Re: [Pharo-users] ZnURL and parsing URL with diacritics
Pharo Smalltalk Users mailing list wrote
OK. Thanks for examples. But in my case, the bad URL (with diacritics) comes directly from the Zomato.com REST API (they probably do not read specs), so I'll end up with a few "hacks" with strings.
Sven actually found a trick to handle this case and then forgot he he [1]. Just in case you still have the issue: 'http://myhost/path/with/umlaut/äöü.txt' asFileReference asUrl. 1. http://forum.world.st/Umlauts-in-ZnUrl-tp4793736.html ----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
I recall seeing this trick when Sven published it, but I have never tried it. Trying it now, I get strange results. I entered: 'https://fr.wiktionary.org/wiki/péripétie' asFileReference asUrl. And when I inspect the result, it is the address of a non-existent file in my image directory. I am using Moose 6.1 ( Pharo 6.0 Latest update: #60541) on Windows 10. This is not a current image, I know, but it is more recent than the date of Sven's post (Dec 2014). Has something changed since 2014? Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'. This works fine, and is neater than the alternative with explicit percent encoding which I currently use. So thanks Sean for pointing me to the thread. Peter Kenny -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sean P. DeNigris Sent: 23 March 2019 04:00 To: pharo-users@lists.pharo.org Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics Pharo Smalltalk Users mailing list wrote
OK. Thanks for examples. But in my case, the bad URL (with diacritics) comes directly from the Zomato.com REST API (they probably do not read specs), so I'll end up with a few "hacks" with strings.
Sven actually found a trick to handle this case and then forgot he he [1]. Just in case you still have the issue: 'http://myhost/path/with/umlaut/äöü.txt' asFileReference asUrl. 1. http://forum.world.st/Umlauts-in-ZnUrl-tp4793736.html ----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it. Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/ ----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed. I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error. The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error. The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
Sean, Sven Thinking about this, I have found a simple (maybe too simple) way round it. The obvious first approach is to apply 'urlEncoded' to the received url string, but this fails because it also encodes the slashes and other segment dividers. A simple-minded approach is to scan the received string, copy the slashes and other segment dividers unchanged and percent encode everything else. I cobbled together the following in a playground, but it could easily be turned into a method in String class. urlEncodedSegments := [ :url||outStream| outStream := String new writeStream. url asString do: [ :ch|(':/?' includes: ch ) ifTrue: [ outStream nextPut: ch ] ifFalse:[outStream nextPutAll: ch asString urlEncoded ] ]. outStream contents]. urlEncodedSegments value: 'https://fr.wiktionary.org/wiki/péripétie' => https://fr.wiktionary.org/wiki/p%C3%A9rip%C3%A9tie This may fail if a slash can occur in a url other than as a segment divider. I am not sure if this is possible - could there be some sort of escaped slash within a segment? Anyway, if the received url strings are well-behaved, apart from the diacritics, this approach could be used as a hack for Sean's problem. HTH Peter Kenny Note to Sven: The comment to String>>urlEncoded says: ' This is an encoding where characters that are illegal in a URL are escaped.' Slashes are escaped but are quite legal. Should the comment be changed, or the method? -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 23 March 2019 20:03 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed. I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error. The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error. The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
Well it didn't take long to find a potential problem in what I wrote, at least as a general solution. If the input string contains something which has already been percent encoded, it will re-encode the percent signs. In this case, decoding will recover the once-encoded version, but we need to decode twice to recover the original text. Any web site receiving this version will almost certainly decode once only, and so will not see the right details. The solution is simple - just include the percent sign in the list of excluded characters in the third line, so it becomes: url asString do: [ :ch|(':/?