
    struct tftphdr * volatile rdp;     /* data buffer */
    struct tftphdr *rap;      /* ack buffer */
  
    recvblock = 0;
    rdp = w_init();
  #if defined(HAVE_ALARM) && defined(SIGALRM)
    mysignal(SIGALRM, timer);
  #endif
    rap = &ackbuf.hdr;
    do {
      timeout = 0;
      rap->th_opcode = htons((unsigned short)opcode_ACK);
      rap->th_block = htons(recvblock);
      recvblock++;
  #ifdef HAVE_SIGSETJMP
      (void) sigsetjmp(timeoutbuf, 1);
  #endif
  send_ack:
      if(swrite(peer, &ackbuf.storage[0], 4) != 4) {
        logmsg("write: fail\n");
        goto abort;
      }
      write_behind(test, pf->f_convert);
      for(;;) {
  #ifdef HAVE_ALARM
        alarm(rexmtval);
  #endif
        n = sread(peer, rdp, PKTSIZE);
  #ifdef HAVE_ALARM
        alarm(0);
  #endif
        if(got_exit_signal)
          goto abort;
        if(n < 0) {                       /* really? */
          logmsg("read: fail\n");
          goto abort;
        }
        rdp->th_opcode = ntohs((unsigned short)rdp->th_opcode);
        rdp->th_block = ntohs(rdp->th_block);
        if(rdp->th_opcode == opcode_ERROR)
          goto abort;
        if(rdp->th_opcode == opcode_DATA) {
          if(rdp->th_block == recvblock) {
            break;                         /* normal */
          }
          /* Re-synchronize with the other side */
          (void) synchnet(peer);
          if(rdp->th_block == (recvblock-1))
            goto send_ack;                 /* rexmit */
        }
      }
  
      size = writeit(test, &rdp, (int)(n - 4), pf->f_convert);
      if(size != (n-4)) {                 /* ahem */
        if(size < 0)
          nak(errno + 100);
        else
          nak(ENOSPACE);
        goto abort;
      }
    } while(size == SEGSIZE);
    write_behind(test, pf->f_convert);
  
    rap->th_opcode = htons((unsigned short)opcode_ACK);  /* send the "final"
                                                            ack */
    rap->th_block = htons(recvblock);
    (void) swrite(peer, &ackbuf.storage[0], 4);
  #if defined(HAVE_ALARM) && defined(SIGALRM)
    mysignal(SIGALRM, justtimeout);        /* just abort read on timeout */
    alarm(rexmtval);
  #endif
    /* normally times out and quits */
    n = sread(peer, &buf.storage[0], sizeof(buf.storage));
  #ifdef HAVE_ALARM
    alarm(0);
  #endif
    if(got_exit_signal)
      goto abort;
    if(n >= 4 &&                               /* if read some data */
       rdp->th_opcode == opcode_DATA &&        /* and got a data block */
       recvblock == rdp->th_block) {           /* then my last ack was lost */
      (void) swrite(peer, &ackbuf.storage[0], 4);  /* resend final ack */
    }
  abort:
    return;
  }
  
  /*
   * 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 = &buf.hdr;
    tp->th_opcode = htons((unsigned short)opcode_ERROR);
    tp->th_code = htons((unsigned 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;   /* set 'undef' errorcode */
    }
    length = (int)strlen(pe->e_msg);
  
    /* we use memcpy() instead of strcpy() in order to avoid buffer overflow
     * report from glibc with FORTIFY_SOURCE */
    memcpy(tp->th_msg, pe->e_msg, length + 1);
    length += 5;
    if(swrite(peer, &buf.storage[0], length) != length)
      logmsg("nak: fail\n");
  }
  