/*

 * nstat.c	handy utility to read counters /proc/net/netstat and snmp

 *

 *		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.

 *

 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>

 */

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <fcntl.h>

#include <string.h>

#include <errno.h>

#include <time.h>

#include <sys/time.h>

#include <fnmatch.h>

#include <sys/file.h>

#include <sys/socket.h>

#include <sys/un.h>

#include <sys/poll.h>

#include <sys/wait.h>

#include <sys/stat.h>

#include <signal.h>

#include <math.h>

#include <getopt.h>

#include <json_writer.h>

#include <SNAPSHOT.h>

#include "utils.h"

int dump_zeros;

int reset_history;

int ignore_history;

int no_output;

int json_output;

int no_update;

int scan_interval;

int time_constant;

double W;

char **patterns;

int npatterns;

char info_source[128];

int source_mismatch;

static int generic_proc_open(const char *env, char *name)

{

	char store[128];

	char *p = getenv(env);

	if (!p) {

		p = getenv("PROC_ROOT") ? : "/proc";

		snprintf(store, sizeof(store)-1, "%s/%s", p, name);

		p = store;

	}

	return open(p, O_RDONLY);

}

static int net_netstat_open(void)

{

	return generic_proc_open("PROC_NET_NETSTAT", "net/netstat");

}

static int net_snmp_open(void)

{

	return generic_proc_open("PROC_NET_SNMP", "net/snmp");

}

static int net_snmp6_open(void)

{

	return generic_proc_open("PROC_NET_SNMP6", "net/snmp6");

}

static int net_sctp_snmp_open(void)

{

	return generic_proc_open("PROC_NET_SCTP_SNMP", "net/sctp/snmp");

}

struct nstat_ent {

	struct nstat_ent *next;

	char		 *id;

	unsigned long long val;

	double		   rate;

};

struct nstat_ent *kern_db;

struct nstat_ent *hist_db;

static const char *useless_numbers[] = {

	"IpForwarding", "IpDefaultTTL",

	"TcpRtoAlgorithm", "TcpRtoMin", "TcpRtoMax",

	"TcpMaxConn", "TcpCurrEstab"

};

static int useless_number(const char *id)

{

	int i;

	for (i = 0; i < ARRAY_SIZE(useless_numbers); i++)

		if (strcmp(id, useless_numbers[i]) == 0)

			return 1;

	return 0;

}

static int match(const char *id)

{

	int i;

	if (npatterns == 0)

		return 1;

	for (i = 0; i < npatterns; i++) {

		if (!fnmatch(patterns[i], id, 0))

			return 1;

	}

	return 0;

}

static void load_good_table(FILE *fp)

{

	char buf[4096];

	struct nstat_ent *db = NULL;

	struct nstat_ent *n;

	while (fgets(buf, sizeof(buf), fp) != NULL) {

		int nr;

		unsigned long long val;

		double rate;

		char idbuf[sizeof(buf)];

		if (buf[0] == '#') {

			buf[strlen(buf)-1] = 0;

			if (info_source[0] && strcmp(info_source, buf+1))

				source_mismatch = 1;

			info_source[0] = 0;

			strncat(info_source, buf+1, sizeof(info_source)-1);

			continue;

		}

		/* idbuf is as big as buf, so this is safe */

		nr = sscanf(buf, "%s%llu%lg", idbuf, &val, &rate;;

		if (nr < 2) {

			fprintf(stderr, "%s:%d: error parsing history file\n",

				__FILE__, __LINE__);

			exit(-2);

		}

		if (nr < 3)

			rate = 0;

		if (useless_number(idbuf))

			continue;

		if ((n = malloc(sizeof(*n))) == NULL) {

			perror("nstat: malloc");

			exit(-1);

		}

		n->id = strdup(idbuf);

		n->val = val;

		n->rate = rate;

		n->next = db;

		db = n;

	}

	while (db) {

		n = db;

		db = db->next;

		n->next = kern_db;

		kern_db = n;

	}

}

static int count_spaces(const char *line)

