@@ -37,13 +37,20 @@ typedef struct urusai {

         client *clients;

 } urusai;

+typedef enum seenaction {

+	seen_error=0,

+	seen_new,

+	seen_updated,

+	seen_nochange

+} seenaction;

+

 static int signal_init(int signum, void (*fn)(int));

 static void sigint(int signum);

 volatile int sigint_flag=0;

 urusai *urusai_init(void);

 void urusai_free(urusai *u);

-client *urusai_clientseen(urusai *u, char *id, struct sockaddr_in *addr);

+client *urusai_clientseen(urusai *u, char *id, struct sockaddr_in *addr, seenaction *seen);

 int urusai_clientdeleteold(urusai *u, int timeout);

 client *urusai_clientget(urusai *u, char *id);

 int urusai_send(urusai *u, char *outbuf, int outbuf_used, client *destclient);

@@ -62,6 +69,7 @@ main(int argc, char *argv[])

         urusai *u;

         client *origclient, *destclient;

         char *serial,*origid,*destid,*cmd,*contents;

+	seenaction seen;	

         if((u=urusai_init())==NULL) {

                 printf("ERROR: Couldn'n get/bind socket or insufficient memory\n");

                 return(1);

@@ -69,15 +77,16 @@ main(int argc, char *argv[])

         sigint_flag=0;

         signal_init(SIGINT,sigint);

         while(!sigint_flag) {

+		memset(&clientaddr,0,sizeof(clientaddr));

                 clientaddr_len=sizeof(clientaddr);

                 if((inbuf_used=recvfrom(u->fd,inbuf,sizeof(inbuf),0,(struct sockaddr *)&clientaddr,&clientaddr_len))==-1)

                         continue; /* interrupted by signal */

                 if(msg_parse(inbuf,inbuf_used,&serial,&origid,&destid,&cmd,&contents)!=0)

                         continue;

-                if((origclient=urusai_clientseen(u,origid,&clientaddr))==NULL)

+                if((origclient=urusai_clientseen(u,origid,&clientaddr,&seen))==NULL)

                         continue;

                 if(strcmp(cmd,"ping")==0) {

-                        outbuf_used=msg_compose(outbuf, sizeof(outbuf), serial, NULL, origid,"pong",NULL);

+                        outbuf_used=msg_compose(outbuf, sizeof(outbuf), serial, NULL, origid,"pong",(seen==seen_new)?"new":(seen==seen_updated)?"updated":(seen==seen_nochange)?"nochange":NULL);

                         urusai_send(u,outbuf,outbuf_used,origclient);

                 } else if(strcmp(cmd,"message")==0) {

                         if((destclient=urusai_clientget(u,destid))==NULL) {

@@ -154,12 +163,15 @@ urusai_free(urusai *u)

 }

 client *

-urusai_clientseen(urusai *u, char *id, struct sockaddr_in *addr)

+urusai_clientseen(urusai *u, char *id, struct sockaddr_in *addr,seenaction *seen)

 {

         int i,ifree;

         client *c;

-        if(u==NULL)

+        if(u==NULL || id==NULL || addr==NULL || seen==NULL) {

+		if(seen!=NULL)

+			*seen=seen_error;

                 return(NULL);

+	}

         if(u->numclients==u->sizeclients) {

                 client *newc;

                 if((newc=realloc(u->clients,sizeof(client)*(u->sizeclients+CLIENTBLOCK)))==NULL)

@@ -176,13 +188,21 @@ urusai_clientseen(urusai *u, char *id, struct sockaddr_in *addr)

                         break;

         }

         if(i==u->sizeclients) {

-                if(ifree==-1)

+                if(ifree==-1) {

+			*seen=seen_error;

                         return(NULL);

+		}

                 i=ifree;

                 c=u->clients+i;

                 strncpy(c->id,id,sizeof(c->id));

                 c->id[sizeof(c->id)-1]='\0';

-        }

+		*seen=seen_new;

+        } else {

+		if(memcmp(&(c->addr),addr,sizeof(c->addr))==0)

+			*seen=seen_nochange;

+		else

+			*seen=seen_updated;

+	}

         c->lastrecv=time(NULL);

         memcpy(&(c->addr),addr,sizeof(c->addr));

         return(c);

new file mode 100644

@@ -0,0 +1,291 @@

+/*

+ * urusaiserver.c

+ *

+ * UDP notificator server implementing simple messaging.