%' includes: ch ) -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 12:11 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics Sean, Sven Thinking about this, I have found a simple (maybe too simple) way round it. The obvious first approach is to apply 'urlEncoded' to the received url string, but this fails because it also encodes the slashes and other segment dividers. A simple-minded approach is to scan the received string, copy the slashes and other segment dividers unchanged and percent encode everything else. I cobbled together the following in a playground, but it could easily be turned into a method in String class. urlEncodedSegments := [ :url||outStream| outStream := String new writeStream. url asString do: [ :ch|(':/?' includes: ch ) ifTrue: [ outStream nextPut: ch ] ifFalse:[outStream nextPutAll: ch asString urlEncoded ] ]. outStream contents]. urlEncodedSegments value: 'https://fr.wiktionary.org/wiki/péripétie' => https://fr.wiktionary.org/wiki/p%C3%A9rip%C3%A9tie This may fail if a slash can occur in a url other than as a segment divider. I am not sure if this is possible - could there be some sort of escaped slash within a segment? Anyway, if the received url strings are well-behaved, apart from the diacritics, this approach could be used as a hack for Sean's problem. HTH Peter Kenny Note to Sven: The comment to String>>urlEncoded says: ' This is an encoding where characters that are illegal in a URL are escaped.' Slashes are escaped but are quite legal. Should the comment be changed, or the method? -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 23 March 2019 20:03 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed. I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error. The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error. The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
Sean I have realized that the method I proposed can be expressed entirely within the Zinc system, which may make it a bit neater and easier to follow. There probably is no completely general solution, but there is a completely general way of finding a solution for your problem domain. It is important to realize that String>>urlEncoded is defined as: ZnPercentEncoder new encode: self. ZnPercentEncoder does not attempt to parse the input string as a url. It scans the entire string, and percent encodes any character that is not in its safe set (see the comment to ZnPercentEncoder>>encode:). Sven has given as default a minimum safe set, which does not include slash, but there is a setter method to redefine the safe set. So the general way to find a solution for your domain is to collect a representative set of the url strings, apply String>>urlEncoded to each, and work out which characters have been percent encoded wrongly for your domain. For any url cases this is likely to include ':/?#', as well as '%' if it includes things already percent encoded, but there may be others specific to your domain. Now construct an instance of ZnPercentEncoder with the safe set extended to include these characters - note that the default safe set is given by the class method ZnPercentEncoder class>> rfc3986UnreservedCharacters. Apply this instance to encode all your test incoming url strings and verify that they work. Iterate, extending the safe set, until everything passes. If you want to keep the neatness being able to write something like 'incomingString urlEncoded asZnUrl', you can add a method to String; for the case of the common url characters mentioned above: String>> urlEncodedMyWay "As urlEncoded, but with the safe set extended to include characters commonly found in a url" ^ ZnPercentEncoder new safeSet: ':/?#%', (ZnPercentEncoder rfc3986UnreservedCharacters); encode: self This works in much the same way as the snippet I posted originally, because my code simply reproduces the essentials of ZnPercentEncoder>>encode:. I seem to be trying to monopolize this thread, so I shall shut up now. HTH Peter Kenny -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 15:36 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics Well it didn't take long to find a potential problem in what I wrote, at least as a general solution. If the input string contains something which has already been percent encoded, it will re-encode the percent signs. In this case, decoding will recover the once-encoded version, but we need to decode twice to recover the original text. Any web site receiving this version will almost certainly decode once only, and so will not see the right details. The solution is simple - just include the percent sign in the list of excluded characters in the third line, so it becomes: url asString do: [ :ch|(':/?