tun2socks: fix an unlikely integer overflow, and some cosmetic changes
tun2socks: fix an unlikely integer overflow, and some cosmetic changes

DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn,DavidCox1979/badvpn