ZeroTierOne/tcp-proxy/tcp-proxy.cpp

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/*
* ZeroTier One - Network Virtualization Everywhere
* Copyright (C) 2011-2015 ZeroTier, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* --
*
* ZeroTier may be used and distributed under the terms of the GPLv3, which
* are available at: http://www.gnu.org/licenses/gpl-3.0.html
*
* If you would like to embed ZeroTier into a commercial application or
* redistribute it in a modified binary form, please contact ZeroTier Networks
* LLC. Start here: http://www.zerotier.com/
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <stdint.h>
#include <unistd.h>
#include <signal.h>
#include <map>
#include <set>
#include <string>
#include <algorithm>
#include <vector>
#include "../osdep/Phy.hpp"
#define ZT_TCP_PROXY_UDP_POOL_SIZE 1024
#define ZT_TCP_PROXY_UDP_POOL_START_PORT 10000
#define ZT_TCP_PROXY_CONNECTION_TIMEOUT_SECONDS 300
#define ZT_TCP_PROXY_TCP_PORT 443
using namespace ZeroTier;
/*
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* ZeroTier TCP Proxy Server
*
* This implements a simple packet encapsulation that is designed to look like
* a TLS connection. It's not a TLS connection, but it sends TLS format record
* headers. It could be extended in the future to implement a fake TLS
* handshake.
*
* At the moment, each packet is just made to look like TLS application data:
* <[1] TLS content type> - currently 0x17 for "application data"
* <[1] TLS major version> - currently 0x03 for TLS 1.2
* <[1] TLS minor version> - currently 0x03 for TLS 1.2
* <[2] payload length> - 16-bit length of payload in bytes
* <[...] payload> - Message payload
*
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* TCP is inherently inefficient for encapsulating Ethernet, since TCP and TCP
* like protocols over TCP lead to double-ACKs. So this transport is only used
* to enable access when UDP or other datagram protocols are not available.
*
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* Clients send a greeting, which is a four-byte message that contains:
* <[1] ZeroTier major version>
* <[1] minor version>
* <[2] revision>
*
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* If a client has sent a greeting, it uses the new version of this protocol
* in which every encapsulated ZT packet is prepended by an IP address where
* it should be forwarded (or where it came from for replies). This causes
* this proxy to act as a remote UDP socket similar to a socks proxy, which
* will allow us to move this function off the supernodes and onto dedicated
* proxy nodes.
*
* Older ZT clients that do not send this message get their packets relayed
* to/from 127.0.0.1:9993, which will allow them to talk to and relay via
* the ZT node on the same machine as the proxy. We'll only support this for
* as long as such nodes appear to be in the wild.
*/
struct TcpProxyService;
struct TcpProxyService
{
Phy<TcpProxyService *> *phy;
PhySocket *udpPool[ZT_TCP_PROXY_UDP_POOL_SIZE];
struct Client
{
char tcpReadBuf[131072];
char tcpWriteBuf[131072];
unsigned long tcpWritePtr;
unsigned long tcpReadPtr;
PhySocket *tcp;
PhySocket *assignedUdp;
time_t lastActivity;
bool newVersion;
};
std::map< PhySocket *,Client > clients;
struct ReverseMappingKey
{
uint64_t sourceZTAddress;
PhySocket *sendingUdpSocket;
uint32_t destIp;
unsigned int destPort;
ReverseMappingKey() {}
ReverseMappingKey(uint64_t zt,PhySocket *s,uint32_t ip,unsigned int port) : sourceZTAddress(zt),sendingUdpSocket(s),destIp(ip),destPort(port) {}
