Purely forwarding DNS proxy

Specified many CFLAGS
Corrected configure.in

.gitignore

@@ -5,6 +5,7 @@ configure
 depcomp
 install-sh
 missing
+config.cache
 config.log
 config.status
 src/.deps/
@@ -13,3 +14,10 @@ src/Makefile.in
 Makefile
 src/Makefile
 INSTALL
+
+# build
+*.o
+wrapsix-dnsproxy
+
+# debug
+core

configure.in

@@ -1,7 +1,11 @@
 AC_INIT([WrapSix], [0.1.99.0], [xhire@mujmalysvet.cz])
 AM_INIT_AUTOMAKE([-Wall -Werror])
 AC_PROG_CC
-AC_OUTPUT([
+AC_CONFIG_FILES([
 	Makefile
 	src/Makefile
 ])
+
+CFLAGS="-g -ggdb -O0 -pipe -Wall -Wshadow -Wall -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wold-style-definition -Wdeclaration-after-statement -Wmissing-declarations -Wmissing-prototypes -Wredundant-decls -Wmissing-noreturn -Wshadow -Wpointer-arith -Wcast-align -Wwrite-strings -Winline -Wformat-nonliteral -Wformat-security -Wswitch-enum -Wswitch-default -Winit-self -Wmissing-include-dirs -Wundef -Waggregate-return -Wmissing-format-attribute -Wnested-externs -Wunsafe-loop-optimizations"
+
+AC_OUTPUT

src/Makefile.am

@@ -1,2 +1,2 @@
-bin_PROGRAMS = wrapsix-dnsproxy
+sbin_PROGRAMS = wrapsix-dnsproxy
 wrapsix_dnsproxy_SOURCES = dnsproxy.c

src/dnsproxy.c

@@ -0,0 +1,143 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2009  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 of the
+ *  License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>		/* inet_pton */
+#include <unistd.h>		/* close */
+#include <string.h>		/* memcpy */
+
+#define BUFFER_SIZE	512		/* maximum of a DNS packet */
+#define IP		"::2"
+#define RESOLVER	"::1"
+#define PORT		53
+
+int resolver_connect(int *sock, struct sockaddr_in6 *sock_addr);
+int udp_receive(int *sock, struct sockaddr_in6 *sock_addr, char *buffer, int *length);
+int udp_send(int *sock, struct sockaddr_in6 *sock_addr, char *data, int length);
+
+int resolver_connect(int *sock, struct sockaddr_in6 *sock_addr)
+{
+	int tmp_sock;
+	struct sockaddr_in6 tmp_sock_addr;
+	char resolver[] = RESOLVER;
+
+	/* create a socket */
+	if ((tmp_sock = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
+		fprintf(stderr, "[Error] Unable to create UDP socket for outgoing connections\n");
+		return 1;
+	}
+
+	/* setup the socket */
+	tmp_sock_addr.sin6_family = AF_INET6;
+	tmp_sock_addr.sin6_port = htons(PORT);
+	inet_pton(AF_INET6, (char *) &resolver, &(tmp_sock_addr.sin6_addr));
+
+	/* return correct data */
+	memcpy(sock, &tmp_sock, sizeof(int));
+	memcpy(sock_addr, &tmp_sock_addr, sizeof(struct sockaddr_in6));
+
+	return 0;
+}
+
+int udp_receive(int *sock, struct sockaddr_in6 *sock_addr, char *buffer, int *length)
+{
+	int tmp_length;
+	int addrlen;
+
+	addrlen = sizeof(struct sockaddr_in6);
+	if ((tmp_length = recvfrom(*sock, buffer, BUFFER_SIZE, 0, (struct sockaddr *) sock_addr, (socklen_t *) &addrlen)) == -1) {
+		char str_ip[128];
+		inet_ntop(AF_INET6, &(sock_addr->sin6_addr), (char *) &str_ip, 128);
+
+		fprintf(stderr, "[Error] Unable to read from UDP socket [%s]:%d\n", str_ip, PORT);
+
+		return 1;
+	}
+
+	memcpy(length, &tmp_length, sizeof(int));
+
+	return 0;
+}
+
+int udp_send(int *sock, struct sockaddr_in6 *sock_addr, char *data, int length)
+{
+	int addrlen;
+
+	addrlen = sizeof(struct sockaddr_in6);
+	if (sendto(*sock, data, length, 0, (struct sockaddr *) sock_addr, addrlen) != length) {
+		char str_ip[128];
+		inet_ntop(AF_INET6, &(sock_addr->sin6_addr), (char *) &str_ip, 128);
+
+		fprintf(stderr, "[Error] Unable to write to UDP socket [%s]:%d\n", str_ip, PORT);
+		return 1;
+	}
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int length;
+
+	char ip[] = IP;
+	char buffer[BUFFER_SIZE];
+
+	int sock;
+	struct sockaddr_in6 sock_addr,
+			    client_sock_addr;
+
+	int resolver_sock;
+	struct sockaddr_in6 resolver_sock_addr;
+
+	/* create the socket */
+	if ((sock = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
+		fprintf(stderr, "[Error] Unable to create UDP socket\n");
+		return 1;
+	}
+
+	/* setup the socket */
+	sock_addr.sin6_family = AF_INET6;
+	sock_addr.sin6_port = htons(PORT);
+	inet_pton(AF_INET6, (char *) &ip, &(sock_addr.sin6_addr));
+
+	/* bind the socket to address and port */
+	if (bind(sock, (struct sockaddr *) &(sock_addr), sizeof(sock_addr)) == -1) {
+		fprintf(stderr, "[Error] Unable to bind UDP socket to %s:%d\n", IP, PORT);
+		return 1;
+	}
+
+	/* fetch a request */
+	udp_receive(&sock, &client_sock_addr, (char *) &buffer, &length);
+
+	/* forward it to resolver */
+	resolver_connect(&resolver_sock, &resolver_sock_addr);
+	udp_send(&resolver_sock, &resolver_sock_addr, (char *) &buffer, length);
+
+	/* fetch the answer and forward it to the client */
+	udp_receive(&resolver_sock, &resolver_sock_addr, (char *) &buffer, (int *) &length);
+	udp_send(&sock, &client_sock_addr, (char *) &buffer, length);
+
+	/* clean-up */
+	close(resolver_sock);
+
+	/* final clean-up */
+	close(sock);
+
+	return 0;
+}