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Select in an simple p2p program

Shadowofsora (1)
Heyho,
i have a rather annoying problem:
i've written a simple p2p program, that should exchange data between 3 clients
Problem: the first client i start is the only one, for whom select is 1 for every single run in the transfer loop. the other clients just get every time 0.
the first client gets all the data he should (at least that is working).

so far i tinkered a bit around, tried poll() and searched for errors, but i'm at my wits end.

Here my transfer code:

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int selecting (int fd)
{			
	struct timeval tv;
	tv.tv_sec =0;
	tv.tv_usec = rnd(50000,1000000);
	fd_set readset;
	FD_ZERO(&readset);
   	FD_SET(fd, &readset);
	int err = select(fd + 1, &readset, NULL, NULL, &tv);
	std::cout << err << "\n";
	if (err <1)
		return 0;
	if (FD_ISSET(fd,&readset))
		return 1;
	return 0;
}
...
int main()
...
case 6:
{
    if(!filename.empty())
    {
        time_t start, now;
        time(&start);
        double elapsedtime = 0;
        char *recvbuf;
        char *sendbuf;
        recvbuf = new char[1024];
        sendbuf = new char[1024];
        int recvfd, sendfd,err, port;
        int errormarker = 0;
        if((recvfd = socket(AF_INET,SOCK_DGRAM,0)) == -1)
        {
            std::cout << "Error setting socket\n";
            errormarker =1;
        }
        if(errormarker ==1)
            break;
        struct sockaddr_in server_address;
        server_address.sin_family = AF_INET;
        server_address.sin_addr.s_addr = INADDR_ANY;
        server_address.sin_port = htons(50001);
        for (int i =0; i<=9;i++)
        {
            port = 50001+i;
            errormarker = bind(recvfd,(sockaddr*) &server_address, sizeof   (server_address));
            if(errormarker ==-1)
                server_address.sin_port = htons(server_address.sin_port+1);
            else
                break;
        }
        if(errormarker == -1)
        {
            std::cout << "all ports are used, please wait a minute and try again\n";
            break;
        }
        std::cout << "Searching for other musicdata owners\n";
        fd_set readset;
        while (elapsedtime < 15)
        {
            if(errormarker != 0)
                break;
            memset(recvbuf, 0, sizeof(recvbuf));
            memset(sendbuf, 0, sizeof(sendbuf));
	    if (selecting(recvfd))
	    {
	        int result = recvfrom(recvfd, recvbuf, 1024, NULL,NULL,NULL);
	        if (result != -1)
	        {
		    buftofile(recvbuf,filename);
		    addnewdata(filename);
		    std::cout << "ARE YOU HERE?\n";
	        }
		else
		    std::cout << "error receiving data \n";
	    }
            filetobuf(sendbuf,filename);
            for(int i = 50001; i<=50010;i++)
            {
                struct addrinfo hints, *servinfo, *p;
                memset(&hints, 0, sizeof hints);
                hints.ai_family = AF_UNSPEC;
                hints.ai_socktype =SOCK_DGRAM;
                std::string s_port = to_string(i);
                err = getaddrinfo(NULL,s_port.c_str(),&hints,&servinfo);
                for(p=servinfo;p!=NULL;p=p->ai_next)                                
                {
                    if(i == port)
                    {
                        err = sendto(recvfd, sendbuf,strlen(sendbuf), 0, p->ai_addr,p->ai_addrlen);
                        continue;
                    }
                    if((sendfd = socket(p->ai_family, p->ai_socktype,p->ai_protocol)) == -1)
                    {
                        continue;
                    }
                    else
                    {
                        err=sendto(sendfd,sendbuf,strlen(sendbuf), 0, p->ai_addr,p->ai_addrlen);
                        close(sendfd);                              
                    }
                }
                freeaddrinfo(servinfo);
            }
            time(&now);
            elapsedtime=difftime(now,start);
        }
        close(recvfd);
 
    }
    else
        std::cout << "Error, please choose a file to save your data first!" << std::endl;
}
break;



and here a simplified code example, to see the problem i have:

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#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <unistd.h>
#include <iostream>
#include <string>
#include <cstring>
#include <limits>
#include <fstream>
#include <time.h>
#include <netdb.h>
#include<sstream>
 
std::string to_string(int value)
{
//create an output string stream
    std::ostringstream os ;
//throw the value into the string stream
    os << value ;
//convert the string stream into a string and return
    return os.str() ;
}
 
int rnd(int start, int range)
{
    srand (time(NULL));
    return rand() % range + start;
}
 
int main()
{
 
    std::fstream fs;
    std::string filename, tmpline;
    filename = "test";
    time_t start, now;
    time(&start);
    double elapsedtime = 0;
    char *recvbuf;
    char *sendbuf;
    recvbuf = new char[1024];
    sendbuf = new char[1024];
    int recvfd, sendfd,err, port;
    int errormarker = 0;
    if((recvfd = socket(AF_INET,SOCK_DGRAM,0)) == -1)
    {
        std::cout << "Error setting socket\n";
        errormarker =1;        
    }
    struct sockaddr_in server_address;
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = INADDR_ANY;
    server_address.sin_port = htons(50001);
    for (int i =0; i<=9;i++)
    {
        port = 50001+i;
        errormarker = bind(recvfd,(sockaddr*) &server_address, sizeof   (server_address));
        if(errormarker ==-1)
            server_address.sin_port = htons(server_address.sin_port+1);
        else
            break;
    }
    if(errormarker == -1)
    {
        std::cout << "all ports are used, please wait a minute and try again\n";
    }
    std::cout << "Searching for other musicdata owners\n";
    fd_set readset;
    while (elapsedtime < 15)
    {
        if(errormarker != 0)
            break;
        memset(recvbuf, 0, sizeof(recvbuf));
        memset(sendbuf, 0, sizeof(sendbuf));
        struct timeval tv;
        tv.tv_sec =0;
        tv.tv_usec = rnd(10000,50000);
        FD_ZERO(&readset);
        FD_SET(recvfd, &readset);
        int result = select(recvfd + 1, &readset, NULL, NULL, &tv);
        std::cout << result << "\n";
        if (result >0)
        {
            result = recvfrom(recvfd, recvbuf, 1024, NULL,NULL,NULL);
            if (result != -1)
            {
                fs.open("test",  std::fstream::in | std::fstream::out | std::fstream::app);
                fs << recvbuf << "\n";
                fs.close();
            }
            else
                std::cout << "error receiving data \n";
        }
        for(int i = 50001; i<=50010;i++)
        {
            std::cout << "for\n";
            struct addrinfo hints, *servinfo, *p;
            memset(&hints, 0, sizeof hints);
            hints.ai_family = AF_UNSPEC;
            hints.ai_socktype =SOCK_DGRAM;
            std::string s_port = to_string(i);
            err = getaddrinfo(NULL,s_port.c_str(),&hints,&servinfo);
            for(p=servinfo;p!=NULL;p=p->ai_next)                               
            {
                if(i == port)
                {
                    err = sendto(recvfd, "Hello from Client 1",20, 0, p->ai_addr,p->ai_addrlen);
                    continue;
                }
                if((sendfd = socket(p->ai_family, p->ai_socktype,p->ai_protocol)) == -1)
                {
                    continue;
                }
                else
                {
                    err=sendto(sendfd,"Hello from Client 1",20, 0, p->ai_addr,p->ai_addrlen);
                    close(sendfd);
                }
            }
                        freeaddrinfo(servinfo);
        }
        time(&now);
        elapsedtime=difftime(now,start);
    }
    close(recvfd);             
}


thanks in advance for the help
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