nl80211: Implement netlink extended ACK support

Implement netlink extended ACK support to print out the error
message (if any).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 39a02d3ee51f4620d27276b7ecce7c1d566cd5ea..b26894f8316c2dc984d280733618e26691be3aa7 100644 (file)
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -40,6 +40,29 @@
 #include "driver_nl80211.h"
 
 
+/* support for extack if compilation headers are too old */
+#ifndef NETLINK_EXT_ACK
+#define NETLINK_EXT_ACK 11
+enum nlmsgerr_attrs {
+       NLMSGERR_ATTR_UNUSED,
+       NLMSGERR_ATTR_MSG,
+       NLMSGERR_ATTR_OFFS,
+       NLMSGERR_ATTR_COOKIE,
+
+       __NLMSGERR_ATTR_MAX,
+       NLMSGERR_ATTR_MAX = __NLMSGERR_ATTR_MAX - 1
+};
+#endif
+#ifndef NLM_F_CAPPED
+#define NLM_F_CAPPED 0x100
+#endif
+#ifndef NLM_F_ACK_TLVS
+#define NLM_F_ACK_TLVS 0x200
+#endif
+#ifndef SOL_NETLINK
+#define SOL_NETLINK 270
+#endif
+
 #ifndef CONFIG_LIBNL20
 /*
  * libnl 1.1 has a bug, it tries to allocate socket numbers densely
@@ -302,8 +325,35 @@ static int finish_handler(struct nl_msg *msg, void *arg)
 static int error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err,
                         void *arg)
 {
+       struct nlmsghdr *nlh = (struct nlmsghdr *) err - 1;
+       int len = nlh->nlmsg_len;
+       struct nlattr *attrs;
+       struct nlattr *tb[NLMSGERR_ATTR_MAX + 1];
        int *ret = arg;
+       int ack_len = sizeof(*nlh) + sizeof(int) + sizeof(*nlh);
+
        *ret = err->error;
+
+       if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
+               return NL_SKIP;
+
+       if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
+               ack_len += err->msg.nlmsg_len - sizeof(*nlh);
+
+       if (len <= ack_len)
+               return NL_STOP;
+
+       attrs = (void *) ((unsigned char *) nlh + ack_len);
+       len -= ack_len;
+
+       nla_parse(tb, NLMSGERR_ATTR_MAX, attrs, len, NULL);
+       if (tb[NLMSGERR_ATTR_MSG]) {
+               len = strnlen((char *) nla_data(tb[NLMSGERR_ATTR_MSG]),
+                             nla_len(tb[NLMSGERR_ATTR_MSG]));
+               wpa_printf(MSG_ERROR, "nl80211: kernel reports: %*s",
+                          len, (char *) nla_data(tb[NLMSGERR_ATTR_MSG]));
+       }
+
        return NL_SKIP;
 }
 
@@ -342,7 +392,7 @@ static int send_and_recv(struct nl80211_global *global,
                         void *valid_data)
 {
        struct nl_cb *cb;
-       int err = -ENOMEM;
+       int err = -ENOMEM, opt;
 
        if (!msg)
                return -ENOMEM;
@@ -351,6 +401,11 @@ static int send_and_recv(struct nl80211_global *global,
        if (!cb)
                goto out;
 
+       /* try to set NETLINK_EXT_ACK to 1, ignoring errors */
+       opt = 1;
+       setsockopt(nl_socket_get_fd(nl_handle), SOL_NETLINK,
+                  NETLINK_EXT_ACK, &opt, sizeof(opt));
+
        err = nl_send_auto_complete(nl_handle, msg);
        if (err < 0)
                goto out;