HelenOS sources

ICMPV6_ECHO_REPLY   74 uspace/srv/net/inetsrv/icmpv6.c 	reply->type = ICMPV6_ECHO_REPLY;
ICMPV6_ECHO_REPLY  146 uspace/srv/net/inetsrv/icmpv6.c 	case ICMPV6_ECHO_REPLY:
HelenOS homepage, sources at GitHub