fixed tftp error message output

PATCH New Andreas Oberritter 2 participants 6 messages Jul 19, 2003 – Jul 20, 2003

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Andreas Oberritter

author

2003-07-19 02:34 UTC #0 lore raw

PATCH 1/1 fixed tftp error message output

This patch fixes tftp error message output, i.e. does not print the last two bytes which contain garbage (at least for my setup, I hope this is not a tftp server issue).

Changelog:

Patch by Andreas Oberritter, 19 July 03
- fixed tftp error message output
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Wolfgang Denk

2003-07-19 19:28 UTC #1 lore raw

PATCH 1/1 fixed tftp error message output

Dear Andreas,

Quoted 4 lines · in message <1058582070.943.37.camel@localhost> you wrote:

This patch fixes tftp error message output, i.e. does not print the last two bytes which contain garbage (at least for my setup, I hope this is not a tftp server issue).

Is there a way to provoke such an error, so we can test this?

Review

Quoted 10 lines

(quoted diff) +7 -2

 	case TFTP_ERROR:
-		printf ("\nTFTP error: '%s' (%d)\n",
-					pkt + 2, ntohs(*(ushort *)pkt));
+		printf ("\nTFTP error %d: ", ntohs(*(ushort *)pkt));
+		pkt += 2;
+		len -= 2;
+		while (len--)
+			printf("%c", *pkt++);
+		printf("\n");
+

Patch rejected. What happens if "len" turns out to be zero? Also, the code is unnecessary complex.

If there really is such a problem, this should do as well (and maybe better):

	printf ("\nTFTP error: '%.*s' (%d)\n",
		len - 2,
		pkt + 2,
		ntohs(*(ushort *)pkt) );

Can you please test this (and eventually re-submit the patch) ?

Thanks.

Best regards,

Wolfgang Denk

Signature · 4 lines

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
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Andreas Oberritter

author

2003-07-19 20:28 UTC #2 lore raw

PATCH 1/1 fixed tftp error message output

Quoted 5 lines · Wolfgang Denk

Quoted 3 lines
This patch fixes tftp error message output, i.e. does not print the last two bytes which contain garbage (at least for my setup, I hope this is not a tftp server issue).
Is there a way to provoke such an error, so we can test this?

Just try to tftp a file which does not exist on the server or which does not have correct permissions (leading to a "file not found" message). I am using atftpd on debian sarge and sid.

Quoted 1 line

What happens if "len" turns out to be zero?

Ok, I'll add a check for it.

Quoted 9 lines

If there really is such a problem, this should do as well (and maybe better):
	printf ("\nTFTP error: '%.*s' (%d)\n",
		len - 2,
		pkt + 2,
		ntohs(*(ushort *)pkt) );
Can you please test this (and eventually re-submit the patch) ?

I see, this would indeed be simpler. I didn't know %.*s until now. I will try it when I come home next week.

Regards,
Andreas

Wolfgang Denk

2003-07-19 21:59 UTC #3 lore raw

PATCH 1/1 fixed tftp error message output

Quoted 4 lines · In message <1058646514.774.55.camel@localhost> you wrote:

Just try to tftp a file which does not exist on the server or which does not have correct permissions (leading to a "file not found" message). I am using atftpd on debian sarge and sid.

Done - I get this then:

=> tftp 100000 foo
TFTP from server 10.0.0.14; our IP address is 10.0.0.99 Filename 'foo'.
Load address: 0x100000
Loading: *
TFTP error: 'File not found' (1)
Starting again

Nothing wrong, or am I missing something?

Quoted 4 lines

Quoted 1 line
Can you please test this (and eventually re-submit the patch) ?
I see, this would indeed be simpler. I didn't know %.*s until now. I will try it when I come home next week.

Thanks!

Best regards,

Wolfgang Denk

Signature · 3 lines

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Computers are not intelligent. They only think they are.

Andreas Oberritter

author

2003-07-19 22:31 UTC #4 lore raw

PATCH 1/1 fixed tftp error message output

Quoted 17 lines · Wolfgang Denk

Quoted 4 lines · In message <1058646514.774.55.camel@localhost> you wrote:
Just try to tftp a file which does not exist on the server or which does not have correct permissions (leading to a "file not found" message). I am using atftpd on debian sarge and sid.
Done - I get this then:
=> tftp 100000 foo
TFTP from server 10.0.0.14; our IP address is 10.0.0.99 Filename 'foo'.
Load address: 0x100000
Loading: *
TFTP error: 'File not found' (1)
Starting again

Quoted 1 line

Nothing wrong, or am I missing something?

My guess is that your tftp server correctly appends \0 to the error message and atftpd does not. Strange. Having a look at atftpd source code I suspect that its use of strncpy for the error message is the cause, but I think u-boot should not rely on the trailing \0, because the length of the error message is known anyway. I'll report when I have been able to test it.

Regards,
Andreas

Wolfgang Denk

2003-07-20 12:53 UTC #5 lore raw

PATCH 1/1 fixed tftp error message output

Quoted 9 lines · In message <1058653888.774.80.camel@localhost> you wrote:

Quoted 2 lines
Nothing wrong, or am I missing something?
My guess is that your tftp server correctly appends \0 to the error message and atftpd does not. Strange. Having a look at atftpd source code I suspect that its use of strncpy for the error message is the cause, but I think u-boot should not rely on the trailing \0, because the length of the error message is known anyway. I'll report when I have been able to test it.

The TFTP protocol explicitely requires the error string to be '\0' terminated:

Quote from RFC 1350 "THE TFTP PROTOCOL (REVISION 2)":

Figure 5-4: ERROR packet

An ERROR packet (opcode 5) takes the form depicted in Figure 5-4. An ERROR packet can be the acknowledgment of any other type of packet. The error code is an integer indicating the nature of the error. A table of values and meanings is given in the appendix. (Note that several error codes have been added to this version of this document.) The error message is intended for human consumption, and should be in netascii. Like all other strings, it is terminated with a zero byte.
...

IMHO the "it is terminated with a zero byte" is mandatory, so no change to U-Boot sems to be necessary.

Best regards,

Wolfgang Denk

Signature · 4 lines

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
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