/* lnstat.c:  Unified linux network statistics
 *
 * Copyright (C) 2004 by Harald Welte <laforge@gnumonks.org>
 *
 * Development of this code was funded by Astaro AG, http://www.astaro.com/
 *
 * Based on original concept and ideas from predecessor rtstat.c:
 *
 * Copyright 2001 by Robert Olsson <robert.olsson@its.uu.se>
 *                                 Uppsala University, Sweden
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
#include <limits.h>
#include <time.h>

#include <sys/time.h>
#include <sys/types.h>

#include "lnstat.h"

/* size of temp buffer used to read lines from procfiles */
#define FGETS_BUF_SIZE 1024


#define RTSTAT_COMPAT_LINE "entries  in_hit in_slow_tot in_no_route in_brd in_martian_dst in_martian_src  out_hit out_slow_tot out_slow_mc  gc_total gc_ignored gc_goal_miss gc_dst_overflow in_hlist_search out_hlist_search\n"

/* Read (and summarize for SMP) the different stats vars. */
static int scan_lines(struct lnstat_file *lf, int i)
{
        char buf[FGETS_BUF_SIZE];
        int j, num_lines = 0;

        for (j = 0; j < lf->num_fields; j++)
                lf->fields[j].values[i] = 0;

        rewind(lf->fp);
        /* skip first line */
        if (!lf->compat && !fgets(buf, sizeof(buf)-1, lf->fp))
                return -1;

        while (!feof(lf->fp) && fgets(buf, sizeof(buf)-1, lf->fp)) {
                char *ptr = buf;

                num_lines++;

                gettimeofday(&lf->last_read, NULL);

                for (j = 0; j < lf->num_fields; j++) {
                        unsigned long f = strtoul(ptr, &ptr, 16);

                        if (j == 0)
                                lf->fields[j].values[i] = f;
                        else
                                lf->fields[j].values[i] += f;
                }
        }
        return num_lines;
}

static int time_after(struct timeval *last,
                      struct timeval *tout,
                      struct timeval *now)
{
        if (now->tv_sec > last->tv_sec + tout->tv_sec)
                return 1;

        if (now->tv_sec == last->tv_sec + tout->tv_sec) {
                if (now->tv_usec > last->tv_usec + tout->tv_usec)
                        return 1;
        }

        return 0;
}

int lnstat_update(struct lnstat_file *lnstat_files)
{
        struct lnstat_file *lf;
        struct timeval tv;

        gettimeofday(&tv, NULL);

        for (lf = lnstat_files; lf; lf = lf->next) {
                if (time_after(&lf->last_read, &lf->interval, &tv)) {
                        int i;
                        struct lnstat_field *lfi;

                        scan_lines(lf, 1);

                        for (i = 0, lfi = &lf->fields[i];
                             i < lf->num_fields; i++, lfi = &lf->fields[i]) {
                                if (i == 0)
                                        lfi->result = lfi->values[1];
                                else
                                        lfi->result = (lfi->values[1]-lfi->values[0])
                                                        / lf->interval.tv_sec;
                        }

                        scan_lines(lf, 0);
                }
        }

        return 0;
}

/* scan first template line and fill in per-field data structures */
static int __lnstat_scan_fields(struct lnstat_file *lf, char *buf)
{
        char *tok;
        int i;

        tok = strtok(buf, " \t\n");
        for (i = 0; i < LNSTAT_MAX_FIELDS_PER_LINE; i++) {
                lf->fields[i].file = lf;
                strncpy(lf->fields[i].name, tok, LNSTAT_MAX_FIELD_NAME_LEN);
                /* has to be null-terminate since we initialize to zero
                 * and field size is NAME_LEN + 1 */
                tok = strtok(NULL, " \t\n");
                if (!tok) {
                        lf->num_fields = i+1;
                        return 0;
                }
        }
        return 0;
}

static int lnstat_scan_fields(struct lnstat_file *lf)
{
        char buf[FGETS_BUF_SIZE];

        rewind(lf->fp);
        if (!fgets(buf, sizeof(buf)-1, lf->fp))
                return -1;

        return __lnstat_scan_fields(lf, buf);
}

/* fake function emulating lnstat_scan_fields() for old kernels */
static int lnstat_scan_compat_rtstat_fields(struct lnstat_file *lf)
{
        char buf[FGETS_BUF_SIZE];

        strncpy(buf, RTSTAT_COMPAT_LINE, sizeof(buf) - 1);
        buf[sizeof(buf) - 1] = '\0';

        return __lnstat_scan_fields(lf, buf);
}

/* find out whether string 'name; is in given string array */
static int name_in_array(const int num, const char **arr, const char *name)
{
        int i;

        for (i = 0; i < num; i++) {
                if (!strcmp(arr[i], name))
                        return 1;
        }
        return 0;
}