inline bool operator<(const ReverseMappingKey &k) const throw() { return (memcmp((const void *)this,(const void *)&k,sizeof(ReverseMappingKey)) < 0); }
inline bool operator==(const ReverseMappingKey &k) const throw() { return (memcmp((const void *)this,(const void *)&k,sizeof(ReverseMappingKey)) == 0); }
};
std::map< ReverseMappingKey,Client * > reverseMappings;
void phyOnDatagram(PhySocket *sock,void **uptr,const struct sockaddr *from,void *data,unsigned long len)
{
if ((from->sa_family == AF_INET)&&(len > 16)&&(len < 2048)) {
const uint64_t destZt = (
(((uint64_t)(((const unsigned char *)data)[8])) << 32) |
(((uint64_t)(((const unsigned char *)data)[9])) << 24) |
(((uint64_t)(((const unsigned char *)data)[10])) << 16) |
(((uint64_t)(((const unsigned char *)data)[11])) << 8) |
((uint64_t)(((const unsigned char *)data)[12])) );
const uint32_t fromIp = ((const struct sockaddr_in *)from)->sin_addr.s_addr;
const unsigned int fromPort = ntohs(((const struct sockaddr_in *)from)->sin_port);
std::map< ReverseMappingKey,Client * >::iterator rm(reverseMappings.find(ReverseMappingKey(destZt,sock,fromIp,fromPort)));
if (rm != reverseMappings.end()) {
Client &c = *(rm->second);
unsigned long mlen = len;
if (c.newVersion)
mlen += 7; // new clients get IP info
if ((c.tcpWritePtr + 5 + mlen) <= sizeof(c.tcpWriteBuf)) {
if (!c.tcpWritePtr)
phy->tcpSetNotifyWritable(c.tcp,true);
c.tcpWriteBuf[c.tcpWritePtr++] = 0x17; // look like TLS data
c.tcpWriteBuf[c.tcpWritePtr++] = 0x03; // look like TLS 1.2
c.tcpWriteBuf[c.tcpWritePtr++] = 0x03; // look like TLS 1.2
c.tcpWriteBuf[c.tcpWritePtr++] = (char)((mlen >> 8) & 0xff);
c.tcpWriteBuf[c.tcpWritePtr++] = (char)(mlen & 0xff);
if (c.newVersion) {
c.tcpWriteBuf[c.tcpWritePtr++] = (char)4; // IPv4
*((uint32_t *)(c.tcpWriteBuf + c.tcpWritePtr)) = fromIp;
c.tcpWritePtr += 4;
c.tcpWriteBuf[c.tcpWritePtr++] = (char)((fromPort >> 8) & 0xff);
c.tcpWriteBuf[c.tcpWritePtr++] = (char)(fromPort & 0xff);
}
for(unsigned long i=0;i<len;++i)
c.tcpWriteBuf[c.tcpWritePtr++] = ((const char *)data)[i];
}
}
}
}
void phyOnTcpConnect(PhySocket *sock,void **uptr,bool success)
{
// unused, we don't initiate
}
void phyOnTcpAccept(PhySocket *sockL,PhySocket *sockN,void **uptrL,void **uptrN,const struct sockaddr *from)
{
Client &c = clients[sockN];
c.tcpWritePtr = 0;
c.tcpReadPtr = 0;
c.tcp = sockN;
c.assignedUdp = udpPool[rand() % ZT_TCP_PROXY_UDP_POOL_SIZE];
c.lastActivity = time((time_t *)0);
c.newVersion = false;
*uptrN = (void *)&c;
}
void phyOnTcpClose(PhySocket *sock,void **uptr)
{
for(std::map< ReverseMappingKey,Client * >::iterator rm(reverseMappings.begin());rm!=reverseMappings.end();) {
if (rm->second == (Client *)*uptr)
reverseMappings.erase(rm++);
else ++rm;
}
clients.erase(sock);
}
void phyOnTcpData(PhySocket *sock,void **uptr,void *data,unsigned long len)
{
Client &c = *((Client *)*uptr);
c.lastActivity = time((time_t *)0);
for(unsigned long i=0;i<len;++i) {
if (c.tcpReadPtr >= sizeof(c.tcpReadBuf)) {
phy->close(sock);
return;
}
c.tcpReadBuf[c.tcpReadPtr++] = ((const char *)data)[i];
if (c.tcpReadPtr >= 5) {
unsigned long mlen = ( ((((unsigned long)c.tcpReadBuf[3]) & 0xff) << 8) | (((unsigned long)c.tcpReadBuf[4]) & 0xff) );
if (c.tcpReadPtr >= (mlen + 5)) {
if (mlen == 4) {
// Right now just sending this means the client is 'new enough' for the IP header
c.newVersion = true;
} else if (mlen >= 7) {
char *payload = c.tcpReadBuf + 5;
unsigned long payloadLen = mlen;
struct sockaddr_in dest;
memset(&dest,0,sizeof(dest));
if (c.newVersion) {
if (*payload == (char)4) {
// New clients tell us where their packets go.
