/*
	Poor man dhcp sort of
	The idea is to allocate an IP number (for a vserver) based
	on its name (a key).
	You use this when you have many vservers running on a host in
	a private network. This host is seen as a gateway to the private server.
	This is useful for test environnement where new vservers appear and
	go.
*/
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <signal.h>
#include <map>
#include <set>
#include <string>

using namespace std;

static const char *lockfile = "/var/run/alloc_ip.lock";
static const char *datafile = "/var/run/alloc_ip.data";

typedef map<string,string> mapss;
typedef mapss::iterator mapss_it;

#include "vipalias.lock.h"

int main (int argc, char *argv[])
{
	int ret = -1;
	if (argc != 3){
		fprintf (stderr,"alloc_ip key IP_prefix\n");
		fprintf (stderr,"alloc_ip server1 192.168.1\n");
	}else{
		const char *argkey = argv[1];
		const char *ipprefix = argv[2];
		if (vipalias_lock() != -1){
			mapss mp;
			set<string> st;
			FILE *fin = fopen (datafile,"r");
			if (fin != NULL){
				char buf[100];
				while (fgets(buf,sizeof(buf)-1,fin)!=NULL){
					char key[100],ip[100];
					if (sscanf(buf,"%s %s",ip,key)==2){
						mp[key] = ip;
						st.insert (ip);
					}
				}
				fclose (fin);
			}
			bool changed = false;
			mapss_it it=mp.find(argkey);
			if (it == mp.end()){
				for (int i=1; i<254; i++){
					char tmp[20];
					snprintf (tmp,sizeof(tmp)-1,"%s.%d",ipprefix,i);
					if (st.count(tmp)==0){
						mp[argkey] = tmp;
						printf ("%s\n",tmp);
						changed = true;
						ret = 0;
						break;
					}
				}
				if (!changed){
					fprintf (stderr,"No IP available\n");
				}
			}else{
				printf ("%s\n",it->second.c_str());
				ret = 0;
			}
			if (changed){
				FILE *fout = fopen (datafile,"w");
				if (fout == NULL){
					fprintf (stderr,"Can't open datafile %s (%s)\n"
						,datafile,strerror(errno));
				}else{
					for (mapss_it it=mp.begin();
						it != mp.end(); it++){
						fprintf (fout,"%s %s\n",it->second.c_str()
							,it->first.c_str());
					}
					fclose (fout);
				}
			}
			vipalias_unlock();
		}
	}
	return ret;
}