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server.nim
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server.nim
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#
#
# nimSocks
# SOCKS4/4a/5 proxy server
# (c) Copyright 2020
# David Krause, Tobias Freitag
#
# See the file "LICENSE", included in this
# distribution, for details about the copyright.
#
## SOCKS4/4a/5 proxy server
import asyncdispatch, asyncnet, nativesockets, tables, dbg
import reverseDomainNotation
import pump
import byteCounter
import isPrivateIp
import serverTypes
export serverTypes
proc newSocksServer*(
listenPort: Port = Port(DEFAULT_PORT),
listenHost: string = "",
allowedAuthMethods: set[AuthenticationMethod] = {USERNAME_PASSWORD},
allowedSocksVersions: set[SOCKS_VERSION] = {SOCKS_V4, SOCKS_V5},
): SocksServer =
result = SocksServer()
result.listenPort = listenPort
result.listenHost = listenHost
result.blacklistHostFancy = @[]
result.whitelistHostFancy = @[]
result.serverSocket = newAsyncSocket()
result.staticHosts = initTable[string, string]()
result.users = newTable[string, SHA512Digest]()
result.allowedAuthMethods = allowedAuthMethods
result.allowedSocksCmds = {SocksCmd.CONNECT}
result.allowedSocksVersions = allowedSocksVersions
result.stallingTimeout = STALLING_TIMEOUT
result.byteCounter = newByteCounter()
proc isBlacklisted(proxy: SocksServer, host: string): bool =
return proxy.blacklistHost.isListed(host) or proxy.blacklistHostFancy.isListed(host)
proc isWhitelisted(proxy: SocksServer, host: string): bool =
return proxy.whitelistHost.isListed(host) or proxy.whitelistHostFancy.isListed(host)
proc isListed(proxy: SocksServer, host: string): bool =
if proxy.prohibitPrivate:
if host.isPrivate(): return true
if proxy.whitelistHost.len == 0 and proxy.whitelistHostFancy.len == 0:
if proxy.isBlacklisted(host):
echo "Blacklisted host:", host
return true
else:
if not proxy.isWhitelisted(host):
echo "Not whitelisted host:", host
return true
proc authenticate(proxy: SocksServer, username, password: string): bool =
result = false
dbg "username: ", username
dbg "password: ", password
if username.len == 0: return
if password.len == 0: return
if not proxy.users.hasKey(username):
dbg "user unknown: ", username
return false
var
hashedPassword = initSHA[SHA512]()
hashFromDb = proxy.users[username]
hashedPassword.update(username)
hashedPassword.update(password)
dbg "hashedPassword: ", hashedPassword
dbg "hashFromDb: ", hashFromDb
if hashedPassword.final() == hashFromDb:
result = true
proc addUser*(proxy: SocksServer, username: string, password: string) =
if proxy.users.hasKey(username): raise newException(ValueError, "User already exists.")
if username.len == 0: raise newException(ValueError, "Username required.")
if password.len == 0: raise newException(ValueError, "Password required.")
