bugfix: wip: Set headers in the tail of a list rather than in the head #2182
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
It seems that ngx_http_variable_headers_internal function in nginx/src/http/ngx_http_variables.c relies on the fact that the last header values is stored in the last element of a list. Therefore we should avoid changing a random element in the head of a list of headers and either change the last element or add a new element to the list.
oxpa
changed the title
ssdr
reviewed
Apr 23, 2023
|
|
||
| h = *headers; | ||
|
|
||
| if (h->hash == 0) { |
There was a problem hiding this comment.
Oh no, I'm afraid here h is NULL ptr after last for loop iterate...
ssdr
reviewed
Apr 23, 2023
|
|
||
| for (ph = headers; *ph; ph = &(*ph)->next) { /* void */ } | ||
| } else { | ||
| ho = ngx_list_push(&r->headers_out.headers); |
There was a problem hiding this comment.
when last element is valid and other elements are not, here will make a new element, right? Does it mean that the invalid elements never be reused in pool? So why not just nullifying the first element next for simplicity?
There was a problem hiding this comment.
Actually when set builtin multi input header, it just nullifying the next pointer.
can we do same thing for output headers?
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
It seems that ngx_http_variable_headers_internal function in nginx/src/http/ngx_http_variables.c relies on the fact that the last header values is stored in the last element of a list. Therefore we should avoid changing a random element in the head of a list of headers and either change the last element or add a new element to the list.
Not sure if this is the proper fix.
Thanks to @ssdr for pointing out the problem in #2177
I hereby granted the copyright of the changes in this pull request
to the authors of this lua-nginx-module project.