Comments (4)
Okay, after reading the code some more, I think get what's going on.
parseCharset(str, i)
takes a str
of the following formats,
utf-8
iso-8859-1;q=0.5
*;q=0.1
The interesting bit is when we have the "quality value" specified (q=<number>
).
https://github.com/jshttp/negotiator/blob/master/lib/charset.js#L60
//Replaced `const` with `var` to show that those values do not change
const params = match[2].split(';')
//This `var i` is problematic
//It is only ever used as a loop index to access `params[i]`
//However, we accidentally overwrite *parameter* `i`, this is very likely unintentional
for (var i = 0; i < params.length; i ++) {
const p = params[i].trim().split('=');
if (p[0] === 'q') {
q = parseFloat(p[1]);
break;
}
}
So, the i
value being changed seems like a bug.
from negotiator.
With the above bug, it's possible for me to craft a header that breaks preferredCharsets()
,
//Notice the double semi-colon, "first;;q"
preferredCharsets("first;;q=1,second;q=1,third")
Expected,
["first", "second", "third"]
Actual,
["second", "first", "third"]
Of course, in practice, I don't think anyone would craft such a header.
There are other headers that end up relying on Array.sort()
being stable (This is not guaranteed!),
parseAcceptCharset("first;q=0.1,second;q=0.1,third")
[
{
"charset": "first",
"q": 0.1,
"i": 0
},
{
"charset": "second",
"q": 0.1,
"i": 0
},
{
"charset": "third",
"q": 1,
"i": 2
}
]
If we were to run sort()
with compareSpecs()
on the array, it's possible for "first" and "second" to be switched around because compareSpecs()
would return 0
.
However, since Array.sort()
seems to be stable in most environments, we don't notice the bug as much.
from negotiator.
Thanks for the report. The first bug you found is also resulting in the sort instability as well. The i
property is what keeps the sort stable, as long as it is actually not getting altered in that for
loop. I have a fix.
If I'm misunderstanding you on the sort issue, though, please take a look at the commit that closed this issue and if you don't think that fixes the sort issue, if you can provide some reproduction steps based on the current master
branch, I can get a fix for that too 👍
from negotiator.
Just tested and your commit fixes everything. Thank you for handling this so quickly!
from negotiator.
Related Issues (20)
- Fails to parse quoted parameters HOT 10
- Parameter names should be case insensitive HOT 4
- Parameter value case-sensitivity is media-type specific HOT 5
- Is there a reason this library doesn't support charset as a parameter on Accept header? HOT 8
- `Accept: *` results in no media types. HOT 6
- language function does not return expected language HOT 1
- Negotiator behavior on duplicate accept content-types HOT 1
- es6 support HOT 2
- Caching the availableMediaTypes HOT 1
- Functionnal API HOT 2
- Accept-Language comparing standard currently differs between `getLanguagePriority` and `compareSpecs` HOT 5
- [Question] More preferredCharset() stuff HOT 2
- [Question] parseMediaType(), and parameters after q-value HOT 4
- Ship version 1 and adopt semver? HOT 9
- 0.6.3 Release HOT 8
- Inconsistent mediaType/s handling HOT 1
- Returning */* no matter what I set as header. HOT 4
- language function does not return the expected language in nextjs middleware HOT 3
- Language negotiator returns first item of availableLanguages array no matter what HOT 3
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