[PATCH 3/3] tftp_recv(): handle opcode field in a more natural way

[Antony Pavlov]

RFC1350 uses the 'opcode' term for the first 2-bytes field
of TFTP packet. But the U-boot tftp code uses the 'proto' term
for the same thing.

The patch takes back original term and makes opcode calculation
more clear.

Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
---
 fs/tftp.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/tftp.c b/fs/tftp.c
index e36c1c8..0de215e 100644
--- a/fs/tftp.c
+++ b/fs/tftp.c
@@ -256,22 +256,21 @@ static void tftp_timer_reset(struct file_priv *priv)
 static void tftp_recv(struct file_priv *priv,
 			uint8_t *pkt, unsigned len, uint16_t uh_sport)
 {
-	uint16_t proto;
-	uint16_t *s;
+	uint16_t opcode;
 
 	/* according to RFC1350 minimal tftp packet length is 4 bytes */
 	if (len < 4)
 		return;
 
-	len -= 2;
+	opcode = ntohs(*(uint16_t *)pkt);
 
-	s = (uint16_t *)pkt;
-	proto = *s++;
-	pkt = (unsigned char *)s;
+	/* skip tftp opcode 2-byte field */
+	len -= 2;
+	pkt += 2;
 
-	debug("%s: proto 0x%04x\n", __func__, proto);
+	debug("%s: opcode 0x%04x\n", __func__, opcode);
 
-	switch (ntohs(proto)) {
+	switch (opcode) {
 	case TFTP_RRQ:
 	case TFTP_WRQ:
 	default:
-- 
2.1.4