path: root/contrib/libs/curl/lib/tftp.c

/*************************************************************************** 
 *                                  _   _ ____  _ 
 *  Project                     ___| | | |  _ \| | 
 *                             / __| | | | |_) | | 
 *                            | (__| |_| |  _ <| |___ 
 *                             \___|\___/|_| \_\_____| 
 * 
 * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
 * 
 * This software is licensed as described in the file COPYING, which 
 * you should have received as part of this distribution. The terms 
 * are also available at https://curl.se/docs/copyright.html.
 * 
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell 
 * copies of the Software, and permit persons to whom the Software is 
 * furnished to do so, under the terms of the COPYING file. 
 * 
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY 
 * KIND, either express or implied. 
 * 
 ***************************************************************************/ 
 
#include "curl_setup.h" 
 
#ifndef CURL_DISABLE_TFTP 
 
#ifdef HAVE_NETINET_IN_H 
#include <netinet/in.h> 
#endif 
#ifdef HAVE_NETDB_H 
#include <netdb.h> 
#endif 
#ifdef HAVE_ARPA_INET_H 
#include <arpa/inet.h> 
#endif 
#ifdef HAVE_NET_IF_H 
#include <net/if.h> 
#endif 
#ifdef HAVE_SYS_IOCTL_H 
#include <sys/ioctl.h> 
#endif 
 
#ifdef HAVE_SYS_PARAM_H 
#include <sys/param.h> 
#endif 
 
#include "urldata.h" 
#include <curl/curl.h> 
#include "transfer.h" 
#include "sendf.h" 
#include "tftp.h" 
#include "progress.h" 
#include "connect.h" 
#include "strerror.h" 
#include "sockaddr.h" /* required for Curl_sockaddr_storage */ 
#include "multiif.h" 
#include "url.h" 
#include "strcase.h"
#include "speedcheck.h" 
#include "select.h"
#include "escape.h"
 
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h" 
#include "memdebug.h" 
 
/* RFC2348 allows the block size to be negotiated */ 
#define TFTP_BLKSIZE_DEFAULT 512 
#define TFTP_BLKSIZE_MIN 8 
#define TFTP_BLKSIZE_MAX 65464 
#define TFTP_OPTION_BLKSIZE "blksize" 
 
/* from RFC2349: */ 
#define TFTP_OPTION_TSIZE    "tsize" 
#define TFTP_OPTION_INTERVAL "timeout" 
 
typedef enum { 
  TFTP_MODE_NETASCII = 0,
  TFTP_MODE_OCTET 
} tftp_mode_t; 
 
typedef enum { 
  TFTP_STATE_START = 0,
  TFTP_STATE_RX, 
  TFTP_STATE_TX, 
  TFTP_STATE_FIN 
} tftp_state_t; 
 
typedef enum { 
  TFTP_EVENT_NONE = -1, 
  TFTP_EVENT_INIT = 0, 
  TFTP_EVENT_RRQ = 1, 
  TFTP_EVENT_WRQ = 2, 
  TFTP_EVENT_DATA = 3, 
  TFTP_EVENT_ACK = 4, 
  TFTP_EVENT_ERROR = 5, 
  TFTP_EVENT_OACK = 6, 
  TFTP_EVENT_TIMEOUT 
} tftp_event_t; 
 
typedef enum { 
  TFTP_ERR_UNDEF = 0,
  TFTP_ERR_NOTFOUND, 
  TFTP_ERR_PERM, 
  TFTP_ERR_DISKFULL, 
  TFTP_ERR_ILLEGAL, 
  TFTP_ERR_UNKNOWNID, 
  TFTP_ERR_EXISTS, 
  TFTP_ERR_NOSUCHUSER,  /* This will never be triggered by this code */ 
 
  /* The remaining error codes are internal to curl */ 
  TFTP_ERR_NONE = -100, 
  TFTP_ERR_TIMEOUT, 
  TFTP_ERR_NORESPONSE 
} tftp_error_t; 
 
struct tftp_packet {
  unsigned char *data; 
};
 
struct tftp_state_data {
  tftp_state_t    state; 
  tftp_mode_t     mode; 
  tftp_error_t    error; 
  tftp_event_t    event; 
  struct connectdata      *conn; 
  curl_socket_t   sockfd; 
  int             retries; 
  int             retry_time; 
  int             retry_max; 
  time_t          start_time; 
  time_t          max_time; 
  time_t          rx_time; 
  unsigned short  block; 
  struct Curl_sockaddr_storage   local_addr; 
  struct Curl_sockaddr_storage   remote_addr; 
  curl_socklen_t  remote_addrlen; 
  int             rbytes; 
  int             sbytes; 
  int             blksize; 
  int             requested_blksize; 
  struct tftp_packet rpacket;
  struct tftp_packet spacket;
};
 
 
/* Forward declarations */ 
static CURLcode tftp_rx(struct tftp_state_data *state, tftp_event_t event);
static CURLcode tftp_tx(struct tftp_state_data *state, tftp_event_t event);
static CURLcode tftp_connect(struct connectdata *conn, bool *done); 
static CURLcode tftp_disconnect(struct connectdata *conn, 
                                bool dead_connection); 
static CURLcode tftp_do(struct connectdata *conn, bool *done); 
static CURLcode tftp_done(struct connectdata *conn, 
                          CURLcode, bool premature); 
static CURLcode tftp_setup_connection(struct connectdata *conn);
static CURLcode tftp_multi_statemach(struct connectdata *conn, bool *done); 
static CURLcode tftp_doing(struct connectdata *conn, bool *dophase_done); 
static int tftp_getsock(struct connectdata *conn, curl_socket_t *socks);
static CURLcode tftp_translate_code(tftp_error_t error); 
 
