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dnspcap.cc
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dnspcap.cc
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/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#define __FAVOR_BSD
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "dnspcap.hh"
#include <boost/format.hpp>
#include <fcntl.h>
#include "namespaces.hh"
PcapPacketReader::PcapPacketReader(const string& fname) : d_fname(fname)
{
d_fp = pdns::UniqueFilePtr(fopen(fname.c_str(), "r"));
if (!d_fp) {
unixDie("Unable to open file " + fname);
}
int flags = fcntl(fileno(d_fp.get()), F_GETFL, 0);
fcntl(fileno(d_fp.get()), F_SETFL, flags & (~O_NONBLOCK)); // bsd needs this in stdin (??)
checkedFread(&d_pfh);
if (d_pfh.magic != 2712847316UL) {
throw runtime_error((boost::format("PCAP file %s has bad magic %x, should be %x") % fname % d_pfh.magic % 2712847316UL).str());
}
if( d_pfh.linktype==1) {
d_skipMediaHeader=sizeof(struct ether_header);
}
else if( d_pfh.linktype==12) { // LOOP
d_skipMediaHeader=4;
}
else if(d_pfh.linktype==101) {
d_skipMediaHeader=0;
}
else if(d_pfh.linktype==113) {
d_skipMediaHeader=16;
}
else throw runtime_error((boost::format("Unsupported link type %d") % d_pfh.linktype).str());
d_runts = d_oversized = d_correctpackets = d_nonetheripudp = 0;
size_t alignmentCorrection = d_skipMediaHeader % alignof(struct ip);
d_buffer = d_readbuffer + alignmentCorrection;
d_bufsize = sizeof(d_readbuffer) - alignmentCorrection;
if (d_skipMediaHeader > d_bufsize) throw runtime_error("media header is too big");
}
void PcapPacketReader::checkedFreadSize(void* ptr, size_t size)
{
int ret = fread(ptr, 1, size, d_fp.get());
if (ret < 0) {
unixDie( (boost::format("Error reading %d bytes from %s") % size % d_fname).str());
}
if(!ret)
throw EofException();
if((size_t)ret != size)
throw EofException((boost::format("Incomplete read from '%s', got only %d bytes") % d_fname % ret).str());
}
bool PcapPacketReader::getUDPPacket()
try
{
for(;;) {
checkedFread(&d_pheader);
if(!d_pheader.caplen) {
d_runts++;
continue;
}
if(d_pheader.caplen > d_bufsize) {
d_oversized++;
throw runtime_error((boost::format("Can't handle a %d byte packet, have space for %zu") % d_pheader.caplen % d_bufsize).str());
}
checkedFreadSize(d_buffer, d_pheader.caplen);
if(d_pheader.caplen < d_pheader.len) {
d_runts++;
continue;
}
if (d_pheader.caplen < d_skipMediaHeader) {
d_runts++;
continue;
}
d_ip=reinterpret_cast<struct ip*>(d_buffer + d_skipMediaHeader);
d_ip6=reinterpret_cast<struct ip6_hdr*>(d_buffer + d_skipMediaHeader);
uint16_t contentCode=0;
if(d_pfh.linktype==1) {
if (d_pheader.caplen < sizeof(*d_ether)) {
d_runts++;
continue;
}
d_ether=reinterpret_cast<struct ether_header*>(d_buffer);
contentCode=ntohs(d_ether->ether_type);
}
else if(d_pfh.linktype == 12) { // LOOP
if (d_pheader.caplen < (d_skipMediaHeader + sizeof(*d_ip))) {
d_runts++;
continue;
}
if(d_ip->ip_v == 4)
contentCode = 0x0800;
else
contentCode = 0x86dd;
}
else if(d_pfh.linktype==101) {
if (d_pheader.caplen < (d_skipMediaHeader + sizeof(*d_ip))) {
d_runts++;
continue;
}
if(d_ip->ip_v==4)
contentCode = 0x0800;
else
contentCode = 0x86dd;
}
else if(d_pfh.linktype==113) {
