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tftp: add support of blksize option to client #62

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tftp: add support of blksize option to client #62

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128 changes: 122 additions & 6 deletions src/apps/tftp/tftp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,14 +57,15 @@
#include "lwip/timeouts.h"
#include "lwip/debug.h"

#define TFTP_MAX_PAYLOAD_SIZE 512
#define TFTP_DEFAULT_BLOCK_SIZE 512
#define TFTP_HEADER_LENGTH 4

#define TFTP_RRQ 1
#define TFTP_WRQ 2
#define TFTP_DATA 3
#define TFTP_ACK 4
#define TFTP_ERROR 5
#define TFTP_OACK 6

enum tftp_error {
TFTP_ERROR_FILE_NOT_FOUND = 1,
Expand All @@ -88,9 +89,11 @@ struct tftp_state {
int timer;
int last_pkt;
u16_t blknum;
u16_t blksize;
u8_t retries;
u8_t mode_write;
u8_t tftp_mode;
bool wait_oack;
};

static struct tftp_state tftp_state;
Expand Down Expand Up @@ -137,18 +140,33 @@ send_request(const ip_addr_t *addr, u16_t port, u16_t opcode, const char* fname,
{
size_t fname_length = strlen(fname)+1;
size_t mode_length = strlen(mode)+1;
struct pbuf* p = init_packet(opcode, 0, fname_length + mode_length - 2);
size_t blksize_length = 0;
int blksize = tftp_state.blksize;
struct pbuf* p;
char* payload;
err_t ret;

if (blksize) {
/* 'blksize\0'.\0" with . = 1 digit */
blksize_length = strlen("blksize") + 1 + 1 + 1;
while (blksize >= 10) {
blksize /= 10;
blksize_length++;
}
}

p = init_packet(opcode, 0, fname_length + mode_length + blksize_length - 2);
if (p == NULL) {
return ERR_MEM;
}

payload = (char*) p->payload;
MEMCPY(payload+2, fname, fname_length);
MEMCPY(payload+2+fname_length, mode, mode_length);
if (tftp_state.blksize)
sprintf(payload+2+fname_length+mode_length, "blksize%c%d%c", 0, tftp_state.blksize, 0);

tftp_state.wait_oack = true;
ret = udp_sendto(tftp_state.upcb, p, addr, port);
pbuf_free(p);
return ret;
Expand Down Expand Up @@ -221,14 +239,14 @@ send_data(const ip_addr_t *addr, u16_t port)
pbuf_free(tftp_state.last_data);
}

tftp_state.last_data = init_packet(TFTP_DATA, tftp_state.blknum, TFTP_MAX_PAYLOAD_SIZE);
tftp_state.last_data = init_packet(TFTP_DATA, tftp_state.blknum, TFTP_DEFAULT_BLOCK_SIZE);
if (tftp_state.last_data == NULL) {
return;
}

payload = (u16_t *) tftp_state.last_data->payload;

ret = tftp_state.ctx->read(tftp_state.handle, &payload[2], TFTP_MAX_PAYLOAD_SIZE);
ret = tftp_state.ctx->read(tftp_state.handle, &payload[2], TFTP_DEFAULT_BLOCK_SIZE);
if (ret < 0) {
send_error(addr, port, TFTP_ERROR_ACCESS_VIOLATION, "Error occurred while reading the file.");
close_handle();
Expand All @@ -239,6 +257,64 @@ send_data(const ip_addr_t *addr, u16_t port)
resend_data(addr, port);
}

static u16_t payload_size(void)
{
if (tftp_state.blksize)
return tftp_state.blksize;
return TFTP_DEFAULT_BLOCK_SIZE;
}

/**
* find_option() - check if OACK message contains option
*
* @p: message buffer
* @option: option key
* Return: option value
*/
static const char *
find_option(struct pbuf *p, const char *option)
{
const char *pos = p->payload;
int rem = p->len;

/*
* According to RFC 2347 the OACK packet has the following format:
*
* +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
* | opc | opt1 | 0 | value1 | 0 | optN | 0 | valueN | 0 |
* +-------+---~~---+---+---~~---+---+---~~---+---+---~~---+---+
*/

