Udp_client_server_using Multi-threading - c++

Question

I implented basic udp client server application using multi threading but actually the thread is not invoking...can any body help 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 to 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 from %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 some text to send to the 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 is 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 is 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 for each client a thread has to be invoked but it is not invoking..

Answer 1

What is probably happening is that your thread crashes. The reason would be undefined behavior when you try to access the ModuleRequest pointer, as it points to a local variable inside ModuleUdpAccept.
When ModuleUdpAccept returns, that pointer is no longer pointing to valid memory, and you get undefined behavior, which may (or may not) cause the thread to crash.