var hashedPassword = initSHA[SHA512]()
hashedPassword.update(username)
hashedPassword.update(password)
proxy.users[username] = hashedPassword.final()
proc logHost(proxy: SocksServer, host: string) =
if not proxy.logFile.isNil:
proxy.logFile.writeLine(host)
proxy.logFile.flushFile()
if not proxy.logFileReverse.isNil:
proxy.logFileReverse.writeLine(host.reverseNotation() )
proxy.logFileReverse.flushFile()
proc getStaticRewrite(proxy: SocksServer, host: string): string =
if proxy.staticHosts.contains host:
return proxy.staticHosts[host]
return host
proc handleSocks5Connect(
proxy: SocksServer,
client: AsyncSocket,
socksReq: SocksRequest
): Future[(bool, AsyncSocket)] {.async.} =
var
host = socksReq.dst_addr.parseDestAddress(socksReq.atyp)
remoteSocket: AsyncSocket
dbg "host: ", host
dbg "hosR: ", repr(host)
dbg "--->: ", host.reverseNotation()
host = proxy.getStaticRewrite(host)
if proxy.isListed(host):
dbg "CONNECTION_NOT_ALLOWED_BY_RULESET"
var socksResp = newSocksResponse(socksReq, CONNECTION_NOT_ALLOWED_BY_RULESET)
await client.send($socksResp)
return (false, nil)
if proxy.shouldLogHost:
proxy.logHost host
var connectSuccess = true
try:
remoteSocket = await asyncnet.dial(host, socksReq.dst_port.port())
except:
connectSuccess = false
if not connectSuccess:
var socksResp = newSocksResponse(socksReq, HOST_UNREACHABLE)
await client.send($socksResp)
echo "HOST_UNREACHABLE:", host
return (false, nil)
return (true, remoteSocket)
proc processSocks5(proxy: SocksServer, client: AsyncSocket): Future[bool] {.async.} =
# Handshake/Authentication
result = false
var reqMessageSelection = RequestMessageSelection()
if (await client.recvRequestMessageSelection(reqMessageSelection)) == false:
dbg "could not parse RequestMessageSelection: ", reqMessageSelection.version
return
var respMessageSelection = ResponseMessageSelection()
respMessageSelection.version = reqMessageSelection.version
# Check if authentication method is supported and allowed by server
if not (reqMessageSelection.methods in proxy.allowedAuthMethods):
respMessageSelection.selectedMethod = NO_ACCEPTABLE_METHODS
await client.send($respMessageSelection)
return
# Chose authentication methods
if USERNAME_PASSWORD in reqMessageSelection.methods:
dbg "Got user password Authentication"
respMessageSelection.selectedMethod = USERNAME_PASSWORD
await client.send($respMessageSelection)
var socksUserPasswordReq = SocksUserPasswordRequest()
if (await client.recvSocksUserPasswordRequest(socksUserPasswordReq)) == false:
dbg "return from recvSocksUserPasswordRequest"
return
var socksUserPasswordResp = SocksUserPasswordResponse()
socksUserPasswordResp.authVersion = AuthVersionV1
if proxy.authenticate($socksUserPasswordReq.uname, $socksUserPasswordReq.passwd):
socksUserPasswordResp.status = UserPasswordStatus.SUCCEEDED
dbg "Sending good: ", repr($socksUserPasswordResp)
await client.send($socksUserPasswordResp)
else:
socksUserPasswordResp.status = UserPasswordStatus.FAILED
dbg "Sending bad: ", repr($socksUserPasswordResp)
await client.send($socksUserPasswordResp)
return
elif NO_AUTHENTICATION_REQUIRED in reqMessageSelection.methods:
respMessageSelection.selectedMethod = NO_AUTHENTICATION_REQUIRED
await client.send($respMessageSelection)
else:
dbg "Not supported authentication method"
return
var socksReq = SocksRequest()
if (await client.recvSocksRequest(socksReq)) == false:
dbg "Could not parse socksReq"