+ *

+ * Author: Dario Rodriguez dario@softhome.net

+ */

+

+#include <stdio.h>

+#include <stdlib.h>

+#include <unistd.h>

+#include <string.h>

+#include <arpa/inet.h>

+#include <sys/types.h>

+#include <sys/socket.h>

+#include <signal.h>

+#include <time.h>

+#include <errno.h>

+

+#define SERVERPORT 20245

+#define BUFLEN 2048

+#define MAXID 32

+#define CLIENTBLOCK 128

+#define MAXPACKETSIZE 1300

+

+typedef struct client {

+        struct sockaddr_in addr;

+        time_t lastrecv;

+        char id[MAXID];

+} client;

+

+typedef struct urusai {

+        int fd;

+        struct sockaddr_in myaddr;

+        int numclients;

+        int sizeclients;

+        client *clients;

+} urusai;

+

+static int signal_init(int signum, void (*fn)(int));

+static void sigint(int signum);

+volatile int sigint_flag=0;

+

+urusai *urusai_init(void);

+void urusai_free(urusai *u);

+client *urusai_clientseen(urusai *u, char *id, struct sockaddr_in *addr);

+int urusai_clientdeleteold(urusai *u, int timeout);

+client *urusai_clientget(urusai *u, char *id);

+int urusai_send(urusai *u, char *outbuf, int outbuf_used, client *destclient);

+

+

+int msg_parse(char *inbuf, int inbuf_used,char **serial,char **origid,char **destid,char **cmd, char **contents);

+int msg_compose(char *outbuf, int bufsize, char *serial, char *origid, char *destid, char *cmd, char *contents);

+

+int

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

+{

+        char inbuf[BUFLEN],outbuf[BUFLEN];;

+        int inbuf_used,outbuf_used;

+        struct sockaddr_in clientaddr;

+        socklen_t clientaddr_len;

+        urusai *u;

+        client *origclient, *destclient;

+        char *serial,*origid,*destid,*cmd,*contents;

+        if((u=urusai_init())==NULL) {

+                printf("ERROR: Couldn'n get/bind socket or insufficient memory\n");

+                return(1);

+        }

+        sigint_flag=0;

+        signal_init(SIGINT,sigint);

+        while(!sigint_flag) {

+                clientaddr_len=sizeof(clientaddr);

+                if((inbuf_used=recvfrom(u->fd,inbuf,sizeof(inbuf),0,(struct sockaddr *)&clientaddr,&clientaddr_len))==-1)

+                        continue; /* interrupted by signal */

+                if(msg_parse(inbuf,inbuf_used,&serial,&origid,&destid,&cmd,&contents)!=0)

+                        continue;

+                if((origclient=urusai_clientseen(u,origid,&clientaddr))==NULL)

+                        continue;

+                if(strcmp(cmd,"ping")==0) {

+                        outbuf_used=msg_compose(outbuf, sizeof(outbuf), serial, NULL, origid,"pong",NULL);

+                        urusai_send(u,outbuf,outbuf_used,origclient);

+                } else if(strcmp(cmd,"message")==0) {

+                        if((destclient=urusai_clientget(u,destid))==NULL) {

+                                outbuf_used=msg_compose(outbuf, sizeof(outbuf), serial, NULL, origid,"messageerror","destid_unknown");

+                                urusai_send(u,outbuf,outbuf_used,origclient);

+                        } else {

+                                outbuf_used=msg_compose(outbuf, sizeof(outbuf), serial, origid, destid,"message",contents);

+                                urusai_send(u,outbuf,outbuf_used,destclient);

+                        }

+                } else if(strcmp(cmd,"receipt")==0) {

+                        if((destclient=urusai_clientget(u,destid))==NULL) {

+                                outbuf_used=msg_compose(outbuf, sizeof(outbuf), serial, NULL, origid,"receipterror","destid_unknown");

+                                urusai_send(u,outbuf,outbuf_used,origclient);

+                        } else {

+                                outbuf_used=msg_compose(outbuf, sizeof(outbuf), serial, origid, destid,"receipt",contents);

+                                urusai_send(u,outbuf,outbuf_used,destclient);

+                        }

+                }

+        }

+        urusai_free(u),u=NULL;

+        return(0);

+}

+

+static int

+signal_init(int signum, void (*fn)(int))

+{

+        struct sigaction sa;

+        sa.sa_handler=fn;

+        sigemptyset(&sa.sa_mask);

+        sa.sa_flags=0;

+        return(sigaction(signum,&sa,0));

+}

+

+static void

+sigint(int signum)

+{

+        sigint_flag=1;

+}

+

+urusai *

+urusai_init(void)

+{

+        urusai *u;

+        if((u=malloc(sizeof(urusai)))==NULL)

+                return(NULL);

+        memset(u,0,sizeof(urusai));

+        if((u->fd=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1) {

+                urusai_free(u),u=NULL;

+                return(NULL);

+        }

+        u->myaddr.sin_family=AF_INET;

+        u->myaddr.sin_port=htons(SERVERPORT);

+        u->myaddr.sin_addr.s_addr=htonl(INADDR_ANY);

+        if(bind(u->fd,(struct sockaddr *)&(u->myaddr),sizeof(u->myaddr))==-1) {

+                urusai_free(u),u=NULL;

+                return(NULL);

+        }

+        return(u);

+}

+

+void

+urusai_free(urusai *u)

+{

+        if(u==NULL)

+                return;

+        if(u->fd!=-1)

+                close(u->fd),u->fd=-1;

+        if(u->clients) {

+                free(u->clients),u->clients=NULL;

+                u->numclients=0;

+                u->sizeclients=0;

+        }

+        free(u),u=NULL;

+}

+

+client *

+urusai_clientseen(urusai *u, char *id, struct sockaddr_in *addr)

