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+/*
+ * lib/handlers.c default netlink message handlers
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * Copyright (c) 2003-2006 Thomas Graf <tgraf@suug.ch>
+ */
+
+/**
+ * @ingroup nl
+ * @defgroup cb Callbacks/Customization
+ * @brief
+ *
+ * Callbacks and overwriting capabilities are provided to take influence
+ * in various control flows inside the library. All callbacks are packed
+ * together in struct nl_cb which is then attached to a netlink socket or
+ * passed on to the respective functions directly.
+ *
+ * Callbacks can control the flow of the underlying layer by returning
+ * the appropriate error codes:
+ * @code
+ * Action ID | Description
+ * -----------------+-------------------------------------------------------
+ * NL_OK | Proceed with whatever comes next.
+ * NL_SKIP | Skip message currently being processed and continue
+ * | with next message.
+ * NL_STOP | Stop parsing and discard all remaining messages in
+ * | this set of messages.
+ * @endcode
+ *
+ * All callbacks are optional and a default action is performed if no
+ * application specific implementation is provided:
+ *
+ * @code
+ * Callback ID | Default Return Value
+ * ------------------+----------------------
+ * NL_CB_VALID | NL_OK
+ * NL_CB_FINISH | NL_STOP
+ * NL_CB_OVERRUN | NL_STOP
+ * NL_CB_SKIPPED | NL_SKIP
+ * NL_CB_ACK | NL_STOP
+ * NL_CB_MSG_IN | NL_OK
+ * NL_CB_MSG_OUT | NL_OK
+ * NL_CB_INVALID | NL_STOP
+ * NL_CB_SEQ_CHECK | NL_OK
+ * NL_CB_SEND_ACK | NL_OK
+ * |
+ * Error Callback | NL_STOP
+ * @endcode
+ *
+ * In order to simplify typical usages of the library, different sets of
+ * default callback implementations exist:
+ * @code
+ * NL_CB_DEFAULT: No additional actions
+ * NL_CB_VERBOSE: Automatically print warning and error messages to a file
+ * descriptor as appropriate. This is useful for CLI based
+ * applications.
+ * NL_CB_DEBUG: Print informal debugging information for each message
+ * received. This will result in every message beint sent or
+ * received to be printed to the screen in a decoded,
+ * human-readable format.
+ * @endcode
+ *
+ * @par 1) Setting up a callback set
+ * @code
+ * // Allocate a callback set and initialize it to the verbose default set
+ * struct nl_cb *cb = nl_cb_alloc(NL_CB_VERBOSE);
+ *
+ * // Modify the set to call my_func() for all valid messages
+ * nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, my_func, NULL);
+ *
+ * // Set the error message handler to the verbose default implementation
+ * // and direct it to print all errors to the given file descriptor.
+ * FILE *file = fopen(...);
+ * nl_cb_err(cb, NL_CB_VERBOSE, NULL, file);
+ * @endcode
+ * @{
+ */
+
+#include <netlink-local.h>
+#include <netlink/netlink.h>
+#include <netlink/utils.h>
+#include <netlink/msg.h>
+#include <netlink/handlers.h>
+
+static void print_header_content(FILE *ofd, struct nlmsghdr *n)
+{
+ char flags[128];
+ char type[32];
+
+ fprintf(ofd, "type=%s length=%u flags=<%s> sequence-nr=%u pid=%u",
+ nl_nlmsgtype2str(n->nlmsg_type, type, sizeof(type)),
+ n->nlmsg_len, nl_nlmsg_flags2str(n->nlmsg_flags, flags,
+ sizeof(flags)), n->nlmsg_seq, n->nlmsg_pid);
+}
+
+static int nl_valid_handler_verbose(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stdout;
+
+ fprintf(ofd, "-- Warning: unhandled valid message: ");
+ print_header_content(ofd, nlmsg_hdr(msg));
+ fprintf(ofd, "\n");
+