%' includes: ch ) -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 12:11 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics Sean, Sven Thinking about this, I have found a simple (maybe too simple) way round it. The obvious first approach is to apply 'urlEncoded' to the received url string, but this fails because it also encodes the slashes and other segment dividers. A simple-minded approach is to scan the received string, copy the slashes and other segment dividers unchanged and percent encode everything else. I cobbled together the following in a playground, but it could easily be turned into a method in String class. urlEncodedSegments := [ :url||outStream| outStream := String new writeStream. url asString do: [ :ch|(':/?' includes: ch ) ifTrue: [ outStream nextPut: ch ] ifFalse:[outStream nextPutAll: ch asString urlEncoded ] ]. outStream contents]. urlEncodedSegments value: 'https://fr.wiktionary.org/wiki/péripétie' => https://fr.wiktionary.org/wiki/p%C3%A9rip%C3%A9tie This may fail if a slash can occur in a url other than as a segment divider. I am not sure if this is possible - could there be some sort of escaped slash within a segment? Anyway, if the received url strings are well-behaved, apart from the diacritics, this approach could be used as a hack for Sean's problem. HTH Peter Kenny Note to Sven: The comment to String>>urlEncoded says: ' This is an encoding where characters that are illegal in a URL are escaped.' Slashes are escaped but are quite legal. Should the comment be changed, or the method? -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 23 March 2019 20:03 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed. I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error. The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error. The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
I would use a variant of your original transformation. The issue (the error in the URL) is that all kinds of non-ASCII characters occur unencoded. We should/could assume that other special/reserved ASCII characters _are_ properly encoded (so we do not need to handle them). So I would literally patch/fix the problem, like this: | bogusUrl fixedUrl url | bogusUrl := 'https://en.wikipedia.org/wiki/Äeská republika'. fixedUrl := String streamContents: [ :out | bogusUrl do: [ :each | (each codePoint < 127 and: [ each ~= $ ]) ifTrue: [ out nextPut: each ] ifFalse: [ out nextPutAll: each asString urlEncoded ] ] ]. fixedUrl asUrl retrieveContents. I made and extra case for the space character, it works either way in the example given, but a space cannot occur freely.
On 26 Mar 2019, at 12:53, PBKResearch <peter@pbkresearch.co.uk> wrote:
Sean
I have realized that the method I proposed can be expressed entirely within the Zinc system, which may make it a bit neater and easier to follow. There probably is no completely general solution, but there is a completely general way of finding a solution for your problem domain.
It is important to realize that String>>urlEncoded is defined as: ZnPercentEncoder new encode: self. ZnPercentEncoder does not attempt to parse the input string as a url. It scans the entire string, and percent encodes any character that is not in its safe set (see the comment to ZnPercentEncoder>>encode:). Sven has given as default a minimum safe set, which does not include slash, but there is a setter method to redefine the safe set.
So the general way to find a solution for your domain is to collect a representative set of the url strings, apply String>>urlEncoded to each, and work out which characters have been percent encoded wrongly for your domain. For any url cases this is likely to include ':/?#', as well as '%' if it includes things already percent encoded, but there may be others specific to your domain. Now construct an instance of ZnPercentEncoder with the safe set extended to include these characters - note that the default safe set is given by the class method ZnPercentEncoder class>> rfc3986UnreservedCharacters. Apply this instance to encode all your test incoming url strings and verify that they work. Iterate, extending the safe set, until everything passes.
If you want to keep the neatness being able to write something like 'incomingString urlEncoded asZnUrl', you can add a method to String; for the case of the common url characters mentioned above:
String>> urlEncodedMyWay
"As urlEncoded, but with the safe set extended to include characters commonly found in a url"
^ ZnPercentEncoder new safeSet: ':/?#%', (ZnPercentEncoder rfc3986UnreservedCharacters); encode: self
This works in much the same way as the snippet I posted originally, because my code simply reproduces the essentials of ZnPercentEncoder>>encode:.
I seem to be trying to monopolize this thread, so I shall shut up now.
HTH
Peter Kenny
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 15:36 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Well it didn't take long to find a potential problem in what I wrote, at least as a general solution. If the input string contains something which has already been percent encoded, it will re-encode the percent signs. In this case, decoding will recover the once-encoded version, but we need to decode twice to recover the original text. Any web site receiving this version will almost certainly decode once only, and so will not see the right details.