{

	int count = 0;

	char c;

	while ((c = *line++) != 0)

		count += c == ' ' || c == '\n';

	return count;

}

static void load_ugly_table(FILE *fp)

{

	char *buf = NULL;

	size_t buflen = 0;

	ssize_t nread;

	struct nstat_ent *db = NULL;

	struct nstat_ent *n;

	while ((nread = getline(&buf, &buflen, fp)) != -1) {

		char idbuf[4096];

		int  off;

		char *p;

		int count1, count2, skip = 0;

		p = strchr(buf, ':');

		if (!p) {

			fprintf(stderr, "%s:%d: error parsing history file\n",

				__FILE__, __LINE__);

			exit(-2);

		}

		count1 = count_spaces(buf);

		*p = 0;

		idbuf[0] = 0;

		strncat(idbuf, buf, sizeof(idbuf) - 1);

		off = p - buf;

		p += 2;

		while (*p) {

			char *next;

			if ((next = strchr(p, ' ')) != NULL)

				*next++ = 0;

			else if ((next = strchr(p, '\n')) != NULL)

				*next++ = 0;

			if (off < sizeof(idbuf)) {

				idbuf[off] = 0;

				strncat(idbuf, p, sizeof(idbuf) - off - 1);

			}

			n = malloc(sizeof(*n));

			if (!n) {

				perror("nstat: malloc");

				exit(-1);

			}

			n->id = strdup(idbuf);

			n->rate = 0;

			n->next = db;

			db = n;

			p = next;

		}

		n = db;

		nread = getline(&buf, &buflen, fp);

		if (nread == -1) {

			fprintf(stderr, "%s:%d: error parsing history file\n",

				__FILE__, __LINE__);

			exit(-2);

		}

		count2 = count_spaces(buf);

		if (count2 > count1)

			skip = count2 - count1;

		do {

			p = strrchr(buf, ' ');

			if (!p) {

				fprintf(stderr, "%s:%d: error parsing history file\n",

					__FILE__, __LINE__);

				exit(-2);

			}

			*p = 0;

			if (sscanf(p+1, "%llu", &n->val) != 1) {

				fprintf(stderr, "%s:%d: error parsing history file\n",

					__FILE__, __LINE__);

				exit(-2);

			}

			/* Trick to skip "dummy" trailing ICMP MIB in 2.4 */

			if (skip)

				skip--;

			else

				n = n->next;

		} while (p > buf + off + 2);

	}

	free(buf);

	while (db) {

		n = db;

		db = db->next;

		if (useless_number(n->id)) {

			free(n->id);

			free(n);

		} else {

			n->next = kern_db;

			kern_db = n;

		}

	}

}

static void load_sctp_snmp(void)

{

	FILE *fp = fdopen(net_sctp_snmp_open(), "r");

	if (fp) {

		load_good_table(fp);

		fclose(fp);

	}

}

static void load_snmp(void)

{

	FILE *fp = fdopen(net_snmp_open(), "r");

	if (fp) {

		load_ugly_table(fp);

		fclose(fp);

	}

}

static void load_snmp6(void)

{

	FILE *fp = fdopen(net_snmp6_open(), "r");

	if (fp) {

		load_good_table(fp);

		fclose(fp);

	}

}

static void load_netstat(void)

{

	FILE *fp = fdopen(net_netstat_open(), "r");

	if (fp) {

		load_ugly_table(fp);

		fclose(fp);

	}

}

static void dump_kern_db(FILE *fp, int to_hist)

{

	json_writer_t *jw = json_output ? jsonw_new(fp) : NULL;

	struct nstat_ent *n, *h;

	h = hist_db;

	if (jw) {

		jsonw_start_object(jw);

		jsonw_pretty(jw, pretty);

		jsonw_name(jw, info_source);

		jsonw_start_object(jw);

