c++ - Udp_client_server_using Multi-threading -

i implented basic udp client server application using multi threading thread not invoking...can body me..

class uu_frameworksocket  {  protected: struct sockaddr_in modulemysocketaddress; uu_int32 modulehostportk; uu_char* modulehostnamek; uu_int32 modulesockflagk; uu_int32* modulesockoptvaluep;  public: uu_void uu_moduleinitsocket(uu_int32,uu_int32); uu_void uu_modulesetsocketoptions(uu_int32); uu_void sethostname(uu_char* ); uu_void setportnumber(uu_int32 ); uu_void uu_moduleclosesocket(uu_int32 ); uu_frameworksocket(){          modulehostportk = 3232;         modulehostnamek = (uu_char*) malloc(20);         strcpy(modulehostnamek,"127.0.0.1");     } };  uu_void uu_frameworksocket :: sethostname(uu_char *pshostname){ modulehostnamek = (uu_char*) malloc(20); strcpy(modulehostnamek,pshostname); }  uu_void uu_frameworksocket :: setportnumber(uu_int32 iportnumber){ modulehostportk=iportnumber; }   uu_void uu_frameworksocket :: uu_moduleclosesocket(uu_int32 isocketfd){ close(isocketfd); }   uu_void uu_frameworksocket :: uu_moduleinitsocket(uu_int32 itypefamily,uu_int32 itypeprotocol){ if(itypefamily == uu_project_module_ipv4) { if(itypeprotocol == uu_project_module_tcp) modulesockflagk = socket(af_inet, sock_stream, 0); else modulesockflagk = socket(af_inet, sock_dgram, 0); } else { if(itypeprotocol == uu_project_module_tcp) modulesockflagk = socket(af_inet6, sock_stream, 0); else modulesockflagk = socket(af_inet6, sock_dgram, 0); } if (modulesockflagk == -1){             printf("error while initializing socket.\n");             exit(0);         }  }  uu_void uu_frameworksocket :: uu_modulesetsocketoptions(uu_int32 itypefamily){ modulesockoptvaluep = (uu_int32*)malloc(sizeof(uu_int32));         *modulesockoptvaluep = 1;          if( (setsockopt(modulesockflagk, sol_socket, so_reuseaddr,    (uu_char*)modulesockoptvaluep, sizeof(uu_int32)) == -1 ) ){             printf("error while setting socket options.\n");             free(modulesockoptvaluep);             exit(0);         }         free(modulesockoptvaluep);         if(itypefamily == uu_project_module_ipv4)         modulemysocketaddress.sin_family = af_inet ;         else         modulemysocketaddress.sin_family = af_inet6 ;                    modulemysocketaddress.sin_port = htons(modulehostportk);         memset(&(modulemysocketaddress.sin_zero), 0, 8);                     modulemysocketaddress.sin_addr.s_addr = inet_addr(modulehostnamek);  }   class uu_projectmoduleudp : public uu_frameworksocket { protected:     socklen_t modulemysockaddrlength;     uu_int32* modulesockconnflag;     sockaddr_in moduleipsockaddr;     pthread_t modulethreadid;  public:  struct request{ sockaddr_in moduleclientsockaddr; uu_int32 moduleclientsocket; };  uu_void moduleudpbind(){         if( bind( modulesockflagk, (sockaddr*)&modulemysocketaddress,    sizeof(modulemysocketaddress)) == -1 ){             fprintf(stderr,"error while binding socket:%d\n",errno);             exit(0);         }     }   uu_void moduleudpaccept(){         modulemysockaddrlength = sizeof(sockaddr_in);         uu_char msg[100];         uu_int32 n;     struct request modulerequeststructure;         while(true){                 if(( n= recvfrom( modulesockflagk,msg,100,0, (sockaddr*)&moduleipsockaddr, &modulemysockaddrlength))!