The solution is simple - just include the percent sign in the list of excluded characters in the third line, so it becomes: url asString do: [ :ch|(':/?%' includes: ch )
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 12:11 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Sean, Sven
Thinking about this, I have found a simple (maybe too simple) way round it. The obvious first approach is to apply 'urlEncoded' to the received url string, but this fails because it also encodes the slashes and other segment dividers. A simple-minded approach is to scan the received string, copy the slashes and other segment dividers unchanged and percent encode everything else. I cobbled together the following in a playground, but it could easily be turned into a method in String class.
urlEncodedSegments := [ :url||outStream| outStream := String new writeStream. url asString do: [ :ch|(':/?' includes: ch ) ifTrue: [ outStream nextPut: ch ] ifFalse:[outStream nextPutAll: ch asString urlEncoded ] ]. outStream contents].
urlEncodedSegments value: 'https://fr.wiktionary.org/wiki/péripétie' => https://fr.wiktionary.org/wiki/p%C3%A9rip%C3%A9tie
This may fail if a slash can occur in a url other than as a segment divider. I am not sure if this is possible - could there be some sort of escaped slash within a segment? Anyway, if the received url strings are well-behaved, apart from the diacritics, this approach could be used as a hack for Sean's problem.
HTH
Peter Kenny
Note to Sven: The comment to String>>urlEncoded says: ' This is an encoding where characters that are illegal in a URL are escaped.' Slashes are escaped but are quite legal. Should the comment be changed, or the method?
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 23 March 2019 20:03 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed.
I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error.
The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error.
The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
Sven That would certainly work, and represents the most liberal possible approach. An equivalent, keeping entirely within Zinc, would be to use a special-purpose instance of ZnPercentEncoder, in which the safe set is defined as all characters between code points 33 and 126 inclusive. (Starting at 33 fixes your space point.) Using 'bogusUrl' as a variable name seems a bit pejorative. I am looking up French and German words in Wiktionary all the time, and I am building a Pharo app to do it for me. The version of the url with the accented characters will not work in Zinc until I have urlEncoded it, but it works perfectly well in a browser and is much easier to read. Peter Kenny -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 26 March 2019 12:26 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics I would use a variant of your original transformation. The issue (the error in the URL) is that all kinds of non-ASCII characters occur unencoded. We should/could assume that other special/reserved ASCII characters _are_ properly encoded (so we do not need to handle them). So I would literally patch/fix the problem, like this: | bogusUrl fixedUrl url | bogusUrl := 'https://en.wikipedia.org/wiki/Äeská republika'. fixedUrl := String streamContents: [ :out | bogusUrl do: [ :each | (each codePoint < 127 and: [ each ~= $ ]) ifTrue: [ out nextPut: each ] ifFalse: [ out nextPutAll: each asString urlEncoded ] ] ]. fixedUrl asUrl retrieveContents. I made and extra case for the space character, it works either way in the example given, but a space cannot occur freely.
On 26 Mar 2019, at 12:53, PBKResearch <peter@pbkresearch.co.uk> wrote:
Sean
I have realized that the method I proposed can be expressed entirely within the Zinc system, which may make it a bit neater and easier to follow. There probably is no completely general solution, but there is a completely general way of finding a solution for your problem domain.
It is important to realize that String>>urlEncoded is defined as: ZnPercentEncoder new encode: self. ZnPercentEncoder does not attempt to parse the input string as a url. It scans the entire string, and percent encodes any character that is not in its safe set (see the comment to ZnPercentEncoder>>encode:). Sven has given as default a minimum safe set, which does not include slash, but there is a setter method to redefine the safe set.
So the general way to find a solution for your domain is to collect a representative set of the url strings, apply String>>urlEncoded to each, and work out which characters have been percent encoded wrongly for your domain. For any url cases this is likely to include ':/?#', as well as '%' if it includes things already percent encoded, but there may be others specific to your domain. Now construct an instance of ZnPercentEncoder with the safe set extended to include these characters - note that the default safe set is given by the class method ZnPercentEncoder class>> rfc3986UnreservedCharacters. Apply this instance to encode all your test incoming url strings and verify that they work. Iterate, extending the safe set, until everything passes.
