mirror of
https://github.com/yarrick/iodine.git
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556 lines
10 KiB
C
556 lines
10 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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#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 <stdlib.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 "read.h"
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#include "structs.h"
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#include "dns.h"
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static int host2dns(const char *, char *, int);
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static int dns_write(int, int, char *, int, char);
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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 *host, const char *domain)
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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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struct hostent *h;
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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(0);
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addr.sin_addr.s_addr = htonl(INADDR_ANY);
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fd = socket(AF_INET, SOCK_DGRAM, 0);
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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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printf("Opened UDP socket\n");
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printf("Sending queries for %s to %s\n", domain, host);
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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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// Save top domain used
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strncpy(topdomain, domain, sizeof(topdomain) - 2);
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topdomain[sizeof(topdomain) - 1] = 0;
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// Init chunk id
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chunkid = 0;
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pingid = 0;
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return fd;
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}
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int
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open_dnsd(const char *domain)
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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(53);
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addr.sin_addr.s_addr = htonl(INADDR_ANY);
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fd = socket(AF_INET, SOCK_DGRAM, 0);
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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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printf("Opened UDP socket\n");
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printf("Listening to dns for domain %s\n", domain);
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// Save top domain used
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strncpy(topdomain, domain, sizeof(topdomain) - 2);
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topdomain[sizeof(topdomain) - 1] = 0;
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packetlen = 0;
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return fd;
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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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//printf("Sent %d bytes of %d remaining\n", lastlen, avail);
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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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// printf("No reply on chunk, discarding\n");
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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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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 += host2dns(host, p, strlen(host));
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PUTSHORT(type, p);
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PUTSHORT(C_IN, p);
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// EDNS0
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*p++ = 0x00; //Root
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PUTSHORT(0x0029, p); // OPT
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PUTSHORT(0x1000, p); // Payload size: 4096
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PUTSHORT(0x0000, p); // Higher bits/ edns version
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PUTSHORT(0x8000, p); // Z
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PUTSHORT(0x0000, p); // 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 void
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put_hex(char *p, char h)
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{
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int t;
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static const char to_hex[] = "0123456789ABCDEF";
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t = (h & 0xF0) >> 4;
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p[0] = to_hex[t];
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t = h & 0x0F;
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p[1] = to_hex[t];
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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 i;
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int final;
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char data[257];
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char *d;
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#define CHUNK 31
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// 31 bytes expands to 62 chars in domain
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// We just use hex as encoding right now
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avail = 0xFF - strlen(topdomain) - 2;
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avail /= 2; // use two chars per byte in encoding
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avail -= (avail/CHUNK); // make space for parts
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avail = MIN(avail, len); // do not use more bytes than is available;
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final = (avail == len); // is this the last block?
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bzero(data, sizeof(data));
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d = data;
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if (flag != 0) {
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*d = flag;
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} else {
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// First byte is 0 for middle packet and 1 for last packet
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*d = '0' + final;
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}
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d++;
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if (len > 0) {
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for (i = 0; i < avail; i++) {
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if (i > 0 && i % 31 == 0) {
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*d = '.';
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d++;
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}
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put_hex(d, buf[i]);
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d += 2;
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}
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}
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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 avail;
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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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long 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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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 == -1) {
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perror("recvfrom");
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} else {
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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, name, data);
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READSHORT(type, data);
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READSHORT(class, data);
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}
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if(ancount == 1) {
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READNAME(packet, name, data);
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READSHORT(type, data);
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READSHORT(class, data);
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READLONG(ttl, data);
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READSHORT(rlen, data);
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READDATA(rdata, data, rlen);
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}
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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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// printf("IP packet size %d sent successfully!\n", packetlen);
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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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if(type == T_NULL && rlen > 2) {
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memcpy(buf, rdata, rlen);
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return rlen;
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} else {
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return 0;
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}
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}
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}
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return 0;
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}
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static int
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host2dns(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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h = strdup(host);
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memset(buffer, 0, size);
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p = buffer;
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word = strtok(h, ".");
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while(word) {
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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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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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p += host2dns(q->name, p, strlen(q->name));
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PUTSHORT(q->type, p);
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PUTSHORT(C_IN, p);
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p += host2dns(q->name, p, strlen(q->name));
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PUTSHORT(q->type, p);
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PUTSHORT(C_IN, p);
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PUTLONG(0, p);
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q->id = 0;
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if(datalen > 0) {
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PUTSHORT(datalen, p);
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memcpy(p, data, datalen);
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p += datalen;
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} else {
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PUTSHORT(0, p);
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}
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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 r;
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int len;
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char *dp;
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char *domain;
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const char *np;
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len = 1;
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domain = strstr(name, topdomain);
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buf[0] = name[0];
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dp = buf + 1;
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np = name + 1;
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while(len < buflen && np < domain) {
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if(*np == '.') {
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np++;
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continue;
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}
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sscanf(np, "%02X", &r);
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*dp++ = (char)r;
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np+=2;
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len++;
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}
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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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void
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close_dnsd(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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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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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[255];
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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 == -1) {
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perror("recvfrom");
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} else {
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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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bzero(name, sizeof(name));
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READNAME(packet, name, data);
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READSHORT(type, data);
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READSHORT(class, data);
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// Store needed info about delayed response
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strncpy(q->name, name, 256);
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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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return decodepacket(name, buf, buflen);
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}
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}
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}
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return 0;
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}
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