1 | /* vi: set sw=4 ts=4: */
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2 | /* -------------------------------------------------------------------------
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3 | * tftp.c
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4 | *
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5 | * A simple tftp client for busybox.
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6 | * Tries to follow RFC1350.
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7 | * Only "octet" mode supported.
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8 | * Optional blocksize negotiation (RFC2347 + RFC2348)
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9 | *
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10 | * Copyright (C) 2001 Magnus Damm <damm@opensource.se>
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11 | *
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12 | * Parts of the code based on:
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13 | *
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14 | * atftp: Copyright (C) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>
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15 | * and Remi Lefebvre <remi@debian.org>
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16 | *
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17 | * utftp: Copyright (C) 1999 Uwe Ohse <uwe@ohse.de>
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18 | *
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19 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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20 | * ------------------------------------------------------------------------- */
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21 |
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22 | #include "libbb.h"
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23 |
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24 |
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25 | #if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
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26 |
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27 | #define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
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28 | #define TFTP_TIMEOUT 5 /* seconds */
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29 | #define TFTP_NUM_RETRIES 5 /* number of retries */
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30 |
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31 | /* opcodes we support */
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32 | #define TFTP_RRQ 1
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33 | #define TFTP_WRQ 2
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34 | #define TFTP_DATA 3
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35 | #define TFTP_ACK 4
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36 | #define TFTP_ERROR 5
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37 | #define TFTP_OACK 6
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38 |
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39 | #if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
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40 | #define USE_GETPUT(...)
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41 | #define CMD_GET(cmd) 1
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42 | #define CMD_PUT(cmd) 0
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43 | #elif !ENABLE_FEATURE_TFTP_GET && ENABLE_FEATURE_TFTP_PUT
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44 | #define USE_GETPUT(...)
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45 | #define CMD_GET(cmd) 0
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46 | #define CMD_PUT(cmd) 1
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47 | #else
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48 | #define USE_GETPUT(...) __VA_ARGS__
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49 | /* masks coming from getpot32 */
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50 | #define CMD_GET(cmd) ((cmd) & 1)
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51 | #define CMD_PUT(cmd) ((cmd) & 2)
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52 | #endif
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53 | /* NB: in the code below
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54 | * CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
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55 | */
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56 |
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57 |
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58 | #if ENABLE_FEATURE_TFTP_BLOCKSIZE
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59 |
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60 | static int tftp_blocksize_check(int blocksize, int bufsize)
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61 | {
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62 | /* Check if the blocksize is valid:
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63 | * RFC2348 says between 8 and 65464,
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64 | * but our implementation makes it impossible
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65 | * to use blocksizes smaller than 22 octets.
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66 | */
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67 |
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68 | if ((bufsize && (blocksize > bufsize))
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69 | || (blocksize < 8) || (blocksize > 65564)
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70 | ) {
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71 | bb_error_msg("bad blocksize");
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72 | return 0;
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73 | }
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74 |
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75 | return blocksize;
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76 | }
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77 |
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78 | static char *tftp_option_get(char *buf, int len, const char *option)
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79 | {
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80 | int opt_val = 0;
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81 | int opt_found = 0;
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82 | int k;
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83 |
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84 | while (len > 0) {
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85 | /* Make sure the options are terminated correctly */
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86 | for (k = 0; k < len; k++) {
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87 | if (buf[k] == '\0') {
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88 | goto nul_found;
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89 | }
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90 | }
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91 | return NULL;
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92 | nul_found:
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93 | if (opt_val == 0) {
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94 | if (strcasecmp(buf, option) == 0) {
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95 | opt_found = 1;
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96 | }
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97 | } else if (opt_found) {
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98 | return buf;
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99 | }
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100 |
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101 | k++;
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102 | buf += k;
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103 | len -= k;
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104 | opt_val ^= 1;
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105 | }
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106 |
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107 | return NULL;
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108 | }
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109 |
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110 | #endif
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111 |
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112 | static int tftp( USE_GETPUT(const int cmd,)
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113 | len_and_sockaddr *peer_lsa,
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114 | const char *remotefile, const int localfd,
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115 | unsigned port, int tftp_bufsize)
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116 | {
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117 | struct timeval tv;
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118 | fd_set rfds;
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119 | int socketfd;
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120 | int len;
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121 | int send_len;
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122 | USE_FEATURE_TFTP_BLOCKSIZE(smallint want_option_ack = 0;)
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123 | smallint finished = 0;
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124 | uint16_t opcode;
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125 | uint16_t block_nr = 1;