If you want to keep the neatness being able to write something like 'incomingString urlEncoded asZnUrl', you can add a method to String; for the case of the common url characters mentioned above:
String>> urlEncodedMyWay
"As urlEncoded, but with the safe set extended to include characters commonly found in a url"
^ ZnPercentEncoder new safeSet: ':/?#%', (ZnPercentEncoder rfc3986UnreservedCharacters); encode: self
This works in much the same way as the snippet I posted originally, because my code simply reproduces the essentials of ZnPercentEncoder>>encode:.
I seem to be trying to monopolize this thread, so I shall shut up now.
HTH
Peter Kenny
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 15:36 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Well it didn't take long to find a potential problem in what I wrote, at least as a general solution. If the input string contains something which has already been percent encoded, it will re-encode the percent signs. In this case, decoding will recover the once-encoded version, but we need to decode twice to recover the original text. Any web site receiving this version will almost certainly decode once only, and so will not see the right details.
The solution is simple - just include the percent sign in the list of excluded characters in the third line, so it becomes: url asString do: [ :ch|(':/?%' includes: ch )
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 12:11 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Sean, Sven
Thinking about this, I have found a simple (maybe too simple) way round it. The obvious first approach is to apply 'urlEncoded' to the received url string, but this fails because it also encodes the slashes and other segment dividers. A simple-minded approach is to scan the received string, copy the slashes and other segment dividers unchanged and percent encode everything else. I cobbled together the following in a playground, but it could easily be turned into a method in String class.
urlEncodedSegments := [ :url||outStream| outStream := String new writeStream. url asString do: [ :ch|(':/?' includes: ch ) ifTrue: [ outStream nextPut: ch ] ifFalse:[outStream nextPutAll: ch asString urlEncoded ] ]. outStream contents].
urlEncodedSegments value: 'https://fr.wiktionary.org/wiki/péripétie' => https://fr.wiktionary.org/wiki/p%C3%A9rip%C3%A9tie
This may fail if a slash can occur in a url other than as a segment divider. I am not sure if this is possible - could there be some sort of escaped slash within a segment? Anyway, if the received url strings are well-behaved, apart from the diacritics, this approach could be used as a hack for Sean's problem.
HTH
Peter Kenny
Note to Sven: The comment to String>>urlEncoded says: ' This is an encoding where characters that are illegal in a URL are escaped.' Slashes are escaped but are quite legal. Should the comment be changed, or the method?
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 23 March 2019 20:03 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed.
I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error.
The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error.
The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
Peter, It *is* a bogus URL, please go and read some RFCs. A browser's address/search box is an entirely different thing that adds convenience features, such as the issue we are discussing here. Sven
On 26 Mar 2019, at 16:02, PBKResearch <peter@pbkresearch.co.uk> wrote:
Sven
That would certainly work, and represents the most liberal possible approach. An equivalent, keeping entirely within Zinc, would be to use a special-purpose instance of ZnPercentEncoder, in which the safe set is defined as all characters between code points 33 and 126 inclusive. (Starting at 33 fixes your space point.)
Using 'bogusUrl' as a variable name seems a bit pejorative. I am looking up French and German words in Wiktionary all the time, and I am building a Pharo app to do it for me. The version of the url with the accented characters will not work in Zinc until I have urlEncoded it, but it works perfectly well in a browser and is much easier to read.
Peter Kenny
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 26 March 2019 12:26 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
I would use a variant of your original transformation.
The issue (the error in the URL) is that all kinds of non-ASCII characters occur unencoded. We should/could assume that other special/reserved ASCII characters _are_ properly encoded (so we do not need to handle them).