+{

+        int i,ifree;

+        client *c;

+        if(u==NULL)

+                return(NULL);

+        if(u->numclients==u->sizeclients) {

+                client *newc;

+                if((newc=realloc(u->clients,sizeof(client)*(u->sizeclients+CLIENTBLOCK)))==NULL)

+                        return(NULL);

+                u->clients=newc;

+                memset(u->clients+u->sizeclients,0,CLIENTBLOCK*sizeof(client));

+                u->sizeclients+=CLIENTBLOCK;

+        }

+        for(i=0,ifree=-1;i<u->sizeclients;i++) {

+                c=u->clients+i;

+                if(c->id[0]=='\0' && ifree==-1)

+                        ifree=i;

+                if(strcmp(id,c->id)==0)

+                        break;

+        }

+        if(i==u->sizeclients) {

+                if(ifree==-1)

+                        return(NULL);

+                i=ifree;

+                c=u->clients+i;

+                strncpy(c->id,id,sizeof(c->id));

+                c->id[sizeof(c->id)-1]='\0';

+        }

+        c->lastrecv=time(NULL);

+        memcpy(&(c->addr),addr,sizeof(c->addr));

+        return(c);

+}

+

+int

+urusai_clientdeleteold(urusai *u, int timeout)

+{

+        time_t cuttime;

+        int i;

+        client *c;

+        if(u==NULL)

+                return(-1);

+        cuttime=time(NULL)-timeout;

+        for(i=0;i<u->sizeclients;i++) {

+                c=u->clients+i;

+                if(c->id[0]=='\0' || c->lastrecv>cuttime)

+                        continue;

+                memset(c,0,sizeof(client));

+        }

+        return(0);

+}

+

+client *

+urusai_clientget(urusai *u, char *id)

+{

+        int i;

+        client *c;

+        if(u==NULL || id[0]=='\0')

+                return(NULL);

+        for(i=0;i<u->sizeclients;i++) {

+                c=u->clients+i;

+                if(strcmp(id,c->id)==0)

+                        return(c);

+        }

+        return(NULL);

+}

+

+int

+urusai_send(urusai *u, char *outbuf, int outbuf_used, client *destclient)

+{

+        struct sockaddr_in to;

+        if(u==NULL || outbuf==NULL || outbuf_used<=0 || destclient==NULL)

+                return(-1);

+        memcpy(&to,&(destclient->addr),sizeof(to));

+        if(sendto(u->fd,outbuf,outbuf_used,0,(struct sockaddr *)&to,sizeof(to))==-1)

+                return(-1);

+        return(0);

+}

+

+int

+msg_parse(char *inbuf, int inbuf_used,char **serial,char **origid,char **destid,char **cmd, char **contents)

+{

+        char *ptr;

+        if(inbuf==NULL || inbuf_used<=0)

+                return(-1);

+        *serial=inbuf;

+        if((ptr=memchr(*serial,0,inbuf_used-(*serial-inbuf)))==NULL)

+                return(-1);

+        *origid=ptr+1;

+        if((ptr=memchr(*origid,0,inbuf_used-(*origid-inbuf)))==NULL)

+                return(-1);

+        *destid=ptr+1;

+        if((ptr=memchr(*destid,0,inbuf_used-(*destid-inbuf)))==NULL)

+                return(-1);

+        *cmd=ptr+1;

+        if((ptr=memchr(*cmd,0,inbuf_used-(*cmd-inbuf)))==NULL)

+                return(-1);

+        *contents=ptr+1;

+        if((ptr=memchr(*contents,0,inbuf_used-(*contents-inbuf)))==NULL)

+                return(-1);

+        return(0);

+}

+

+int msg_compose(char *outbuf, int bufsize, char *serial, char *origid, char *destid, char *cmd, char *contents)

+{

+        int totallen,len;

+        char *ptr;

+        if(outbuf==NULL || bufsize<=0 || serial==NULL)

+                return(-1);

+        totallen=strlen(serial)+1+

+                ((origid==NULL)?0:strlen(origid))+1+

+                ((destid==NULL)?0:strlen(destid))+1+

+                ((cmd==NULL)?0:strlen(cmd))+1+

+                ((contents==NULL)?0:strlen(contents))+1;

+        if(totallen>bufsize || totallen>MAXPACKETSIZE)

+                return(-1);

+        ptr=outbuf;

+        len=strlen(serial);

+        memcpy(ptr,serial,len),ptr+=len;

+        *(ptr++)=0;

+        len=(origid==NULL)?0:strlen(origid);

+        memcpy(ptr,origid,len),ptr+=len;

+        *(ptr++)=0;

+        len=(destid==NULL)?0:strlen(destid);

+        memcpy(ptr,destid,len),ptr+=len;

+        *(ptr++)=0;

+        len=(cmd==NULL)?0:strlen(cmd);

+        memcpy(ptr,cmd,len),ptr+=len;

+        *(ptr++)=0;

+        len=(contents==NULL)?0:strlen(contents);

+        memcpy(ptr,contents,len),ptr+=len;

+        *(ptr++)=0;

+        return(ptr-outbuf);

+}

+