/*
* tftp.c - a simple, read-only tftp server for qemu
*
* Copyright (c) 2004 Magnus Damm <damm@opensource.se>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <slirp.h>
#include "qemu-common.h" // for pstrcpy
struct tftp_session {
int in_use;
unsigned char filename[TFTP_FILENAME_MAX];
uint32_t client_ip;
uint16_t client_port;
int timestamp;
};
static struct tftp_session tftp_sessions[TFTP_SESSIONS_MAX];
const char *tftp_prefix;
static void tftp_session_update(struct tftp_session *spt)
{
spt->timestamp = curtime;
spt->in_use = 1;
}
static void tftp_session_terminate(struct tftp_session *spt)
{
spt->in_use = 0;
}
static int tftp_session_allocate(struct tftp_t *tp)
{
struct tftp_session *spt;
int k;
for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
spt = &tftp_sessions[k];
if (!spt->in_use)
goto found;
/* sessions time out after 5 inactive seconds */
if ((int)(curtime - spt->timestamp) > 5000)
goto found;
}
return -1;
found:
memset(spt, 0, sizeof(*spt));
spt->client_ip = ip_geth(tp->ip.ip_src);
spt->client_port = port_geth(tp->udp.uh_sport);
tftp_session_update(spt);
return k;
}
static int tftp_session_find(struct tftp_t *tp)
{
struct tftp_session *spt;
int k;
for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
spt = &tftp_sessions[k];
if (spt->in_use) {
if (spt->client_ip == ip_geth(tp->ip.ip_src)) {
if (spt->client_port == port_geth(tp->udp.uh_sport)) {
return k;
}
}
}
}
return -1;
}
static int tftp_read_data(struct tftp_session *spt, u_int16_t block_nr,
u_int8_t *buf, int len)
{
int fd;
int bytes_read = 0;
char buffer[1024];
int n;
n = snprintf(buffer, sizeof(buffer), "%s/%s",
tftp_prefix, spt->filename);
if (n >= sizeof(buffer))
return -1;
fd = open(buffer, O_RDONLY | O_BINARY);
if (fd < 0) {
return -1;
}
if (len) {
lseek(fd, block_nr * 512, SEEK_SET);
bytes_read = read(fd, buf, len);
}
close(fd);
return bytes_read;
}
static int tftp_send_oack(struct tftp_session *spt,
const char *key, uint32_t value,
struct tftp_t *recv_tp)
{
SockAddress saddr, daddr;
struct mbuf *m;
struct tftp_t *tp;
int n = 0;
m = m_get();
if (!m)
return -1;
memset(m->m_data, 0, m->m_size);
m->m_data += IF_MAXLINKHDR;
tp = (void *)m->m_data;
m->m_data += sizeof(struct udpiphdr);
tp->tp_op = htons(TFTP_OACK);
n += snprintf((char *)tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%s",
key) + 1;
n += snprintf((char *)tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%u",
value) + 1;
sock_address_init_inet( &saddr,
ip_geth(recv_tp->ip.ip_dst),
port_geth(recv_tp->udp.uh_dport) );
sock_address_init_inet( &daddr,
spt->client_ip,
spt->client_port );
m->m_len = sizeof(struct tftp_t) - 514 + n -
sizeof(struct ip) - sizeof(struct udphdr);
udp_output2_(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
return 0;
}
static int tftp_send_error(struct tftp_session *spt,
u_int16_t errorcode, const char *msg,
struct tftp_t *recv_tp)
{
SockAddress saddr, daddr;
struct mbuf *m;
struct tftp_t *tp;
m = m_get();
if (!m) {
return -1;
}
memset(m->m_data, 0, m->m_size);
m->m_data += IF_MAXLINKHDR;
tp = (void *)m->m_data;
m->m_data += sizeof(struct udpiphdr);
tp->tp_op = htons(TFTP_ERROR);
tp->x.tp_error.tp_error_code = htons(errorcode);
pstrcpy((char *)tp->x.tp_error.tp_msg, sizeof(tp->x.tp_error.tp_msg), msg);
sock_address_init_inet( &saddr,
ip_geth(recv_tp->ip.ip_dst),
port_geth(recv_tp->udp.uh_dport) );
sock_address_init_inet( &daddr,
spt->client_ip,
spt->client_port );
m->m_len = sizeof(struct tftp_t) - 514 + 3 + strlen(msg) -
