Multiple issues in components/prism-nginx.js

1. nginx shouldn’t inherit anything from clike. nginx doesn’t have classes, booleans, operators, etc.;
2. Directive shouldn’t be classified as keyword, because some parameters are keywords too.

Comments

1. The current regex fails in the following example.

http {# This must be recognized as a comment
}

1. The current regex doesn’t consider single­‑quoted strings.

location ~ '/example'# This shouldn’t be recognized as a comment
{}

Directives

Problem statement

Directives list is obsolete and inconsistent. AFAIK, the current list is based largely on a third­‑party gist.

Currently Prism supports 339 directives. nginx contains more than 693 directives. Beside that, some directives shown in components/prism-nginx.js are undocumented, removed years ago or not directives at all. See the table below.

Directive	Status in nginx
CONTENT_, DOCUMENT_, etc.	Unknown
auth	Renamed to pop3_auth in 2007 ⁠¹
devpoll_changes	An undocumented directive
devpoll_events	An undocumented directive
epoll_events	An undocumented directive
fastcgi_redirect_errors	Renamed to fastcgi_intercept_errors in 2006 ⁠¹
if_not_empty	A parameter for fastcgi_param and scgi_param
kqueue_changes	An undocumented directive
kqueue_events	An undocumented directive
log_format_combined	Must be log_format combined. combined is a parameter
more_set_headers	A part of ngx_headers_more. It is not distributed with nginx ⁠²
optimize_server_names	Replaced by server_name_in_redirect in 2008 ⁠¹, removed in 2015 ⁠³
post_action	A dangerous undocumented directive
proxy	A parameter ⁠¹
proxy_redirect_errors	Renamed to proxy_intercept_errors in 2006 ⁠¹
proxy_upstream_fail_timeout	Not supported since 2006 ⁠¹
proxy_upstream_max_fails	Not supported since 2006 ⁠¹
rtsig_overflow_events	Removed in 2015 ⁠¹
rtsig_overflow_test	Removed in 2015 ⁠¹
rtsig_overflow_threshold	Removed in 2015 ⁠¹
rtsig_signo	Removed in 2015 ⁠¹
satisfy_any	Replaced by satisfy in 2008 ⁠¹, removed in 2015 ⁠³
so_keepalive	A parameter for listen
worker_rlimit_sigpending	Removed in 2015 ⁠⁴
xslt_entities	Misspelled xml_entities?

¹ ⁠https://nginx.org/en/CHANGES. ² ⁠https://github.com/openresty/headers-more-nginx-module. ³ ⁠https://hg.nginx.org/nginx/rev/2911b7e5491b. ⁴ ⁠https://hg.nginx.org/nginx/rev/967594ba7571.

There are many more removed directives. Here they are:

• obsolete aio directives and rtsig_signo (see http://hg.nginx.org/nginx/rev/adba26ff70b5) were removed in 2015;
• limit_zone is removed in 2014;
• secure_link_expires is removed in 2010;
• open_file_cache_retest is removed in 2007;
• fastcgi_upstream_fail_timeout, fastcgi_upstream_max_fails, fastcgi_x_powered_by, memcached_upstream_fail_timeout, memcached_upstream_max_fails, proxy_pass_server, proxy_pass_x_powered_by, restrict_host_names were removed in 2006;
• fastcgi_root, fastcgi_set_var, fastcgi_params, default_charset, post_accept_timeout, proxy_add_x_forwarded_for, proxy_pass_unparsed_uri, proxy_preserve_host, proxy_set_x_real_ip, proxy_set_x_url, proxy_x_var, redirect, server_names_hash_threshold, server_names_hash were removed in 2005.

There are many more undocumented directives. These are degradation, degrade, eventport_events, gzip_hash, gzip_no_buffer, gzip_window, http2_pool_size, http2_streams_index_size, postpone_gzipping, ssi_ignore_recycled_buffers, uwsgi_string (see https://forum.nginx.org/read.php?29,277920,277920).

A proposed solution

On the one hand, there is a relatively fast way to update the list:

1. save directives list from components/prism-nginx.js as old.txt;
2. replace all occurrences of | in old.txt with \n;
3. sort lines in old.txt alphabetically;
4. save directives list from https://nginx.org/en/docs/dirindex.html as new.txt;
5. remove names of modules from new.txt: \s+\(\w+\);
6. replace (^[\w]+)(?:\n\1)+$ in new.txt with \1 to remove duplicates;
7. find entries to remove: diff old.txt new.txt | grep '^<' | sed 's/^< *//';
8. find entries to add: diff old.txt new.txt | grep '^>' | sed 's/^> *//'.

On the other hand, the resulting list is gonna be really long (I get 631 entries without third­‑party modules).

Maybe it’s better to replace the list with a single regular expression?

Numbers

Is it obligatory to highlight numbers? What about domain2.com, 128k, 192.168.0.1:8000?

Strings

1. Add EOLs. No escaping required. Moreover, escaping is impossible.
2. Add escape sequences. Only the following escape sequences are available: \", \', \\, \n, \r, \t. I’ve checked all the other symbols from 0x00 to 0x7E inside both " and '. \xFF, \uFFFF, \u{FFFF} are not supported.
3. Add interpolation ("$example" and "${example}"). As I previously mentioned, the dollar sign ($) can’t be escaped with \, so nginx interprets \$x as a slash (\) and a subsequent $x variable.

Variables

1. Variable names can contain digits. Examples are $geoip_city_country_code3, $geoip_country_code3, $http2, $time_iso8601. See https://nginx.org/en/docs/varindex.html.
2. Names of user­‑defined variables (set $name value;) can only consist of digits, uppercase and lowercase English letters and underscores. Position is irrelevant ($0, $_ are OK). /\$\w+/ is the best choice for a regular variable.
3. Built­‑in variables with an underscore at the end ($arg_, $cookie_, $http_, $jwt_claim_, $jwt_header_, $sent_http_, $sent_trailer_, $upstream_cookie_, $upstream_http_, $upstream_trailer_) accept a trailing part. This part can contain any character except /[\x00-\x1F\s"';\\{]/. /[;{]/ are only allowed inside strings ("$arg_;", "$arg_{" are OK). Escaping with a slash (\) is useless.

[ghost]

this should work.

Your solution is perfect!

[ghost]

Sorry, but I don’t see the proof

Damn. There are examples of ; # and { #, but there are no examples of anything #. I’m sorry. See the explanation below.

Also, is there a spec page of the NGINX configuration syntax?

I’m not sure. I haven’t found it yet. I use nginx -t -c /path/to/nginx.conf to reveal the rules.

events # A comment
{
    worker_connections 512;
}

# A comment

http# This is not a comment. There is no space
{
    server {# A comment
        listen 80;# A comment

        location = "/example1" # This is a comment. There is a space
        {# This is a comment after "{". No spaces required
            return 200 "Hello, world!";# This is a comment after ";". No spaces required
        }# This is a comment after "}". No spaces required

        location = /example2 # This is a comment. There is a space
        {}

        location = "/example3"# This is not a comment. There is no space
        {}

        location = /example4# This is not a comment. There is no space
        {}
    }# A comment
}

nginx outputs the following:

nginx: [emerg] unknown directive "http#" in /path/to/nginx.conf:9
nginx: [emerg] unexpected "#" in /path/to/nginx.conf:21
nginx: [emerg] invalid number of arguments in "location" directive in /path/to/nginx.conf:25

Thus, the # This is not a comment part in your example is actually a comment.

location = "/example" # This is not a comment
{}

P.S. I hope I don’t bother you too much 😃