/* allocate lnstat_file and open given file */
static struct lnstat_file *alloc_and_open(const char *path, const char *file)
{
        struct lnstat_file *lf;

        /* allocate */
        lf = calloc(1, sizeof(*lf));
        if (!lf) {
                fprintf(stderr, "out of memory\n");
                return NULL;
        }

        /* initialize */
        snprintf(lf->basename, sizeof(lf->basename), "%s", file);
        snprintf(lf->path, sizeof(lf->path), "%s/%s", path, file);

        /* initialize to default */
        lf->interval.tv_sec = 1;

        /* open */
        lf->fp = fopen(lf->path, "r");
        if (!lf->fp) {
                perror(lf->path);
                free(lf);
                return NULL;
        }

        return lf;
}


/* lnstat_scan_dir - find and parse all available statistics files/fields */
struct lnstat_file *lnstat_scan_dir(const char *path, const int num_req_files,
                                    const char **req_files)
{
        DIR *dir;
        struct lnstat_file *lnstat_files = NULL;
        struct dirent *de;

        if (!path)
                path = PROC_NET_STAT;

        dir = opendir(path);
        if (!dir) {
                struct lnstat_file *lf;
                /* Old kernel, before /proc/net/stat was introduced */
                fprintf(stderr, "Your kernel doesn't have lnstat support. ");

                /* we only support rtstat, not multiple files */
                if (num_req_files >= 2) {
                        fputc('\n', stderr);
                        return NULL;
                }

                /* we really only accept rt_cache */
                if (num_req_files && !name_in_array(num_req_files,
                                                    req_files, "rt_cache")) {
                        fputc('\n', stderr);
                        return NULL;
                }

                fprintf(stderr, "Fallback to old rtstat-only operation\n");

                lf = alloc_and_open("/proc/net", "rt_cache_stat");
                if (!lf)
                        return NULL;
                lf->compat = 1;
                strncpy(lf->basename, "rt_cache", sizeof(lf->basename));

                /* FIXME: support for old files */
                if (lnstat_scan_compat_rtstat_fields(lf) < 0)
                        return NULL;

                lf->next = lnstat_files;
                lnstat_files = lf;
                return lnstat_files;
        }

        while ((de = readdir(dir))) {
                struct lnstat_file *lf;

                if (de->d_type != DT_REG)
                        continue;

                if (num_req_files && !name_in_array(num_req_files,
                                                    req_files, de->d_name))
                        continue;

                lf = alloc_and_open(path, de->d_name);
                if (!lf) {
                        closedir(dir);
                        return NULL;
                }

                /* fill in field structure */
                if (lnstat_scan_fields(lf) < 0) {
                        closedir(dir);
                        return NULL;
                }

                /* prepend to global list */
                lf->next = lnstat_files;
                lnstat_files = lf;
        }
        closedir(dir);

        return lnstat_files;
}

int lnstat_dump(FILE *outfd, struct lnstat_file *lnstat_files)
{
        struct lnstat_file *lf;

        for (lf = lnstat_files; lf; lf = lf->next) {
                int i;

                fprintf(outfd, "%s:\n", lf->path);

                for (i = 0; i < lf->num_fields; i++)
                        fprintf(outfd, "\t%2u: %s\n", i+1, lf->fields[i].name);

        }
        return 0;
}

struct lnstat_field *lnstat_find_field(struct lnstat_file *lnstat_files,
                                       const char *name)
{
        struct lnstat_file *lf;
        struct lnstat_field *ret = NULL;
        const char *colon = strchr(name, ':');
        char *file;
        const char *field;

        if (colon) {
                file = strndup(name, colon-name);
                field = colon+1;
        } else {
                file = NULL;
                field = name;
        }

        for (lf = lnstat_files; lf; lf = lf->next) {
                int i;

                if (file && strcmp(file, lf->basename))
                        continue;

                for (i = 0; i < lf->num_fields; i++) {
                        if (!strcmp(field, lf->fields[i].name)) {
                                ret = &lf->fields[i];
                                goto out;
                        }
                }
        }
out:
        free(file);

        return ret;
}