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126 | uint16_t recv_blk;
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127 | int timeout = TFTP_NUM_RETRIES;
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128 | char *cp;
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129 |
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130 | unsigned org_port;
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131 | len_and_sockaddr *const from = alloca(offsetof(len_and_sockaddr, sa) + peer_lsa->len);
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132 |
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133 | /* Can't use RESERVE_CONFIG_BUFFER here since the allocation
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134 | * size varies meaning BUFFERS_GO_ON_STACK would fail */
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135 | /* We must keep the transmit and receive buffers seperate */
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136 | /* In case we rcv a garbage pkt and we need to rexmit the last pkt */
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137 | char *xbuf = xmalloc(tftp_bufsize += 4);
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138 | char *rbuf = xmalloc(tftp_bufsize);
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139 |
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140 | port = org_port = htons(port);
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141 |
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142 | socketfd = xsocket(peer_lsa->sa.sa_family, SOCK_DGRAM, 0);
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143 |
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144 | /* build opcode */
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145 | opcode = TFTP_WRQ;
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146 | if (CMD_GET(cmd)) {
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147 | opcode = TFTP_RRQ;
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148 | }
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149 | cp = xbuf + 2;
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150 | /* add filename and mode */
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151 | /* fill in packet if the filename fits into xbuf */
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152 | len = strlen(remotefile) + 1;
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153 | if (2 + len + sizeof("octet") >= tftp_bufsize) {
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154 | bb_error_msg("remote filename is too long");
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155 | goto ret;
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156 | }
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157 | strcpy(cp, remotefile);
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158 | cp += len;
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159 | /* add "mode" part of the package */
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160 | strcpy(cp, "octet");
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161 | cp += sizeof("octet");
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162 |
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163 | #if ENABLE_FEATURE_TFTP_BLOCKSIZE
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164 | len = tftp_bufsize - 4; /* data block size */
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165 | if (len != TFTP_BLOCKSIZE_DEFAULT) {
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166 | /* rfc2348 says that 65464 is a max allowed value */
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167 | if ((&xbuf[tftp_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
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168 | bb_error_msg("remote filename is too long");
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169 | goto ret;
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170 | }
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171 | /* add "blksize", <nul>, blocksize */
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172 | strcpy(cp, "blksize");
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173 | cp += sizeof("blksize");
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174 | cp += snprintf(cp, 6, "%d", len) + 1;
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175 | want_option_ack = 1;
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176 | }
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177 | #endif
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178 | /* First packet is built, so skip packet generation */
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179 | goto send_pkt;
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180 |
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181 | /* Using mostly goto's - continue/break will be less clear
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182 | * in where we actually jump to */
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183 |
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184 | while (1) {
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185 | /* Build ACK or DATA */
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186 | cp = xbuf + 2;
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187 | *((uint16_t*)cp) = htons(block_nr);
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188 | cp += 2;
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189 | block_nr++;
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190 | opcode = TFTP_ACK;
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191 | if (CMD_PUT(cmd)) {
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192 | opcode = TFTP_DATA;
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193 | len = full_read(localfd, cp, tftp_bufsize - 4);
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194 | if (len < 0) {
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195 | bb_perror_msg(bb_msg_read_error);
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196 | goto ret;
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197 | }
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198 | if (len != (tftp_bufsize - 4)) {
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199 | finished = 1;
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200 | }
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201 | cp += len;
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202 | }
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203 | send_pkt:
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204 | /* Send packet */
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205 | *((uint16_t*)xbuf) = htons(opcode); /* fill in opcode part */
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206 | send_len = cp - xbuf;
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207 | /* NB: send_len value is preserved in code below
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208 | * for potential resend */
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209 | send_again:
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210 | #if ENABLE_DEBUG_TFTP
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211 | fprintf(stderr, "sending %u bytes\n", send_len);
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212 | for (cp = xbuf; cp < &xbuf[send_len]; cp++)
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213 | fprintf(stderr, "%02x ", (unsigned char) *cp);
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214 | fprintf(stderr, "\n");
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215 | #endif
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216 | xsendto(socketfd, xbuf, send_len, &peer_lsa->sa, peer_lsa->len);
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217 | /* Was it final ACK? then exit */
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218 | if (finished && (opcode == TFTP_ACK))
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219 | goto ret;
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220 |
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221 | timeout = TFTP_NUM_RETRIES; /* re-initialize */
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222 | recv_again:
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223 | /* Receive packet */
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224 | tv.tv_sec = TFTP_TIMEOUT;
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225 | tv.tv_usec = 0;
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226 | FD_ZERO(&rfds);
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227 | FD_SET(socketfd, &rfds);
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228 | switch (select(socketfd + 1, &rfds, NULL, NULL, &tv)) {
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229 | unsigned from_port;
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230 | case 1:
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231 | from->len = peer_lsa->len;
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232 | memset(&from->sa, 0, peer_lsa->len);
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233 | len = recvfrom(socketfd, rbuf, tftp_bufsize, 0,
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234 | &from->sa, &from->len);
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235 | if (len < 0) {
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236 | bb_perror_msg("recvfrom");
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237 | goto ret;
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238 | }
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239 | from_port = get_nport(&from->sa);
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240 | if (port == org_port) {
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241 | /* Our first query went to port 69
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242 | * but reply will come from different one.