++payload;
dest.sin_family = AF_INET;
dest.sin_addr.s_addr = *((uint32_t *)payload);
payload += 4;
dest.sin_port = *((uint16_t *)payload); // will be in network byte order already
payload += 2;
payloadLen -= 7;
}
} else {
// For old clients we will just proxy everything to a local ZT instance. The
// fact that this will come from 127.0.0.1 will in turn prevent that instance
// from doing unite() with us. It'll just forward. There will not be many of
// these.
dest.sin_family = AF_INET;
dest.sin_addr.s_addr = htonl(0x7f000001); // 127.0.0.1
dest.sin_port = htons(9993);
}
// Note: we do not relay to privileged ports... just an abuse prevention rule.
if ((ntohs(dest.sin_port) > 1024)&&(payloadLen >= 16)) {
if ((payloadLen >= 28)&&(payload[13] != (char)0xff)) {
// Learn reverse mappings -- we will route replies to these packets
// back to their sending TCP socket. They're on a first come first
// served basis.
const uint64_t sourceZt = (
(((uint64_t)(((const unsigned char *)payload)[13])) << 32) |
(((uint64_t)(((const unsigned char *)payload)[14])) << 24) |
(((uint64_t)(((const unsigned char *)payload)[15])) << 16) |
(((uint64_t)(((const unsigned char *)payload)[16])) << 8) |
((uint64_t)(((const unsigned char *)payload)[17])) );
ReverseMappingKey k(sourceZt,c.assignedUdp,dest.sin_addr.s_addr,ntohl(dest.sin_port));
if (reverseMappings.count(k) == 0)
reverseMappings[k] = &c;
}
phy->udpSend(c.assignedUdp,(const struct sockaddr *)&dest,payload,payloadLen);
}
}
memmove(c.tcpReadBuf,c.tcpReadBuf + (mlen + 5),c.tcpReadPtr -= (mlen + 5));
}
}
}
}
void phyOnTcpWritable(PhySocket *sock,void **uptr)
{
Client &c = *((Client *)*uptr);
if (c.tcpWritePtr) {
long n = phy->tcpSend(sock,c.tcpWriteBuf,c.tcpWritePtr);
if (n > 0) {
memmove(c.tcpWriteBuf,c.tcpWriteBuf + n,c.tcpWritePtr -= (unsigned long)n);
if (!c.tcpWritePtr)
phy->tcpSetNotifyWritable(sock,false);
}
} else phy->tcpSetNotifyWritable(sock,false);
}
void doHousekeeping()
{
std::vector<PhySocket *> toClose;
time_t now = time((time_t *)0);
for(std::map< PhySocket *,Client >::iterator c(clients.begin());c!=clients.end();++c) {
if ((now - c->second.lastActivity) >= ZT_TCP_PROXY_CONNECTION_TIMEOUT_SECONDS)
toClose.push_back(c->first);
}
for(std::vector<PhySocket *>::iterator s(toClose.begin());s!=toClose.end();++s)
phy->close(*s); // will call phyOnTcpClose() which does cleanup
}
};
int main(int argc,char **argv)
{
signal(SIGPIPE,SIG_IGN);
signal(SIGHUP,SIG_IGN);
srand(time((time_t *)0));
TcpProxyService svc;
Phy<TcpProxyService *> phy(&svc,true);
svc.phy = &phy;
{
int poolSize = 0;
for(unsigned int p=ZT_TCP_PROXY_UDP_POOL_START_PORT;((poolSize<ZT_TCP_PROXY_UDP_POOL_SIZE)&&(p<=65535));++p) {
struct sockaddr_in laddr;
memset(&laddr,0,sizeof(laddr));
laddr.sin_family = AF_INET;
laddr.sin_port = htons((uint16_t)p);
PhySocket *s = phy.udpBind((const struct sockaddr *)&laddr);
if (s)
svc.udpPool[poolSize++] = s;
}
if (poolSize < ZT_TCP_PROXY_UDP_POOL_SIZE) {
fprintf(stderr,"%s: fatal error: cannot bind %d UDP ports\n",argv[0],ZT_TCP_PROXY_UDP_POOL_SIZE);
return 1;
}
}
{
struct sockaddr_in laddr;
memset(&laddr,0,sizeof(laddr));
laddr.sin_family = AF_INET;
laddr.sin_port = htons(ZT_TCP_PROXY_TCP_PORT);
if (!phy.tcpListen((const struct sockaddr *)&laddr)) {
fprintf(stderr,"%s: fatal error: unable to bind TCP port %d\n",argv[0],ZT_TCP_PROXY_TCP_PORT);
return 1;
}
}
time_t lastDidHousekeeping = time((time_t *)0);
for(;;) {
phy.poll(120000);
time_t now = time((time_t *)0);
if ((now - lastDidHousekeeping) > 120) {
lastDidHousekeeping = now;
svc.doHousekeeping();
}
}
return 0;
}