= -1){                 printf("==\nreceived connection  %s\n",inet_ntoa(moduleipsockaddr.sin_addr));                 printf("received message: %s \n",msg);                 sendto( modulesockflagk,msg,n,0, (sockaddr*)&moduleipsockaddr, modulemysockaddrlength);                  modulerequeststructure.moduleclientsockaddr=moduleipsockaddr;                  modulerequeststructure.moduleclientsocket=modulesockflagk;                 pthread_create(&modulethreadid,0,&moduleudpsockethandler,  (uu_void*)&modulerequeststructure );                 pthread_detach(modulethreadid);             }             else{                 fprintf(stderr, "error accepting... %d\n", errno);             }         }     }  static uu_void* moduleudpsockethandler(uu_void* modulerequeststruct){          request *modulerequest=(request *)modulerequeststruct;         uu_int32 iclientsocket=modulerequest->moduleclientsocket;         sockaddr_in clientsockaddr=modulerequest->moduleclientsockaddr;     socklen_t modulemysockaddrlength = sizeof(sockaddr_in);         uu_char acbuffer[1024];         uu_int32 ibufferlen = 1024;         uu_int32 ibytecount;          while(true){             memset(acbuffer, '\0', ibufferlen);             if((ibytecount = recvfrom(iclientsocket,acbuffer,ibufferlen,0,(sockaddr*)&clientsockaddr,&modulemysockaddrlength))== -1){                 fprintf(stderr, "error receiving data %d\n", errno);                 exit(0);             }             printf("received bytes: %d\nreceived string: %s \n", ibytecount, acbuffer);              if((ibytecount = sendto(iclientsocket, acbuffer, strlen(acbuffer), 0,(sockaddr*)&clientsockaddr,modulemysockaddrlength))== -1){                 fprintf(stderr, "error sending data %d\n", errno);                 exit(0);              }              printf("sent bytes %d\n", ibytecount);         }     }   uu_void moduleudpafterconn(){         uu_char acbuffer[1024];         uu_int32 ibytecount;         uu_int32 ibufferlen=0;         modulemysockaddrlength = sizeof(sockaddr_in);         ibufferlen = 1024;          while(true){             memset(acbuffer, '\0', ibufferlen);              printf("enter text send server (press enter):\n");             fgets(acbuffer, 1024, stdin);             acbuffer[strlen(acbuffer)-1]='\0';              if( (ibytecount=sendto(modulesockflagk, acbuffer, strlen(acbuffer),0,(sockaddr*)&modulemysocketaddress,modulemysockaddrlength))== -1){                 fprintf(stderr, "error sending data %d\n", errno);                 exit(0);             }             printf("sent bytes %d\n", ibytecount);              if((ibytecount = recvfrom(modulesockflagk, acbuffer, ibufferlen, 0,null,null))== -1){                 fprintf(stderr, "error receiving data %d\n", errno);                 exit(0);             }             printf("recieved bytes: %d\nreceived string: \"%s\"\n", ibytecount, acbuffer);         }         close(modulesockflagk);     }  };  int main(int argc, char **argv){  if(strcmp(argv[1],"udp")==0){ if(strcmp(argv[2],"server")==0){     printf("this udp server");     uu_projectmoduleudp server;     server.setportnumber(6745);     server.uu_moduleinitsocket(uu_project_module_ipv4,uu_project_module_udp);     server.uu_modulesetsocketoptions(uu_project_module_ipv4);     server.moduleudpbind();     server.moduleudpaccept();  }  else if(strcmp(argv[2],"client")==0){     printf("this udp client");     uu_projectmoduleudp client;     client.setportnumber(6745);     client.uu_moduleinitsocket(uu_project_module_ipv4,uu_project_module_udp);     client.uu_modulesetsocketoptions(uu_project_module_ipv4);     client.moduleudpafterconn();  } }  else     printf("wrong/missing arguments\n"); return 0; } 

here each client thread has invoked not invoking..

what happening thread crashes. reason undefined behavior when try access modulerequest pointer, points local variable inside moduleudpaccept.

when moduleudpaccept returns, pointer no longer pointing valid memory, , undefined behavior, may (or may not) cause thread crash.