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tftp_io.c
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tftp_io.c
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/* hey emacs! -*- Mode: C; c-file-style: "k&r"; indent-tabs-mode: nil -*- */
/*
* tftp_io.c
* I/O operation routines common to both client and server
*
* $Id: tftp_io.c,v 1.24 2004/02/19 01:30:00 jp Exp $
*
* Copyright (c) 2000 Jean-Pierre Lefebvre <helix@step.polymtl.ca>
* and Remi Lefebvre <remi@debian.org>
*
* atftp is free software; you can redistribute them and/or modify them
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/tftp.h>
#include <errno.h>
#include "string.h"
#include "tftp_io.h"
#include "logger.h"
/*
* 2 bytes string 1 byte string 1 byte string 1 byte string
* --------------------------------------------------------------------->
*| Opcode | Filename | 0 | Mode | 0 | Opt1 | 0 | Value1 <
* --------------------------------------------------------------------->
*
* string 1 byte string 1 byte
* >--------------------------------
* < OptN | 0 | ValueN | 0 |
* >--------------------------------
*/
int tftp_send_request(int socket, struct sockaddr_storage *sa, short type,
char *data_buffer, int data_buffer_size,
struct tftp_opt *tftp_options)
{
int i;
int result;
int buf_index = 0;
struct tftphdr *tftphdr = (struct tftphdr *)data_buffer;
char *filename = tftp_options[OPT_FILENAME].value;
char *mode = tftp_options[OPT_MODE].value;
/* write the opcode */
tftphdr->th_opcode = htons(type);
buf_index += 2;
/* write file name */
Strncpy(data_buffer + buf_index, filename, data_buffer_size - buf_index);
buf_index += strlen(filename);
buf_index++;
Strncpy(data_buffer + buf_index, mode, data_buffer_size - buf_index);
buf_index += strlen(mode);
buf_index++;
for (i = 2; i < OPT_NUMBER; i++)
{
if (strlen(tftp_options[i].option) == 0)
break;
if (tftp_options[i].enabled && tftp_options[i].specified)
{
if (i != OPT_PASSWORD)
{
Strncpy(data_buffer + buf_index, tftp_options[i].option,
data_buffer_size - buf_index);
buf_index += strlen(tftp_options[i].option);
buf_index++;
}
Strncpy(data_buffer + buf_index, tftp_options[i].value,
data_buffer_size - buf_index);
buf_index += strlen(tftp_options[i].value);
buf_index++;
}
}
/* send the buffer */
result = sendto(socket, data_buffer, buf_index, 0,
(struct sockaddr *)sa, sizeof(*sa));
if (result < 0)
return ERR;
return OK;
}
/*
* 2 bytes 2 bytes
* -------------------
*| Opcode | Block # |
* -------------------
*/
int tftp_send_ack(int socket, struct sockaddr_storage *sa, short block_number)
{
struct tftphdr tftphdr;
int result;
tftphdr.th_opcode = htons(ACK);
tftphdr.th_block = htons(block_number);
result = sendto(socket, &tftphdr, 4, 0, (struct sockaddr *)sa,
sizeof(*sa));
if (result < 0)
return ERR;
return OK;
}
/*
* 2 bytes string 1 byte string 1 byte string 1 byte string 1 byte
* ---------------------------------------------------------------------------
*| Opcode | Opt1 | 0 | Value1 | 0 | OptN | 0 | ValueN | 0 |
* ---------------------------------------------------------------------------
*/
int tftp_send_oack(int socket, struct sockaddr_storage *sa, struct tftp_opt *tftp_options,
char *buffer, int buffer_size)
{
int i;
int result;
int index = 0;
struct tftphdr *tftphdr = (struct tftphdr *)buffer;
/* write the opcode */
tftphdr->th_opcode = htons(OACK);
index += 2;
for (i = 2; i < OPT_NUMBER; i++)
{
if (tftp_options[i].enabled && tftp_options[i].specified)
{
Strncpy(buffer + index, tftp_options[i].option, buffer_size - index);
index += strlen(tftp_options[i].option);
index++;
Strncpy(buffer + index, tftp_options[i].value, buffer_size - index);
index += strlen(tftp_options[i].value);
index++;
}
}
/* send the buffer */
result = sendto(socket, buffer, index, 0, (struct sockaddr *)sa,
sizeof(*sa));
if (result < 0)
return ERR;
return OK;
}
/*
* 2 bytes 2 bytes string 1 byte
* ---------------------------------------
*| Opcode | ErrorCode | ErrMsg | 0 |
* ---------------------------------------
*/
int tftp_send_error(int socket, struct sockaddr_storage *sa, short err_code,
char *buffer, int buffer_size)
{
int size;
int result;
struct tftphdr *tftphdr = (struct tftphdr *)buffer;
if (err_code > EOPTNEG)
return ERR;
