vubr_backend_recv_cb(int sock, void *ctx) { VubrDev *vubr = (VubrDev *) ctx; VuDev *dev = &vubr->vudev; VuVirtq *vq = vu_get_queue(dev, 0); VuVirtqElement *elem = NULL; struct iovec mhdr_sg[VIRTQUEUE_MAX_SIZE]; struct virtio_net_hdr_mrg_rxbuf mhdr; unsigned mhdr_cnt = 0; int hdrlen = vubr->hdrlen; int i = 0; struct virtio_net_hdr hdr = { .flags = 0, .gso_type = VIRTIO_NET_HDR_GSO_NONE }; DPRINT("\n\n *** IN UDP RECEIVE CALLBACK ***\n\n"); DPRINT(" hdrlen = %d\n", hdrlen); if (!vu_queue_enabled(dev, vq) || !vu_queue_started(dev, vq) || !vu_queue_avail_bytes(dev, vq, hdrlen, 0)) { DPRINT("Got UDP packet, but no available descriptors on RX virtq.\n"); return; } do { struct iovec *sg; ssize_t ret, total = 0; unsigned int num; elem = vu_queue_pop(dev, vq, sizeof(VuVirtqElement)); if (!elem) { break; } if (elem->in_num < 1) { fprintf(stderr, "virtio-net contains no in buffers\n"); break; } sg = elem->in_sg; num = elem->in_num; if (i == 0) { if (hdrlen == 12) { mhdr_cnt = iov_copy(mhdr_sg, ARRAY_SIZE(mhdr_sg), sg, elem->in_num, offsetof(typeof(mhdr), num_buffers), sizeof(mhdr.num_buffers)); } iov_from_buf(sg, elem->in_num, 0, &hdr, sizeof hdr); total += hdrlen; ret = iov_discard_front(&sg, &num, hdrlen); assert(ret == hdrlen); } struct msghdr msg = { .msg_name = (struct sockaddr *) &vubr->backend_udp_dest, .msg_namelen = sizeof(struct sockaddr_in), .msg_iov = sg, .msg_iovlen = elem->in_num, .msg_flags = MSG_DONTWAIT, }; do { ret = recvmsg(vubr->backend_udp_sock, &msg, 0); } while (ret == -1 && (errno == EINTR)); if (i == 0) { iov_restore_front(elem->in_sg, sg, hdrlen); } if (ret == -1) { if (errno == EWOULDBLOCK) { vu_queue_rewind(dev, vq, 1); break; } vubr_die("recvmsg()"); } total += ret; iov_truncate(elem->in_sg, elem->in_num, total); vu_queue_fill(dev, vq, elem, total, i++); free(elem); elem = NULL; } while (false); /* could loop if DONTWAIT worked? */ if (mhdr_cnt) { mhdr.num_buffers = i; iov_from_buf(mhdr_sg, mhdr_cnt, 0, &mhdr.num_buffers, sizeof mhdr.num_buffers); } vu_queue_flush(dev, vq, i); vu_queue_notify(dev, vq); free(elem); }