there and back again, a hobbits tail

Makefile

@@ -1,20 +1,26 @@
 CC = gcc
-OUT = dnstun
+DNS = dnstun
-OBJS = dnstun.o tun.o dns.o
+DNSOBJS = dnstun.o tun.o dns.o
+DNSD = dnstund
+DNSDOBJS = dnstund.o tun.o dnsd.o
 
 OS = `uname | tr "a-z" "A-Z"`
 
 LDFLAGS = 
 CFLAGS = -c -g -Wall -D$(OS)
 
-all: stateos $(OUT)
+all: stateos $(DNS) $(DNSD)
 
 stateos:
 	@echo OS is $(OS)
 
-$(OUT): $(OBJS)
+$(DNS): $(DNSOBJS)
 	@echo LD $@
-	@$(CC) $(OBJS) -o $(OUT) $(LDFLAGS)
+	@$(CC) $(DNSOBJS) -o $(DNS) $(LDFLAGS)
+
+$(DNSD): $(DNSDOBJS)
+	@echo LD $@
+	@$(CC) $(DNSDOBJS) -o $(DNSD) $(LDFLAGS)
 
 .c.o: 
 	@echo CC $<
@@ -22,7 +28,5 @@ $(OUT): $(OBJS)
 
 clean:
 	@echo "Cleaning..."
-	@rm -f $(OUT) *~ *.o *.core
+	@rm -f $(DNS) $(DNSD) *~ *.o *.core
 
-run: $(OUT)
-	./$(OUT)

dnsd.c

@@ -0,0 +1,236 @@
+/*
+ * Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <arpa/nameser.h>
+#include <netdb.h>
+#include <time.h>
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "dns.h"
+
+static int host2dns(const char *, char *, int);
+
+struct sockaddr_in peer;
+char topdomain[256];
+
+static int
+readname(char *packet, char *dst, char *src)
+{
+	char l;
+	int len;
+	int offset;
+
+	len = 0;
+
+	while(*src) {
+		l = *src++;
+		len++;
+
+		if(l & 0x80 && l & 0x40) {
+			offset = ((src[-1] & 0x3f) << 8) | src[0];		
+			readname(packet, dst, packet + offset);
+			dst += strlen(dst);
+			break;
+		}
+
+		while(l) {
+			*dst++ = *src++;
+			l--;
+			len++;
+		}
+
+		*dst++ = '.';
+	}
+
+	*dst = '\0';
+	src++;
+	len++;
+
+	return len;
+}
+
+#define READNAME(packet, dst, src) (src) += readname((packet), (dst), (src));
+
+#define READSHORT(dst, src) \
+	(dst) = ntohs(*(short*)(src)); (src)+=2; 
+
+#define READLONG(dst, src) \
+	(dst) = ntohl(*(long*)(src)); (src)+=4; 
+
+#define READDATA(dst, src, len) \
+	memcpy((dst), (src), (len)); (src)+=(len);
+
+int 
+open_dnsd(const char *domain) 
+{
+	int fd;
+	int flag;
+	struct sockaddr_in addr;
+
+	bzero(&addr, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_port = htons(53);
+	addr.sin_addr.s_addr = htonl(INADDR_ANY);
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if(fd < 0) {
+		warn("socket");
+		return 0;
+	}
+
+	flag = 1;
+#ifdef SO_REUSEPORT
+	setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &flag, sizeof(flag));
+#endif
+	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag));
+
+	if(bind(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
+		warn("bind");
+		return 0;
+	}
+
+	printf("Opened UDP socket\n");
+
+	return fd;
+}
+
+void
+close_dnsd(int fd)
+{
+	close(fd);
+}
+
+static int
+host2dns(const char *host, char *buffer, int size)
+{
+	char *h;
+	char *p;
+	char *word;
+
+	h = strdup(host);
+	memset(buffer, 0, size);
+	p = buffer;
+	
+	word = strtok(h, ".");
+	while(word) {
+		*p++ = (char)strlen(word);
+		memcpy(p, word, strlen(word));
+		p += strlen(word);
+
+		word = strtok(NULL, ".");
+	}
+
+	*p++ = 0;
+
+	free(h);
+
+	return p - buffer;
+}
+
+static void
+dnsd_respond(int fd, struct sockaddr_in from)
+{
+	int len;
+	int size;
+	HEADER *header;
+	char *p;
+	char buf[1024];
+
+	memset(buf, 0, sizeof(buf));
+
+	len = 0;
+	header = (HEADER*)buf;	
+
+	header->id = 0;
+	header->qr = 1;
+	header->opcode = 0;
+	header->aa = 1;
+	header->tc = 0;
+	header->rd = 0;
+	header->ra = 0;
+
+	header->ancount = htons(1);
+
+	p = buf + sizeof(HEADER);
+	
+	p += host2dns("fluff", p, 5);	
+	PUTSHORT(T_PTR, p);
+	PUTSHORT(C_IN, p);
+	PUTLONG(htons(3600), p);
+
+	size = host2dns("mupp", p+2, 4);
+	PUTSHORT(size, p);
+	p += size;
+
+	len = p - buf;
+	printf("%d\n", len);
+	sendto(fd, buf, len, 0, (struct sockaddr*)&from, sizeof(from));
+}
+
+int
+dnsd_read(int fd, char *buf, int buflen)
+{
+	int i;
+	int r;
+	short type;
+	short class;
+	short qdcount;
+	char *data;
+	char name[255];
+	HEADER *header;
+	socklen_t addrlen;
+	char packet[64*1024];
+	struct sockaddr_in from;
+
+	addrlen = sizeof(struct sockaddr);
+	r = recvfrom(fd, packet, sizeof(packet), 0, (struct sockaddr*)&from, &addrlen);
+
+	printf("Read %d bytes DNS query from %s\n", r, inet_ntoa(from.sin_addr));
+
+	if(r == -1) {
+		perror("recvfrom");
+	} else {
+		header = (HEADER*)packet;
+		
+		data = packet + sizeof(HEADER);
+
+		if(!header->qr) {
+			qdcount = ntohs(header->qdcount);		
+
+			for(i=0;i<qdcount;i++) {
+				bzero(name, sizeof(name));
+				READNAME(packet, name, data);
+				READSHORT(type, data);
+				READSHORT(class, data);
+				
+				printf("%s %d %d\n", name, type, class);
+				
+				dnsd_respond(fd, from);
+			}
+		}
+	}
+
+	return 0;
+}