	} else

		fprintf(fp, "#%s\n", info_source);

	for (n = kern_db; n; n = n->next) {

		unsigned long long val = n->val;

		if (!dump_zeros && !val && !n->rate)

			continue;

		if (!match(n->id)) {

			struct nstat_ent *h1;

			if (!to_hist)

				continue;

			for (h1 = h; h1; h1 = h1->next) {

				if (strcmp(h1->id, n->id) == 0) {

					val = h1->val;

					h = h1->next;

					break;

				}

			}

		}

		if (jw)

			jsonw_uint_field(jw, n->id, val);

		else

			fprintf(fp, "%-32s%-16llu%6.1f\n", n->id, val, n->rate);

	}

	if (jw) {

		jsonw_end_object(jw);

		jsonw_end_object(jw);

		jsonw_destroy(&jw;;

	}

}

static void dump_incr_db(FILE *fp)

{

	json_writer_t *jw = json_output ? jsonw_new(fp) : NULL;

	struct nstat_ent *n, *h;

	h = hist_db;

	if (jw) {

		jsonw_start_object(jw);

		jsonw_pretty(jw, pretty);

		jsonw_name(jw, info_source);

		jsonw_start_object(jw);

	} else

		fprintf(fp, "#%s\n", info_source);

	for (n = kern_db; n; n = n->next) {

		int ovfl = 0;

		unsigned long long val = n->val;

		struct nstat_ent *h1;

		for (h1 = h; h1; h1 = h1->next) {

			if (strcmp(h1->id, n->id) == 0) {

				if (val < h1->val) {

					ovfl = 1;

					val = h1->val;

				}

				val -= h1->val;

				h = h1->next;

				break;

			}

		}

		if (!dump_zeros && !val && !n->rate)

			continue;

		if (!match(n->id))

			continue;

		if (jw)

			jsonw_uint_field(jw, n->id, val);

		else

			fprintf(fp, "%-32s%-16llu%6.1f%s\n", n->id, val,

				n->rate, ovfl?" (overflow)":"");

	}

	if (jw) {

		jsonw_end_object(jw);

		jsonw_end_object(jw);

		jsonw_destroy(&jw;;

	}

}

static int children;

static void sigchild(int signo)

{

}

static void update_db(int interval)

{

	struct nstat_ent *n, *h;

	n = kern_db;

	kern_db = NULL;

	load_netstat();

	load_snmp6();

	load_snmp();

	load_sctp_snmp();

	h = kern_db;

	kern_db = n;

	for (n = kern_db; n; n = n->next) {

		struct nstat_ent *h1;

		for (h1 = h; h1; h1 = h1->next) {

			if (strcmp(h1->id, n->id) == 0) {

				double sample;

				unsigned long long incr = h1->val - n->val;

				n->val = h1->val;

				sample = (double)incr * 1000.0 / interval;

				if (interval >= scan_interval) {

					n->rate += W*(sample-n->rate);

				} else if (interval >= 1000) {

					if (interval >= time_constant) {

						n->rate = sample;

					} else {

						double w = W*(double)interval/scan_interval;

						n->rate += w*(sample-n->rate);

					}

				}

				while (h != h1) {

					struct nstat_ent *tmp = h;

					h = h->next;

					free(tmp->id);

					free(tmp);

				};

				h = h1->next;

				free(h1->id);

				free(h1);

				break;

			}

		}

	}

}

#define T_DIFF(a, b) (((a).tv_sec-(b).tv_sec)*1000 + ((a).tv_usec-(b).tv_usec)/1000)

static void server_loop(int fd)

{

	struct timeval snaptime = { 0 };

	struct pollfd p;

	p.fd = fd;

	p.events = p.revents = POLLIN;

	sprintf(info_source, "%d.%lu sampling_interval=%d time_const=%d",

		getpid(), (unsigned long)random(), scan_interval/1000, time_constant/1000);

	load_netstat();

	load_snmp6();

	load_snmp();

	load_sctp_snmp();

	for (;;) {

		int status;

		time_t tdiff;

		struct timeval now;

		gettimeofday(&now, NULL);

		tdiff = T_DIFF(now, snaptime);

		if (tdiff >= scan_interval) {

			update_db(tdiff);

			snaptime = now;

			tdiff = 0;

