conn_read
.bread = conn_read,
static int conn_read(BIO *h, char *buf, int size);
conn->bev = bufferevent_new(afd, conn_read, conn_write,
void conn_read(struct bufferevent *bev, void *data);
switch(conn_read(notify_pipe)){
ret = conn_read(tcp);
int conn_read(struct xfrd_tcp* conn);