tftphdr->th_opcode = htons(ERROR);
tftphdr->th_code = htons(err_code);
Strncpy(tftphdr->th_msg, tftp_errmsg[err_code], buffer_size - 4);
size = 4 + strlen(tftp_errmsg[err_code]) + 1;
result = sendto(socket, tftphdr, size, 0, (struct sockaddr *)sa,
sizeof(*sa));
if (result < 0)
return ERR;
return OK;
}
/*
* 2 bytes 2 bytes N bytes
* ----------------------------
*| Opcode | Block # | Data |
* ----------------------------
*/
int tftp_send_data(int socket, struct sockaddr_storage *sa, short block_number,
int size, char *data)
{
struct tftphdr *tftphdr = (struct tftphdr *)data;
int result;
tftphdr->th_opcode = htons(DATA);
tftphdr->th_block = htons(block_number);
result = sendto(socket, data, size, 0, (struct sockaddr *)sa,
sizeof(*sa));
if (result < 0)
return ERR;
return OK;
}
/*
* Wait for a packet. This function can listen on 2 sockets. This is
* needed by the multicast tftp client.
*/
int tftp_get_packet(int sock1, int sock2, int *sock, struct sockaddr_storage *sa,
struct sockaddr_storage *sa_from, struct sockaddr_storage *sa_to,
int timeout, int *size, char *data)
{
int result;
struct timeval tv;
fd_set rfds;
struct sockaddr_storage from;
struct tftphdr *tftphdr = (struct tftphdr *)data;
struct msghdr msg; /* used to get client's packet info */
struct cmsghdr *cmsg;
struct in_pktinfo *pktinfo4;
struct in6_pktinfo *pktinfo6;
struct iovec iov;
char cbuf[1024];
/* initialise structure */
memset(&from, 0, sizeof(from));
iov.iov_base = data;
iov.iov_len = *size;
msg.msg_name = &from;
msg.msg_namelen = sizeof(from);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
/* Wait up to five seconds. */
tv.tv_sec = timeout;
tv.tv_usec = 0;
/* Watch socket to see when it has input. */
FD_ZERO(&rfds);
FD_SET(sock1, &rfds);
if (sock2 > -1)
FD_SET(sock2, &rfds);
/* wait for data on sockets */
result = select(FD_SETSIZE, &rfds, NULL, NULL, &tv);
switch (result)
{
case -1:
logger(LOG_ERR, "select: %s", strerror(errno));
return ERR;
case 0:
return GET_TIMEOUT;
break;
case 1:
case 2:
result = 0;
if (FD_ISSET(sock1, &rfds))
{
result = recvmsg(sock1, &msg, 0);
if (sock)
*sock = sock1;
}
else
{
if ((sock2 > -1) && (FD_ISSET(sock2, &rfds)))
{
result = recvmsg(sock2, &msg, 0);
if (sock)
*sock = sock2;
}
}
if (result == 0)
return ERR;
if (result == -1)
{
logger(LOG_ERR, "recvmsg: %s", strerror(errno));
return ERR;
}
/* if needed read data from message control */
if (sa_to)
{
for (cmsg = CMSG_FIRSTHDR(&msg);
cmsg != NULL && cmsg->cmsg_len >= sizeof(*cmsg);
cmsg = CMSG_NXTHDR(&msg, cmsg))
{
#if defined(SOL_IP) && defined(IP_PKTINFO)
if (cmsg->cmsg_level == SOL_IP
&& cmsg->cmsg_type == IP_PKTINFO)
{
pktinfo4 = (struct in_pktinfo *)CMSG_DATA(cmsg);
sa_to->ss_family = AF_INET;
((struct sockaddr_in *)sa_to)->sin_addr =
pktinfo4->ipi_addr;
}
#endif
#if defined(SOL_IPV6) && defined(IPV6_PKTINFO)
if (cmsg->cmsg_level == SOL_IPV6
&& cmsg->cmsg_type == IPV6_PKTINFO)
{
pktinfo6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
sa_to->ss_family = AF_INET6;
((struct sockaddr_in6 *)sa_to)->sin6_addr =
pktinfo6->ipi6_addr;
}
#endif
break;
}
}
/* return the size to the caller */
*size = result;
/* return the peer address/port to the caller */
if (sa_from != NULL)
memcpy(sa_from, &from, sizeof(from));
/* if sa as never been initialised, port is still 0 */
if (sockaddr_get_port(sa) == 0)
memcpy(sa, &from, sizeof(from));
switch (ntohs(tftphdr->th_opcode))
{
case RRQ:
return GET_RRQ;
case WRQ:
return GET_WRQ;
case ACK:
return GET_ACK;
case OACK:
return GET_OACK;
case ERROR:
return GET_ERROR;
case DATA:
return GET_DATA;
default:
return GET_DISCARD;
}
break;
default:
return ERR;
}
}
/*
* Read from file and do netascii conversion if needed
*/
int tftp_file_read(FILE *fp, char *data_buffer, int data_buffer_size, int block_number,
int convert, int *prev_block_number, int *prev_file_pos,
int *block_number_rollover, int *temp)
{
int i;
int c;
char prevchar = *temp & 0xff;
char newline = (*temp & 0xff00) >> 8;
int data_size;
/* In case of a rollover calculate the real block_number */
if (*prev_block_number > 0 && block_number == 0)
{
(*block_number_rollover)++;
}
block_number = *block_number_rollover * 65536 + block_number;
if (!convert)
{
/* In this case, just read the requested data block.