So I would literally patch/fix the problem, like this:
| bogusUrl fixedUrl url | bogusUrl := 'https://en.wikipedia.org/wiki/Äeská republika'. fixedUrl := String streamContents: [ :out | bogusUrl do: [ :each | (each codePoint < 127 and: [ each ~= $ ]) ifTrue: [ out nextPut: each ] ifFalse: [ out nextPutAll: each asString urlEncoded ] ] ]. fixedUrl asUrl retrieveContents.
I made and extra case for the space character, it works either way in the example given, but a space cannot occur freely.
On 26 Mar 2019, at 12:53, PBKResearch <peter@pbkresearch.co.uk> wrote:
Sean
I have realized that the method I proposed can be expressed entirely within the Zinc system, which may make it a bit neater and easier to follow. There probably is no completely general solution, but there is a completely general way of finding a solution for your problem domain.
It is important to realize that String>>urlEncoded is defined as: ZnPercentEncoder new encode: self. ZnPercentEncoder does not attempt to parse the input string as a url. It scans the entire string, and percent encodes any character that is not in its safe set (see the comment to ZnPercentEncoder>>encode:). Sven has given as default a minimum safe set, which does not include slash, but there is a setter method to redefine the safe set.
So the general way to find a solution for your domain is to collect a representative set of the url strings, apply String>>urlEncoded to each, and work out which characters have been percent encoded wrongly for your domain. For any url cases this is likely to include ':/?#', as well as '%' if it includes things already percent encoded, but there may be others specific to your domain. Now construct an instance of ZnPercentEncoder with the safe set extended to include these characters - note that the default safe set is given by the class method ZnPercentEncoder class>> rfc3986UnreservedCharacters. Apply this instance to encode all your test incoming url strings and verify that they work. Iterate, extending the safe set, until everything passes.
If you want to keep the neatness being able to write something like 'incomingString urlEncoded asZnUrl', you can add a method to String; for the case of the common url characters mentioned above:
String>> urlEncodedMyWay
"As urlEncoded, but with the safe set extended to include characters commonly found in a url"
^ ZnPercentEncoder new safeSet: ':/?#%', (ZnPercentEncoder rfc3986UnreservedCharacters); encode: self
This works in much the same way as the snippet I posted originally, because my code simply reproduces the essentials of ZnPercentEncoder>>encode:.
I seem to be trying to monopolize this thread, so I shall shut up now.
HTH
Peter Kenny
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 15:36 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Well it didn't take long to find a potential problem in what I wrote, at least as a general solution. If the input string contains something which has already been percent encoded, it will re-encode the percent signs. In this case, decoding will recover the once-encoded version, but we need to decode twice to recover the original text. Any web site receiving this version will almost certainly decode once only, and so will not see the right details.
The solution is simple - just include the percent sign in the list of excluded characters in the third line, so it becomes: url asString do: [ :ch|(':/?%' includes: ch )
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 12:11 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Sean, Sven
Thinking about this, I have found a simple (maybe too simple) way round it. The obvious first approach is to apply 'urlEncoded' to the received url string, but this fails because it also encodes the slashes and other segment dividers. A simple-minded approach is to scan the received string, copy the slashes and other segment dividers unchanged and percent encode everything else. I cobbled together the following in a playground, but it could easily be turned into a method in String class.
urlEncodedSegments := [ :url||outStream| outStream := String new writeStream. url asString do: [ :ch|(':/?' includes: ch ) ifTrue: [ outStream nextPut: ch ] ifFalse:[outStream nextPutAll: ch asString urlEncoded ] ]. outStream contents].
urlEncodedSegments value: 'https://fr.wiktionary.org/wiki/péripétie' => https://fr.wiktionary.org/wiki/p%C3%A9rip%C3%A9tie
This may fail if a slash can occur in a url other than as a segment divider. I am not sure if this is possible - could there be some sort of escaped slash within a segment? Anyway, if the received url strings are well-behaved, apart from the diacritics, this approach could be used as a hack for Sean's problem.