return
var
remoteSocket: AsyncSocket = nil
handleCmdSucceed: bool = false
if socksReq.cmd.SocksCmd notin proxy.allowedSocksCmds:
dbg "proxy command not allowed"
return
case socksReq.cmd.SocksCmd:
of SocksCmd.CONNECT:
dbg "socks5 connect"
(handleCmdSucceed, remoteSocket) = await proxy.handleSocks5Connect(client, socksReq)
of SocksCmd.BIND:
echo "BIND not implemented"
# (handleCmdSucceed, remoteSocket) = await proxy.handleSocks5Bind(client, socksReq)
return
of SocksCmd.UDP_ASSOCIATE:
echo "UDP_ASSOCIATE not implemented"
return
if handleCmdSucceed == false:
dbg "Handling command: failed"
return
dbg "Handling command: succeed"
var
socksResp = newSocksResponse(socksReq, REP.SUCCEEDED)
await client.send($socksResp)
# From here on we start relaying data
asyncCheck pump(proxy.byteCounter, remoteSocket, client, downstream , socksReq.dst_addr, socksReq.atyp.ATYP)
asyncCheck pump(proxy.byteCounter, client, remoteSocket, upstream , socksReq.dst_addr, socksReq.atyp.ATYP)
return true
proc handleSocks4Connect(
proxy: SocksServer,
client: AsyncSocket,
socksReq: Socks4Request
): Future[(bool, AsyncSocket)] {.async.} =
var
host = socksReq.dst_ip.parseDestAddress(IP_V4_ADDRESS)
remoteSocket: AsyncSocket
dbg "host: ", host
dbg "--->: ", host.reverseNotation()
if socksReq.dst_ip.isSocks4aHack():
dbg "socks4a"
host = (await client.recvNullTerminated()).parseDestAddress(DOMAINNAME)
dbg "REALHOST:",host
host = proxy.getStaticRewrite(host)
if proxy.isListed(host):
dbg "REQUEST_REJECTED_OR_FAILED"
var socksResp = newSocks4Response(REQUEST_REJECTED_OR_FAILED)
await client.send($socksResp)
return (false, nil)
if proxy.shouldLogHost:
proxy.logHost(host)
var connectSuccess = true
try:
remoteSocket = await asyncnet.dial(host, socksReq.dst_port.port())
except:
dbg "DIAL FAILED"
dbg getCurrentExceptionMsg()
connectSuccess = false
if not connectSuccess:
var socksResp = newSocks4Response(REQUEST_REJECTED_OR_FAILED)
await client.send($socksResp)
echo "HOST_UNREACHABLE:", host
return (false, nil)
return (true, remoteSocket)
proc processSocks4(proxy: SocksServer, client: AsyncSocket): Future[bool] {.async.} =
result = false
dbg "socks4"
if not proxy.allowedAuthMethods.contains(NO_AUTHENTICATION_REQUIRED):
dbg "socks4 socks4a does not support authentication, ensure that allowedAuthMethods contains NO_AUTHENTICATION_REQUIRED"
return
var socks4Request = Socks4Request()
if (await client.recvSocks4Request(socks4Request)) == false:
dbg "could not parse Socks4Request: " #, socks4Request
return
var
remoteSocket: AsyncSocket = nil
handleCmdSucceed: bool = false
if socks4Request.cmd.SocksCmd notin proxy.allowedSocksCmds:
dbg "proxy command not allowed"
return
case socks4Request.cmd.Socks4Cmd
of Socks4Cmd.CONNECT:
(handleCmdSucceed, remoteSocket) = await proxy.handleSocks4Connect(client, socks4Request)
of Socks4Cmd.BIND:
echo "BIND not implemented"
return
if handleCmdSucceed == false:
dbg "Handling command: failed"
return
dbg "Handling command: succeed"
var socksResp = newSocks4Response(REQUEST_GRANTED)
await client.send($socksResp)
# From here on we start relaying data
asyncCheck pump(proxy.byteCounter, remoteSocket, client, downstream , socks4Request.dst_ip, ATYP.IP_V4_ADDRESS)
asyncCheck pump(proxy.byteCounter, client, remoteSocket, upstream , socks4Request.dst_ip, ATYP.IP_V4_ADDRESS)
return true
proc processClient(proxy: SocksServer, client: AsyncSocket): Future[void] {.async.} =
