Add contrib directory (#45)

The new contrib directory contains a script that generates an EC key-pair that satisfies golang >=1.15 CommonName deprecation. 

Co-authored-by: J.C. Jones <[email protected]>
Co-authored-by: Samantha <[email protected]>

contrib/README.md

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+# Contrib
+This collection of scripts and files helps us further configure our unbounds and unbound_exporters.
+
+## unbound-control-setup.sh
+
+From [Golang 1.15 docs:](https://golang.google.cn/doc/go1.15#commonname)
+> X.509 CommonName deprecation
+> The deprecated, legacy behavior of treating the CommonName field on X.509 certificates as a host name when no Subject Alternative Names are present is now disabled by default. It can be temporarily re-enabled by adding the value x509ignoreCN=0 to the GODEBUG environment variable.
+> Note that if the CommonName is an invalid host name, it's always ignored, regardless of GODEBUG settings. Invalid names include those with any characters other than letters, digits, hyphens and underscores, and those with empty labels or trailing dots.
+
+Unbound still ships with an `unbound-control-setup` that generates a problematic keypair. This script will generate a keypair that satisfies newer versions of Golang.
+
+Generate the new keypair
+```
+$ bash unbound-control-setup.sh
+```
+
+You'll then want to configure `/etc/unbound/unbound.conf` with the following stanza
+
+```
+$ cat /etc/unbound/unbound.conf
+...
+remote-control:
+    control-enable: yes
+    control-use-cert: yes
+    server-key-file: "/etc/unbound/unbound_server_ec.key"
+    server-cert-file: "/etc/unbound/unbound_server_ec.pem"
+    control-key-file: "/etc/unbound/unbound_control_ec.key"
+    control-cert-file: "/etc/unbound/unbound_control_ec.pem"
+```
+
+Test that you can still communicate with unbound via `unbound_control`. You should be able to see metrics.
+```
+$ unbound-control stats_noreset
+thread0.num.queries=35
+thread0.num.queries_ip_ratelimited=0
+thread0.num.cachehits=25
+thread0.num.cachemiss=10
+thread0.num.prefetch=0
+thread0.num.expired=0
+...
+
+```
+
+To reconfigure `unbound_exporter` as a systemd service, see [this file](unbound_exporter.service).

