HI
I want to create a UDP concurrent server
can any one give the code for UDP concurrent server
Threaded or not?
Which OS?
Hi can u please send the code for this if u have
thanks regards
Please take a look at the tftpd source at:
Inetutils - GNU internet utilities.
There are numerous non-trivial problems with using udp concurrently and reliably.
As an exercise this threaded example which is pretty broken.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/select.h>
#include <fcntl.h>
#include <pthread.h>
int numthreads = 0;
pthread_mutex_t threadwatch = PTHREAD_MUTEX_INITIALIZER;
char *OOSMSG = "Maximum connections exceeded.\n";
#define noblock(sck) (fcntl(sck,F_SETFL,O_NONBLOCK))
#define DSZ 256
#define ACREDLEN 20
#define MAXTHREADS 20
typedef struct _assoc_data_ {
int msgnum;
short data_type_id;
char reserved;
char assoc_auth_creds[ACREDLEN];
char data[DSZ];
} APKT;
void decrement_threadcount(void) {
pthread_mutex_lock(&threadwatch);
numthreads--;
pthread_mutex_unlock(&threadwatch);
}
void increment_threadcount(void) {
pthread_mutex_lock(&threadwatch);
numthreads++;
pthread_mutex_unlock(&threadwatch);
}
void print_apkt(APKT dta) {
printf("Msgnum = %d, data_type_id = %d,reserved = %c\n \
assoc_auth_creds = %s, data = %s\n",dta.msgnum,dta.data_type_id,dta.reserved,dta.assoc_auth_creds,dta.data);
}
void *handleclient(void *sck) {
int privsock, tsz, sock;
short syn_ack = 0x11;
APKT rdata;
struct sockaddr_in relation, peer;
pthread_detach(pthread_self());
memcpy(&sock,sck,sizeof(sock));
bzero(&rdata,sizeof(rdata));
tsz = sizeof(relation);
increment_threadcount();
/*reading data like the below is broken across various machine specific boundaries, byte ordering, word size, etc..buyer beware*/
if (recvfrom(sock,&rdata,sizeof(rdata),0,(struct sockaddr *)&relation,&tsz) <= 0) {
perror("recvfrom()");
decrement_threadcount();
pthread_exit(NULL);
}
print_apkt(rdata);
if ( (privsock = retudpsrv("0.0.0.0",0)) < 0) {decrement_threadcount(); pthread_exit(NULL);}
/*for udp concurrency one should bind an ephemeral port and re-negotiate with the client for communication on the new port->address. One should also find the interface
that the original packet arrived on and only bind this address. */
noblock(privsock);
sendto(privsock,&syn_ack,sizeof(syn_ack),0,(struct sockaddr *)&relation,tsz); /*acknowledge data receipt*/
/*process data in rdata, verify peer credentials and transaction signature/viability and finally send back result to client here*/
close(privsock);
decrement_threadcount();
pthread_exit(NULL);
}
int retudpsrv(char *addr, int pno) {
int sck, option = 1;
struct sockaddr_in srv;
bzero(&srv,sizeof(srv));
srv.sin_addr.s_addr = inet_addr(addr);
srv.sin_port = htons(pno);
srv.sin_family = AF_INET;
if ( (sck = socket(AF_INET,SOCK_DGRAM,0)) < 0) {
perror("socket()");
return -1;
}
setsockopt(sck,SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
/*could and should use IP options for IF and RECVADDR here for recvmsg, but this is more complicated than desirable for an example*/
noblock(sck);
if (bind(sck,(struct sockaddr *)&srv,sizeof(srv)) < 0) {
perror("bind()");
return -1;
}
return sck;
}
int main(int argc, char **argv) {
int vopt,sock;
fd_set fds;
pthread_t tids[MAXTHREADS];
if (argc != 3) {printf("Please specify:\n1) Address to bind\n2)Port number to bind\n"); exit(1);}
if ( (sock = retudpsrv(argv[1],atoi(argv[2]))) < 0) {return -1;}
FD_ZERO(&fds);
FD_SET(sock,&fds);
noblock(sock);
while (1) {
if ( (vopt = select(sock + 1,&fds,NULL,NULL,NULL)) < 0) {
perror("select()");
return -1;
}
/*select may return a number of times before data becomes available to the client handler..this causes multiple thread creation
and overhead..with non-blocking i/o and quick exits for bad reads it's fairly painless but this is still bad design in a production
server*/
if (numthreads >= MAXTHREADS) {continue;}
pthread_create(&tids[numthreads],NULL,handleclient,(void *)&sock);
printf("Currently handling client. %d threads in use.\n",numthreads);
}
}
Thanks for sending server code but we are not able to map to the client
could u please send the client code too.
Buy W.Richard Stevens "Unix Network Programming".
You'll learn nothing if you put forth zero effort.
hi thanks for advice
but we don't have that much time to study the book and understand the subject thats why i asked to u to send the code for client also for the deadline is 24 th of this month
please send me the code if u have
and y r u using this short syn_ack = 0x11; variable while sending to the client ,
for udp concurrency one should bind an ephemeral port and re-negotiate with the client for communication on the new port->address. One should also find the interface
that the original packet arrived on and only bind this address
here should we bind in the client also or simple client can manage connection to this server code pleaswe clarify with this
Dude..seriously...you can't maintain the code or produce it without understanding the mechanics. Buy the book...read it and use it. I'm sure google is available as well.
If you have specific questions then I'm sure people will help..otherwise this is nonsense and a waste of my time.
I agree with Ramon_Noodle. Get the book and study up on how to write your OWN code.