Fix doxygen output (#940)

Several fields were missing descriptions in the generated docs.
This PR fixes the docs to actually show the relevant descriptions.

Signed-off-by: Dave Thaler <dthaler@microsoft.com>

Co-authored-by: Alan Jowett <alanjo@microsoft.com>

include/ebpf_nethooks.h

@@ -123,22 +123,27 @@ typedef struct bpf_sock_addr
     uint32_t family; ///< IP address family.
     struct
     {
+        /**
+         * @brief Source IP address in network byte order.
+         * Local for ingress, remote for egress.
+         */
         union
         {
             uint32_t msg_src_ip4;
             uint32_t msg_src_ip6[4];
-        };                     ///< Source IP address in network byte order.
-                               ///< Local for ingress, remote for egress.
+        };
         uint16_t msg_src_port; ///< Source port in network byte order.
     };
     struct
     {
+        /* @brief Destination IP address in network byte order.
+         * Local for egress, remote for ingress.
+         */
         union
         {
             uint32_t user_ip4;
             uint32_t user_ip6[4];
-        };                  ///< Destination IP address in network byte order.
-                            ///< Local for egress, remote for ingress.
+        };
         uint16_t user_port; ///< Destination port in network byte order.
     };
     uint32_t protocol;       ///< IP protocol.

include/ebpf_result.h

@@ -92,19 +92,19 @@ extern "C"
         /// The enumeration found no more keys.
         EBPF_NO_MORE_KEYS, // = 25
 
-        // The requested key is already present.
+        /// The requested key is already present.
         EBPF_KEY_ALREADY_EXISTS,
 
         /// Caller has reached tail call limit.
         EBPF_NO_MORE_TAIL_CALLS,
 
-        // Requested action is still pending.
+        /// Requested action is still pending.
         EBPF_PENDING,
 
-        // The container can not hold additional elements.
+        /// The container can not hold additional elements.
         EBPF_OUT_OF_SPACE,
 
-        // Operation was canceled.
+        /// Operation was canceled.
         EBPF_CANCELED, // = 30
     } ebpf_result_t;
 

include/linux/bpf.h

@@ -71,8 +71,12 @@ typedef struct
 {
     uint32_t bpf_fd;   ///< File descriptor referring to an eBPF object.
     uint64_t info;     ///< Pointer to memory in which to write the info obtained.
-    uint32_t info_len; ///< On input, contains the maximum number of bytes to write into the info. On output, contains
-                       ///< the actual number of bytes written.
+
+    /**
+     * @brief On input, contains the maximum number of bytes to write into the info. On output, contains
+     * the actual number of bytes written.
+     */
+    uint32_t info_len;
 } bpf_obj_info_attr_t;
 
 /// Attributes used by BPF_LINK_DETACH.