if (d_pheader.caplen < sizeof(*d_lcc)) {
d_runts++;
continue;
}
d_lcc=reinterpret_cast<struct pdns_lcc_header*>(d_buffer);
contentCode=ntohs(d_lcc->lcc_protocol);
}
if(contentCode==0x0800 && (d_pheader.caplen >= (d_skipMediaHeader + sizeof(*d_ip))) && d_ip->ip_p==17) { // udp
if (d_pheader.caplen < (d_skipMediaHeader + (4 * d_ip->ip_hl) + sizeof(*d_udp))) {
d_runts++;
continue;
}
d_udp=reinterpret_cast<const struct udphdr*>(d_buffer + d_skipMediaHeader + 4 * d_ip->ip_hl);
d_payload = (unsigned char*)d_udp + sizeof(struct udphdr);
d_len = ntohs(d_udp->uh_ulen) - sizeof(struct udphdr);
if (d_pheader.caplen < (d_skipMediaHeader + (4 * d_ip->ip_hl) + sizeof(*d_udp) + d_len)) {
d_runts++;
continue;
}
if((const char*)d_payload + d_len > d_buffer + d_pheader.caplen) {
d_runts++;
continue;
}
d_correctpackets++;
return true;
}
else if(contentCode==0x86dd && (d_pheader.caplen >= (d_skipMediaHeader + sizeof(*d_ip6))) && d_ip6->ip6_ctlun.ip6_un1.ip6_un1_nxt==17) { // udpv6, we ignore anything with extension hdr
if (d_pheader.caplen < (d_skipMediaHeader + sizeof(struct ip6_hdr) + sizeof(struct udphdr))) {
d_runts++;
continue;
}
d_udp=reinterpret_cast<const struct udphdr*>(d_buffer + d_skipMediaHeader + sizeof(struct ip6_hdr));
d_payload = (unsigned char*)d_udp + sizeof(struct udphdr);
d_len = ntohs(d_udp->uh_ulen) - sizeof(struct udphdr);
if (d_pheader.caplen < (d_skipMediaHeader + sizeof(struct ip6_hdr) + sizeof(struct udphdr) + d_len)) {
d_runts++;
continue;
}
if((const char*)d_payload + d_len > d_buffer + d_pheader.caplen) {
d_runts++;
continue;
}
d_correctpackets++;
return true;
}
else {
d_nonetheripudp++;
}
}
}
catch(const EofException&) {
return false;
}
ComboAddress PcapPacketReader::getSource() const
{
ComboAddress ret;
if(d_ip->ip_v == 4) {
ret.sin4.sin_family = AF_INET;
ret.sin4.sin_addr = d_ip->ip_src;
ret.sin4.sin_port = d_udp->uh_sport; // should deal with TCP too!
} else {
ret.sin6.sin6_family = AF_INET6;
ret.sin6.sin6_addr = d_ip6->ip6_src;
ret.sin6.sin6_port = d_udp->uh_sport; // should deal with TCP too!
}
return ret;
}
ComboAddress PcapPacketReader::getDest() const
{
ComboAddress ret;
if(d_ip->ip_v == 4) {
ret.sin4.sin_family = AF_INET;
ret.sin4.sin_addr = d_ip->ip_dst;
ret.sin4.sin_port = d_udp->uh_dport; // should deal with TCP too!
} else {
ret.sin6.sin6_family = AF_INET6;
ret.sin6.sin6_addr = d_ip6->ip6_dst;
ret.sin6.sin6_port = d_udp->uh_dport; // should deal with TCP too!
}
return ret;
}
PcapPacketWriter::PcapPacketWriter(const string& fname, const PcapPacketReader& ppr) : PcapPacketWriter(fname)
{
setPPR(ppr);
}
PcapPacketWriter::PcapPacketWriter(const string& fname) : d_fname(fname)
{
d_fp = pdns::openFileForWriting(fname, 0600, true, false);
if (!d_fp) {
unixDie("Unable to open file");
}
int flags = fcntl(fileno(d_fp.get()), F_GETFL, 0);
fcntl(fileno(d_fp.get()), F_SETFL,flags & (~O_NONBLOCK)); // bsd needs this in stdin (??)
}
void PcapPacketWriter::write()
{
if (!d_ppr) {
return;
}
if(d_first) {
fwrite(&d_ppr->d_pfh, 1, sizeof(d_ppr->d_pfh), d_fp.get());
d_first=false;
}
fwrite(&d_ppr->d_pheader, 1, sizeof(d_ppr->d_pheader), d_fp.get());
fwrite(d_ppr->d_buffer, 1, d_ppr->d_pheader.caplen, d_fp.get());
}