+ return NL_OK;
+}
+
+static int nl_invalid_handler_verbose(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Error: Invalid message: ");
+ print_header_content(ofd, nlmsg_hdr(msg));
+ fprintf(ofd, "\n");
+
+ return NL_STOP;
+}
+
+static int nl_overrun_handler_verbose(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Error: Netlink Overrun: ");
+ print_header_content(ofd, nlmsg_hdr(msg));
+ fprintf(ofd, "\n");
+
+ return NL_STOP;
+}
+
+static int nl_error_handler_verbose(struct sockaddr_nl *who,
+ struct nlmsgerr *e, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Error received: %s\n-- Original message: ",
+ strerror(-e->error));
+ print_header_content(ofd, &e->msg);
+ fprintf(ofd, "\n");
+
+ return e->error;
+}
+
+static int nl_valid_handler_debug(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Debug: Unhandled Valid message: ");
+ print_header_content(ofd, nlmsg_hdr(msg));
+ fprintf(ofd, "\n");
+
+ return NL_OK;
+}
+
+static int nl_finish_handler_debug(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Debug: End of multipart message block: ");
+ print_header_content(ofd, nlmsg_hdr(msg));
+ fprintf(ofd, "\n");
+
+ return NL_STOP;
+}
+
+static int nl_msg_in_handler_debug(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Debug: Received Message:\n");
+ nl_msg_dump(msg, ofd);
+
+ return NL_OK;
+}
+
+static int nl_msg_out_handler_debug(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Debug: Sent Message:\n");
+ nl_msg_dump(msg, ofd);
+
+ return NL_OK;
+}
+
+static int nl_skipped_handler_debug(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Debug: Skipped message: ");
+ print_header_content(ofd, nlmsg_hdr(msg));
+ fprintf(ofd, "\n");
+
+ return NL_SKIP;
+}
+
+static int nl_ack_handler_debug(struct nl_msg *msg, void *arg)
+{
+ FILE *ofd = arg ? arg : stderr;
+
+ fprintf(ofd, "-- Debug: ACK: ");
+ print_header_content(ofd, nlmsg_hdr(msg));
+ fprintf(ofd, "\n");
+
+ return NL_STOP;
+}
+
+static nl_recvmsg_msg_cb_t cb_def[NL_CB_TYPE_MAX+1][NL_CB_KIND_MAX+1] = {
+ [NL_CB_VALID] = {
+ [NL_CB_VERBOSE] = nl_valid_handler_verbose,
+ [NL_CB_DEBUG] = nl_valid_handler_debug,
+ },
+ [NL_CB_FINISH] = {
+ [NL_CB_DEBUG] = nl_finish_handler_debug,
+ },
+ [NL_CB_INVALID] = {
+ [NL_CB_VERBOSE] = nl_invalid_handler_verbose,
+ [NL_CB_DEBUG] = nl_invalid_handler_verbose,
+ },
+ [NL_CB_MSG_IN] = {
+ [NL_CB_DEBUG] = nl_msg_in_handler_debug,
+ },
+ [NL_CB_MSG_OUT] = {
+ [NL_CB_DEBUG] = nl_msg_out_handler_debug,
+ },
+ [NL_CB_OVERRUN] = {
+ [NL_CB_VERBOSE] = nl_overrun_handler_verbose,
+ [NL_CB_DEBUG] = nl_overrun_handler_verbose,
+ },
+ [NL_CB_SKIPPED] = {
+ [NL_CB_DEBUG] = nl_skipped_handler_debug,
+ },
+ [NL_CB_ACK] = {
+ [NL_CB_DEBUG] = nl_ack_handler_debug,
+ },
+};
+
+static nl_recvmsg_err_cb_t cb_err_def[NL_CB_KIND_MAX+1] = {
+ [NL_CB_VERBOSE] = nl_error_handler_verbose,
+ [NL_CB_DEBUG] = nl_error_handler_verbose,
+};
+
+/**
+ * @name Callback Handle Management
+ * @{
+ */
+
+/**
+ * Allocate a new callback handle
+ * @arg kind callback kind to be used for initialization
+ * @return Newly allocated callback handle or NULL
+ */
+struct nl_cb *nl_cb_alloc(enum nl_cb_kind kind)
+{
+ int i;
+ struct nl_cb *cb;
+
+ if (kind < 0 || kind > NL_CB_KIND_MAX)
+ return NULL;
+
+ cb = calloc(1, sizeof(*cb));
+ if (!cb) {
+ nl_errno(ENOMEM);
+ return NULL;
+ }
+
+ cb->cb_refcnt = 1;
+
+ for (i = 0; i <= NL_CB_TYPE_MAX; i++)
+ nl_cb_set(cb, i, kind, NULL, NULL);
+
+ nl_cb_err(cb, kind, NULL, NULL);
