dabba: print EINVAL if error code is NULL.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabba: made further assertion refactoring.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
test: move /sys/class/net query function to lib.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
test: reenable w/o dabbad test cases.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabba: do not overdo autoreconnect retries.

No need to retry too much/too long to get contact with dabbad.
On a unix domain socket, connection are very fast.
With TCP, a 300-ms round-trip time start to be high.

Reduced autoreconnect to 3 retries every 100ms.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>