[PATCH bpf-next 2/2] samples: bpf: get ifindex from ifname

[Matteo Croce]

Find the ifindex via ioctl(SIOCGIFINDEX) instead of requiring the
numeric ifindex.

Signed-off-by: Matteo Croce <mcr...@redhat.com>
---
 samples/bpf/xdp1_user.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/samples/bpf/xdp1_user.c b/samples/bpf/xdp1_user.c
index 4f3d824fc044..a1d0c5dcee9c 100644
--- a/samples/bpf/xdp1_user.c
+++ b/samples/bpf/xdp1_user.c
@@ -15,6 +15,9 @@
 #include <unistd.h>
 #include <libgen.h>
 #include <sys/resource.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <linux/if.h>
 
 #include "bpf_util.h"
 #include "bpf/bpf.h"
@@ -59,7 +62,7 @@ static void poll_stats(int map_fd, int interval)
 static void usage(const char *prog)
 {
        fprintf(stderr,
-               "usage: %s [OPTS] IFINDEX\n\n"
+               "usage: %s [OPTS] IFACE\n\n"
                "OPTS:\n"
                "    -S    use skb-mode\n"
                "    -N    enforce native mode\n",
@@ -74,9 +77,11 @@ int main(int argc, char **argv)
        };
        const char *optstr = "SN";
        int prog_fd, map_fd, opt;
+       struct ifreq ifr = { 0 };
        struct bpf_object *obj;
        struct bpf_map *map;
        char filename[256];
+       int sock;
 
        while ((opt = getopt(argc, argv, optstr)) != -1) {
                switch (opt) {
@@ -102,7 +107,24 @@ int main(int argc, char **argv)
                return 1;
        }
 
-       ifindex = strtoul(argv[optind], NULL, 0);
+       sock = socket(AF_UNIX, SOCK_DGRAM, 0);
+       if (sock == -1) {
+               perror("socket");
+               return 1;
+       }
+
+       if (strlen(argv[optind]) >= IFNAMSIZ) {
+               printf("invalid ifname '%s'\n", argv[optind]);
+               return 1;
+       }
+
+       strcpy(ifr.ifr_name, argv[optind]);
+       if (ioctl(sock, SIOCGIFINDEX, &ifr) < 0) {
+               perror("SIOCGIFINDEX");
+               return 1;
+       }
+       close(sock);
+       ifindex = ifr.ifr_ifindex;
 
        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
        prog_load_attr.file = filename;
-- 
2.19.1