Are the laws that limit the proximity of a protest constitutional?

They have held up so far. For example, a number of state laws that tried to ban protests like that -wipe Fred Phelps and his "God" Hates Fags gang from the Westboro Babtist "Church" in Kansas have been overturned. Laws that limited their protests to no closer than a few hundred feet from the funeral or graveside service seem to be holding up.