goutils/cmd/stealchain-server/main.go

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package main
import (
"crypto/rand"
"crypto/tls"
"crypto/x509"
"encoding/hex"
"encoding/pem"
"flag"
"fmt"
"io/ioutil"
"net"
"os"
"git.wntrmute.dev/kyle/goutils/die"
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)
func main() {
cfg := &tls.Config{}
var sysRoot, listenAddr, certFile, keyFile string
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var verify bool
flag.StringVar(&sysRoot, "ca", "", "provide an alternate CA bundle")
flag.StringVar(&listenAddr, "listen", ":443", "address to listen on")
flag.StringVar(&certFile, "cert", "", "server certificate to present to clients")
flag.StringVar(&keyFile, "key", "", "key for server certificate")
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flag.BoolVar(&verify, "verify", false, "verify client certificates")
flag.Parse()
if verify {
cfg.ClientAuth = tls.RequireAndVerifyClientCert
} else {
cfg.ClientAuth = tls.RequestClientCert
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}
if certFile == "" {
fmt.Println("[!] missing required flag -cert")
os.Exit(1)
}
if keyFile == "" {
fmt.Println("[!] missing required flag -key")
os.Exit(1)
}
cert, err := tls.LoadX509KeyPair(certFile, keyFile)
if err != nil {
fmt.Printf("[!] could not load server key pair: %v", err)
os.Exit(1)
}
cfg.Certificates = append(cfg.Certificates, cert)
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if sysRoot != "" {
pemList, err := ioutil.ReadFile(sysRoot)
die.If(err)
roots := x509.NewCertPool()
if !roots.AppendCertsFromPEM(pemList) {
fmt.Printf("[!] no valid roots found")
roots = nil
}
cfg.RootCAs = roots
}
l, err := net.Listen("tcp", listenAddr)
if err != nil {
fmt.Println(err.Error())
os.Exit(1)
}
for {
conn, err := l.Accept()
if err != nil {
fmt.Println(err.Error())
}
raddr := conn.RemoteAddr()
tconn := tls.Server(conn, cfg)
err = tconn.Handshake()
if err != nil {
fmt.Printf("[+] %v: failed to complete handshake: %v\n", raddr, err)
continue
}
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cs := tconn.ConnectionState()
if len(cs.PeerCertificates) == 0 {
fmt.Printf("[+] %v: no chain presented\n", raddr)
continue
}
var chain []byte
for _, cert := range cs.PeerCertificates {
p := &pem.Block{
Type: "CERTIFICATE",
Bytes: cert.Raw,
}
chain = append(chain, pem.EncodeToMemory(p)...)
}
var nonce [16]byte
_, err = rand.Read(nonce[:])
if err != nil {
panic(err)
}
fname := fmt.Sprintf("%v-%v.pem", raddr, hex.EncodeToString(nonce[:]))
err = ioutil.WriteFile(fname, chain, 0644)
die.If(err)
fmt.Printf("%v: [+] wrote %v.\n", raddr, fname)
}
}