conn_write
.bwrite = conn_write,
ret = conn_write(bp, str, n);
static int conn_write(BIO *h, const char *buf, int num);
conn->bev = bufferevent_new(afd, conn_read, conn_write,
void conn_write(struct bufferevent *bev, void *data);
ret = conn_write(tcp);
ret = conn_write(tcp);
int conn_write(struct xfrd_tcp* conn);