This repo contains experimental code porting some simple C server code from Beej's Guide to Network Programming to Fortran.

It should work on OSX, and hopefully, eventually, other platforms as well.

I'm learning Fortran, and this seemed like an interesting challenge. I don't think any sane person would ever want to actually try to write a production web service in Fortran.

Run make to compile, then ./server. This will bind to port 3491, send "hello world" to clients that connect, with nc localhost 3491 for example, and print the connecting IP address.

The makefile passes the -g flag to compilers for debugging aid.

It uses some modern Fortran 2003 features, like c_f_pointer and c_loc, as well as some utility methods from Joseph Krahn's c_interface_module.

Some functionality is still currently implemented in C, e.g.:

• errno is a macro on OSX, so we can't just create a Fortran interface for it
• haven't got around to implementing the signal handling in Fortran, mostly because I don't understand enough about how it works, or how to verify it is working as intended.

• posix.f90 isn't really properly named, since not all of the interfaces in there are strictly POSIX, I think, and some of the BSD/XNU stuff isn't strictly POSIX compliant.
• More of the code could probably be moved out of server.c into server.f90.
• man 3 getaddrinfo, and other documentation, describe addrinfo structs as having ai_canonname after ai_addr but inspection in LLDB shows it coming before, and that layout is the only way to get this code to work.
• the Fortran code that prepares the call to inet_ntop has to use some ugly workarounds for the fact that calling c_loc on nested derived types is not fully c-interoperable. Also, this code is probably broken for ipv6.