In D28199#636696, @rew wrote:

bhyve/ipc: use SOCK_DGRAM

• use SOCK_DGRAM instead of SOCK_STREAM
• have bhyvectl(8) share ipc.h from bhyve(8)
• fix naming semantics of MAX_SNAPSHOT_VMNAME, now called MAX_SNAPSHOT_FILENAME.

Previously, snapshot.h and bhyvectl.c each had their own
#define MAX_VMNAME 100, this is now shared at vmmapi.h - the
value has also been changed to 89. It's a limitation for the
unix domain socket path as constrained by SUNPATHLEN (104).
The prefix for the socket path is BHYVE_RUN_DIR, which by default
is '/var/run/bhyve/' (15). 104-15 = 89.