+
+ return cb;
+}
+
+/**
+ * Clone an existing callback handle
+ * @arg orig original callback handle
+ * @return Newly allocated callback handle being a duplicate of
+ * orig or NULL
+ */
+struct nl_cb *nl_cb_clone(struct nl_cb *orig)
+{
+ struct nl_cb *cb;
+
+ cb = nl_cb_alloc(NL_CB_DEFAULT);
+ if (!cb)
+ return NULL;
+
+ memcpy(cb, orig, sizeof(*orig));
+ cb->cb_refcnt = 1;
+
+ return cb;
+}
+
+struct nl_cb *nl_cb_get(struct nl_cb *cb)
+{
+ cb->cb_refcnt++;
+
+ return cb;
+}
+
+void nl_cb_put(struct nl_cb *cb)
+{
+ if (!cb)
+ return;
+
+ cb->cb_refcnt--;
+
+ if (cb->cb_refcnt < 0)
+ BUG();
+
+ if (cb->cb_refcnt <= 0)
+ free(cb);
+}
+
+/** @} */
+
+/**
+ * @name Callback Setup
+ * @{
+ */
+
+/**
+ * Set up a callback
+ * @arg cb callback set
+ * @arg type callback to modify
+ * @arg kind kind of implementation
+ * @arg func callback function (NL_CB_CUSTOM)
+ * @arg arg argument passed to callback
+ *
+ * @return 0 on success or a negative error code
+ */
+int nl_cb_set(struct nl_cb *cb, enum nl_cb_type type, enum nl_cb_kind kind,
+ nl_recvmsg_msg_cb_t func, void *arg)
+{
+ if (type < 0 || type > NL_CB_TYPE_MAX)
+ return nl_error(ERANGE, "Callback type out of range");
+
+ if (kind < 0 || kind > NL_CB_KIND_MAX)
+ return nl_error(ERANGE, "Callback kind out of range");
+
+ if (kind == NL_CB_CUSTOM) {
+ cb->cb_set[type] = func;
+ cb->cb_args[type] = arg;
+ } else {
+ cb->cb_set[type] = cb_def[type][kind];
+ cb->cb_args[type] = arg;
+ }
+
+ return 0;
+}
+
+/**
+ * Set up a all callbacks
+ * @arg cb callback set
+ * @arg kind kind of callback
+ * @arg func callback function
+ * @arg arg argument to be passwd to callback function
+ *
+ * @return 0 on success or a negative error code
+ */
+int nl_cb_set_all(struct nl_cb *cb, enum nl_cb_kind kind,
+ nl_recvmsg_msg_cb_t func, void *arg)
+{
+ int i, err;
+
+ for (i = 0; i <= NL_CB_TYPE_MAX; i++) {
+ err = nl_cb_set(cb, i, kind, func, arg);
+ if (err < 0)
+ return err;
+ }
+
+ return 0;
+}
+
+/**
+ * Set up an error callback
+ * @arg cb callback set
+ * @arg kind kind of callback
+ * @arg func callback function
+ * @arg arg argument to be passed to callback function
+ */
+int nl_cb_err(struct nl_cb *cb, enum nl_cb_kind kind,
+ nl_recvmsg_err_cb_t func, void *arg)
+{
+ if (kind < 0 || kind > NL_CB_KIND_MAX)
+ return nl_error(ERANGE, "Callback kind out of range");
+
+ if (kind == NL_CB_CUSTOM) {
+ cb->cb_err = func;
+ cb->cb_err_arg = arg;
+ } else {
+ cb->cb_err = cb_err_def[kind];
+ cb->cb_err_arg = arg;
+ }
+
+ return 0;
+}
+
+/** @} */
+
+/**
+ * @name Overwriting
+ * @{
+ */
+
+/**
+ * Overwrite internal calls to nl_recvmsgs()
+ * @arg cb callback set
+ * @arg func replacement callback for nl_recvmsgs()
+ */
+void nl_cb_overwrite_recvmsgs(struct nl_cb *cb,
+ int (*func)(struct nl_handle *, struct nl_cb *))
+{
+ cb->cb_recvmsgs_ow = func;
+}
+
+/**
+ * Overwrite internal calls to nl_recv()
+ * @arg cb callback set
+ * @arg func replacement callback for nl_recv()
+ */
+void nl_cb_overwrite_recv(struct nl_cb *cb,
+ int (*func)(struct nl_handle *, struct sockaddr_nl *,
+ unsigned char **, struct ucred **))
+{
+ cb->cb_recv_ow = func;
+}
+
+/**
+ * Overwrite internal calls to nl_send()
+ * @arg cb callback set
+ * @arg func replacement callback for nl_send()
+ */
+void nl_cb_overwrite_send(struct nl_cb *cb,
+ int (*func)(struct nl_handle *, struct nl_msg *))
+{
+ cb->cb_send_ow = func;
+}
+
+/** @} */
+
+/** @} */