mirror of
https://github.com/yarrick/iodine.git
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482 lines
9 KiB
C
482 lines
9 KiB
C
/*
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* Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <arpa/nameser.h>
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#ifdef DARWIN
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#include <arpa/nameser8_compat.h>
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#endif
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#include <netdb.h>
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#include <time.h>
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#include <err.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <string.h>
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#include <ctype.h>
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#include "structs.h"
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#include "dns.h"
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#include "encoding.h"
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#include "read.h"
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// For FreeBSD
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#ifndef MIN
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#define MIN(a,b) ((a)<(b)?(a):(b))
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#endif
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static int dns_write(int, int, char *, int, char);
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static void dns_query(int, int, char *, int);
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struct sockaddr_in peer;
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char topdomain[256];
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// Current IP packet
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char activepacket[4096];
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int lastlen;
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int packetpos;
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int packetlen;
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uint16_t chunkid;
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uint16_t pingid;
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int
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open_dns(const char *domain, int localport, in_addr_t listen_ip)
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{
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int fd;
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int flag;
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struct sockaddr_in addr;
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bzero(&addr, sizeof(addr));
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addr.sin_family = AF_INET;
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addr.sin_port = htons(localport);
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/* listen_ip already in network byte order from inet_addr, or 0 */
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addr.sin_addr.s_addr = listen_ip;
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fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
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if(fd < 0) {
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warn("socket");
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return -1;
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}
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flag = 1;
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#ifdef SO_REUSEPORT
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setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &flag, sizeof(flag));
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#endif
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setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag));
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if(bind(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
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warn("bind");
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return -1;
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}
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// Save top domain used
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strncpy(topdomain, domain, sizeof(topdomain) - 1);
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topdomain[sizeof(topdomain) - 1] = '\0';
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printf("Opened UDP socket\n");
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return fd;
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}
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int
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dns_settarget(const char *host)
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{
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struct hostent *h;
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// Init dns target struct
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h = gethostbyname(host);
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if (!h) {
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printf("Could not resolve name %s, exiting\n", host);
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return -1;
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}
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bzero(&peer, sizeof(peer));
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peer.sin_family = AF_INET;
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peer.sin_port = htons(53);
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peer.sin_addr = *((struct in_addr *) h->h_addr);
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// Init chunk id
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chunkid = 0;
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pingid = 0;
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return 0;
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}
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void
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close_dns(int fd)
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{
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close(fd);
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}
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int
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dns_sending()
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{
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return (packetlen != 0);
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}
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static void
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dns_send_chunk(int fd)
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{
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int avail;
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char *p;
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p = activepacket;
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p += packetpos;
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avail = packetlen - packetpos;
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lastlen = dns_write(fd, ++chunkid, p, avail, 0);
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}
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void
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dns_handle_tun(int fd, char *data, int len)
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{
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memcpy(activepacket, data, MIN(len, sizeof(activepacket)));
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lastlen = 0;
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packetpos = 0;
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packetlen = len;
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dns_send_chunk(fd);
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}
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void
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dns_ping(int dns_fd)
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{
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char data[2];
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if (dns_sending()) {
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lastlen = 0;
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packetpos = 0;
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packetlen = 0;
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}
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data[0] = (pingid & 0xFF00) >> 8;
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data[1] = (pingid & 0xFF);
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dns_write(dns_fd, ++pingid, data, 2, 'P');
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}
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void
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dns_handshake(int dns_fd)
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{
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char data[2];
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data[0] = (pingid & 0xFF00) >> 8;
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data[1] = (pingid & 0xFF);
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dns_write(dns_fd, ++pingid, data, 2, 'H');
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}
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static void
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dns_query(int fd, int id, char *host, int type)
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{
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char *p;
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int len;
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int peerlen;
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char buf[1024];
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HEADER *header;
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len = 0;
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memset(buf, 0, sizeof(buf));
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header = (HEADER*)buf;
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header->id = htons(id);
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header->qr = 0;
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header->opcode = 0;
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header->aa = 0;
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header->tc = 0;
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header->rd = 1;
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header->ra = 0;
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header->qdcount = htons(1);
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header->arcount = htons(1);
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p = buf + sizeof(HEADER);
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p += dns_encode_hostname(host, p, strlen(host));
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putshort(&p, type);
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putshort(&p, C_IN);
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// EDNS0
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putbyte(&p, 0x00); //Root
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putshort(&p, 0x0029); // OPT
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putshort(&p, 0x1000); // Payload size: 4096
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putshort(&p, 0x0000); // Higher bits/edns version
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putshort(&p, 0x8000); // Z
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putshort(&p, 0x0000); // Data length
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peerlen = sizeof(peer);
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len = p - buf;
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sendto(fd, buf, len, 0, (struct sockaddr*)&peer, peerlen);
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}
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static int
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dns_write(int fd, int id, char *buf, int len, char flag)
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{
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int avail;
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int written;
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int encoded;
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char data[257];
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char *d;
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avail = 0xFF - strlen(topdomain) - 2;
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bzero(data, sizeof(data));
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d = data;
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written = encode_data(buf, len, avail, d, flag);
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encoded = strlen(data);
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d += encoded;
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if (*d != '.') {
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*d++ = '.';
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}
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strncpy(d, topdomain, strlen(topdomain)+1);
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dns_query(fd, id, data, T_NULL);
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return written;
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}
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int
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dns_read(int fd, char *buf, int buflen)
