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#include "logging.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
const char *logfile = "netmon.log";
int check_interval_seconds = 30; // seconds to sleep between checks
int max_check_failure = 5; // how many failures to reboot the system
int as_daemon = 0; // should run as a daemon process
volatile int require_reboot = 0;
void *logger = NULL;
void daemonize() {
pid_t pid = 0;
pid_t sid = 0;
pid = fork();
if (pid < 0) {
perror("fork()");
log_error(logger, "fork() failed.");
exit(1);
}
if (pid > 0) {
char buf[32];
snprintf(buf, 31, "Child process: %d", pid);
log_info(logger, buf);
exit(0); // exit parent process
}
// unmask the file mode
umask(0);
// set new session
sid = setsid();
if (sid < 0) {
perror("setsid()");
log_error(logger, "setsid() failed.");
exit(1);
}
chdir("/");
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
}
///**
// * Read and escape a string, then write to another buffer, with length limit.
// * @param si
// * @param so
// * @param maxlen
// */
//void escape(const char *si, char *so, size_t maxlen) {
// size_t wb = 0; // bytes written
// char c[4] = {'\0'};
// while ((c[0] = *si++) != '\0') {
// const char *s;
// switch (c[0]) {
// case '\r':
// s = "\r";
// break;
// case '\n':
// s = "\n";
// break;
// case '\t':
// s = "\t";
// break;
// case '\v':
// s = "\v";
// break;
// case '\b':
// s = "\b";
// break;
// case '\a':
// s = "\a";
// break;
// case '\f':
// s = "\f";
// break;
// default:
// s = c;
// break;
// }
// strcpy(so, s)
// }
//}
/**
* Check network availability.
* @return Zero if success, non-zero if failed.
*/
int check_network() {
#define RETURN(r) do { rv = (r); goto RET; } while(0)
#define READ_SIZE 32
int sock = -1, rv = 0;
struct sockaddr_in serv_addr;
const char *msg = "GET / HTTP/1.1\r\n"
"Host: www.gov.cn\r\n"
"\r\n";
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("socket()");
log_error(logger, "socket() failed.");
RETURN(-1);
}
const struct hostent *host = gethostbyname("www.gov.cn"); // TODO cache this
if (!host) {
herror("gethostbyname()");
log_error(logger, "Cannot resolve test host.");
RETURN(-1);
}
if (host->h_length <= 0) {
log_error(logger, "Test host does not have at least one address.");
RETURN(-1);
}
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(80);
serv_addr.sin_addr = **((struct in_addr **) host->h_addr_list);
if (connect(sock, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
log_error(logger, "connect() failed.");
RETURN(-1);
}
ssize_t ss = 0; // send size
while (ss < strlen(msg)) {
ssize_t rd = send(sock, msg, strlen(msg), 0);
if (rd < 0) {
perror("send()");
log_error(logger, "send() failed.");
RETURN(-1);
}
ss += rd;
}
log_debug(logger, "HTTP request is sent. Reading response.");
char response[READ_SIZE] = {0};
ssize_t rs = 0; // receive size
while (rs < READ_SIZE) {
ssize_t rd = read(sock, response, READ_SIZE - rs);
if (rd < 0) {
perror("read()");
log_error(logger, "read() failed.");
RETURN(-1);
} else {
rs += rd;
}
}
const char *expected = "HTTP/1.1 200 OK\r\n";
if (memcmp(response, expected, strlen(expected)) != 0) {
char buf[64];
snprintf(buf, 63, "Unexpected response: %s", response);
log_error(logger, buf);
RETURN(-1);
}
RETURN(0);
RET:
if (sock >= 0) close(sock);
return rv;
#undef RETURN
#undef READ_SIZE
}
void loop() {
// check network and sleep
// if fails too many times continuously, set require_reboot flag and return
int failures = 0;
#pragma clang diagnostic push
#pragma ide diagnostic ignored "EndlessLoop"
while (1) {
log_info(logger, "Check network.");
if (check_network() != 0) {
++failures;
char buf[64];
snprintf(buf, 63, "Network failure detected. counter=%d", failures);
log_info(logger, buf);
} else {
log_info(logger, "Network is OK.");
failures = 0;
}
if (failures > max_check_failure) {
log_info(logger, "Max failure times exceeded.");
require_reboot = 1;
return;
}
log_info(logger, "Sleeping...");
unsigned int t = check_interval_seconds;
while ((t = sleep(t)));
}
#pragma clang diagnostic pop
}
int main(int argc, char *argv[]) {
for (int i = 1; i < argc; ++i) {
if (!strcmp(argv[i], "-t")) {
check_interval_seconds = atoi(argv[i + 1]);
++i; // skip next value
} else if (!strcmp(argv[i], "-n")) {
max_check_failure = atoi(argv[i + 1]);
++i; // skip next value
} else if (!strcmp(argv[i], "-l")) {
logfile = argv[i + 1];
++i; // skip next value
} else if (!strcmp(argv[i], "-d")) {
as_daemon = 1;
} else {
int invalid = strcmp(argv[i], "-h") != 0 && strcmp(argv[i], "--help") != 0;
if (invalid) printf("Unrecognized parameter \"%s\".\n", argv[i]);
printf("Usage:\n"
" %s [-t <check_interval>] [-n <max_failure>] [-l <log_file>] [-d]\n", argv[0]);
return invalid != 0;
}
}
logger = log_init(logfile);
log_debug(logger, "DEBUG logging is enabled.");
if (as_daemon) {
log_info(logger, "Daemonizing...");
daemonize();
}
log_info(logger, "netmon is started.");
loop();
log_info(logger, "netmon is stopped.");
if (require_reboot) {
log_info(logger, "Trigger system reboot.");
system("reboot");
}
log_free(logger);
return 0;
}
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