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qemu-irix/slirp/tftp.c

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/*
* 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 "qemu/osdep.h"
#include "slirp.h"
#include "qemu-common.h"
#include "qemu/cutils.h"
static inline int tftp_session_in_use(struct tftp_session *spt)
{
return (spt->slirp != NULL);
}
static inline void tftp_session_update(struct tftp_session *spt)
{
spt->timestamp = curtime;
}
static void tftp_session_terminate(struct tftp_session *spt)
{
if (spt->fd >= 0) {
close(spt->fd);
spt->fd = -1;
}
g_free(spt->filename);
spt->slirp = NULL;
}
static int tftp_session_allocate(Slirp *slirp, struct sockaddr_storage *srcsas,
struct tftp_t *tp)
{
struct tftp_session *spt;
int k;
for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
spt = &slirp->tftp_sessions[k];
if (!tftp_session_in_use(spt))
goto found;
/* sessions time out after 5 inactive seconds */
if ((int)(curtime - spt->timestamp) > 5000) {
tftp_session_terminate(spt);
goto found;
}
}
return -1;
found:
memset(spt, 0, sizeof(*spt));
spt->client_addr = *srcsas;
spt->fd = -1;
spt->block_size = 512;
spt->client_port = tp->udp.uh_sport;
spt->slirp = slirp;
tftp_session_update(spt);
return k;
}
static int tftp_session_find(Slirp *slirp, struct sockaddr_storage *srcsas,
struct tftp_t *tp)
{
struct tftp_session *spt;
int k;
for (k = 0; k < TFTP_SESSIONS_MAX; k++) {
spt = &slirp->tftp_sessions[k];
if (tftp_session_in_use(spt)) {
if (sockaddr_equal(&spt->client_addr, srcsas)) {
if (spt->client_port == tp->udp.uh_sport) {
return k;
}
}
}
}
return -1;
}
static int tftp_read_data(struct tftp_session *spt, uint32_t block_nr,
uint8_t *buf, int len)
{
int bytes_read = 0;
if (spt->fd < 0) {
spt->fd = open(spt->filename, O_RDONLY | O_BINARY);
}
if (spt->fd < 0) {
return -1;
}
if (len) {
lseek(spt->fd, block_nr * spt->block_size, SEEK_SET);
bytes_read = read(spt->fd, buf, len);
}
return bytes_read;
}
static struct tftp_t *tftp_prep_mbuf_data(struct tftp_session *spt,
struct mbuf *m)
{
struct tftp_t *tp;
memset(m->m_data, 0, m->m_size);
m->m_data += IF_MAXLINKHDR;
if (spt->client_addr.ss_family == AF_INET6) {
m->m_data += sizeof(struct ip6);
} else {
m->m_data += sizeof(struct ip);
}
tp = (void *)m->m_data;
m->m_data += sizeof(struct udphdr);
return tp;
}
static void tftp_udp_output(struct tftp_session *spt, struct mbuf *m,
struct tftp_t *recv_tp)
{
if (spt->client_addr.ss_family == AF_INET6) {
struct sockaddr_in6 sa6, da6;
sa6.sin6_addr = spt->slirp->vhost_addr6;
sa6.sin6_port = recv_tp->udp.uh_dport;
da6.sin6_addr = ((struct sockaddr_in6 *)&spt->client_addr)->sin6_addr;
da6.sin6_port = spt->client_port;
udp6_output(NULL, m, &sa6, &da6);
} else {
struct sockaddr_in sa4, da4;
sa4.sin_addr = spt->slirp->vhost_addr;
sa4.sin_port = recv_tp->udp.uh_dport;
da4.sin_addr = ((struct sockaddr_in *)&spt->client_addr)->sin_addr;
da4.sin_port = spt->client_port;
udp_output(NULL, m, &sa4, &da4, IPTOS_LOWDELAY);
}
}
static int tftp_send_oack(struct tftp_session *spt,
const char *keys[], uint32_t values[], int nb,
struct tftp_t *recv_tp)
{
struct mbuf *m;
struct tftp_t *tp;
int i, n = 0;
m = m_get(spt->slirp);
if (!m)
return -1;
tp = tftp_prep_mbuf_data(spt, m);
tp->tp_op = htons(TFTP_OACK);
for (i = 0; i < nb; i++) {
n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%s",
keys[i]) + 1;
n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%u",
values[i]) + 1;
}
m->m_len = sizeof(struct tftp_t) - (TFTP_BLOCKSIZE_MAX + 2) + n
- sizeof(struct udphdr);
tftp_udp_output(spt, m, recv_tp);
return 0;
}
static void tftp_send_error(struct tftp_session *spt,
uint16_t errorcode, const char *msg,
struct tftp_t *recv_tp)
{
struct mbuf *m;
struct tftp_t *tp;
m = m_get(spt->slirp);
if (!m) {
goto out;
}
tp = tftp_prep_mbuf_data(spt, m);
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);
m->m_len = sizeof(struct tftp_t) - (TFTP_BLOCKSIZE_MAX + 2) + 3 + strlen(msg)
- sizeof(struct udphdr);
tftp_udp_output(spt, m, recv_tp);
out:
tftp_session_terminate(spt);
}
static void tftp_send_next_block(struct tftp_session *spt,
struct tftp_t *recv_tp)
{
struct mbuf *m;
struct tftp_t *tp;
int nobytes;
m = m_get(spt->slirp);
if (!m) {
return;
}
tp = tftp_prep_mbuf_data(spt, m);
tp->tp_op = htons(TFTP_DATA);