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{
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int r;
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socklen_t addrlen;
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char packet[64*1024];
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struct sockaddr_in from;
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HEADER *header;
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addrlen = sizeof(struct sockaddr);
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r = recvfrom(fd, packet, sizeof(packet), 0, (struct sockaddr*)&from, &addrlen);
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if(r == -1) {
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perror("recvfrom");
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return 0;
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}
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header = (HEADER*)packet;
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if (dns_sending() && chunkid == ntohs(header->id)) {
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/* Got ACK on sent packet */
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packetpos += lastlen;
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if (packetpos == packetlen) {
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/* Packet completed */
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packetpos = 0;
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packetlen = 0;
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lastlen = 0;
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} else {
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/* More to send */
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dns_send_chunk(fd);
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}
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}
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return dns_parse_reply(buf, buflen, packet, r);
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}
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int
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dns_parse_reply(char *outbuf, int buflen, char *packet, int packetlen)
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{
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int rv;
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uint32_t ttl;
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short rlen;
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short type;
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short class;
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short qdcount;
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short ancount;
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char *data;
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char name[255];
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char rdata[4*1024];
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HEADER *header;
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rv = 0;
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header = (HEADER*)packet;
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data = packet + sizeof(HEADER);
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if(header->qr) { /* qr=1 => response */
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qdcount = ntohs(header->qdcount);
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ancount = ntohs(header->ancount);
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rlen = 0;
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if(qdcount == 1) {
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readname(packet, packetlen, &data, name, sizeof(name));
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readshort(packet, &data, &type);
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readshort(packet, &data, &class);
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}
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if(ancount == 1) {
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readname(packet, packetlen, &data, name, sizeof(name));
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readshort(packet, &data, &type);
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readshort(packet, &data, &class);
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readlong(packet, &data, &ttl);
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readshort(packet, &data, &rlen);
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rv = MIN(rlen, sizeof(rdata));
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readdata(packet, &data, rdata, rv);
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}
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if(type == T_NULL && rv > 2) {
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rv = MIN(rv, buflen);
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memcpy(outbuf, rdata, rv);
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}
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}
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return rv;
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}
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int
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dns_encode_hostname(const char *host, char *buffer, int size)
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{
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char *h;
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char *p;
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char *word;
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int left;
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h = strdup(host);
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memset(buffer, 0, size);
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p = buffer;
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left = size;
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word = strtok(h, ".");
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while(word) {
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if (strlen(word) > 63 || strlen(word) > left) {
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return -1;
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}
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left -= (strlen(word) + 1);
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*p++ = (char)strlen(word);
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memcpy(p, word, strlen(word));
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p += strlen(word);
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word = strtok(NULL, ".");
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}
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*p++ = 0;
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free(h);
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return p - buffer;
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}
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void
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dnsd_send(int fd, struct query *q, char *data, int datalen)
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{
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int len;
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char *p;
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char buf[64*1024];
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short name;
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HEADER *header;
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memset(buf, 0, sizeof(buf));
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len = 0;
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header = (HEADER*)buf;
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header->id = htons(q->id);
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header->qr = 1;
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header->opcode = 0;
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header->aa = 1;
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header->tc = 0;
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header->rd = 0;
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header->ra = 0;
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header->qdcount = htons(1);
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header->ancount = htons(1);
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p = buf + sizeof(HEADER);
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name = 0xc000 | ((p - buf) & 0x3fff);
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p += dns_encode_hostname(q->name, p, strlen(q->name));
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putshort(&p, q->type);
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putshort(&p, C_IN);
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putshort(&p, name);
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putshort(&p, q->type);
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putshort(&p, C_IN);
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putlong(&p, 0);
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q->id = 0;
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putshort(&p, datalen);
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putdata(&p, data, datalen);
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len = p - buf;
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sendto(fd, buf, len, 0, (struct sockaddr*)&q->from, q->fromlen);
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}
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static int
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decodepacket(const char *name, char *buf, int buflen)
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{
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int len;
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char *domain;
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domain = strstr(name, topdomain);
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len = decode_data(buf, buflen, name, domain);
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if (len == buflen)
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return -1;
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return len;
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}
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int
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dnsd_read(int fd, struct query *q, char *buf, int buflen)
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{
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int r;
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int rv;
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short id;
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short type;
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short class;
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short qdcount;
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char *data;
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char name[257];
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HEADER *header;
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socklen_t addrlen;
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char packet[64*1024];
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struct sockaddr_in from;
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addrlen = sizeof(struct sockaddr);
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r = recvfrom(fd, packet, sizeof(packet), 0, (struct sockaddr*)&from, &addrlen);
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if (r >= sizeof(HEADER)) {
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header = (HEADER*)packet;
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id = ntohs(header->id);
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data = packet + sizeof(HEADER);
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if(!header->qr) {
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qdcount = ntohs(header->qdcount);
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if(qdcount == 1) {
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readname(packet, r, &data, name, sizeof(name) -1);
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name[256] = 0;
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readshort(packet, &data, &type);
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readshort(packet, &data, &class);
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strncpy(q->name, name, 257);
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q->type = type;
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q->id = id;
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q->fromlen = addrlen;
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memcpy((struct sockaddr*)&q->from, (struct sockaddr*)&from, addrlen);
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rv = decodepacket(name, buf, buflen);
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}
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}
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} else if (r < 0) { // Error
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perror("recvfrom");
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rv = 0;
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} else { // Packet too small to be dns protocol
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rv = 0;
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}
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return rv;
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}
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