#! /bin/bash

# Usage:
#   ./gen_certs.sh [cert-kind]
#
# [cert-kind]:
#   ed25519
#   rsa_sha256
#   ecdsa_nistp256_sha256
#   ecdsa_nistp384_sha384
#
# Generate a certificate of the [cert-kind] key type, or if no cert-kind is
# specified, all of the certificates.
#
# Examples:
#   ./gen_certs.sh ed25519
#   ./gen_certs.sh rsa_sha256

# TODO: `rustls` (really, `webpki`) doesn't currently use the CN in the subject
# to check if a certificate is valid for a server name sent via SNI. It's not
# clear if this is intended, since certificates _should_ have a `subjectAltName`
# with a DNS name, or if it simply hasn't been implemented yet. See
# https://bugzilla.mozilla.org/show_bug.cgi?id=552346 for a bit more info.

CA_SUBJECT="/C=US/ST=CA/O=Rocket CA/CN=Rocket Root CA"
SUBJECT="/C=US/ST=CA/O=Rocket/CN=localhost"
ALT="DNS:localhost"

function gen_ca() {
  openssl genrsa -out ca_key.pem 4096
  openssl req -new -x509 -days 3650 -key ca_key.pem \
    -subj "${CA_SUBJECT}" -out ca_cert.pem
}

function gen_ca_if_non_existent() {
  if ! [ -f ./ca_cert.pem ]; then gen_ca; fi
}

function gen_rsa_sha256() {
  gen_ca_if_non_existent

  openssl req -newkey rsa:4096 -nodes -sha256 -keyout rsa_sha256_key.pem \
    -subj "${SUBJECT}" -out server.csr

  openssl x509 -req -sha256 -extfile <(printf "subjectAltName=${ALT}") -days 3650 \
    -CA ca_cert.pem -CAkey ca_key.pem -CAcreateserial \
    -in server.csr -out rsa_sha256_cert.pem

  rm ca_cert.srl server.csr
}

function gen_ed25519() {
  gen_ca_if_non_existent

  openssl genpkey -algorithm ED25519 > ed25519_key.pem

  openssl req -new -key ed25519_key.pem -subj "${SUBJECT}" -out server.csr
  openssl x509 -req -extfile <(printf "subjectAltName=${ALT}") -days 3650 \
    -CA ca_cert.pem -CAkey ca_key.pem -CAcreateserial \
    -in server.csr -out ed25519_cert.pem

  rm ca_cert.srl server.csr
}

function gen_ecdsa_nistp256_sha256() {
  gen_ca_if_non_existent

  openssl ecparam -out ecdsa_nistp256_sha256_key.pem -name prime256v1 -genkey

  # Convert to pkcs8 format supported by rustls
  openssl pkcs8 -topk8 -nocrypt -in ecdsa_nistp256_sha256_key.pem \
    -out ecdsa_nistp256_sha256_key_pkcs8.pem

  openssl req -new -nodes -sha256 -key ecdsa_nistp256_sha256_key_pkcs8.pem \
    -subj "${SUBJECT}" -out server.csr

  openssl x509 -req -sha256 -extfile <(printf "subjectAltName=${ALT}") -days 3650 \
    -CA ca_cert.pem -CAkey ca_key.pem -CAcreateserial \
    -in server.csr -out ecdsa_nistp256_sha256_cert.pem

  rm ca_cert.srl server.csr ecdsa_nistp256_sha256_key.pem
}

function gen_ecdsa_nistp384_sha384() {
  gen_ca_if_non_existent

  openssl ecparam -out ecdsa_nistp384_sha384_key.pem -name secp384r1 -genkey

  # Convert to pkcs8 format supported by rustls
  openssl pkcs8 -topk8 -nocrypt -in ecdsa_nistp384_sha384_key.pem \
    -out ecdsa_nistp384_sha384_key_pkcs8.pem

  openssl req -new -nodes -sha384 -key ecdsa_nistp384_sha384_key_pkcs8.pem \
    -subj "${SUBJECT}" -out server.csr

  openssl x509 -req -sha384 -extfile <(printf "subjectAltName=${ALT}") -days 3650 \
    -CA ca_cert.pem -CAkey ca_key.pem -CAcreateserial \
    -in server.csr -out ecdsa_nistp384_sha384_cert.pem

  rm ca_cert.srl server.csr ecdsa_nistp384_sha384_key.pem
}

case $1 in
  ed25519) gen_ed25519 ;;
  rsa_sha256) gen_rsa_sha256 ;;
  ecdsa_nistp256_sha256) gen_ecdsa_nistp256_sha256 ;;
  ecdsa_nistp384_sha384) gen_ecdsa_nistp384_sha384 ;;
  *)
    gen_ed25519
    gen_rsa_sha256
    gen_ecdsa_nistp256_sha256
    gen_ecdsa_nistp384_sha384
    ;;
esac