tp->x.tp_data.tp_block_nr = htons((spt->block_nr + 1) & 0xffff);
nobytes = tftp_read_data(spt, spt->block_nr, tp->x.tp_data.tp_buf,
spt->block_size);
if (nobytes < 0) {
m_free(m);
/* send "file not found" error back */
tftp_send_error(spt, 1, "File not found", tp);
return;
}
m->m_len = sizeof(struct tftp_t) - (TFTP_BLOCKSIZE_MAX - nobytes)
- sizeof(struct udphdr);
tftp_udp_output(spt, m, recv_tp);
if (nobytes == spt->block_size) {
tftp_session_update(spt);
}
else {
tftp_session_terminate(spt);
}
spt->block_nr++;
}
static void tftp_handle_rrq(Slirp *slirp, struct sockaddr_storage *srcsas,
struct tftp_t *tp, int pktlen)
{
struct tftp_session *spt;
int s, k;
size_t prefix_len;
char *req_fname;
const char *option_name[2];
uint32_t option_value[2];
int nb_options = 0;
/* check if a session already exists and if so terminate it */
s = tftp_session_find(slirp, srcsas, tp);
if (s >= 0) {
tftp_session_terminate(&slirp->tftp_sessions[s]);
}
s = tftp_session_allocate(slirp, srcsas, tp);
if (s < 0) {
return;
}
spt = &slirp->tftp_sessions[s];
/* unspecified prefix means service disabled */
if (!slirp->tftp_prefix) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
/* skip header fields */
k = 0;
pktlen -= offsetof(struct tftp_t, x.tp_buf);
/* prepend tftp_prefix */
prefix_len = strlen(slirp->tftp_prefix);
spt->filename = g_malloc(prefix_len + TFTP_FILENAME_MAX + 2);
memcpy(spt->filename, slirp->tftp_prefix, prefix_len);
spt->filename[prefix_len] = '/';
/* get name */
req_fname = spt->filename + prefix_len + 1;
while (1) {
if (k >= TFTP_FILENAME_MAX || k >= pktlen) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
req_fname[k] = tp->x.tp_buf[k];
if (req_fname[k++] == '\0') {
break;
}
}
/* check mode */
if ((pktlen - k) < 6) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
if (strcasecmp(&tp->x.tp_buf[k], "octet") != 0) {
tftp_send_error(spt, 4, "Unsupported transfer mode", tp);
return;
}
k += 6; /* skipping octet */
/* do sanity checks on the filename */
if (!strncmp(req_fname, "../", 3) ||
req_fname[strlen(req_fname) - 1] == '/' ||
strstr(req_fname, "/../")) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
/* check if the file exists */
if (tftp_read_data(spt, 0, NULL, 0) < 0) {
tftp_send_error(spt, 1, "File not found", tp);
return;
}
if (tp->x.tp_buf[pktlen - 1] != 0) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
while (k < pktlen && nb_options < ARRAY_SIZE(option_name)) {
const char *key, *value;
key = &tp->x.tp_buf[k];
k += strlen(key) + 1;
if (k >= pktlen) {
tftp_send_error(spt, 2, "Access violation", tp);
return;
}
value = &tp->x.tp_buf[k];
k += strlen(value) + 1;
if (strcasecmp(key, "tsize") == 0) {
int tsize = atoi(value);
struct stat stat_p;
if (tsize == 0) {
if (stat(spt->filename, &stat_p) == 0)
tsize = stat_p.st_size;
else {
tftp_send_error(spt, 1, "File not found", tp);
return;
}
}
option_name[nb_options] = "tsize";
option_value[nb_options] = tsize;
nb_options++;
} else if (strcasecmp(key, "blksize") == 0) {
int blksize = atoi(value);
/* Accept blksize up to our maximum size */
if (blksize > 0) {
spt->block_size = MIN(blksize, TFTP_BLOCKSIZE_MAX);
option_name[nb_options] = "blksize";
option_value[nb_options] = spt->block_size;
nb_options++;
}
}
}
if (nb_options > 0) {
assert(nb_options <= ARRAY_SIZE(option_name));
tftp_send_oack(spt, option_name, option_value, nb_options, tp);
return;
}
spt->block_nr = 0;
tftp_send_next_block(spt, tp);
}
static void tftp_handle_ack(Slirp *slirp, struct sockaddr_storage *srcsas,
struct tftp_t *tp, int pktlen)
{
int s;
s = tftp_session_find(slirp, srcsas, tp);
if (s < 0) {
return;
}
tftp_send_next_block(&slirp->tftp_sessions[s], tp);
}
static void tftp_handle_error(Slirp *slirp, struct sockaddr_storage *srcsas,
struct tftp_t *tp, int pktlen)
{
int s;
s = tftp_session_find(slirp, srcsas, tp);
if (s < 0) {
return;
}
tftp_session_terminate(&slirp->tftp_sessions[s]);
}
void tftp_input(struct sockaddr_storage *srcsas, struct mbuf *m)
{
struct tftp_t *tp = (struct tftp_t *)m->m_data;
switch(ntohs(tp->tp_op)) {
case TFTP_RRQ:
tftp_handle_rrq(m->slirp, srcsas, tp, m->m_len);
break;
case TFTP_ACK:
tftp_handle_ack(m->slirp, srcsas, tp, m->m_len);
break;
case TFTP_ERROR:
tftp_handle_error(m->slirp, srcsas, tp, m->m_len);
break;
}
}
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