contrib/unbound-cert-setup.sh

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+#!/usr/bin/env bash
+
+# Generally based on /usr/sbin/unbound-control-setup but adapted to catch
+# up to ~2010. You know, x509v3, secp384r1, AKIs, stuff like that.
+
+# directory for files
+DESTDIR="${UNBOUND_CONFIG_DIR:-/etc/unbound}"
+
+# validity period for certificates
+DAYS="${UNBOUND_CERT_LIFETIME:-397}"
+
+# hash algorithm
+HASH=sha256
+
+# base name for unbound CA keys
+CA_BASE=unbound_ca_ec
+
+# base name for unbound server keys
+SVR_BASE=unbound_server_ec
+
+# base name for unbound-control keys
+CTL_BASE=unbound_control_ec
+
+# we want -rw-r----- access (say you run this as root: grp=yes (server), all=no).
+umask 0027
+
+# end of options
+
+# functions:
+error ( ) {
+        echo "$0 fatal error: ${1}"
+        exit 1
+}
+
+# go!:
+echo "setup in directory ${DESTDIR}"
+cd "${DESTDIR}" || error "could not cd to ${DESTDIR}"
+
+# create certificate keys; do not recreate if they already exist.
+if test -f "${CA_BASE}.key"; then
+        echo "${CA_BASE}.key exists"
+else
+        echo "generating ${CA_BASE}.key"
+        openssl ecparam -genkey -name secp384r1 > ${CA_BASE}.key || error "could not gen ecdsa"
+fi
+if test -f "${SVR_BASE}.key"; then
+        echo "${SVR_BASE}.key exists"
+else
+        echo "generating ${SVR_BASE}.key"
+        openssl ecparam -genkey -name secp384r1 > ${SVR_BASE}.key || error "could not gen ecdsa"
+fi
+if test -f "${CTL_BASE}.key"; then
+        echo "${CTL_BASE}.key exists"
+else
+        echo "generating ${CTL_BASE}.key"
+        openssl ecparam -genkey -name secp384r1 > ${CTL_BASE}.key || error "could not gen ecdsa"
+fi
+
+# create self-signed cert CSR for server
+cat > ca_request.cfg <<EOCAConfig
+[req]
+prompt                 = no
+distinguished_name     = req_distinguished_name
+x509_extensions        = req_v3_extensions
+
+[req_distinguished_name]
+commonName             = unbound-ca
+
+[req_v3_extensions]
+subjectKeyIdentifier   = hash
+authorityKeyIdentifier = keyid:always,issuer:always
+basicConstraints       = CA:true
+EOCAConfig
+test -f ca_request.cfg || error "could not create ca_request.cfg"
+
+echo "creating ${CA_BASE}.pem (self signed certificate)"
+openssl req -key "${CA_BASE}.key" -config ca_request.cfg  -new -x509 -days "${DAYS}" -out "${CA_BASE}.pem" || error "could not create ${CA_BASE}.pem"
+
+# --------------
+
+# create server cert CSR and sign it, piped
+cat > server_request.cfg <<EOServerConfig
+[req]
+prompt                 = no
+distinguished_name     = req_distinguished_name
+
+[req_distinguished_name]
+commonName             = unbound
+EOServerConfig
+test -f server_request.cfg || error "could not create server_request.cfg"
+
+cat > server_exts.cfg <<EOServerConfig
+subjectAltName         = @alt_names
+subjectKeyIdentifier   = hash
+authorityKeyIdentifier = keyid:always,issuer:always
+extendedKeyUsage       = serverAuth
+
+[alt_names]
+DNS.1                  = $(hostname)
+DNS.2                  = unbound
+DNS.3                  = localhost
+EOServerConfig
+test -f server_exts.cfg || error "could not create server_exts.cfg"
+
+echo "create ${SVR_BASE}.pem (signed server certificate)"
+openssl req -key "${SVR_BASE}.key" -config server_request.cfg -new | openssl x509 -req -days "${DAYS}" -CA "${CA_BASE}.pem" -CAkey "${CA_BASE}.key" -CAcreateserial -"${HASH}" -extfile server_exts.cfg -out "${SVR_BASE}.pem"
+test -f ${SVR_BASE}.pem || error "could not create ${SVR_BASE}.pem"
+
+# --------------
+
+# create client cert CSR and sign it, piped
+cat > client_request.cfg <<EOCertConfig
+[req]
+prompt                 = no
+distinguished_name     = req_distinguished_name
+
+[req_distinguished_name]
+commonName             = unbound-control
+EOCertConfig
+test -f client_request.cfg || error "could not create client_request.cfg"
+
+cat > client_exts.cfg <<EOCertConfig
+extendedKeyUsage       = clientAuth
+EOCertConfig
+test -f client_exts.cfg || error "could not create client_exts.cfg"
+
+echo "create ${CTL_BASE}.pem (signed client certificate)"
+openssl req -key "${CTL_BASE}.key" -config client_request.cfg -new | openssl x509 -req -days "${DAYS}" -CA "${CA_BASE}.pem" -CAkey "${CA_BASE}.key" -CAcreateserial -"${HASH}" -extfile client_exts.cfg -out "${CTL_BASE}.pem"
+test -f "${CTL_BASE}.pem" || error "could not create ${CTL_BASE}.pem"
+
+# --------------
+
+# set desired permissions
+chmod 0640 "${CA_BASE}.key" "${SVR_BASE}.key" "${CTL_BASE}.key"
+chmod 0644 "${CA_BASE}.pem" "${SVR_BASE}.pem" "${CTL_BASE}.pem"
+
+# cleanup
+rm -f ca_request.cfg client_request.cfg client_exts.cfg server_request.cfg server_exts.cfg  *.srl
+
+openssl x509 -text -in "${CA_BASE}.pem"
+openssl x509 -text -in "${SVR_BASE}.pem"
+openssl x509 -text -in "${CTL_BASE}.pem"
+
+echo "Satisfy unbound daemon/remote.c SSL_CTX_use_certificate_chain_file by appending ${CA_BASE}.pem to ${SVR_BASE}.pem"
+cat "${CA_BASE}.pem" >> "${SVR_BASE}.pem"
+
+echo "Setup success. Certificates created."

contrib/unbound_exporter.service

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+[Unit]
+Description=Prometheus exporter for Unbound metrics, written in Go with pluggable metric collectors. The metrics exporter converts Unbound metric names to Prometheus metric names and labels by using a set of regular expressions.
+Documentation=https://github.com/letsencrypt/unbound_exporter
+After=network.target
+
+[Service]
+Type=simple
+ExecStart=/bin/unbound_exporter \
+    -unbound.ca "/etc/unbound/unbound_ca_ec.pem" \
+    -unbound.cert "/etc/unbound/unbound_control_ec.pem" \
+    -unbound.key "/etc/unbound/unbound_control_ec.key" \
+    -unbound.host "tcp://localhost:8953"
+
+[Install]
+WantedBy=multi-user.target