XBitHack full with group execute bit set to enable If-Modified-Since only works partially. While it adds the Last-Modified header correctly, subsequent requests using If-Modified-Since results in an empty response (connection closed, no response headers at all). The access.log indicates a 304 response was sent however.. but none is sent to the client.
strace of an request accept(3, {sa_family=AF_INET, sin_port=htons(40506), sin_addr=inet_addr("127.0.0.1")}, [16]) = 8 fcntl64(8, F_GETFL) = 0x2 (flags O_RDWR) fcntl64(8, F_SETFL, O_RDWR|O_NONBLOCK) = 0 read(8, "GET / HTTP/1.0\r\nIf-Modified-Sinc"..., 8000) = 386 gettimeofday({1188770501, 263022}, NULL) = 0 stat64("/export/www/www.henriknordstrom.net/html/", {st_mode=S_IFDIR|S_ISGID|0775, st_size=4096, ...}) = 0 open("/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) open("/export/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) open("/export/www/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) open("/export/www/www.henriknordstrom.net/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) open("/export/www/www.henriknordstrom.net/html/.htaccess", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) stat64("/export/www/www.henriknordstrom.net/html/index", 0xbfd0cd8c) = -1 ENOENT (No such file or directory) lstat64("/export", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0 lstat64("/export/www", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0 lstat64("/export/www/www.henriknordstrom.net", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0 lstat64("/export/www/www.henriknordstrom.net/html", {st_mode=S_IFDIR|S_ISGID|0775, st_size=4096, ...}) = 0 lstat64("/export/www/www.henriknordstrom.net/html/index", 0xbfd0cd8c) = -1 ENOENT (No such file or directory) open("/export/www/www.henriknordstrom.net/html/", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 9 fstat64(9, {st_mode=S_IFDIR|S_ISGID|0775, st_size=4096, ...}) = 0 fcntl64(9, F_SETFD, FD_CLOEXEC) = 0 getdents64(9, /* 38 entries */, 4096) = 1440 stat64("/export/www/www.henriknordstrom.net/html/index.html", {st_mode=S_IFREG|0754, st_size=862, ...}) = 0 getdents64(9, /* 0 entries */, 4096) = 0 close(9) = 0 open("/export/www/www.henriknordstrom.net/html/index.html", O_RDONLY|O_LARGEFILE) = 9 close(9) = 0 read(8, 0x8beeb38, 8000) = -1 EAGAIN (Resource temporarily unavailable) write(7, "127.0.0.1 www.henriknordstrom.ne"..., 96) = 96 shutdown(8, 1 /* send */) = 0 poll([{fd=8, events=POLLIN, revents=POLLIN|POLLHUP}], 1, 2000) = 1 read(8, "", 512) = 0 close(8) = 0 read(4, 0xbfd0d087, 1) = -1 EAGAIN (Resource temporarily unavailable)
Can you reproduce this with 2.2.6? It seems to work fine with the current 2.2.7-dev branch. > GET /modules/include/xbithack/full/test.html HTTP/1.1 > User-Agent: curl/7.16.2 (x86_64-redhat-linux-gnu) libcurl/7.16.2 OpenSSL/0.9.8b zlib/1.2.3 libidn/0.6.8 > Host: localhost:8529 > Accept: */* > If-Modified-Since: Mon, 19 Feb 2007 23:48:28 GMT > < HTTP/1.1 304 Not Modified < Date: Fri, 12 Oct 2007 10:55:39 GMT < Server: Apache/2.2.7-dev (Unix) mod_ssl/2.2.7-dev OpenSSL/0.9.8b DAV/2
I'm seeing this with Debian's 2.2.11 build. I normally sit behind a squid proxy that auto-retries, so this problem was being masked. I can reliably reproduce it with a browser hitting the site directly. Occasionally the requests DO succeed, but most fail. I've confirmed with tcpdump that the HTTP server is closing the connection without sending a response. The failures seem to be correlated only with index files with the XBitHack set. My strace output looks essentially identical to the other poster's. Here's a diff between a 'good' request and a 'bad' request: getdents64(18, /* 0 entries */, 4096) = 0 close(18) = 0 open("/www/fastolfe.net/htdocs/2009/index.html", O_RDONLY|O_LARGEFILE) = 18 -mmap2(NULL, 13, PROT_READ, MAP_SHARED, 18, 0) = 0xb7f6c000 -writev(15, [{"HTTP/1.1 200 OK\r\nDate: Mon, 22 Ju"..., 342}, {"Test content\n"..., 13}], 2) = 355 -munmap(0xb7f6c000, 13) = 0 -write(16, "216.239.45.4 - - - [22/Jun/2009:0"..., 188) = 188 +close(18) = 0 +read(15, 0x82ddec8, 8000) = -1 EAGAIN (Resource temporarily unavailable) +write(16, "216.239.45.4 - - - [22/Jun/2009:1"..., 187) = 187 shutdown(15, 1 /* send */) = 0 poll([{fd=15, events=POLLIN}], 1, 2000) = 1 ([{fd=15, revents=POLLIN|POLLHUP}]) read(15, ""..., 512) = 0 close(15) = 0 read(7, 0xbf86fb57, 1) = -1 EAGAIN (Resource temporarily unavailable) -close(18) = 0 -semop(10059778, 0xb7f195d4, 1) = 0 -epoll_wait(13, {{EPOLLIN, {u32=137158752, u64=137158752}}}, 2, -1) = 1 +semop(10059778, 0xb7f195d4, 1 The bad request fails to mmap the index.html and fails to write a response before closing the connection. If I chmod g-x index.html, the file gets delivered reliably. Nothing is logged to the error log, and the access log always reports a normal 304 response.
Note that I am also using MultiViews, so it might be a multi-way interaction.
As I experiment this on 2.2.9, either XBitHack on or XBitHack full would cause empty pages in browser for index pages, presumably due to 0-byte pages. chmod g-x does not cure this. Detail of my trial is recorded in bug 45225 and in bug 50914.
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