Anyway, in the multicast case it can be in random
order. */
if (fseek(fp, block_number * data_buffer_size, SEEK_SET) != 0)
return ERR;
data_size = fread(data_buffer, 1, data_buffer_size, fp);
*prev_block_number = block_number;
return data_size;
}
else
{
/*
* When converting data, it become impossible to seek in
* the file based on the block number. So we must always
* remember the position in the file from were to read the
* data requested by the client. Client can only request data
* for the same block or the next, but we cannot assume this
* block number will increase at every ACK since it can be
* lost in transmission.
*
* The strategy is to remember the file position as well as
* the block number from the current call to this function.
* If the client request a block number different from that
* we return ERR.
*
* If the client request many time the same block, the
* netascii conversion is done each time. Since this is not
* a normal condition it should not be a problem for system
* performance.
*
*/
if ((block_number != *prev_block_number) && (block_number != *prev_block_number + 1))
return ERR;
if (block_number == *prev_block_number && fseek(fp, *prev_file_pos, SEEK_SET) != 0)
return ERR;
*prev_block_number = block_number;
*prev_file_pos = ftell(fp);
/*
* convert to netascii, based on netkit-tftp-0.17 routine in tftpsubs.c
* i index output buffer
*/
for (i = 0; i < data_buffer_size; i++)
{
if (newline)
{
if (prevchar == '\n')
c = '\n'; /* lf to cr,lf */
else
c = '\0'; /* cr to cr,nul */
newline = 0;
}
else
{
c = fgetc(fp);
if (c == EOF)
break;
if (c == '\n' || c == '\r')
{
prevchar = c;
c = '\r';
newline = 1;
}
}
data_buffer[i] = c;
}
/* save state */
*temp = (newline << 8) | prevchar;
return i;
}
}
/*
* Write to file and do netascii conversion if needed
*/
int tftp_file_write(FILE *fp, char *data_buffer, int data_buffer_size, int block_number, int data_size,
int convert, int *prev_block_number, int *temp)
{
int i;
int c;
char prevchar = *temp;
if (!convert)
{
/* Simple case, just seek and write */
if (fseek(fp, (block_number - 1) * data_buffer_size, SEEK_SET) == 0)
data_size = fwrite(data_buffer, 1, data_size, fp);
else
data_size = 0;
return data_size;
}
else
{
/*
* Same principle than for reading, but simpler since when client
* send same block twice there is no need to rewrite it to the
* file
*/
if ((block_number != *prev_block_number) && (block_number != *prev_block_number + 1))
return ERR;
if (block_number == *prev_block_number)
return data_size;
*prev_block_number = block_number;
/*
* convert to netascii, based on netkit-tftp-0.17 routine in tftpsubs.c
* i index input buffer
*/
for (i = 0; i < data_size; i++)
{
c = data_buffer[i];
if (prevchar == '\r')
{
if (c == '\n')
{
if (fseek(fp, -1, SEEK_CUR) != 0) /* cr,lf to lf */
return ERR;
if (fputc(c, fp) == EOF)
return ERR;
}
else if (c != '\0') /* cr,nul to cr */
{
if (fputc(c, fp) == EOF)
return ERR;
}
}
else
{
if (fputc(c, fp) == EOF)
return ERR;
}
prevchar = c;
}
/* save state */
*temp = prevchar;
return i;
}
}