You could check if the file/archive is corrupted with the utility
file(1)
Code:
$ file /home/packages/rsync-3.0.7.tgz
/home/packages/rsync-3.0.7.tgz: gzip compressed data, from Unix
Then do a verbose test with
tar(1)
Code:
$ tar tvzf xxxxxx.tgz
Alternatively you could set the PKG_PATH variable to a ftp mirror so you can just use
pkg_add package_name
Code:
PKG_PATH=ftp://ftp.eu.openbsd.org/pub/OpenBSD/49/packages/i386/
export PKG_PATH