 
/* 
 * TFTP protocol handler. 
 */ 
 
const struct Curl_handler Curl_handler_tftp = { 
  "TFTP",                               /* scheme */ 
  tftp_setup_connection,                /* setup_connection */ 
  tftp_do,                              /* do_it */ 
  tftp_done,                            /* done */ 
  ZERO_NULL,                            /* do_more */ 
  tftp_connect,                         /* connect_it */ 
  tftp_multi_statemach,                 /* connecting */ 
  tftp_doing,                           /* doing */ 
  tftp_getsock,                         /* proto_getsock */ 
  tftp_getsock,                         /* doing_getsock */ 
  ZERO_NULL,                            /* domore_getsock */ 
  ZERO_NULL,                            /* perform_getsock */ 
  tftp_disconnect,                      /* disconnect */ 
  ZERO_NULL,                            /* readwrite */ 
  ZERO_NULL,                            /* connection_check */
  PORT_TFTP,                            /* defport */ 
  CURLPROTO_TFTP,                       /* protocol */ 
  CURLPROTO_TFTP,                       /* family */
  PROTOPT_NONE | PROTOPT_NOURLQUERY     /* flags */ 
}; 
 
/********************************************************** 
 * 
 * tftp_set_timeouts - 
 * 
 * Set timeouts based on state machine state. 
 * Use user provided connect timeouts until DATA or ACK 
 * packet is received, then use user-provided transfer timeouts 
 * 
 * 
 **********************************************************/ 
static CURLcode tftp_set_timeouts(struct tftp_state_data *state)
{ 
  time_t maxtime, timeout; 
  timediff_t timeout_ms;
  bool start = (state->state == TFTP_STATE_START) ? TRUE : FALSE; 
 
  time(&state->start_time); 
 
  /* Compute drop-dead time */ 
  timeout_ms = Curl_timeleft(state->conn->data, NULL, start); 
 
  if(timeout_ms < 0) { 
    /* time-out, bail out, go home */ 
    failf(state->conn->data, "Connection time-out"); 
    return CURLE_OPERATION_TIMEDOUT; 
  } 
 
  if(start) { 
 
    maxtime = (time_t)(timeout_ms + 500) / 1000; 
    state->max_time = state->start_time + maxtime;
 
    /* Set per-block timeout to total */ 
    timeout = maxtime;
 
    /* Average restart after 5 seconds */ 
    state->retry_max = (int)timeout/5; 
 
    if(state->retry_max < 1) 
      /* avoid division by zero below */ 
      state->retry_max = 1; 
 
    /* Compute the re-start interval to suit the timeout */ 
    state->retry_time = (int)timeout/state->retry_max; 
    if(state->retry_time<1) 
      state->retry_time = 1;
 
  } 
  else { 
    if(timeout_ms > 0) 
      maxtime = (time_t)(timeout_ms + 500) / 1000; 
    else 
      maxtime = 3600; 
 
    state->max_time = state->start_time + maxtime;
 
    /* Set per-block timeout to total */ 
    timeout = maxtime; 
 
    /* Average reposting an ACK after 5 seconds */ 
    state->retry_max = (int)timeout/5; 
  } 
  /* But bound the total number */ 
  if(state->retry_max<3) 
    state->retry_max = 3;
 
  if(state->retry_max>50) 
    state->retry_max = 50;
 
  /* Compute the re-ACK interval to suit the timeout */ 
  state->retry_time = (int)(timeout/state->retry_max); 
  if(state->retry_time<1) 
    state->retry_time = 1;
 
  infof(state->conn->data, 
        "set timeouts for state %d; Total %ld, retry %d maxtry %d\n", 
        (int)state->state, (long)(state->max_time-state->start_time), 
        state->retry_time, state->retry_max); 
 
  /* init RX time */ 
  time(&state->rx_time); 
 
  return CURLE_OK; 
} 
 
/********************************************************** 
 * 
 * tftp_set_send_first 
 * 
 * Event handler for the START state 
 * 
 **********************************************************/ 
 
static void setpacketevent(struct tftp_packet *packet, unsigned short num)
{ 
  packet->data[0] = (unsigned char)(num >> 8); 
  packet->data[1] = (unsigned char)(num & 0xff); 
} 
 
 
static void setpacketblock(struct tftp_packet *packet, unsigned short num)
{ 
  packet->data[2] = (unsigned char)(num >> 8); 
  packet->data[3] = (unsigned char)(num & 0xff); 
} 
 
static unsigned short getrpacketevent(const struct tftp_packet *packet)
{ 
  return (unsigned short)((packet->data[0] << 8) | packet->data[1]); 
} 
 
static unsigned short getrpacketblock(const struct tftp_packet *packet)
{ 
  return (unsigned short)((packet->data[2] << 8) | packet->data[3]); 
} 
 
static size_t Curl_strnlen(const char *string, size_t maxlen) 
{ 
  const char *end = memchr(string, '\0', maxlen);
  return end ? (size_t) (end - string) : maxlen; 
} 
 
static const char *tftp_option_get(const char *buf, size_t len, 
                                   const char **option, const char **value) 
{ 
  size_t loc; 
 
  loc = Curl_strnlen(buf, len);
  loc++; /* NULL term */ 
 
  if(loc >= len) 
    return NULL; 
  *option = buf; 
 
  loc += Curl_strnlen(buf + loc, len-loc);
  loc++; /* NULL term */ 
 
  if(loc > len) 
    return NULL; 
  *value = &buf[strlen(*option) + 1]; 
 
  return &buf[loc]; 
} 
 
static CURLcode tftp_parse_option_ack(struct tftp_state_data *state,
                                      const char *ptr, int len) 
{ 
  const char *tmp = ptr; 
  struct Curl_easy *data = state->conn->data;
 