# Check for socks version.
try:
var socksVersionRef = SocksVersionRef()
if (await client.recvSocksVersion(socksVersionRef)) == false:
dbg "unknown socks version: ", socksVersionRef.socksVersion
client.close()
return
var stayOpen: bool = false
if socksVersionRef.socksVersion.SOCKS_VERSION notin proxy.allowedSocksVersions:
dbg "socket version not allowed"
client.close()
return
case socksVersionRef.socksVersion.SOCKS_VERSION
of SOCKS_V4:
stayOpen = await proxy.processSocks4(client)
of SOCKS_V5:
stayOpen = await proxy.processSocks5(client)
if not client.isClosed and not stayOpen:
client.close()
except:
echo "processClient exception:"
echo getCurrentExceptionMsg()
if not client.isClosed:
client.close()
return
proc serve*(proxy: SocksServer): Future[void] {.async.} =
proxy.serverSocket.setSockOpt(OptReusePort, true)
# proxy.serverSocket.getFd.setSockOptInt(SOL_SOCKET.cint, )
proxy.serverSocket.setSockOpt(OptNoDelay, true) # TODO test if this is good
# proxy.serverSocket.setSockOpt(TCP_QUICKACK, true)
proxy.serverSocket.bindAddr(proxy.listenPort, proxy.listenHost)
proxy.serverSocket.listen()
var
address: string
client: AsyncSocket
stalling: bool = false
while true:
if stalling: await sleepAsync(proxy.stallingTimeout)
try:
(address, client) = await proxy.serverSocket.acceptAddr()
echo "connection from: ", address
stalling = false
except:
dbg "could not accept new connection:"
dbg getCurrentExceptionMsg()
stalling = true
continue
client.setSockOpt(OptNoDelay, true) # TODO test if this is good
client.setSockOpt(OptReuseAddr, true)
asyncCheck proxy.processClient(client)
when not defined release:
block:
var proxy = newSocksServer()
proxy.addUser("hans", "peter")
assert proxy.authenticate("hans", "peter") == true
assert proxy.authenticate(" hans", "peter") == false
assert proxy.authenticate("hans", "peter ") == false
assert proxy.authenticate(" hans", "peter ") == false
assert proxy.authenticate("as hans", "dd cpeter ") == false
when isMainModule:
import throughput, os
var proxy = newSocksServer(listenPort = 1080.Port)
echo "SOCKS Proxy listens on: ", proxy.listenPort
## Socks 4 has no authentication
# proxy.allowedSocksVersions = {SOCKS_V4}
# proxy.allowedAuthMethods = {NO_AUTHENTICATION_REQUIRED}
## Socks 5 has authentication!
proxy.allowedSocksVersions = {SOCKS_V4, SOCKS_V5}
proxy.allowedAuthMethods = {USERNAME_PASSWORD, NO_AUTHENTICATION_REQUIRED}
## Prohibit proxy to reach private ips
proxy.prohibitPrivate = true
## If the proxy server should log hosts
proxy.shouldLogHost = false
if proxy.shouldLogHost:
proxy.logFile = open("hosts.txt", fmAppend)
proxy.logFileReverse = open("hostsReverse.txt", fmAppend)
## Add a valid user / password combination
proxy.addUser("hans", "peter")
## Download blacklist, !! this overwrites the old list !!
# import httpclient
# let blacklistUrl = "https://raw.githubusercontent.com/notracking/hosts-blocklists/master/dnscrypt-proxy/dnscrypt-proxy.blacklist.txt"
# var client = newHttpClient()
# writeFile(getAppDir() / "blacklist.txt", client.getContent(blacklistUrl))
## Files for black and whitelisting
proxy.blacklistHost = loadList(getAppDir() / "blacklist.txt")
# proxy.blacklistHostFancy = loadListFancy("blacklistFancy.txt")
# proxy.whitelistHostFancy = loadListFancy("whitelistFancy.txt")
# proxy.whitelistHost = @[
# "example.org"
# ]
## For a static host replacement:
proxy.staticHosts["peter.peter"] = "ch4t.code0.xyz"
asyncCheck proxy.serve()
asyncCheck proxy.dumpThroughput()
runForever()