sizeof(struct ip) - sizeof(struct udphdr);
udp_output2_(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
tftp_session_terminate(spt);
return 0;
}
static int tftp_send_data(struct tftp_session *spt,
u_int16_t block_nr,
struct tftp_t *recv_tp)
{
SockAddress saddr, daddr;
struct mbuf *m;
struct tftp_t *tp;
int nobytes;
if (block_nr < 1) {
return -1;
}
m = m_get();
if (!m) {
return -1;
}
memset(m->m_data, 0, m->m_size);
m->m_data += IF_MAXLINKHDR;
tp = (void *)m->m_data;
m->m_data += sizeof(struct udpiphdr);
tp->tp_op = htons(TFTP_DATA);
tp->x.tp_data.tp_block_nr = htons(block_nr);
sock_address_init_inet( &saddr,
ip_geth(recv_tp->ip.ip_dst),
port_geth(recv_tp->udp.uh_dport) );
sock_address_init_inet( &daddr,
spt->client_ip,
spt->client_port );
nobytes = tftp_read_data(spt, block_nr - 1, tp->x.tp_data.tp_buf, 512);
if (nobytes < 0) {
m_free(m);
/* send "file not found" error back */
tftp_send_error(spt, 1, "File not found", tp);
return -1;
}
m->m_len = sizeof(struct tftp_t) - (512 - nobytes) -
sizeof(struct ip) - sizeof(struct udphdr);
udp_output2_(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
if (nobytes == 512) {
tftp_session_update(spt);
}
else {
tftp_session_terminate(spt);
}
return 0;
}
static void tftp_handle_rrq(struct tftp_t *tp, int pktlen)
{
struct tftp_session *spt;
int s, k, n;
u_int8_t *src, *dst;
s = tftp_session_allocate(tp);
if (s < 0) {
return;
}
spt = &tftp_sessions[s];
src = tp->x.tp_buf;
dst = spt->filename;
n = pktlen - ((uint8_t *)&tp->x.tp_buf[0] - (uint8_t *)tp);
/* get name */
for (k = 0; k < n; k++) {
if (k < TFTP_FILENAME_MAX) {
dst[k] = src[k];
}
else {
return;
}
if (src[k] == '\0') {
break;
}
}
if (k >= n) {
return;
}
k++;
/* check mode */
if ((n - k) < 6) {
return;
}
if (memcmp(&src[k], "octet\0", 6) != 0) {
tftp_send_error(spt, 4, "Unsupported transfer mode", tp);
return;
}
k += 6; /* skipping octet */
/* do sanity checks on the filename */
if ((spt->filename[0] != '/')
|| (spt->filename[strlen((char *)spt->filename) - 1] == '/')
|| strstr((char *)spt->filename, "/../")) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
/* only allow exported prefixes */
if (!tftp_prefix) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
/* check if the file exists */
if (tftp_read_data(spt, 0, spt->filename, 0) < 0) {
tftp_send_error(spt, 1, "File not found", tp);
return;
}
if (src[n - 1] != 0) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
while (k < n) {
const char *key, *value;
key = (char *)src + k;
k += strlen(key) + 1;
if (k >= n) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
value = (char *)src + k;
k += strlen(value) + 1;
if (strcmp(key, "tsize") == 0) {
int tsize = atoi(value);
struct stat stat_p;
if (tsize == 0 && tftp_prefix) {
char buffer[1024];
snprintf(buffer, sizeof(buffer), "%s/%s",
tftp_prefix, spt->filename);
if (stat(buffer, &stat_p) == 0)
tsize = stat_p.st_size;
else {
tftp_send_error(spt, 1, "File not found", tp);
return;
}
}
tftp_send_oack(spt, "tsize", tsize, tp);
}
}
tftp_send_data(spt, 1, tp);
}
static void tftp_handle_ack(struct tftp_t *tp, int pktlen)
{
int s;
s = tftp_session_find(tp);
if (s < 0) {
return;
}
if (tftp_send_data(&tftp_sessions[s],
ntohs(tp->x.tp_data.tp_block_nr) + 1,
tp) < 0) {
return;
}
}
void tftp_input(struct mbuf *m)
{
struct tftp_t *tp = (struct tftp_t *)m->m_data;
switch(ntohs(tp->tp_op)) {
case TFTP_RRQ:
tftp_handle_rrq(tp, m->m_len);
break;
case TFTP_ACK:
tftp_handle_ack(tp, m->m_len);
break;
}
}