  /* if OACK doesn't contain blksize option, the default (512) must be used */ 
  state->blksize = TFTP_BLKSIZE_DEFAULT; 
 
  while(tmp < ptr + len) { 
    const char *option, *value; 
 
    tmp = tftp_option_get(tmp, ptr + len - tmp, &option, &value); 
    if(tmp == NULL) { 
      failf(data, "Malformed ACK packet, rejecting"); 
      return CURLE_TFTP_ILLEGAL; 
    } 
 
    infof(data, "got option=(%s) value=(%s)\n", option, value); 
 
    if(checkprefix(option, TFTP_OPTION_BLKSIZE)) { 
      long blksize; 
 
      blksize = strtol(value, NULL, 10);
 
      if(!blksize) { 
        failf(data, "invalid blocksize value in OACK packet"); 
        return CURLE_TFTP_ILLEGAL; 
      } 
      if(blksize > TFTP_BLKSIZE_MAX) {
        failf(data, "%s (%d)", "blksize is larger than max supported", 
              TFTP_BLKSIZE_MAX); 
        return CURLE_TFTP_ILLEGAL; 
      } 
      else if(blksize < TFTP_BLKSIZE_MIN) { 
        failf(data, "%s (%d)", "blksize is smaller than min supported", 
              TFTP_BLKSIZE_MIN); 
        return CURLE_TFTP_ILLEGAL; 
      } 
      else if(blksize > state->requested_blksize) { 
        /* could realloc pkt buffers here, but the spec doesn't call out 
         * support for the server requesting a bigger blksize than the client 
         * requests */ 
        failf(data, "%s (%ld)", 
              "server requested blksize larger than allocated", blksize); 
        return CURLE_TFTP_ILLEGAL; 
      } 
 
      state->blksize = (int)blksize; 
      infof(data, "%s (%d) %s (%d)\n", "blksize parsed from OACK", 
            state->blksize, "requested", state->requested_blksize); 
    } 
    else if(checkprefix(option, TFTP_OPTION_TSIZE)) { 
      long tsize = 0; 
 
      tsize = strtol(value, NULL, 10);
      infof(data, "%s (%ld)\n", "tsize parsed from OACK", tsize); 
 
      /* tsize should be ignored on upload: Who cares about the size of the 
         remote file? */ 
      if(!data->set.upload) { 
        if(!tsize) { 
          failf(data, "invalid tsize -:%s:- value in OACK packet", value); 
          return CURLE_TFTP_ILLEGAL; 
        } 
        Curl_pgrsSetDownloadSize(data, tsize); 
      } 
    } 
  } 
 
  return CURLE_OK; 
} 
 
static CURLcode tftp_option_add(struct tftp_state_data *state, size_t *csize,
                                char *buf, const char *option)
{ 
  if(( strlen(option) + *csize + 1) > (size_t)state->blksize)
    return CURLE_TFTP_ILLEGAL;
  strcpy(buf, option); 
  *csize += strlen(option) + 1;
  return CURLE_OK;
} 
 
static CURLcode tftp_connect_for_tx(struct tftp_state_data *state,
                                    tftp_event_t event) 
{ 
  CURLcode result;
#ifndef CURL_DISABLE_VERBOSE_STRINGS 
  struct Curl_easy *data = state->conn->data;
 
  infof(data, "%s\n", "Connected for transmit"); 
#endif 
  state->state = TFTP_STATE_TX; 
  result = tftp_set_timeouts(state);
  if(result)
    return result;
  return tftp_tx(state, event); 
} 
 
static CURLcode tftp_connect_for_rx(struct tftp_state_data *state,
                                    tftp_event_t event) 
{ 
  CURLcode result;
#ifndef CURL_DISABLE_VERBOSE_STRINGS 
  struct Curl_easy *data = state->conn->data;
 
  infof(data, "%s\n", "Connected for receive"); 
#endif 
  state->state = TFTP_STATE_RX; 
  result = tftp_set_timeouts(state);
  if(result)
    return result;
  return tftp_rx(state, event); 
} 
 
static CURLcode tftp_send_first(struct tftp_state_data *state,
                                tftp_event_t event)
{ 
  size_t sbytes; 
  ssize_t senddata; 
  const char *mode = "octet"; 
  char *filename; 
  struct Curl_easy *data = state->conn->data;
  CURLcode result = CURLE_OK;
 
  /* Set ascii mode if -B flag was used */ 
  if(data->set.prefer_ascii) 
    mode = "netascii"; 
 
  switch(event) { 
 
  case TFTP_EVENT_INIT:    /* Send the first packet out */ 
  case TFTP_EVENT_TIMEOUT: /* Resend the first packet out */ 
    /* Increment the retry counter, quit if over the limit */ 
    state->retries++; 
    if(state->retries>state->retry_max) { 
      state->error = TFTP_ERR_NORESPONSE; 
      state->state = TFTP_STATE_FIN; 
      return result;
    } 
 
    if(data->set.upload) { 
      /* If we are uploading, send an WRQ */ 
      setpacketevent(&state->spacket, TFTP_EVENT_WRQ); 
      state->conn->data->req.upload_fromhere = 
        (char *)state->spacket.data + 4;
      if(data->state.infilesize != -1)
        Curl_pgrsSetUploadSize(data, data->state.infilesize);
    } 
    else { 
      /* If we are downloading, send an RRQ */ 
      setpacketevent(&state->spacket, TFTP_EVENT_RRQ); 
    } 
    /* As RFC3617 describes the separator slash is not actually part of the 
       file name so we skip the always-present first letter of the path 
       string. */ 
    result = Curl_urldecode(data, &state->conn->data->state.up.path[1], 0,
                            &filename, NULL, REJECT_ZERO);
    if(result)
      return result;
 
    if(strlen(filename) > (state->blksize - strlen(mode) - 4)) {
      failf(data, "TFTP file name too long\n");
      free(filename);
      return CURLE_TFTP_ILLEGAL; /* too long file name field */
    }

    msnprintf((char *)state->spacket.data + 2,
              state->blksize,
              "%s%c%s%c", filename, '\0',  mode, '\0');
    sbytes = 4 + strlen(filename) + strlen(mode); 
 
    /* optional addition of TFTP options */
    if(!data->set.tftp_no_options) {
      char buf[64];
      /* add tsize option */
      if(data->set.upload && (data->state.infilesize != -1))
        msnprintf(buf, sizeof(buf), "%" CURL_FORMAT_CURL_OFF_T,
                  data->state.infilesize);
      else
        strcpy(buf, "0"); /* the destination is large enough */
 
      result = tftp_option_add(state, &sbytes,
                               (char *)state->spacket.data + sbytes,
                               TFTP_OPTION_TSIZE);
      if(result == CURLE_OK)
        result = tftp_option_add(state, &sbytes,
                                 (char *)state->spacket.data + sbytes, buf);

