filed ===== Introduction ------------ "filed" is a simple HTTP server for serving local static files over HTTP from Linux. It does the least amount of effort possible to get to the point of handing the actual transfer over to the kernel. It is multithreaded where every thread services a single concurrent client. It attempts to reduce latency by caching open file descriptors as well. It has no configuration file and supports only minimal configuration. Operation is described in the manual page. Usage ----- The simplest usage of "filed" is to run it with no arguments. This will start up an HTTP server listening on port 80 and sharing out the root filesystem for the system as the current user. You probably do not want to share out your root filesystem since that will expose information such as "/etc/passwd" to anonymous access. You probably also don't want to do that as root since then sensitive information such as "/etc/shadow" could be used to compromise the system. Therefore, the "--user" and "--root" options should be used to specify a user for "filed" to run as in addition to a directory to change root (chroot(2)) to prior to serving out files. Example 1, insecure file sharing: $ filed Example 2, sharing sensitive information: # filed Example 3, sharing only a specific directory: # filed --root /www --user nobody Example 4, running as a daemon: # filed --root /www --user nobody --daemon Build Time Considerations ------------------------- In general, it is best to leave all configuration to run-time so that a compiled binary can do as much as possible without needing to be recompiled. However, there are some things that are best done at compile time for various reasons, especially in the name of performance or executable size. filed admits those trade-offs are occasionally required and offers the following tunables that can only be toggled during compile-time: 1. Logging (CFLAGS, -DFILED_DONT_LOG=1) It is possible to disable ALL logging from filed. When logging is completely disabled interlocks (mutexes) for the logging pointer are not engaged and the logging functions are not compiled at all. This results in a slightly smaller and faster binary 2. Kill idle connections (CFLAGS, -DFILED_DONT_TIMEOUT=1) Killing idle connections relies heavily upon C11 atomics. This requires a relatively new version of GCC (4.9+) or other C compiler that implements this aspect of C11 and so it can be disabled at compile time (which is the only time it makes sense). One day an alternate implementation might be present that uses a mutex instead of atomics at which point this documentation will be updated. 3. Debugging (CFLAGS, -DFILED_DEBUG=1) This is an internal option and should only be used during development. 4. Differing HTTP semantics (CFLAGS, -DFILED_NONBLOCK_HTTP=1) It is possible that some HTTP clients may not process the HTTP stream being delivered if they cannot write to the HTTP stream itself. This has not been observed yet, but it is possible. If these semantics are needed (and they should not be) then they can be enabled with this flag at the cost of performance. 5. Differing chroot() semantics (CFLAGS, -DFILED_FAKE_CHROOT=1) In some cases it is desirable to mangle paths with a path prefix rather than call chroot() at startup. This is less secure and slower and should be generally avoided -- however it may be necessary to do. In these cases the executable may be compiled with the FILED_FAKE_CHROOT C preprocessor macro defined and instead of calling chroot() all HTTP requests will have the root suffix specified as the argument to the "-r" or "--root" option prepended to them. 6. MIME Types (MIMETYPES) For single-file convenience "filed" compiles the mapping of file extensions (the string in the filename following its last dot (".")) into the executable. This mapping comes from a file in the format of type1 type1_extension1 type1_extension2... type2 type2_extension1 type2_extension2... ... However it may not be desirable to include this mapping, or it may be desirable to use your own mapping rather than the default one. This can be done by specifying the MIMETYPES macro to "make". If no mapping is desired, "/dev/null" may be specified. Log Files --------- Because "filed" relies on chroot(2) and setuid(2), log files cannot reliably be re-opened. If you need log rotation then a second process, which can close and re-open log files, must be used. Any process may be used for writing logs but if the process does not support log rotation then it will not provide that benefit. For example, if you wish to write logs to syslogd(8) you can use logger(1), such as: # ./filed --root /www --user nobody --log '|logger -t filed' --daemon Troubleshooting --------------- 1. It won't compile, something about stdatomic.h not found or _Atomic not a valid type. => This is a bug in your compiler: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58016 GCC 4.7.x and 4.8.x define the macro indicating that they have C11 support and do not define the macro that C11 requires to indicate that C11 atomics are not available. They should define that macro. You can disable the features in "filed" that require C11 atomics by defining FILED_DONT_TIMEOUT in the Makefile.