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243 | * Remember and use this new port */
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244 | port = from_port;
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245 | set_nport(peer_lsa, from_port);
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246 | }
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247 | if (port != from_port)
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248 | goto recv_again;
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249 | goto process_pkt;
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250 | case 0:
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251 | timeout--;
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252 | if (timeout == 0) {
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253 | bb_error_msg("last timeout");
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254 | goto ret;
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255 | }
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256 | bb_error_msg("last timeout" + 5);
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257 | goto send_again; /* resend last sent pkt */
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258 | default:
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259 | bb_perror_msg("select");
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260 | goto ret;
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261 | }
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262 | process_pkt:
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263 | /* Process recv'ed packet */
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264 | opcode = ntohs( ((uint16_t*)rbuf)[0] );
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265 | recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
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266 |
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267 | #if ENABLE_DEBUG_TFTP
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268 | fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
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269 | #endif
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270 |
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271 | if (opcode == TFTP_ERROR) {
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272 | static const char *const errcode_str[] = {
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273 | "",
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274 | "file not found",
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275 | "access violation",
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276 | "disk full",
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277 | "illegal TFTP operation",
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278 | "unknown transfer id",
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279 | "file already exists",
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280 | "no such user",
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281 | "bad option"
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282 | };
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283 |
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284 | const char *msg = "";
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285 |
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286 | if (rbuf[4] != '\0') {
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287 | msg = &rbuf[4];
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288 | rbuf[tftp_bufsize - 1] = '\0';
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289 | } else if (recv_blk < ARRAY_SIZE(errcode_str)) {
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290 | msg = errcode_str[recv_blk];
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291 | }
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292 | bb_error_msg("server error: (%u) %s", recv_blk, msg);
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293 | goto ret;
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294 | }
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295 |
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296 | #if ENABLE_FEATURE_TFTP_BLOCKSIZE
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297 | if (want_option_ack) {
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298 | want_option_ack = 0;
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299 |
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300 | if (opcode == TFTP_OACK) {
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301 | /* server seems to support options */
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302 | char *res;
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303 |
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304 | res = tftp_option_get(&rbuf[2], len - 2, "blksize");
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305 | if (res) {
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306 | int blksize = xatoi_u(res);
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307 | if (!tftp_blocksize_check(blksize, tftp_bufsize - 4)) {
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308 | /* send ERROR 8 to server... */
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309 | /* htons can be impossible to use in const initializer: */
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310 | /*static const uint16_t error_8[2] = { htons(TFTP_ERROR), htons(8) };*/
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311 | /* thus we open-code big-endian layout */
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312 | static const uint8_t error_8[4] = { 0,TFTP_ERROR, 0,8 };
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313 | xsendto(socketfd, error_8, 4, &peer_lsa->sa, peer_lsa->len);
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314 | bb_error_msg("server proposes bad blksize %d, exiting", blksize);
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315 | goto ret;
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316 | }
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317 | #if ENABLE_DEBUG_TFTP
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318 | fprintf(stderr, "using blksize %u\n",
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319 | blksize);
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320 | #endif
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321 | tftp_bufsize = blksize + 4;
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322 | /* Send ACK for OACK ("block" no: 0) */
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323 | block_nr = 0;
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324 | continue;
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325 | }
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326 | /* rfc2347:
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327 | * "An option not acknowledged by the server
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328 | * must be ignored by the client and server
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329 | * as if it were never requested." */
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330 | }
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331 |
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332 | bb_error_msg("blksize is not supported by server"
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333 | " - reverting to 512");
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334 | tftp_bufsize = TFTP_BLOCKSIZE_DEFAULT + 4;
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335 | }
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336 | #endif
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337 | /* block_nr is already advanced to next block# we expect
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338 | * to get / block# we are about to send next time */
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339 |
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340 | if (CMD_GET(cmd) && (opcode == TFTP_DATA)) {
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341 | if (recv_blk == block_nr) {
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342 | len = full_write(localfd, &rbuf[4], len - 4);
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343 | if (len < 0) {
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344 | bb_perror_msg(bb_msg_write_error);
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345 | goto ret;
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346 | }
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347 | if (len != (tftp_bufsize - 4)) {
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348 | finished = 1;
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349 | }
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350 | continue; /* send ACK */
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351 | }
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352 | if (recv_blk == (block_nr - 1)) {
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353 | /* Server lost our TFTP_ACK. Resend it */
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354 | block_nr = recv_blk;
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355 | continue;
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356 | }
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357 | }
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358 |
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359 | if (CMD_PUT(cmd) && (opcode == TFTP_ACK)) {
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360 | /* did server ACK our last DATA pkt? */
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361 | if (recv_blk == (uint16_t) (block_nr - 1)) {
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362 | if (finished)
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363 | goto ret;
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364 | continue; /* send next block */
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365 | }
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366 | }
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367 | /* Awww... recv'd packet is not recognized! */
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368 | goto recv_again;
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369 | /* why recv_again? - rfc1123 says:
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370 | * "The sender (i.e., the side originating the DATA packets)
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371 | * must never resend the current DATA packet on receipt
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372 | * of a duplicate ACK".