      /* add blksize option */
      msnprintf(buf, sizeof(buf), "%d", state->requested_blksize);
      if(result == CURLE_OK)
        result = tftp_option_add(state, &sbytes,
                                 (char *)state->spacket.data + sbytes,
                                 TFTP_OPTION_BLKSIZE);
      if(result == CURLE_OK)
        result = tftp_option_add(state, &sbytes,
                                 (char *)state->spacket.data + sbytes, buf);
 
      /* add timeout option */
      msnprintf(buf, sizeof(buf), "%d", state->retry_time);
      if(result == CURLE_OK)
        result = tftp_option_add(state, &sbytes,
                                 (char *)state->spacket.data + sbytes,
                                 TFTP_OPTION_INTERVAL);
      if(result == CURLE_OK)
        result = tftp_option_add(state, &sbytes,
                                 (char *)state->spacket.data + sbytes, buf);

      if(result != CURLE_OK) {
        failf(data, "TFTP buffer too small for options");
        free(filename);
        return CURLE_TFTP_ILLEGAL;
      }
    }
 
    /* the typecase for the 3rd argument is mostly for systems that do 
       not have a size_t argument, like older unixes that want an 'int' */ 
    senddata = sendto(state->sockfd, (void *)state->spacket.data, 
                      (SEND_TYPE_ARG3)sbytes, 0, 
                      state->conn->ip_addr->ai_addr, 
                      state->conn->ip_addr->ai_addrlen); 
    if(senddata != (ssize_t)sbytes) { 
      char buffer[STRERROR_LEN];
      failf(data, "%s", Curl_strerror(SOCKERRNO, buffer, sizeof(buffer)));
    } 
    free(filename);
    break; 
 
  case TFTP_EVENT_OACK: 
    if(data->set.upload) { 
      result = tftp_connect_for_tx(state, event);
    } 
    else { 
      result = tftp_connect_for_rx(state, event);
    } 
    break; 
 
  case TFTP_EVENT_ACK: /* Connected for transmit */ 
    result = tftp_connect_for_tx(state, event);
    break; 
 
  case TFTP_EVENT_DATA: /* Connected for receive */ 
    result = tftp_connect_for_rx(state, event);
    break; 
 
  case TFTP_EVENT_ERROR: 
    state->state = TFTP_STATE_FIN; 
    break; 
 
  default: 
    failf(state->conn->data, "tftp_send_first: internal error"); 
    break; 
  } 

  return result;
} 
 
/* the next blocknum is x + 1 but it needs to wrap at an unsigned 16bit 
   boundary */ 
#define NEXT_BLOCKNUM(x) (((x) + 1)&0xffff)
 
/********************************************************** 
 * 
 * tftp_rx 
 * 
 * Event handler for the RX state 
 * 
 **********************************************************/ 
static CURLcode tftp_rx(struct tftp_state_data *state,
                        tftp_event_t event)
{ 
  ssize_t sbytes; 
  int rblock; 
  struct Curl_easy *data = state->conn->data;
  char buffer[STRERROR_LEN];
 
  switch(event) { 
 
  case TFTP_EVENT_DATA: 
    /* Is this the block we expect? */ 
    rblock = getrpacketblock(&state->rpacket); 
    if(NEXT_BLOCKNUM(state->block) == rblock) { 
      /* This is the expected block.  Reset counters and ACK it. */ 
      state->retries = 0; 
    } 
    else if(state->block == rblock) { 
      /* This is the last recently received block again. Log it and ACK it 
         again. */ 
      infof(data, "Received last DATA packet block %d again.\n", rblock); 
    } 
    else { 
      /* totally unexpected, just log it */ 
      infof(data, 
            "Received unexpected DATA packet block %d, expecting block %d\n", 
            rblock, NEXT_BLOCKNUM(state->block)); 
      break; 
    } 
 
    /* ACK this block. */ 
    state->block = (unsigned short)rblock; 
    setpacketevent(&state->spacket, TFTP_EVENT_ACK); 
    setpacketblock(&state->spacket, state->block); 
    sbytes = sendto(state->sockfd, (void *)state->spacket.data, 
                    4, SEND_4TH_ARG, 
                    (struct sockaddr *)&state->remote_addr, 
                    state->remote_addrlen); 
    if(sbytes < 0) { 
      failf(data, "%s", Curl_strerror(SOCKERRNO, buffer, sizeof(buffer)));
      return CURLE_SEND_ERROR; 
    } 
 
    /* Check if completed (That is, a less than full packet is received) */ 
    if(state->rbytes < (ssize_t)state->blksize + 4) {
      state->state = TFTP_STATE_FIN; 
    } 
    else { 
      state->state = TFTP_STATE_RX; 
    } 
    time(&state->rx_time); 
    break; 
 
  case TFTP_EVENT_OACK: 
    /* ACK option acknowledgement so we can move on to data */ 
    state->block = 0; 
    state->retries = 0; 
    setpacketevent(&state->spacket, TFTP_EVENT_ACK); 
    setpacketblock(&state->spacket, state->block); 
    sbytes = sendto(state->sockfd, (void *)state->spacket.data, 
                    4, SEND_4TH_ARG, 
                    (struct sockaddr *)&state->remote_addr, 
                    state->remote_addrlen); 
    if(sbytes < 0) { 
      failf(data, "%s", Curl_strerror(SOCKERRNO, buffer, sizeof(buffer)));
      return CURLE_SEND_ERROR; 
    } 
 
    /* we're ready to RX data */ 
    state->state = TFTP_STATE_RX; 
    time(&state->rx_time); 
    break; 
 
  case TFTP_EVENT_TIMEOUT: 
    /* Increment the retry count and fail if over the limit */ 
    state->retries++; 
    infof(data, 
          "Timeout waiting for block %d ACK.  Retries = %d\n", 
          NEXT_BLOCKNUM(state->block), state->retries); 
    if(state->retries > state->retry_max) { 
      state->error = TFTP_ERR_TIMEOUT; 
      state->state = TFTP_STATE_FIN; 
    } 
    else { 
      /* Resend the previous ACK */ 
      sbytes = sendto(state->sockfd, (void *)state->spacket.data, 
                      4, SEND_4TH_ARG, 
                      (struct sockaddr *)&state->remote_addr, 
                      state->remote_addrlen); 
      if(sbytes<0) { 
        failf(data, "%s", Curl_strerror(SOCKERRNO, buffer, sizeof(buffer)));
        return CURLE_SEND_ERROR; 
      } 
    } 
    break; 
 
  case TFTP_EVENT_ERROR: 
    setpacketevent(&state->spacket, TFTP_EVENT_ERROR); 
    setpacketblock(&state->spacket, state->block); 
    (void)sendto(state->sockfd, (void *)state->spacket.data, 
                 4, SEND_4TH_ARG, 
                 (struct sockaddr *)&state->remote_addr, 
                 state->remote_addrlen); 
    /* don't bother with the return code, but if the socket is still up we 
     * should be a good TFTP client and let the server know we're done */ 
    state->state = TFTP_STATE_FIN; 
    break; 
 
  default: 
    failf(data, "%s", "tftp_rx: internal error"); 
    return CURLE_TFTP_ILLEGAL; /* not really the perfect return code for 
                                  this */ 
  } 
  return CURLE_OK; 
} 
 
