Fixes an issue encountered by mlarkin@ where the auth process was working with an empty list of repositories and kept saying it could not find a repository which was obviously listed in gotd.conf. Now we can see errors from fopen() in the logs instead. Old code was copied from gotwebd where the config file is optional.

In preparation for wide sha256 support; stsp@ agrees. Change done mechanically with find . -iname \*.[cy] -exec sam {} + X ,x/<sha1\.h>/i/\n#include <sha2.h>

It's handy to have a "bad unix socket path" error being reported directly from the main process since can get caught by `gotd -n'. ok jamsek stsp

ok jamsek stsp

This ensures that all repositories exist when the process is first started. It will also help to avoid an "rpath" pledge promise in a future gotd which uses a separate session process, by avoiding realpath() calls while starting new processes.

ok op@

Repository access is now controlled by access rules in gotd.conf, and concurrent connections to the gotd socket by local users are limited by the listen process. We should keep refining our anti-DoS measures in the future, but at least we have something in place now. ok jamsek, op

no need to duplicate what strtonum does; pass the *real* maximum value allowed to it directly. ok stsp@

This allows to use a suffix to indicate the unit of measure, such as "1h" for one hour or "30m" for 30 minutes. The suffix "s" for seconds is also accepted for completeness. ok stsp

spotted by + ok op@

different yacc implementations (e.g. GNU bison) may put the various parts in a different order, and so the definition of the function may not be visible in the generated code.

Allow administrators to tweak the default authentication and request timeouts if needed, and to tweak the limit of concurrent connections for specific user accounts. with several tweaks from and ok op@