		}

		if (poll(&p, 1, scan_interval - tdiff) > 0

		    && (p.revents&POLLIN)) {

			int clnt = accept(fd, NULL, NULL);

			if (clnt >= 0) {

				pid_t pid;

				if (children >= 5) {

					close(clnt);

				} else if ((pid = fork()) != 0) {

					if (pid > 0)

						children++;

					close(clnt);

				} else {

					FILE *fp = fdopen(clnt, "w");

					if (fp)

						dump_kern_db(fp, 0);

					exit(0);

				}

			}

		}

		while (children && waitpid(-1, &status, WNOHANG) > 0)

			children--;

	}

}

static int verify_forging(int fd)

{

	struct ucred cred;

	socklen_t olen = sizeof(cred);

	if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, (void *)&cred, &olen) ||

	    olen < sizeof(cred))

		return -1;

	if (cred.uid == getuid() || cred.uid == 0)

		return 0;

	return -1;

}

static void usage(void) __attribute__((noreturn));

static void usage(void)

{

	fprintf(stderr,

		"Usage: nstat [OPTION] [ PATTERN [ PATTERN ] ]\n"

		"   -h, --help		this message\n"

		"   -a, --ignore	ignore history\n"

		"   -d, --scan=SECS	sample every statistics every SECS\n"

		"   -j, --json		format output in JSON\n"

		"   -n, --nooutput	do history only\n"

		"   -p, --pretty	pretty print\n"

		"   -r, --reset		reset history\n"

		"   -s, --noupdate	don't update history\n"

		"   -t, --interval=SECS	report average over the last SECS\n"

		"   -V, --version	output version information\n"

		"   -z, --zeros		show entries with zero activity\n");

	exit(-1);

}

static const struct option longopts[] = {

	{ "help", 0, 0, 'h' },

	{ "ignore",  0,  0, 'a' },

	{ "scan", 1, 0, 'd'},

	{ "nooutput", 0, 0, 'n' },

	{ "json", 0, 0, 'j' },

	{ "reset", 0, 0, 'r' },

	{ "noupdate", 0, 0, 's' },

	{ "pretty", 0, 0, 'p' },

	{ "interval", 1, 0, 't' },

	{ "version", 0, 0, 'V' },

	{ "zeros", 0, 0, 'z' },

	{ 0 }

};

int main(int argc, char *argv[])

{

	char *hist_name;

	struct sockaddr_un sun;

	FILE *hist_fp = NULL;

	int ch;

	int fd;

	while ((ch = getopt_long(argc, argv, "h?vVzrnasd:t:jp",

				 longopts, NULL)) != EOF) {

		switch (ch) {

		case 'z':

			dump_zeros = 1;

			break;

		case 'r':

			reset_history = 1;

			break;

		case 'a':

			ignore_history = 1;

			break;

		case 's':

			no_update = 1;

			break;

		case 'n':

			no_output = 1;

			break;

		case 'd':

			scan_interval = 1000*atoi(optarg);

			break;

		case 't':

			if (sscanf(optarg, "%d", &time_constant) != 1 ||

			    time_constant <= 0) {

				fprintf(stderr, "nstat: invalid time constant divisor\n");

				exit(-1);

			}

			break;

		case 'j':

			json_output = 1;

			break;

		case 'p':

			pretty = 1;

			break;

		case 'v':

		case 'V':

			printf("nstat utility, iproute2-ss%s\n", SNAPSHOT);

			exit(0);

		case 'h':

		case '?':

		default:

			usage();

		}

	}

	argc -= optind;

	argv += optind;

	sun.sun_family = AF_UNIX;

	sun.sun_path[0] = 0;

	sprintf(sun.sun_path+1, "nstat%d", getuid());

	if (scan_interval > 0) {

		if (time_constant == 0)

			time_constant = 60;

		time_constant *= 1000;

		W = 1 - 1/exp(log(10)*(double)scan_interval/time_constant);

		if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {

			perror("nstat: socket");

			exit(-1);