/********************************************************** 
 * 
 * tftp_tx 
 * 
 * Event handler for the TX state 
 * 
 **********************************************************/ 
static CURLcode tftp_tx(struct tftp_state_data *state, tftp_event_t event)
{ 
  struct Curl_easy *data = state->conn->data;
  ssize_t sbytes; 
  CURLcode result = CURLE_OK;
  struct SingleRequest *k = &data->req; 
  size_t cb; /* Bytes currently read */
  char buffer[STRERROR_LEN];
 
  switch(event) { 
 
  case TFTP_EVENT_ACK: 
  case TFTP_EVENT_OACK: 
    if(event == TFTP_EVENT_ACK) { 
      /* Ack the packet */ 
      int rblock = getrpacketblock(&state->rpacket);
 
      if(rblock != state->block && 
         /* There's a bug in tftpd-hpa that causes it to send us an ack for 
          * 65535 when the block number wraps to 0. So when we're expecting 
          * 0, also accept 65535. See 
          * http://syslinux.zytor.com/archives/2010-September/015253.html 
          * */ 
         !(state->block == 0 && rblock == 65535)) { 
        /* This isn't the expected block.  Log it and up the retry counter */ 
        infof(data, "Received ACK for block %d, expecting %d\n", 
              rblock, state->block); 
        state->retries++; 
        /* Bail out if over the maximum */ 
        if(state->retries>state->retry_max) { 
          failf(data, "tftp_tx: giving up waiting for block %d ack", 
                state->block); 
          result = CURLE_SEND_ERROR;
        } 
        else { 
          /* Re-send the data packet */ 
          sbytes = sendto(state->sockfd, (void *)state->spacket.data, 
                          4 + state->sbytes, SEND_4TH_ARG,
                          (struct sockaddr *)&state->remote_addr, 
                          state->remote_addrlen); 
          /* Check all sbytes were sent */ 
          if(sbytes<0) { 
            failf(data, "%s", Curl_strerror(SOCKERRNO,
                                            buffer, sizeof(buffer)));
            result = CURLE_SEND_ERROR;
          } 
        } 

        return result;
      } 
      /* This is the expected packet.  Reset the counters and send the next 
         block */ 
      time(&state->rx_time); 
      state->block++; 
    } 
    else 
      state->block = 1; /* first data block is 1 when using OACK */ 
 
    state->retries = 0; 
    setpacketevent(&state->spacket, TFTP_EVENT_DATA); 
    setpacketblock(&state->spacket, state->block); 
    if(state->block > 1 && state->sbytes < state->blksize) {
      state->state = TFTP_STATE_FIN; 
      return CURLE_OK; 
    } 

    /* TFTP considers data block size < 512 bytes as an end of session. So
     * in some cases we must wait for additional data to build full (512 bytes)
     * data block.
     * */
    state->sbytes = 0;
    state->conn->data->req.upload_fromhere = (char *)state->spacket.data + 4;
    do {
      result = Curl_fillreadbuffer(state->conn, state->blksize - state->sbytes,
                                   &cb);
      if(result)
        return result;
      state->sbytes += (int)cb;
      state->conn->data->req.upload_fromhere += cb;
    } while(state->sbytes < state->blksize && cb != 0);

    sbytes = sendto(state->sockfd, (void *) state->spacket.data,
                    4 + state->sbytes, SEND_4TH_ARG,
                    (struct sockaddr *)&state->remote_addr, 
                    state->remote_addrlen); 
    /* Check all sbytes were sent */ 
    if(sbytes<0) { 
      failf(data, "%s", Curl_strerror(SOCKERRNO, buffer, sizeof(buffer)));
      return CURLE_SEND_ERROR; 
    } 
    /* Update the progress meter */ 
    k->writebytecount += state->sbytes; 
    Curl_pgrsSetUploadCounter(data, k->writebytecount); 
    break; 
 
  case TFTP_EVENT_TIMEOUT: 
    /* Increment the retry counter and log the timeout */ 
    state->retries++; 
    infof(data, "Timeout waiting for block %d ACK. " 
          " Retries = %d\n", NEXT_BLOCKNUM(state->block), state->retries); 
    /* Decide if we've had enough */ 
    if(state->retries > state->retry_max) { 
      state->error = TFTP_ERR_TIMEOUT; 
      state->state = TFTP_STATE_FIN; 
    } 
    else { 
      /* Re-send the data packet */ 
      sbytes = sendto(state->sockfd, (void *)state->spacket.data, 
                      4 + state->sbytes, SEND_4TH_ARG,
                      (struct sockaddr *)&state->remote_addr, 
                      state->remote_addrlen); 
      /* Check all sbytes were sent */ 
      if(sbytes<0) { 
        failf(data, "%s", Curl_strerror(SOCKERRNO, buffer, sizeof(buffer)));
        return CURLE_SEND_ERROR; 
      } 
      /* since this was a re-send, we remain at the still byte position */ 
      Curl_pgrsSetUploadCounter(data, k->writebytecount); 
    } 
    break; 
 
