uhd-dpdk: Add ARP responder, set MTU, and clean up API

Set MTU of Ethernet ports:
Some NICs (like the Mellanox ones) require this to work.

Add ARP responder to uhd-dpdk.

Clean up pending ARP request list when done:
Threads waiting for an ARP request to complete would be woken up when
the request completed, but they wouldn't get removed from the list of
pending requests. This fixes the issue.

1 files changed, 52 insertions, 1 deletions

diff --git a/host/lib/transport/uhd-dpdk/uhd_dpdk_driver.c b/host/lib/transport/uhd-dpdk/uhd_dpdk_driver.c
index 0af9cc4e5..8388359e7 100644
--- a/host/lib/transport/uhd-dpdk/uhd_dpdk_driver.c
+++ b/host/lib/transport/uhd-dpdk/uhd_dpdk_driver.c
@@ -11,11 +11,53 @@
 #include <arpa/inet.h>
 #include <unistd.h>
 
+int _uhd_dpdk_arp_reply(struct uhd_dpdk_port *port, struct arp_hdr *arp_req)
+{
+    struct rte_mbuf *mbuf;
+    struct ether_hdr *hdr;
+    struct arp_hdr *arp_frame;
+
+    mbuf = rte_pktmbuf_alloc(port->parent->tx_pktbuf_pool);
+    if (unlikely(mbuf == NULL)) {
+        RTE_LOG(WARNING, MEMPOOL, "Could not allocate packet buffer for ARP response\n");
+        return -ENOMEM;
+    }
+
+    hdr = rte_pktmbuf_mtod(mbuf, struct ether_hdr *);
+    arp_frame = (struct arp_hdr *) &hdr[1];
+
+    ether_addr_copy(&arp_req->arp_data.arp_sha, &hdr->d_addr);
+    ether_addr_copy(&port->mac_addr, &hdr->s_addr);
+    hdr->ether_type = rte_cpu_to_be_16(ETHER_TYPE_ARP);
+
+    arp_frame->arp_hrd = rte_cpu_to_be_16(ARP_HRD_ETHER);
+    arp_frame->arp_pro = rte_cpu_to_be_16(ETHER_TYPE_IPv4);
+    arp_frame->arp_hln = 6;
+    arp_frame->arp_pln = 4;
+    arp_frame->arp_op  = rte_cpu_to_be_16(ARP_OP_REPLY);
+    ether_addr_copy(&port->mac_addr, &arp_frame->arp_data.arp_sha);
+    arp_frame->arp_data.arp_sip = port->ipv4_addr;
+    ether_addr_copy(&hdr->d_addr, &arp_frame->arp_data.arp_tha);
+    arp_frame->arp_data.arp_tip = arp_req->arp_data.arp_sip;
+
+    mbuf->pkt_len = 42;
+    mbuf->data_len = 42;
+    mbuf->ol_flags = PKT_TX_IP_CKSUM;
+
+    if (rte_eth_tx_burst(port->id, 0, &mbuf, 1) != 1) {
+        RTE_LOG(WARNING, RING, "%s: TX descriptor ring is full\n", __func__);
+        rte_pktmbuf_free(mbuf);
+        return -EAGAIN;
+    }
+    return 0;
+}
+
 int _uhd_dpdk_process_arp(struct uhd_dpdk_port *port, struct arp_hdr *arp_frame)
 {
     uint32_t dest_ip = arp_frame->arp_data.arp_sip;
     struct ether_addr dest_addr = arp_frame->arp_data.arp_sha;
 
+    /* Add entry to ARP table */
     struct uhd_dpdk_arp_entry *entry = NULL;
     rte_hash_lookup_data(port->arp_table, &dest_ip, (void **) &entry);
     if (!entry) {
@@ -36,11 +78,21 @@ int _uhd_dpdk_process_arp(struct uhd_dpdk_port *port, struct arp_hdr *arp_frame)
         LIST_FOREACH(req, &entry->pending_list, entry) {
             _uhd_dpdk_config_req_compl(req, 0);
         }
+        while (entry->pending_list.lh_first != NULL) {
+            LIST_REMOVE(entry->pending_list.lh_first, entry);
+        }
+    }
+
+    /* Respond if this was an ARP request */
+    if (arp_frame->arp_op == rte_cpu_to_be_16(ARP_OP_REQUEST) &&
+        arp_frame->arp_data.arp_tip == port->ipv4_addr) {
+        _uhd_dpdk_arp_reply(port, arp_frame);
     }
 
     return 0;
 }
 
+/* Send ARP request */
 int _uhd_dpdk_arp_request(struct uhd_dpdk_port *port, uint32_t ip)
 {
     struct rte_mbuf *mbuf;
@@ -82,7 +134,6 @@ int _uhd_dpdk_arp_request(struct uhd_dpdk_port *port, uint32_t ip)
     return 0;
 }
 
-
 int _uhd_dpdk_process_udp(struct uhd_dpdk_port *port, struct rte_mbuf *mbuf, struct udp_hdr *pkt)
 {
     int status = 0;