dnsd.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef _DNSD_H_
+#define _DNSD_H_
+
+extern struct sockaddr_in peer;
+
+int open_dnsd(const char *);
+void close_dnsd(int);
+
+int dnsd_read(int, char *, int);
+
+
+#endif /* _DNSD_H_ */

dnstund.c

@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <err.h>
+
+#include "tun.h"
+#include "dns.h"
+#include "dnsd.h"
+
+#define MAX(a,b) ((a)>(b)?(a):(b))
+
+int running = 1;
+
+static void
+sigint(int sig) {
+	running = 0;
+}
+
+static int
+tunnel(int tun_fd, int dns_fd)
+{
+	int i;
+	int read;
+	fd_set fds;
+	char buf[1024];
+	struct timeval tv;
+	
+	while (running) {
+		tv.tv_sec = 1;
+		tv.tv_usec = 0;
+
+		FD_ZERO(&fds);
+		FD_SET(tun_fd, &fds);
+		FD_SET(dns_fd, &fds);
+
+		i = select(MAX(tun_fd, dns_fd) + 1, &fds, NULL, NULL, &tv);
+		
+		if(i < 0) {
+			if (running) {
+				warn("select");
+			}
+			return 1;
+		}
+		
+		if(i != 0) {
+			if(FD_ISSET(tun_fd, &fds)) {
+				
+			}
+			if(FD_ISSET(dns_fd, &fds)) {
+				read = dnsd_read(dns_fd, buf, sizeof(buf));
+			} 
+		}
+	}
+
+	return 0;
+}
+
+int
+main(int argc, char **argv)
+{
+	int tun_fd;
+	int dnsd_fd;
+
+	if (argc != 2) {
+		printf("Usage: %s topdomain\n", argv[0]);
+		exit(2);
+	}
+
+	tun_fd = open_tun();
+	dnsd_fd = open_dnsd(argv[1]);
+
+	signal(SIGINT, sigint);
+	
+	tunnel(tun_fd, dnsd_fd);
+
+	printf("Closing tunnel\n");
+
+	close_dnsd(dnsd_fd);
+	close_tun(tun_fd);	
+
+	return 0;
+}