Lighttpd

with static content it's working fine:
2008-07-02 21:41:14: (request.c.294) fd: 7 request-len: 221

GET /favicon.ico HTTP/1.1

TE: deflate,gzip;q=0.3

Connection: TE, close

Accept-Encoding: gzip

Host: xxx:2080

2008-07-02 21:41:14: (response.c.128) Response-Header:

HTTP/1.1 200 OK

Connection: close

Content-Type: application/octet-stream

Accept-Ranges: bytes

Vary: Accept-Encoding

Content-Encoding: gzip

Content-Length: 697

Date: Wed, 02 Jul 2008 19:41:14 GMT

Server: lighttpd

2008-07-02 21:41:28: (request.c.294) fd: 7 request-len: 198

GET /favicon.ico HTTP/1.1

TE: deflate,gzip;q=0.3

Connection: TE, close

Host: xxxx:2080

2008-07-02 21:41:28: (response.c.128) Response-Header:

HTTP/1.1 200 OK

Connection: close

Content-Type: application/octet-stream

Accept-Ranges: bytes

Content-Length: 2551

Date: Wed, 02 Jul 2008 19:41:28 GMT

Server: lighttpd

however with dynamic content served via a tcp connected fastcgi server, the new size is not calculated at all (the uncompressed content-length value is used):

2008-07-02 21:40:15: (request.c.294) fd: 7 request-len: 187

GET / HTTP/1.1

TE: deflate,gzip;q=0.3

Connection: TE, close

Host: xxx:2080

2008-07-02 21:40:15: (response.c.128) Response-Header:

HTTP/1.1 200 OK

Connection: close

Content-Length: 21097

Content-Type: text/html;charset=utf-8

Date: Wed, 02 Jul 2008 19:40:15 GMT

Server: lighttpd

with gzip encoding, still the same size:

2008-07-02 21:40:33: (request.c.294) fd: 7 request-len: 210

GET / HTTP/1.1

TE: deflate,gzip;q=0.3

Connection: TE, close

Accept-Encoding: gzip

Host: xxx:2080

2008-07-02 21:40:33: (response.c.128) Response-Header:

HTTP/1.1 200 OK

Connection: close

Transfer-Encoding: chunked

Content-Length: 21097

Content-Type: text/html;charset=utf-8

Vary: Accept-Encoding

Content-Encoding: gzip

Date: Wed, 02 Jul 2008 19:40:33 GMT

Server: lighttpd

relevant config:

url.rewrite-once = (
      "^/((?:static|pub|server-status)/.*)" => "/$1",
      "^/favicon.ico" => "/favicon.ico",
      "^/robots.txt" => "/robots.txt",
      "^/(.*)" => "/fcgi/$1" 
    )

fastcgi.server = (
    "/fcgi" => (
      ( "host" => "127.0.0.1", "port" => 8080, "check-local" => "disable"),
    )
)

$HTTP["url"] =~ "^/" {
    setenv.add-environment = ( "SCRIPT_NAME" => "/" )
}

server.max-fds = 6144
server.max-connections = 2048
server.max-worker = 4
server.event-handler = "linux-sysepoll" 
server.network-backend = "writev" 

deflate.sync-flush = "disable" 
deflate.enabled = "enable" 
deflate.compression-level = 9
deflate.mem-level = 9
deflate.window-size = 15
deflate.bzip2 = "disable" 
deflate.allowed_encodings = ( "gzip", "deflate" )

debug.log-request-header = "enable" 
fastcgi.debug = 1
debug.log-response-header = "enable" 

-- m.stemeseder