selftests: Fix get_ifidx and callers in nettest.c

Dan reported:

    The patch acda655fefae: "selftests: Add nettest" from Aug 1, 2019,
    leads to the following static checker warning:

            ./tools/testing/selftests/net/nettest.c:1690 main()
            warn: unsigned 'tmp' is never less than zero.

    ./tools/testing/selftests/net/nettest.c
      1680                  case '1':
      1681                          args.has_expected_raddr = 1;
      1682                          if (convert_addr(&args, optarg,
      1683                                           ADDR_TYPE_EXPECTED_REMOTE))
      1684                                  return 1;
      1685
      1686                          break;
      1687                  case '2':
      1688                          if (str_to_uint(optarg, 0, 0x7ffffff, &tmp) != 0) {
      1689                                  tmp = get_ifidx(optarg);
      1690                                  if (tmp < 0) {

    "tmp" is unsigned so it can't be negative.  Also all the callers assume
    that get_ifidx() returns negatives on error but it looks like it really
    returns zero on error so it's a bit unclear to me.

Update get_ifidx to return -1 on errors and cleanup callers of it.

Fixes: acda655fefae ("selftests: Add nettest")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/testing/selftests/net/nettest.c b/tools/testing/selftests/net/nettest.c
index 83515e5ea4dcc62f101a982213c30e69aeff4461..c08f4db8330d0e83cb4f856b399a99508c5068e3 100644 (file)
--- a/tools/testing/selftests/net/nettest.c
+++ b/tools/testing/selftests/net/nettest.c
@@ -266,7 +266,7 @@ static int get_ifidx(const char *ifname)
        int sd, rc;
 
        if (!ifname || *ifname == '\0')
-               return 0;
+               return -1;
 
        memset(&ifdata, 0, sizeof(ifdata));
 
@@ -275,14 +275,14 @@ static int get_ifidx(const char *ifname)
        sd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
        if (sd < 0) {
                log_err_errno("socket failed");
-               return 0;
+               return -1;
        }
 
        rc = ioctl(sd, SIOCGIFINDEX, (char *)&ifdata);
        close(sd);
        if (rc != 0) {
                log_err_errno("ioctl(SIOCGIFINDEX) failed");
-               return 0;
+               return -1;
        }
 
        return ifdata.ifr_ifindex;
@@ -419,20 +419,20 @@ static int set_multicast_if(int sd, int ifindex)
        return rc;
 }
 
-static int set_membership(int sd, uint32_t grp, uint32_t addr, const char *dev)
+static int set_membership(int sd, uint32_t grp, uint32_t addr, int ifindex)
 {
        uint32_t if_addr = addr;
        struct ip_mreqn mreq;
        int rc;
 
-       if (addr == htonl(INADDR_ANY) && !dev) {
+       if (addr == htonl(INADDR_ANY) && !ifindex) {
                log_error("Either local address or device needs to be given for multicast membership\n");
                return -1;
        }
 
        mreq.imr_multiaddr.s_addr = grp;
        mreq.imr_address.s_addr = if_addr;
-       mreq.imr_ifindex = dev ? get_ifidx(dev) : 0;
+       mreq.imr_ifindex = ifindex;
 
        rc = setsockopt(sd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
        if (rc < 0) {
@@ -1048,7 +1048,7 @@ static int msock_init(struct sock_args *args, int server)
 
        if (server &&
            set_membership(sd, args->grp.s_addr,
-                          args->local_addr.in.s_addr, args->dev))
+                          args->local_addr.in.s_addr, args->ifindex))
                goto out_err;
 
        return sd;
@@ -1685,15 +1685,16 @@ int main(int argc, char *argv[])
 
                        break;
                case '2':
-                       if (str_to_uint(optarg, 0, 0x7ffffff, &tmp) != 0) {
-                               tmp = get_ifidx(optarg);
-                               if (tmp < 0) {
+                       if (str_to_uint(optarg, 0, INT_MAX, &tmp) == 0) {
+                               args.expected_ifindex = (int)tmp;
+                       } else {
+                               args.expected_ifindex = get_ifidx(optarg);
+                               if (args.expected_ifindex < 0) {
                                        fprintf(stderr,
-                                               "Invalid device index\n");
+                                               "Invalid expected device\n");
                                        return 1;
                                }
                        }
-                       args.expected_ifindex = (int)tmp;
                        break;
                case 'q':
                        quiet = 1;