[PATCH] nbft: use the correct interfaces for NBFT connections

[Stuart Hayes]

The NBFT specifies which network interface should be used to connect to
each namespace (using the HFI descriptor), but that is currently ignored
when "nvme connect-all --nbft" is used. If there are namespaces on
different interfaces, some namespaces can fail to connect, unless the IP
tables were already set up to route these in the desired way when the
interface isn't specified.

Add a bit of logic to look at the HFI descriptors in the NBFT and find the
network interface to use when connecting each namespace.

Signed-off-by: Stuart Hayes <stuart.w.hayes at gmail.com>
---
 libnvme/src/nvme/fabrics.c | 91 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 89 insertions(+), 2 deletions(-)

diff --git a/libnvme/src/nvme/fabrics.c b/libnvme/src/nvme/fabrics.c
index 326287ec6..92ae498da 100644
--- a/libnvme/src/nvme/fabrics.c
+++ b/libnvme/src/nvme/fabrics.c
@@ -11,6 +11,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <fnmatch.h>
+#include <ifaddrs.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <stdbool.h>
@@ -21,7 +22,9 @@
 #include <unistd.h>
 
 #include <arpa/inet.h>
+#include <linux/if_ether.h>
 #include <net/if.h>
+#include <netpacket/packet.h>
 #include <netdb.h>
 #include <sys/param.h>
 #include <sys/stat.h>
@@ -2820,6 +2823,76 @@ static int nbft_discovery(struct libnvme_global_ctx *ctx,
 	return 0;
 }
 
+#define VLAN_PROC_PATH "/proc/net/vlan"
+
+/*
+ * Return 0 for no vlan_id, to be consistent with the NBFT spec.
+ */
+static int get_vlan_id(const char *ifname)
+{
+	char path[256], line[256];
+	int vlan_id = 0;
+	FILE *f;
+
+	snprintf(path, sizeof(path), "%s/%s", VLAN_PROC_PATH, ifname);
+	f = fopen(path, "r");
+	if (!f)
+		return 0;
+
+	while (fgets(line, sizeof(line), f)) {
+		if (sscanf(line, " VID: %d", &vlan_id) == 1) {
+			fclose(f);
+			return vlan_id;
+		}
+	}
+
+	fclose(f);
+	return 0;
+}
+
+/*
+ * Find network interface corresponding to the NBFT HFI
+ * by looking for mac address and vlan id.
+ */
+static char *nbft_find_hfi_iface(struct libnbft_hfi *hfi)
+{
+	struct ifaddrs *ifaddr, *ifa;
+	char *result = NULL;
+
+	if (strcmp((char *)hfi->transport, "tcp"))
+		return NULL;
+
+	if (getifaddrs(&ifaddr) != 0)
+		return NULL;
+
+	for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
+		struct sockaddr_ll *sll;
+
+		if (!ifa->ifa_addr)
+			continue;
+
+		if (ifa->ifa_addr->sa_family != AF_PACKET)
+			continue;
+
+		sll = (struct sockaddr_ll *)ifa->ifa_addr;
+
+		if (sll->sll_halen != ETH_ALEN)
+			continue;
+
+		if (!memcmp(sll->sll_addr, hfi->tcp_info.mac_addr, ETH_ALEN)) {
+			int vlan_id = get_vlan_id(ifa->ifa_name);
+
+			if (vlan_id == hfi->tcp_info.vlan) {
+				result = strdup(ifa->ifa_name);
+				break;
+			}
+		}
+	}
+
+	freeifaddrs(ifaddr);
+	return result;
+}
+
 __public int libnvmf_discovery_nbft(struct libnvme_global_ctx *ctx,
 		struct libnvmf_context *fctx, bool connect, char *nbft_path)
 {
@@ -2905,7 +2978,11 @@ __public int libnvmf_discovery_nbft(struct libnvme_global_ctx *ctx,
 				nfctx.transport = (*ss)->transport;
 				nfctx.traddr = (*ss)->traddr;
 				nfctx.trsvcid = (*ss)->trsvcid;
-				nfctx.host_iface = NULL;
+				nfctx.host_iface = nbft_find_hfi_iface(hfi);
+				if (!nfctx.host_iface)
+					libnvme_msg(ctx, LIBNVME_LOG_INFO,
+						"SSNS %d: could not find host interface for HFI %d\n",
+						(*ss)->index, hfi->index);
 
 				rr = nbft_connect(ctx, &nfctx, h, NULL, *ss);
 
@@ -2929,6 +3006,9 @@ __public int libnvmf_discovery_nbft(struct libnvme_global_ctx *ctx,
 							host_traddr);
 				}
 
+				if (nfctx.host_iface)
+					free((char *)nfctx.host_iface);
+
 				if (rr) {
 					libnvme_msg(ctx, LIBNVME_LOG_ERR,
 						"SSNS %d: no controller found\n",
@@ -2993,7 +3073,11 @@ __public int libnvmf_discovery_nbft(struct libnvme_global_ctx *ctx,
 			nfctx.traddr = uri->host;
 			nfctx.trsvcid = trsvcid;
 			nfctx.host_traddr = host_traddr;
-			nfctx.host_iface = NULL;
+			nfctx.host_iface = nbft_find_hfi_iface(hfi);
+			if (!nfctx.host_iface)
+				libnvme_msg(ctx, LIBNVME_LOG_INFO,
+					"SSNS %d: could not find host interface for HFI %d\n",
+					(*ss)->index, hfi->index);
 
 			/* Lookup existing discovery controller */
 			c = lookup_ctrl(h, &nfctx);
@@ -3013,6 +3097,9 @@ __public int libnvmf_discovery_nbft(struct libnvme_global_ctx *ctx,
 			} else
 				ret = 0;
 
+			if (nfctx.host_iface)
+				free((char *)nfctx.host_iface);
+
 			if (ret) {
 				libnvme_msg(ctx, LIBNVME_LOG_ERR,
 					"Discovery Descriptor %d: failed to add discovery controller: %s\n",
-- 
2.51.0