  case TFTP_EVENT_ERROR: 
    state->state = TFTP_STATE_FIN; 
    setpacketevent(&state->spacket, TFTP_EVENT_ERROR); 
    setpacketblock(&state->spacket, state->block); 
    (void)sendto(state->sockfd, (void *)state->spacket.data, 4, SEND_4TH_ARG, 
                 (struct sockaddr *)&state->remote_addr, 
                 state->remote_addrlen); 
    /* don't bother with the return code, but if the socket is still up we 
     * should be a good TFTP client and let the server know we're done */ 
    state->state = TFTP_STATE_FIN; 
    break; 
 
  default: 
    failf(data, "tftp_tx: internal error, event: %i", (int)(event)); 
    break; 
  } 
 
  return result;
} 
 
/********************************************************** 
 * 
 * tftp_translate_code 
 * 
 * Translate internal error codes to CURL error codes 
 * 
 **********************************************************/ 
static CURLcode tftp_translate_code(tftp_error_t error) 
{ 
  CURLcode result = CURLE_OK;
 
  if(error != TFTP_ERR_NONE) { 
    switch(error) { 
    case TFTP_ERR_NOTFOUND: 
      result = CURLE_TFTP_NOTFOUND;
      break; 
    case TFTP_ERR_PERM: 
      result = CURLE_TFTP_PERM;
      break; 
    case TFTP_ERR_DISKFULL: 
      result = CURLE_REMOTE_DISK_FULL;
      break; 
    case TFTP_ERR_UNDEF: 
    case TFTP_ERR_ILLEGAL: 
      result = CURLE_TFTP_ILLEGAL;
      break; 
    case TFTP_ERR_UNKNOWNID: 
      result = CURLE_TFTP_UNKNOWNID;
      break; 
    case TFTP_ERR_EXISTS: 
      result = CURLE_REMOTE_FILE_EXISTS;
      break; 
    case TFTP_ERR_NOSUCHUSER: 
      result = CURLE_TFTP_NOSUCHUSER;
      break; 
    case TFTP_ERR_TIMEOUT: 
      result = CURLE_OPERATION_TIMEDOUT;
      break; 
    case TFTP_ERR_NORESPONSE: 
      result = CURLE_COULDNT_CONNECT;
      break; 
    default: 
      result = CURLE_ABORTED_BY_CALLBACK;
      break; 
    } 
  } 
  else
    result = CURLE_OK;
 
  return result;
} 
 
/********************************************************** 
 * 
 * tftp_state_machine 
 * 
 * The tftp state machine event dispatcher 
 * 
 **********************************************************/ 
static CURLcode tftp_state_machine(struct tftp_state_data *state,
                                   tftp_event_t event) 
{ 
  CURLcode result = CURLE_OK;
  struct Curl_easy *data = state->conn->data;

  switch(state->state) { 
  case TFTP_STATE_START: 
    DEBUGF(infof(data, "TFTP_STATE_START\n")); 
    result = tftp_send_first(state, event);
    break; 
  case TFTP_STATE_RX: 
    DEBUGF(infof(data, "TFTP_STATE_RX\n")); 
    result = tftp_rx(state, event);
    break; 
  case TFTP_STATE_TX: 
    DEBUGF(infof(data, "TFTP_STATE_TX\n")); 
    result = tftp_tx(state, event);
    break; 
  case TFTP_STATE_FIN: 
    infof(data, "%s\n", "TFTP finished"); 
    break; 
  default: 
    DEBUGF(infof(data, "STATE: %d\n", state->state)); 
    failf(data, "%s", "Internal state machine error"); 
    result = CURLE_TFTP_ILLEGAL;
    break; 
  } 

  return result;
} 
 
/********************************************************** 
 * 
 * tftp_disconnect 
 * 
 * The disconnect callback 
 * 
 **********************************************************/ 
static CURLcode tftp_disconnect(struct connectdata *conn, bool dead_connection) 
{ 
  struct tftp_state_data *state = conn->proto.tftpc;
  (void) dead_connection; 
 
  /* done, free dynamically allocated pkt buffers */ 
  if(state) { 
    Curl_safefree(state->rpacket.data); 
    Curl_safefree(state->spacket.data); 
    free(state); 
  } 
 
  return CURLE_OK; 
} 
 
/********************************************************** 
 * 
 * tftp_connect 
 * 
 * The connect callback 
 * 
 **********************************************************/ 
static CURLcode tftp_connect(struct connectdata *conn, bool *done) 
{ 
  struct tftp_state_data *state;
  int blksize;
  int need_blksize;
 
  blksize = TFTP_BLKSIZE_DEFAULT; 
 
  state = conn->proto.tftpc = calloc(1, sizeof(struct tftp_state_data));
  if(!state) 
    return CURLE_OUT_OF_MEMORY; 
 
  /* alloc pkt buffers based on specified blksize */ 
  if(conn->data->set.tftp_blksize) { 
    blksize = (int)conn->data->set.tftp_blksize; 
    if(blksize > TFTP_BLKSIZE_MAX || blksize < TFTP_BLKSIZE_MIN)
      return CURLE_TFTP_ILLEGAL; 
  } 
 
  need_blksize = blksize;
  /* default size is the fallback when no OACK is received */
  if(need_blksize < TFTP_BLKSIZE_DEFAULT)
    need_blksize = TFTP_BLKSIZE_DEFAULT;

  if(!state->rpacket.data) { 
    state->rpacket.data = calloc(1, need_blksize + 2 + 2);
 
    if(!state->rpacket.data) 
      return CURLE_OUT_OF_MEMORY; 
  } 
 
  if(!state->spacket.data) { 
    state->spacket.data = calloc(1, need_blksize + 2 + 2);
 
    if(!state->spacket.data) 
      return CURLE_OUT_OF_MEMORY; 
  } 
 
  /* we don't keep TFTP connections up basically because there's none or very
   * little gain for UDP */
  connclose(conn, "TFTP");
 
  state->conn = conn; 
  state->sockfd = state->conn->sock[FIRSTSOCKET]; 
  state->state = TFTP_STATE_START; 
  state->error = TFTP_ERR_NONE; 
  state->blksize = TFTP_BLKSIZE_DEFAULT; /* Unless updated by OACK response */
  state->requested_blksize = blksize; 
 
