fix rfc1929 user/pass auth subnegotation response version field

the version field is repurposed here to mean "version of the subnegotation",
which in this case is 1, not 5, as intuitively expected.
interestingly, most socks5 clients don't check the version respond, rather
only the success field.

Author: rofl0r

sockssrv.c

@@ -214,9 +214,9 @@ static void add_auth_ip(struct client*client) {
 	pthread_mutex_unlock(&auth_ips_mutex);
 }
 
-static void send_auth_response(int fd, enum authmethod meth) {
+static void send_auth_response(int fd, int version, enum authmethod meth) {
 	unsigned char buf[2];
-	buf[0] = 5;
+	buf[0] = version;
 	buf[1] = meth;
 	write(fd, buf, 2);
 }
@@ -293,12 +293,12 @@ static void* clientthread(void *data) {
 				am = check_auth_method(buf, n, &t->client);
 				if(am == AM_NO_AUTH) t->state = SS_3_AUTHED;
 				else if (am == AM_USERNAME) t->state = SS_2_NEED_AUTH;
-				send_auth_response(t->client.fd, am);
+				send_auth_response(t->client.fd, 5, am);
 				if(am == AM_INVALID) goto breakloop;
 				break;
 			case SS_2_NEED_AUTH:
 				ret = check_credentials(buf, n);
-				send_auth_response(t->client.fd, ret);
+				send_auth_response(t->client.fd, 1, ret);
 				if(ret != EC_SUCCESS)
 					goto breakloop;
 				t->state = SS_3_AUTHED;