handlers.c

/* SPDX-License-Identifier: LGPL-2.1-only */
/*
 * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
 */
 
/**
 * @ingroup core
 * @defgroup cb Callbacks/Customization
 *
 * Related sections in the development guide:
 * - @core_doc{core_cb, Callback Configuration}
 *
 * @{
 *
 * Header
 * ------
 * ~~~~{.c}
 * #include <netlink/handlers.h>
 * ~~~~
 */
 
#include <netlink-private/netlink.h>
#include <netlink-private/utils.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: ",
                nl_strerror_l(-e->error));
        print_header_content(ofd, &e->msg);
        fprintf(ofd, "\n");
 
        return -nl_syserr2nlerr(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 ((unsigned int) kind > NL_CB_KIND_MAX)
                return NULL;
 
        cb = calloc(1, sizeof(*cb));
        if (!cb)
                return NULL;
 
        cb->cb_refcnt = 1;
        cb->cb_active = NL_CB_TYPE_MAX + 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);
}
 
/**
 * Obtain type of current active callback
 * @arg cb              callback to query
 *
 * @return type or __NL_CB_TYPE_MAX if none active
 */
enum nl_cb_type nl_cb_active_type(struct nl_cb *cb)
{
        return cb->cb_active;
}
 
/** @} */
 
/**
 * @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 ((unsigned int) type > NL_CB_TYPE_MAX)
                return -NLE_RANGE;
 
        if ((unsigned int) kind > NL_CB_KIND_MAX)
                return -NLE_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 ((unsigned int) kind > NL_CB_KIND_MAX)
                return -NLE_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_sock *, 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_sock *, 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_sock *, struct nl_msg *))
{
        cb->cb_send_ow = func;
}
 
/** @} */
 
/** @} */