HTH
Peter Kenny
Note to Sven: The comment to String>>urlEncoded says: ' This is an encoding where characters that are illegal in a URL are escaped.' Slashes are escaped but are quite legal. Should the comment be changed, or the method?
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 23 March 2019 20:03 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed.
I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error.
The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error.
The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
Sven Well RFCs are unreadable - I know, because I looked at 3986 while looking at this question - but OK, I get your point. I suppose I should be looking for something that makes it easier to provide similar convenience features in Pharo. As you say, if this issue is cracked, that is a step on the way. Peter -----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 26 March 2019 15:08 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics Peter, It *is* a bogus URL, please go and read some RFCs. A browser's address/search box is an entirely different thing that adds convenience features, such as the issue we are discussing here. Sven
On 26 Mar 2019, at 16:02, PBKResearch <peter@pbkresearch.co.uk> wrote:
Sven
That would certainly work, and represents the most liberal possible approach. An equivalent, keeping entirely within Zinc, would be to use a special-purpose instance of ZnPercentEncoder, in which the safe set is defined as all characters between code points 33 and 126 inclusive. (Starting at 33 fixes your space point.)
Using 'bogusUrl' as a variable name seems a bit pejorative. I am looking up French and German words in Wiktionary all the time, and I am building a Pharo app to do it for me. The version of the url with the accented characters will not work in Zinc until I have urlEncoded it, but it works perfectly well in a browser and is much easier to read.
Peter Kenny
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 26 March 2019 12:26 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
I would use a variant of your original transformation.
The issue (the error in the URL) is that all kinds of non-ASCII characters occur unencoded. We should/could assume that other special/reserved ASCII characters _are_ properly encoded (so we do not need to handle them).
So I would literally patch/fix the problem, like this:
| bogusUrl fixedUrl url | bogusUrl := 'https://en.wikipedia.org/wiki/Äeská republika'. fixedUrl := String streamContents: [ :out | bogusUrl do: [ :each | (each codePoint < 127 and: [ each ~= $ ]) ifTrue: [ out nextPut: each ] ifFalse: [ out nextPutAll: each asString urlEncoded ] ] ]. fixedUrl asUrl retrieveContents.
I made and extra case for the space character, it works either way in the example given, but a space cannot occur freely.
On 26 Mar 2019, at 12:53, PBKResearch <peter@pbkresearch.co.uk> wrote:
Sean
I have realized that the method I proposed can be expressed entirely within the Zinc system, which may make it a bit neater and easier to follow. There probably is no completely general solution, but there is a completely general way of finding a solution for your problem domain.
It is important to realize that String>>urlEncoded is defined as: ZnPercentEncoder new encode: self. ZnPercentEncoder does not attempt to parse the input string as a url. It scans the entire string, and percent encodes any character that is not in its safe set (see the comment to ZnPercentEncoder>>encode:). Sven has given as default a minimum safe set, which does not include slash, but there is a setter method to redefine the safe set.
So the general way to find a solution for your domain is to collect a representative set of the url strings, apply String>>urlEncoded to each, and work out which characters have been percent encoded wrongly for your domain. For any url cases this is likely to include ':/?#', as well as '%' if it includes things already percent encoded, but there may be others specific to your domain. Now construct an instance of ZnPercentEncoder with the safe set extended to include these characters - note that the default safe set is given by the class method ZnPercentEncoder class>> rfc3986UnreservedCharacters. Apply this instance to encode all your test incoming url strings and verify that they work. Iterate, extending the safe set, until everything passes.
If you want to keep the neatness being able to write something like 'incomingString urlEncoded asZnUrl', you can add a method to String; for the case of the common url characters mentioned above:
String>> urlEncodedMyWay
"As urlEncoded, but with the safe set extended to include characters commonly found in a url"
^ ZnPercentEncoder new safeSet: ':/?#%', (ZnPercentEncoder rfc3986UnreservedCharacters); encode: self
This works in much the same way as the snippet I posted originally, because my code simply reproduces the essentials of ZnPercentEncoder>>encode:.
