Thread: accept() and WSAEFAULT

Hi,
I am trying to make an echo server under Windows similar as one under Linux.

Code:

 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>
#include <ws2tcpip.h>
 
#pragma comment (lib, "ws2_32.lib")
#pragma comment (lib, "mswsock.lib")
#pragma comment (lib, "advapi32.lib")
 
 
fd_set fds_dup(fd_set* src)
{
	unsigned i;
	fd_set src_copy;
	FD_ZERO(&src_copy);
 
	src_copy.fd_count = src->fd_count;
	for (i = 0; i < src_copy.fd_count; ++i)
		src_copy.fd_array[i] = src->fd_array[i];
	return src_copy;
}
 
 
int main()
{
	WSADATA wsaData;
	SOCKET server_sock;
	const char* server_address_s = "localhost";
	const char* PORT = "7000";
	struct addrinfo* server_address;
	BOOL opt_val = FALSE;
	const unsigned int PENDING_SIZE = 5;
	fd_set read_fds;
	struct addrinfo hint;
	const struct timeval timeout = {1, 0};
 
	if (WSAStartup(MAKEWORD(2,2), &wsaData) != 0)
	{
		fprintf(stderr, "main(): error calling 'WSAStartup()'");
		WSACleanup();
		exit(EXIT_FAILURE);
	}
 
	hint.ai_family = 0;
	hint.ai_socktype = SOCK_STREAM;
	hint.ai_flags = AI_PASSIVE;
	hint.ai_protocol = 0;
	hint.ai_addrlen = 0;
	hint.ai_canonname = NULL;
	hint.ai_addr = NULL;
	hint.ai_next = NULL;
 
	if (getaddrinfo(server_address_s, PORT, &hint, &server_address) != 0)
	{
		printf("main(): cannot locate host, error code=%ld, exiting program\n", WSAGetLastError());
		WSACleanup();
		exit(EXIT_FAILURE);
	}
 
	server_sock = socket(server_address->ai_family, server_address->ai_socktype, server_address->ai_protocol);
	if (server_sock == INVALID_SOCKET)
	{
		fprintf(stderr, "main(): cannot create socket, error code=%ld, exiting program\n", WSAGetLastError());
		WSACleanup();
		exit(EXIT_FAILURE);
	}
 
	setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, (char*)&opt_val, sizeof(int));
	if (bind(server_sock, server_address->ai_addr, server_address->ai_addrlen) == SOCKET_ERROR)
	{
		printf("main(): cannot bind, error code=%ld, exiting program\n", WSAGetLastError());
		WSACleanup();
		exit(EXIT_FAILURE);
	}
 
	freeaddrinfo(server_address);
 
	if (listen(server_sock, PENDING_SIZE) == SOCKET_ERROR)
	{
		printf("main(): cannot listen, error code=%ld, exiting program\n", WSAGetLastError());
		WSACleanup();
		exit(EXIT_FAILURE);
	}
 
	FD_ZERO(&read_fds);
	FD_SET(server_sock, &read_fds);
 
	while (1)
	{
		unsigned i;
		int nfds;
		fd_set read_fds_copy;
 
 
		FD_ZERO(&read_fds_copy);
		read_fds_copy = fds_dup(&read_fds);
 
		printf("main(): while...\n");
		nfds = select(0, &read_fds_copy, NULL, NULL, NULL);
		if (nfds == SOCKET_ERROR)
		{
			printf("main(): error calling 'select()', exiting program\n");
			WSACleanup();
			exit(EXIT_FAILURE);
		}
		else if (nfds == 0)
		{
			printf("main(): select time limit expired\n");
			continue;
		}
 
		for (i = 0; i < read_fds_copy.fd_count; ++i)
		{
			SOCKET sock = read_fds_copy.fd_array[i];
			if (sock == server_sock)
			{
					// new client accepted
 
					struct sockaddr_in client_address;
					socklen_t client_address_len = sizeof(struct sockaddr);
					SOCKET client_sock;
					char addr_buf[1000];
					const char* client_address_s;
 
					client_sock = accept(server_sock, (struct sockaddr*)&client_address, &client_address_len);
					//client_sock = accept(server_sock, NULL, NULL);
					if (client_sock == INVALID_SOCKET)
					{
						printf("main(): cannot accept client, error code=%ld, sleeping\n", WSAGetLastError());
						Sleep(1000);
						continue;
					}
					printf("main(): client accepted...\n");
 
					client_address_s = inet_ntop(AF_INET, &client_address, addr_buf, INET_ADDRSTRLEN);
					if (client_address_s == NULL)
						printf("main(): cannot read client address\n");
					else
						printf("main(): client accepted from %s\n", client_address_s);
 
					FD_SET(client_sock, &read_fds);
			}
			else
			{
				// client request
 
				const int REQUEST_LEN = 1000;
				char request[1000];
				int result;
 
				memset(request, '\0', REQUEST_LEN);
				result = recv(sock, request, REQUEST_LEN, 0);
				if (result == SOCKET_ERROR)
				{
					// no request from client
 
					printf("main(): cannot receive request\n");
					closesocket(sock);
					FD_CLR(sock, &read_fds);
					continue;
				}
				else if (result == 0)
				{
					// client closed
 
					printf("main(): client closed\n");
					closesocket(sock);
					FD_CLR(sock, &read_fds);
					continue;
				}
				else
				{
					// echo client's request
 
					printf("main(): request=%s\n", request);
					result = send(sock, request, strlen(request), 0);
					if (result == SOCKET_ERROR)
					{
						fprintf(stderr, "main(): cannot send response\n");
						closesocket(sock);
						FD_CLR(sock, &read_fds);
						continue;
					}
					printf("main(): echo sent\n");
				}
			}
		}	
	}
 
	WSACleanup();
	return EXIT_SUCCESS;
}

If I put a line

Code:

client_sock = accept(server_sock, NULL, NULL);

everything works fine, but if I put

Code:

client_sock = accept(server_sock, (struct sockaddr*)&client_address, &client_address_len);

I get the error 10014. MSDN says that The addrlen parameter is too small or addr is not a valid part of the user address space, but I find that this is not a case, since client_address and client_address_len are initialized. Any ideas?

That's because client_address is casted into (struct sockaddr*). I get the same issue no matter if I put

Code:

socklen_t client_address_len = sizeof(struct sockaddr);
client_sock = accept(server_sock, (struct sockaddr*)&client_address, &client_address_len);

or

Code:

socklen_t client_address_len = sizeof(struct sockaddr_in);
client_sock = accept(server_sock, (struct sockaddr*)&client_address, &client_address_len);