  ((struct sockaddr *)&state->local_addr)->sa_family = 
    (CURL_SA_FAMILY_T)(conn->ip_addr->ai_family);
 
  tftp_set_timeouts(state); 
 
  if(!conn->bits.bound) { 
    /* If not already bound, bind to any interface, random UDP port. If it is 
     * reused or a custom local port was desired, this has already been done! 
     * 
     * We once used the size of the local_addr struct as the third argument 
     * for bind() to better work with IPv6 or whatever size the struct could 
     * have, but we learned that at least Tru64, AIX and IRIX *requires* the 
     * size of that argument to match the exact size of a 'sockaddr_in' struct 
     * when running IPv4-only. 
     * 
     * Therefore we use the size from the address we connected to, which we 
     * assume uses the same IP version and thus hopefully this works for both 
     * IPv4 and IPv6... 
     */ 
    int rc = bind(state->sockfd, (struct sockaddr *)&state->local_addr,
                  conn->ip_addr->ai_addrlen);
    if(rc) { 
      char buffer[STRERROR_LEN];
      failf(conn->data, "bind() failed; %s", 
            Curl_strerror(SOCKERRNO, buffer, sizeof(buffer)));
      return CURLE_COULDNT_CONNECT; 
    } 
    conn->bits.bound = TRUE; 
  } 
 
  Curl_pgrsStartNow(conn->data); 
 
  *done = TRUE; 

  return CURLE_OK;
} 
 
/********************************************************** 
 * 
 * tftp_done 
 * 
 * The done callback 
 * 
 **********************************************************/ 
static CURLcode tftp_done(struct connectdata *conn, CURLcode status, 
                          bool premature) 
{ 
  CURLcode result = CURLE_OK;
  struct tftp_state_data *state = conn->proto.tftpc;
 
  (void)status; /* unused */ 
  (void)premature; /* not used */ 
 
  if(Curl_pgrsDone(conn)) 
    return CURLE_ABORTED_BY_CALLBACK; 
 
  /* If we have encountered an error */ 
  if(state)
    result = tftp_translate_code(state->error);
 
  return result;
} 
 
/********************************************************** 
 * 
 * tftp_getsock 
 * 
 * The getsock callback 
 * 
 **********************************************************/ 
static int tftp_getsock(struct connectdata *conn, curl_socket_t *socks)
{ 
  socks[0] = conn->sock[FIRSTSOCKET]; 
  return GETSOCK_READSOCK(0); 
} 
 
/********************************************************** 
 * 
 * tftp_receive_packet 
 * 
 * Called once select fires and data is ready on the socket 
 * 
 **********************************************************/ 
static CURLcode tftp_receive_packet(struct connectdata *conn) 
{ 
  struct Curl_sockaddr_storage fromaddr; 
  curl_socklen_t        fromlen; 
  CURLcode              result = CURLE_OK; 
  struct Curl_easy  *data = conn->data;
  struct tftp_state_data *state = conn->proto.tftpc;
  struct SingleRequest  *k = &data->req; 
 
  /* Receive the packet */ 
  fromlen = sizeof(fromaddr); 
  state->rbytes = (int)recvfrom(state->sockfd, 
                                (void *)state->rpacket.data, 
                                state->blksize + 4,
                                0, 
                                (struct sockaddr *)&fromaddr, 
                                &fromlen); 
  if(state->remote_addrlen == 0) {
    memcpy(&state->remote_addr, &fromaddr, fromlen); 
    state->remote_addrlen = fromlen; 
  } 
 
  /* Sanity check packet length */ 
  if(state->rbytes < 4) { 
    failf(data, "Received too short packet"); 
    /* Not a timeout, but how best to handle it? */ 
    state->event = TFTP_EVENT_TIMEOUT; 
  } 
  else { 
    /* The event is given by the TFTP packet time */ 
    unsigned short event = getrpacketevent(&state->rpacket);
    state->event = (tftp_event_t)event;
 
    switch(state->event) { 
    case TFTP_EVENT_DATA: 
      /* Don't pass to the client empty or retransmitted packets */ 
      if(state->rbytes > 4 && 
         (NEXT_BLOCKNUM(state->block) == getrpacketblock(&state->rpacket))) { 
        result = Curl_client_write(conn, CLIENTWRITE_BODY, 
                                   (char *)state->rpacket.data + 4,
                                   state->rbytes-4); 
        if(result) { 
          tftp_state_machine(state, TFTP_EVENT_ERROR); 
          return result; 
        } 
        k->bytecount += state->rbytes-4; 
        Curl_pgrsSetDownloadCounter(data, (curl_off_t) k->bytecount); 
      } 
      break; 
    case TFTP_EVENT_ERROR: 
    {
      unsigned short error = getrpacketblock(&state->rpacket);
      char *str = (char *)state->rpacket.data + 4;
      size_t strn = state->rbytes - 4;
      state->error = (tftp_error_t)error;
      if(Curl_strnlen(str, strn) < strn)
        infof(data, "TFTP error: %s\n", str);
      break; 
    }
    case TFTP_EVENT_ACK: 
      break; 
    case TFTP_EVENT_OACK: 
      result = tftp_parse_option_ack(state, 
                                     (const char *)state->rpacket.data + 2,
                                     state->rbytes-2); 
      if(result) 
        return result; 
      break; 
    case TFTP_EVENT_RRQ: 
    case TFTP_EVENT_WRQ: 
    default: 
      failf(data, "%s", "Internal error: Unexpected packet"); 
      break; 
    } 
 
    /* Update the progress meter */ 
    if(Curl_pgrsUpdate(conn)) { 
      tftp_state_machine(state, TFTP_EVENT_ERROR); 
      return CURLE_ABORTED_BY_CALLBACK; 
    } 
  } 
  return result; 
} 
 
/********************************************************** 
 * 
 * tftp_state_timeout 
 * 
 * Check if timeouts have been reached 
 * 
 **********************************************************/ 
static long tftp_state_timeout(struct connectdata *conn, tftp_event_t *event) 
{ 
  time_t current;
  struct tftp_state_data *state = conn->proto.tftpc;
 
  if(event) 
    *event = TFTP_EVENT_NONE; 
 
  time(&current); 
  if(current > state->max_time) { 
    DEBUGF(infof(conn->data, "timeout: %ld > %ld\n", 
                 (long)current, (long)state->max_time)); 
    state->error = TFTP_ERR_TIMEOUT; 
    state->state = TFTP_STATE_FIN; 
    return 0; 
  } 
  if(current > state->rx_time + state->retry_time) {
    if(event) 
      *event = TFTP_EVENT_TIMEOUT; 
    time(&state->rx_time); /* update even though we received nothing */ 
  } 
 