I seem to be trying to monopolize this thread, so I shall shut up now.
HTH
Peter Kenny
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 15:36 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Well it didn't take long to find a potential problem in what I wrote, at least as a general solution. If the input string contains something which has already been percent encoded, it will re-encode the percent signs. In this case, decoding will recover the once-encoded version, but we need to decode twice to recover the original text. Any web site receiving this version will almost certainly decode once only, and so will not see the right details.
The solution is simple - just include the percent sign in the list of excluded characters in the third line, so it becomes: url asString do: [ :ch|(':/?%' includes: ch )
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of PBKResearch Sent: 24 March 2019 12:11 To: 'Any question about pharo is welcome' <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
Sean, Sven
Thinking about this, I have found a simple (maybe too simple) way round it. The obvious first approach is to apply 'urlEncoded' to the received url string, but this fails because it also encodes the slashes and other segment dividers. A simple-minded approach is to scan the received string, copy the slashes and other segment dividers unchanged and percent encode everything else. I cobbled together the following in a playground, but it could easily be turned into a method in String class.
urlEncodedSegments := [ :url||outStream| outStream := String new writeStream. url asString do: [ :ch|(':/?' includes: ch ) ifTrue: [ outStream nextPut: ch ] ifFalse:[outStream nextPutAll: ch asString urlEncoded ] ]. outStream contents].
urlEncodedSegments value: 'https://fr.wiktionary.org/wiki/péripétie' => https://fr.wiktionary.org/wiki/p%C3%A9rip%C3%A9tie
This may fail if a slash can occur in a url other than as a segment divider. I am not sure if this is possible - could there be some sort of escaped slash within a segment? Anyway, if the received url strings are well-behaved, apart from the diacritics, this approach could be used as a hack for Sean's problem.
HTH
Peter Kenny
Note to Sven: The comment to String>>urlEncoded says: ' This is an encoding where characters that are illegal in a URL are escaped.' Slashes are escaped but are quite legal. Should the comment be changed, or the method?
-----Original Message----- From: Pharo-users <pharo-users-bounces@lists.pharo.org> On Behalf Of Sven Van Caekenberghe Sent: 23 March 2019 20:03 To: Any question about pharo is welcome <pharo-users@lists.pharo.org> Subject: Re: [Pharo-users] ZnURL and parsing URL with diacritics
On 23 Mar 2019, at 20:53, Sean P. DeNigris <sean@clipperadams.com> wrote:
Peter Kenny wrote
And when I inspect the result, it is the address of a non-existent file in my image directory.
Ah, no. I see the same result. By "worked" I meant that it created a URL that safari accepted, but I see now it's not the same as correctly parsing it.
Peter Kenny wrote
Incidentally, I tried the other trick Sven cites in the same thread. The same url as above can be written: 'https://fr.wiktionary.org/wiki' asUrl / 'péripétie'.
Yes, this works if you are assembling the URL, but several people presented the use case of processing URLs from elsewhere, leaving one in a chicken-and-egg situation where one can't parse due to the diacritics and can't escape the diacritics (i.e. without incorrectly escaping other things) without parsing :/
Yes, that is pretty close to a catch 22. Strictly speaking, such URLs are incorrect and can't be parsed.
I do understand that sometimes these URLs occur in the wild, but again, strictly speaking they are in error.
The fact that browser search boxes accept them is a service on top of the strict URL syntax, I am not 100% sure how they do it, but it probably involves a lot of heuristics and trial and error.
The parser of ZnUrl is just 3 to 4 methods. There is nothing preventing somebody from making a new ZnLoseUrlParser, but it won't be easy.
----- Cheers, Sean -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html
participants (3)
-
PBKResearch -
Sean P. DeNigris -
Sven Van Caekenberghe