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

#define HOSTNAME "lalis"

int isinarray( int pid, int array[], int n )
{
	//if (n == 0) return 0;
	int x;
	for(x=1;x<=n;x++)
	{
		if( pid == array[x])
		{
			return x;
		}
	}
	return 0;
}

int getcmdline( int ppid, char cmdline[], char cmd[], char user[] )
{
	FILE *fh1;
	char child_path[128];
	char str[1024];
	char * pch;
	int child_pid;
	int flag = 0;
	int r;
	int x = 0;
	int pid = ppid;

	while ( flag == 0)
	{
		sprintf( child_path, "/proc/%d/task/%d/children", pid,pid);
		if ( (fh1 = fopen( child_path, "r" )) == NULL)
		{
			perror(child_path);
			return 3;
		}
		r = fscanf( fh1, "%i", &child_pid );
		if ( r != -1 )
		{
			pid = child_pid;
		}else
		{
			flag = 1;
		}
		fclose(fh1);
	}
	sprintf( child_path, "/proc/%d/cmdline", pid );
	if ( (fh1= fopen( child_path, "r" )) == NULL)
	{
		perror(child_path);
		return 4;
	}
	fgets( str, 1024, fh1);
	flag = 0;
	while ( flag == 0 )
	{
		if ( (int) str[x] == 0 )
		{
			if ( (int) str[x+1] != 0 )
			{
				str[x] = ' ';
			}else
			{
				flag = 1;
			}
		}
		x++;
	}
	sprintf(cmdline, "%s", str);
	fclose(fh1);
	sprintf( child_path, "/proc/%d/comm", pid );
	if ( (fh1= fopen(child_path, "r" )) == NULL)
	{
		perror(child_path);
		return 5;
	}
	fscanf( fh1, "%s", cmd );
	fclose(fh1);
	sprintf( child_path, "/proc/%d/environ", pid );
	if ( (fh1= fopen(child_path, "r" )) == NULL)
	{
		perror(child_path);
		return 5;
	}
	fscanf( fh1, "%s", str);
	pch = strtok( str, "=" );
	pch = strtok( NULL , "=" );
	sprintf( user, "%s", pch);
	fclose(fh1);
	return 0;
}

int main()
{
	FILE *fh;
	FILE *fh1;
	int id;
	int pid;
	int x=0;
	int r;
	int i;
	int j;
	int start =1;
	int childrens[10];
	int flag[10];
	char proc_path[128];
	char commande[] = "/usr/local/bin/send_sms";
	char logfile[] = "/var/log/sshdetect.log";
	char cmd[24];
	char cmdline[1000];
	char user[24];
	char str[1024];
	char date[60];
	time_t now ;

	time( &now );
	sprintf( date, "%s", ctime(&now));
	date[strlen(date)-1] = 0;
	if ( (fh = fopen(logfile, "a")) == NULL)
	{
		perror(logfile);
		return 1;
	}
	fprintf(fh, "%s: Démarrage de sshdetect", date);
	fclose(fh);
	sprintf( str, "%s \"%s - %s: Démarrage de sshdetect\"", commande, HOSTNAME, date );
	id=fork();
	if(id == 0)
	{
		r = system( str );
		exit(r);
	}else if( id<0 )
	{
		printf("erreur de création du fork: %s", str);
	}

	while (1)
	{
		// get the sshd process ID (PID)
		if ( (fh = fopen("/run/sshd.pid", "r" )) == NULL)
		{
			perror("/run/sshd.pid");
			return 1;
		}
		if ( fscanf(fh, "%i", &pid) == 0)
		{
			printf("erreur fscanf: /run/sshd.pid" );
			return 10;
		}
		fclose(fh);
		//printf("%i", pid);

		//get the list of children
		sprintf( proc_path, "/proc/%d/task/%d/children", pid,pid);
		//printf("  %s", proc_path);
		if ((fh = fopen( proc_path, "r")) == NULL)
		{
			perror(proc_path);
			return 1;
		}
		while(fscanf(fh, "%i", &pid) > 0)
		{
			r = isinarray(pid, childrens, x);
			if( r == 0 )
			{
				getcmdline( pid, cmdline, cmd, user );
				if( strcmp( cmd, "sshd") != 0 )
				{
					x++;
					childrens[x] = pid;
					flag[x] = 1;

					time( &now );
					sprintf( date, "%s", ctime(&now));
					date[strlen(date)-1] = 0;
					sprintf( str, "%s \"%s: %s s'est connecté le %s avec la commande: %s %s\"", commande, HOSTNAME, user, date, cmd, cmdline );
					if ( start != 1 )
					{
						id=fork();
						if(id>0)
						{
							if ( (fh1 = fopen(logfile, "a")) == NULL)
							{
								perror(logfile);
								return 7;
							}
							fprintf(fh1, "%s: Connexion de %s\n#%s# %s\n", date, user, cmd, cmdline);
							fclose(fh1);
						}else if (id<0)
						{
							printf("erreur de création du fork: %s", str);
						}else
						{
							//printf("%s\n", str);
							r = system( str );
							exit (r);
						}
					}else
					{
						if ( (fh1 = fopen(logfile, "a")) == NULL)
						{
							perror(logfile);
							return 7;
						}
						if (start == 1)
						{
							fprintf(fh1, "%s: %s Connecté - %s  %s", date, user, cmd, cmdline);
						}
					}
				}
			}else
			{
				flag[r] = 1;
			}
		}
		for(i=1;i<=x;i++)
		{
			if (flag[i] == 0 )
			{
				printf("Session %d terminée\n", childrens[i]);
				for( j=i; j<x; j++ )
				{
					childrens[j] = childrens[j+1];
					flag[j] = flag[j+1];
				}
				i--;
				x--;
			}else
			{
				flag[i] = 0;
			}
		}
		fclose(fh);
		sleep(2);
		start = 0;
	}
	return 0;
}