		}

		if (bind(fd, (struct sockaddr *)&sun, 2+1+strlen(sun.sun_path+1)) < 0) {

			perror("nstat: bind");

			exit(-1);

		}

		if (listen(fd, 5) < 0) {

			perror("nstat: listen");

			exit(-1);

		}

		if (daemon(0, 0)) {

			perror("nstat: daemon");

			exit(-1);

		}

		signal(SIGPIPE, SIG_IGN);

		signal(SIGCHLD, sigchild);

		server_loop(fd);

		exit(0);

	}

	patterns = argv;

	npatterns = argc;

	if ((hist_name = getenv("NSTAT_HISTORY")) == NULL) {

		hist_name = malloc(128);

		sprintf(hist_name, "/tmp/.nstat.u%d", getuid());

	}

	if (reset_history)

		unlink(hist_name);

	if (!ignore_history || !no_update) {

		struct stat stb;

		fd = open(hist_name, O_RDWR|O_CREAT|O_NOFOLLOW, 0600);

		if (fd < 0) {

			perror("nstat: open history file");

			exit(-1);

		}

		if ((hist_fp = fdopen(fd, "r+")) == NULL) {

			perror("nstat: fdopen history file");

			exit(-1);

		}

		if (flock(fileno(hist_fp), LOCK_EX)) {

			perror("nstat: flock history file");

			exit(-1);

		}

		if (fstat(fileno(hist_fp), &stb) != 0) {

			perror("nstat: fstat history file");

			exit(-1);

		}

		if (stb.st_nlink != 1 || stb.st_uid != getuid()) {

			fprintf(stderr, "nstat: something is so wrong with history file, that I prefer not to proceed.\n");

			exit(-1);

		}

		if (!ignore_history) {

			FILE *tfp;

			long uptime = -1;

			if ((tfp = fopen("/proc/uptime", "r")) != NULL) {

				if (fscanf(tfp, "%ld", &uptime) != 1)

					uptime = -1;

				fclose(tfp);

			}

			if (uptime >= 0 && time(NULL) >= stb.st_mtime+uptime) {

				fprintf(stderr, "nstat: history is aged out, resetting\n");

				if (ftruncate(fileno(hist_fp), 0) < 0)

					perror("nstat: ftruncate");

			}

		}

		load_good_table(hist_fp);

		hist_db = kern_db;

		kern_db = NULL;

	}

	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) >= 0 &&

	    (connect(fd, (struct sockaddr *)&sun, 2+1+strlen(sun.sun_path+1)) == 0

	     || (strcpy(sun.sun_path+1, "nstat0"),

		 connect(fd, (struct sockaddr *)&sun, 2+1+strlen(sun.sun_path+1)) == 0))

	    && verify_forging(fd) == 0) {

		FILE *sfp = fdopen(fd, "r");

		if (!sfp) {

			fprintf(stderr, "nstat: fdopen failed: %s\n",

				strerror(errno));

			close(fd);

		} else {

			load_good_table(sfp);

			if (hist_db && source_mismatch) {

				fprintf(stderr, "nstat: history is stale, ignoring it.\n");

				hist_db = NULL;

			}

			fclose(sfp);

		}

	} else {

		if (fd >= 0)

			close(fd);

		if (hist_db && info_source[0] && strcmp(info_source, "kernel")) {

			fprintf(stderr, "nstat: history is stale, ignoring it.\n");

			hist_db = NULL;

			info_source[0] = 0;

		}

		load_netstat();

		load_snmp6();

		load_snmp();

		load_sctp_snmp();

		if (info_source[0] == 0)

			strcpy(info_source, "kernel");

	}

	if (!no_output) {

		if (ignore_history || hist_db == NULL)

			dump_kern_db(stdout, 0);

		else

			dump_incr_db(stdout);

	}

	if (!no_update) {

		if (ftruncate(fileno(hist_fp), 0) < 0)

			perror("nstat: ftruncate");

		rewind(hist_fp);

		json_output = 0;

		dump_kern_db(hist_fp, 1);

		fclose(hist_fp);

	}

	exit(0);

}