/* Skip opc */
pos += 2;
rem -= 2;
if (rem <= 0)
return NULL;

for (;;) {
int len;
int diff;

len = strnlen(pos, rem) + 1;
if (rem < len)
break;
diff = strcmp(pos, option);
/* Skip option */
pos += len;
rem -= len;
len = strnlen(pos, rem) + 1;
if (rem < len)
break;
if (!diff)
return pos;
/* Skip value */
pos += len;
rem -= len;
}

return NULL;
}

static void
tftp_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *addr, u16_t port)
{
Expand Down Expand Up @@ -338,6 +414,15 @@ tftp_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *addr
}

blknum = lwip_ntohs(sbuf[1]);
if (tftp_state.blksize && tftp_state.wait_oack) {
/*
* Data received while we are expecting an OACK for our blksize option.
* This means the server doesn't support it, let's switch back to the
* default block size.
*/
tftp_state.blksize = 0;
tftp_state.wait_oack = false;
}
if (blknum == tftp_state.blknum) {
pbuf_remove_header(p, TFTP_HEADER_LENGTH);

Expand All @@ -349,7 +434,7 @@ tftp_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *addr
send_ack(addr, port, blknum);
}

if (p->tot_len < TFTP_MAX_PAYLOAD_SIZE) {
if (p->tot_len < payload_size()) {
close_handle();
} else {
tftp_state.blknum++;
Expand Down Expand Up @@ -386,7 +471,7 @@ tftp_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *addr
lastpkt = 0;

if (tftp_state.last_data != NULL) {
lastpkt = tftp_state.last_data->tot_len != (TFTP_MAX_PAYLOAD_SIZE + TFTP_HEADER_LENGTH);
lastpkt = tftp_state.last_data->tot_len != (TFTP_DEFAULT_BLOCK_SIZE + TFTP_HEADER_LENGTH);
}

if (!lastpkt) {
Expand All @@ -405,6 +490,25 @@ tftp_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *addr
close_handle();
}
break;
case PP_HTONS(TFTP_OACK): {
const char *optval = find_option(p, "blksize");
u16_t srv_blksize = 0;
tftp_state.wait_oack = false;
if (optval) {
if (!tftp_state.blksize) {
/* We did not request this option */
send_error(addr, port, TFTP_ERROR_ILLEGAL_OPERATION, "blksize unexpected");
}
srv_blksize = atoi(optval);
if (srv_blksize <= 0 || srv_blksize > tftp_state.blksize) {
send_error(addr, port, TFTP_ERROR_ILLEGAL_OPERATION, "Invalid blksize");
}
LWIP_DEBUGF(TFTP_DEBUG | LWIP_DBG_STATE, ("tftp: accepting blksize=%d\n", srv_blksize));
tftp_state.blksize = srv_blksize;
}
send_ack(addr, port, 0);
break;
}
default:
send_error(addr, port, TFTP_ERROR_ILLEGAL_OPERATION, "Unknown operation");
break;
Expand Down Expand Up @@ -493,6 +597,18 @@ tftp_init_client(const struct tftp_context *ctx)
return tftp_init_common(LWIP_TFTP_MODE_CLIENT, ctx);
}

/** @ingroup tftp
* Set the block size to be used by the TFTP client. The server may choose to
* accept a lower value.
* @param blksize Block size in bytes
*/
void
tftp_client_set_blksize(u16_t blksize)
{
if (blksize != TFTP_DEFAULT_BLOCK_SIZE)
tftp_state.blksize = blksize;
}

/** @ingroup tftp
* Deinitialize ("turn off") TFTP client/server.
*/
Expand Down
1 change: 1 addition & 0 deletions src/include/lwip/apps/tftp_client.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ enum tftp_transfer_mode {
};

err_t tftp_init_client(const struct tftp_context* ctx);
void tftp_client_set_blksize(u16_t blksize);
err_t tftp_get(void* handle, const ip_addr_t *addr, u16_t port, const char* fname, enum tftp_transfer_mode mode);
err_t tftp_put(void* handle, const ip_addr_t *addr, u16_t port, const char* fname, enum tftp_transfer_mode mode);

Expand Down