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373 | * DATA pkts are resent ONLY on timeout.
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374 | * Thus "goto send_again" will ba a bad mistake above.
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375 | * See:
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376 | * http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome
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377 | */
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378 | }
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379 | ret:
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380 | if (ENABLE_FEATURE_CLEAN_UP) {
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381 | close(socketfd);
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382 | free(xbuf);
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383 | free(rbuf);
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384 | }
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385 | return finished == 0; /* returns 1 on failure */
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386 | }
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387 |
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388 | int tftp_main(int argc, char **argv);
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389 | int tftp_main(int argc, char **argv)
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390 | {
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391 | len_and_sockaddr *peer_lsa;
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392 | const char *localfile = NULL;
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393 | const char *remotefile = NULL;
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394 | #if ENABLE_FEATURE_TFTP_BLOCKSIZE
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395 | const char *sblocksize = NULL;
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396 | #endif
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397 | int port;
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398 | USE_GETPUT(int cmd;)
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399 | int fd = -1;
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400 | int flags = 0;
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401 | int result;
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402 | int blocksize = TFTP_BLOCKSIZE_DEFAULT;
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403 |
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404 | /* -p or -g is mandatory, and they are mutually exclusive */
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405 | opt_complementary = "" USE_FEATURE_TFTP_GET("g:") USE_FEATURE_TFTP_PUT("p:")
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406 | USE_GETPUT("?g--p:p--g");
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407 |
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408 | USE_GETPUT(cmd =) getopt32(argv,
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409 | USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
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410 | "l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
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411 | &localfile, &remotefile
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412 | USE_FEATURE_TFTP_BLOCKSIZE(, &sblocksize));
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413 | argv += optind;
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414 |
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415 | flags = O_RDONLY;
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416 | if (CMD_GET(cmd))
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417 | flags = O_WRONLY | O_CREAT | O_TRUNC;
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418 |
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419 | #if ENABLE_FEATURE_TFTP_BLOCKSIZE
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420 | if (sblocksize) {
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421 | blocksize = xatoi_u(sblocksize);
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422 | if (!tftp_blocksize_check(blocksize, 0)) {
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423 | return EXIT_FAILURE;
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424 | }
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425 | }
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426 | #endif
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427 |
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428 | if (!localfile)
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429 | localfile = remotefile;
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430 | if (!remotefile)
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431 | remotefile = localfile;
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432 | /* Error if filename or host is not known */
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433 | if (!remotefile || !argv[0])
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434 | bb_show_usage();
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435 |
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436 | fd = CMD_GET(cmd) ? STDOUT_FILENO : STDIN_FILENO;
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437 | if (!LONE_DASH(localfile)) {
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438 | fd = xopen(localfile, flags);
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439 | }
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440 |
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441 | port = bb_lookup_port(argv[1], "udp", 69);
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442 | peer_lsa = xhost2sockaddr(argv[0], port);
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443 |
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444 | #if ENABLE_DEBUG_TFTP
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445 | fprintf(stderr, "using server '%s', remotefile '%s', localfile '%s'\n",
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446 | xmalloc_sockaddr2dotted(&peer_lsa->sa),
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447 | remotefile, localfile);
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448 | #endif
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449 |
|
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450 | result = tftp( USE_GETPUT(cmd,) peer_lsa, remotefile, fd, port, blocksize);
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451 |
|
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452 | if (ENABLE_FEATURE_CLEAN_UP)
|
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453 | close(fd);
|
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454 | if (result != EXIT_SUCCESS && !LONE_DASH(localfile) && CMD_GET(cmd)) {
|
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455 | unlink(localfile);
|
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456 | }
|
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457 | return result;
|
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458 | }
|
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459 |
|
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460 | #endif /* ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT */
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