/**
* @brief receive callback during tftp read operation (not on standard port 69)
* @param arg: pointer on argument passed to callback
* @param udp_pcb: pointer on the udp pcb
* @param pkt_buf: pointer on the received pbuf
* @param addr: pointer on remote IP address
* @param port: pointer on remote udp port
* @retval None
*/
void rrq_recv_callback(void *arg, struct udp_pcb *upcb, struct pbuf *p,
struct ip_addr *addr, u16_t port)
{
/* Get our connection state */
tftp_connection_args *args = (tftp_connection_args *)arg;
if (tftp_is_correct_ack(p->payload, args->block))
{
/* increment block # */
args->block++;
}
else
{
/* we did not receive the expected ACK, so
do not update block #. This causes the current block to be resent. */
}
/* if the last read returned less than the requested number of bytes
* (i.e. TFTP_DATA_LEN_MAX), then we've sent the whole file and we can quit
*/
if (args->data_len < TFTP_DATA_LEN_MAX)
{
/* Clean the connection*/
tftp_cleanup_rd(upcb, args);
pbuf_free(p);
}
/* if the whole file has not yet been sent then continue */
tftp_send_next_block(upcb, args, addr, port);
pbuf_free(p);
}
static void tftp_handle_ack(Slirp *slirp, struct tftp_t *tp, int pktlen)
{
int s;
s = tftp_session_find(slirp, tp);
if (s < 0) {
return;
}
tftp_send_next_block(&slirp->tftp_sessions[s], tp);
}
int tftp_process_read(struct udp_pcb *upcb, struct ip_addr *to, int to_port, char* FileName)
{
tftp_connection_args *args = NULL;
/* If Could not open the file which will be transmitted */
if (file_fopen(&file_SD, &efs1.myFs, FileName, 'r') != 0)
{
tftp_send_error_message(upcb, to, to_port, TFTP_ERR_FILE_NOT_FOUND);
tftp_cleanup_rd(upcb, args);
return 0;
}
/* This function is called from a callback,
* therefore, interrupts are disabled,
* therefore, we can use regular malloc. */
args = mem_malloc(sizeof *args);
/* If we aren't able to allocate memory for a "tftp_connection_args" */
if (!args)
{
/* unable to allocate memory for tftp args */
tftp_send_error_message(upcb, to, to_port, TFTP_ERR_NOTDEFINED);
/* no need to use tftp_cleanup_rd because no
"tftp_connection_args" struct has been malloc'd */
tftp_cleanup_rd(upcb, args);
return 0;
}
/* initialize connection structure */
args->op = TFTP_RRQ;
args->to_ip.addr = to->addr;
args->to_port = to_port;
args->block = 1; /* block number starts at 1 (not 0) according to RFC1350 */
args->tot_bytes = 0;
/* set callback for receives on this UDP PCB (Protocol Control Block) */
udp_recv(upcb, rrq_recv_callback, args);
/* initiate the transaction by sending the first block of data
* further blocks will be sent when ACKs are received
* - the receive callbacks need to get the proper state */
tftp_send_next_block(upcb, args, to, to_port);
return 1;
}
/**
* @brief processes tftp read operation
* @param upcb: pointer on udp pcb
* @param to: pointer on remote IP address
* @param to_port: pointer on remote udp port
* @param FileName: pointer on filename to be read
* @retval error code
*/
int tftp_process_read(struct udp_pcb *upcb, const ip_addr_t *to, unsigned short to_port, char* FileName)
{
tftp_connection_args *args = NULL;
char *path = malloc(strlen(FileName) + sizeof(TFTPD_PATH) + 1);
if(!path)
return 0;
strcpy(path, TFTPD_PATH);
strcat(path, FileName);
/* If Could not open the file which will be transmitted */
if (f_open(&file_SD, (const TCHAR*)path, FA_READ) != FR_OK)
{
tftp_send_error_message(upcb, to, to_port, TFTP_ERR_FILE_NOT_FOUND);
tftp_cleanup_rd(upcb, args);
return 0;
}
args = mem_malloc(sizeof *args);
/* If we aren't able to allocate memory for a "tftp_connection_args" */
if (!args)
{
/* unable to allocate memory for tftp args */
tftp_send_error_message(upcb, to, to_port, TFTP_ERR_NOTDEFINED);
/* no need to use tftp_cleanup_rd because no "tftp_connection_args" struct has been malloc'd */
tftp_cleanup_rd(upcb, args);
return 0;
}
/* initialize connection structure */
args->op = TFTP_RRQ;
args->to_ip.addr = to->addr;
args->to_port = to_port;
args->block = 1; /* block number starts at 1 (not 0) according to RFC1350 */
args->tot_bytes = 0;
/* set callback for receives on this UDP PCB */
udp_recv(upcb, rrq_recv_callback, args);
/* initiate the transaction by sending the first block of data,
further blocks will be sent when ACKs are received */
tftp_send_next_block(upcb, args, to, to_port);
return 1;
}
static void tftp_handle_rrq(Slirp *slirp, 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, tp);
if (s >= 0) {
tftp_session_terminate(&slirp->tftp_sessions[s]);
}
s = tftp_session_allocate(slirp, 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);
/* If blksize option is bigger than what we will
* emit, accept the option with our packet size.
* Otherwise, simply do as we didn't see the option.
*/
if (blksize >= 512) {
option_name[nb_options] = "blksize";
option_value[nb_options] = 512;
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);
}