  /* there's a typecast below here since 'time_t' may in fact be larger than 
     'long', but we estimate that a 'long' will still be able to hold number 
     of seconds even if "only" 32 bit */ 
  return (long)(state->max_time - current); 
} 
 
/********************************************************** 
 * 
 * tftp_multi_statemach 
 * 
 * Handle single RX socket event and return 
 * 
 **********************************************************/ 
static CURLcode tftp_multi_statemach(struct connectdata *conn, bool *done) 
{ 
  tftp_event_t          event; 
  CURLcode              result = CURLE_OK; 
  struct Curl_easy  *data = conn->data;
  struct tftp_state_data *state = conn->proto.tftpc;
  long                  timeout_ms = tftp_state_timeout(conn, &event); 
 
  *done = FALSE; 
 
  if(timeout_ms <= 0) { 
    failf(data, "TFTP response timeout"); 
    return CURLE_OPERATION_TIMEDOUT; 
  } 
  if(event != TFTP_EVENT_NONE) {
    result = tftp_state_machine(state, event); 
    if(result)
      return result;
    *done = (state->state == TFTP_STATE_FIN) ? TRUE : FALSE; 
    if(*done) 
      /* Tell curl we're done */ 
      Curl_setup_transfer(data, -1, -1, FALSE, -1);
  } 
  else { 
    /* no timeouts to handle, check our socket */ 
    int rc = SOCKET_READABLE(state->sockfd, 0);
 
    if(rc == -1) { 
      /* bail out */ 
      int error = SOCKERRNO; 
      char buffer[STRERROR_LEN];
      failf(data, "%s", Curl_strerror(error, buffer, sizeof(buffer)));
      state->event = TFTP_EVENT_ERROR; 
    } 
    else if(rc != 0) { 
      result = tftp_receive_packet(conn); 
      if(result)
        return result;
      result = tftp_state_machine(state, state->event); 
      if(result)
        return result;
      *done = (state->state == TFTP_STATE_FIN) ? TRUE : FALSE; 
      if(*done) 
        /* Tell curl we're done */ 
        Curl_setup_transfer(data, -1, -1, FALSE, -1);
    } 
    /* if rc == 0, then select() timed out */ 
  } 
 
  return result; 
} 
 
/********************************************************** 
 * 
 * tftp_doing 
 * 
 * Called from multi.c while DOing 
 * 
 **********************************************************/ 
static CURLcode tftp_doing(struct connectdata *conn, bool *dophase_done) 
{ 
  CURLcode result; 
  result = tftp_multi_statemach(conn, dophase_done); 
 
  if(*dophase_done) { 
    DEBUGF(infof(conn->data, "DO phase is complete\n")); 
  } 
  else if(!result) {
    /* The multi code doesn't have this logic for the DOING state so we 
       provide it for TFTP since it may do the entire transfer in this 
       state. */ 
    if(Curl_pgrsUpdate(conn)) 
      result = CURLE_ABORTED_BY_CALLBACK; 
    else 
      result = Curl_speedcheck(conn->data, Curl_now());
  } 
  return result; 
} 
 
/********************************************************** 
 * 
 * tftp_peform 
 * 
 * Entry point for transfer from tftp_do, sarts state mach 
 * 
 **********************************************************/ 
static CURLcode tftp_perform(struct connectdata *conn, bool *dophase_done) 
{ 
  CURLcode              result = CURLE_OK; 
  struct tftp_state_data *state = conn->proto.tftpc;
 
  *dophase_done = FALSE; 
 
  result = tftp_state_machine(state, TFTP_EVENT_INIT); 
 
  if((state->state == TFTP_STATE_FIN) || result)
    return result;
 
  tftp_multi_statemach(conn, dophase_done); 
 
  if(*dophase_done) 
    DEBUGF(infof(conn->data, "DO phase is complete\n")); 
 
  return result; 
} 
 
 
/********************************************************** 
 * 
 * tftp_do 
 * 
 * The do callback 
 * 
 * This callback initiates the TFTP transfer 
 * 
 **********************************************************/ 
 
static CURLcode tftp_do(struct connectdata *conn, bool *done) 
{ 
  struct tftp_state_data *state;
  CURLcode result;
 
  *done = FALSE; 
 
  if(!conn->proto.tftpc) { 
    result = tftp_connect(conn, done);
    if(result)
      return result;
  } 

  state = conn->proto.tftpc;
  if(!state)
    return CURLE_TFTP_ILLEGAL;
 
  result = tftp_perform(conn, done);
 
  /* If tftp_perform() returned an error, use that for return code. If it 
     was OK, see if tftp_translate_code() has an error. */ 
  if(!result)
    /* If we have encountered an internal tftp error, translate it. */ 
    result = tftp_translate_code(state->error);
 
  return result;
} 
 
static CURLcode tftp_setup_connection(struct connectdata *conn)
{ 
  struct Curl_easy *data = conn->data;
  char *type;
 
  conn->transport = TRNSPRT_UDP;
 
  /* TFTP URLs support an extension like ";mode=<typecode>" that 
   * we'll try to get now! */ 
  type = strstr(data->state.up.path, ";mode=");
 
  if(!type) 
    type = strstr(conn->host.rawalloc, ";mode="); 
 
  if(type) { 
    char command;
    *type = 0;                   /* it was in the middle of the hostname */ 
    command = Curl_raw_toupper(type[6]); 
 
    switch(command) {
    case 'A': /* ASCII mode */ 
    case 'N': /* NETASCII mode */ 
      data->set.prefer_ascii = TRUE; 
      break; 
 
    case 'O': /* octet mode */ 
    case 'I': /* binary mode */ 
    default: 
      /* switch off ASCII */ 
      data->set.prefer_ascii = FALSE; 
      break; 
    } 
  } 
 
  return CURLE_OK; 
} 
#endif