OpenWRT DDNS: Difference between revisions

Line 448:

Solution: Change the "Sanitize Regular Expression" (DNS_CHARSET, about twenty or thirty lines down in dynamic_dns_functions.sh) to include a space!

* Current Line of Code: DNS_CHARSET="[@a-zA-Z0-9._-]"

*Current Line of Code: DNS_CHARSET="[@a-zA-Z0-9._-]"

* Should modified to be (allowing a single space to occur in-between an IP Address or Host Name and a Port Number, in the range of allowed port numbers 0-65535):

*Should modified to be (allowing a single space to occur in-between an IP Address or Host Name and a Port Number, in the range of allowed port numbers 0-65535);

**Allows multiple spaces anywhere: [@a-zA-Z0-9 ._-]

**Allows a single space in-between the IP Address OR Host Name and Port Number: [@a-zA-Z0-9]*([ ][0-9._-]*)

**To add to the one immediately above, if one wanted to strip spaces before and after, something like this (but NSUPDATE doesn't seem to care, and in fairness doesn't seem to care about multiple spaces in-between the IP / Host and Port);

***[@a-zA-^Z0-9]*([ ][0-9._-]*)[\n]$

And I must say, it's easy to change the original Regular Expression to allow a space. But to also restrict the position of the space and the range of numbers is tough. So thanks to this site: https://regexr.com/ for making that testing possible.

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Line 460:

*

It should also be mentioned that there's a comment in the dynamic_dns_functions.sh file that states: # dns character set. "-" must be the last character, so that's why the ._- is at the end of the Regular Expression. Best guess is that it's equivalent to the ; in C or similar type languages, etc. to mark the end of a line.

...didn't want to get too deep into the regular expression stuff, because even the beginning one doesn't check for a valid IPv4 'dotted' IP Address, etc., so there's a limit to the validation here. Decided to cap it at W.X.Y.Z "a single space only here" and a port number. IE, not going to check for or validate a good IPv4 'dotted' IP Address or a Host.DomainName.DomainSuffix, or DomainName.DomainSuffix, etc., again IE, it will be up to the user to establish / know what a valid IPv4 Address is, the proper Domain Name format, and the limit of Port ranges.

Also thought some of the characters in the Regular Expression might need to be escaped with a backslash for the sake of PHP or something, but didn't need to, for example: [@a-zA-^Z0-9]\*$[ ][0-9._-]\*$[\n]$

And all of the above might be putting the cart before the horse, so here's the 'cart' (IE, the problem that being able to put in a different port number solves): Some internet providers like Comcast use some type of 'transparent' (in real world terms that would be evil and selfish) DNS proxy service that interferes with OpenWRT DDNS updates. This is a known 'issue' (Google it) was tested extensively to verify (a subject for another article coming soon).

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@@ Line 448: / Line 448: @@
 Solution: Change the "Sanitize Regular Expression" (DNS_CHARSET, about twenty or thirty lines down in dynamic_dns_functions.sh) to include a space!
-* Current Line of Code: DNS_CHARSET="[@a-zA-Z0-9._-]"
+*Current Line of Code: DNS_CHARSET="[@a-zA-Z0-9._-]"
-* Should modified to be (allowing a single space to occur in-between an IP Address or Host Name and a Port Number, in the range of allowed port numbers 0-65535):
+*Should modified to be (allowing a single space to occur in-between an IP Address or Host Name and a Port Number, in the range of allowed port numbers 0-65535);
+**Allows multiple spaces anywhere: [@a-zA-Z0-9 ._-]
+**Allows a single space in-between the IP Address OR Host Name and Port Number: [@a-zA-Z0-9]*([ ][0-9._-]*)
+**To add to the one immediately above, if one wanted to strip spaces before and after, something like this (but NSUPDATE doesn't seem to care, and in fairness doesn't seem to care about multiple spaces in-between the IP / Host and Port);
+***[@a-zA-^Z0-9]*([ ][0-9._-]*)[\n]$
 And I must say, it's easy to change the original Regular Expression to allow a space.  But to also restrict the position of the space and the range of numbers is tough.  So thanks to this site: https://regexr.com/ for making that testing possible.
@@ Line 456: / Line 460: @@
 *
+It should also be mentioned that there's a comment in the dynamic_dns_functions.sh file that states: # dns character set. "-" must be the last character, so that's why the ._- is at the end of the Regular Expression.  Best guess is that it's equivalent to the ; in C or similar type languages, etc. to mark the end of a line.
+...didn't want to get too deep into the regular expression stuff, because even the beginning one doesn't check for a valid IPv4 'dotted' IP Address, etc., so there's a limit to the validation here.  Decided to cap it at W.X.Y.Z "a single space only here" and a port number.  IE, not going to check for or validate a good IPv4 'dotted' IP Address or a Host.DomainName.DomainSuffix, or DomainName.DomainSuffix, etc., again IE, it will be up to the user to establish / know what a valid IPv4 Address is, the proper Domain Name format, and the limit of Port ranges.
+Also thought some of the characters in the Regular Expression might need to be escaped with a backslash for the sake of PHP or something, but didn't need to, for example: [@a-zA-^Z0-9]\*\([ ][0-9._-]\*\)[\n]$
 And all of the above might be putting the cart before the horse, so here's the 'cart' (IE, the problem that being able to put in a different port number solves): Some internet providers like Comcast use some type of 'transparent' (in real world terms that would be evil and selfish) DNS proxy service that interferes with OpenWRT DDNS updates.  This is a known 'issue' (Google it) was tested extensively to verify (a subject for another article coming soon).
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