#!/bin/sh
# Alagezia PKI - request a certificate FROM OUTSIDE THE LAN (Linux / macOS / BSD; needs openssl + curl; no root rights).
#
#   curl -fsSO https://pki.hanei-no-choten.com/pki/request-cert-ext.sh && sh request-cert-ext.sh
#   sh request-cert-ext.sh --name laptop [--days N] [--pfx] [--out DIR]
#
# For every network that is not the Alagezia LAN, VPN peers included (inside the LAN: request-cert.sh).
# Nothing goes over plain HTTP. The only server is https://pki.hanei-no-choten.com: TLS ends on the CA host itself
# (the VDS on the way only passes the stream through), and this script accepts it only if the certificate is valid
# for the name AND carries the CA host's own public key (pinned below). A forged certificate for the same name - even a
# real Let's Encrypt one obtained by whoever controls the VDS - has another key and is refused.
#
# Confirmation: VK community - a CLIENT certificate. The script shows an 8-digit code. In a private chat with the
# Alagezia VK community open "Sertifikaty" -> "Vypustit sertifikat" (certificates -> issue), send the code there and
# compare the key fingerprint in the reply. Names: one word gives <word>.external.alagezia.internal; a full name only
# if it is reserved for your VK account. The manual approval queue is a LAN-only route.
# The key is created here and never leaves this host. Plain files in ~/alagezia-certs/<name>/; nothing is installed.
# The issued chain must lead to the Alagezia root built into this file.
#
# ASCII only, deliberately: scripts travel between Windows, Linux and network gear.
set -eu
EXT_HOST=pki.hanei-no-choten.com
# SHA-256 of the CA host's public key (SubjectPublicKeyInfo) of its Let's Encrypt certificate "hanei-ext".
# certbot keeps the key on renewal (reuse_key); if the key is ever replaced, this pin and the .ps1 one must follow.
PIN='sha256//fB+pz4SeGb2VcOHd+4+Vsne3o+4Kg6ZI/Lq8hbIosVY='
ROOT_SHA256=a728875111fc347dc18e7d3418f38daa5c31edb867b1526d5eed0499deac725a
VK_CHAT=https://vk.me/alagezia_al
VK_GROUP='https://vk.ru/alagezia_al (@alagezia_al)'
NAME=""; DAYS=""; OUT=""; PFX=""; INTERACTIVE=1

say()  { printf '  %s\n' "$*"; }
fail() { printf '\n  %s\n' "$*" >&2; exit 1; }
ask()  { printf '  %s' "$1" >&2; read -r REPLY || REPLY=""; }

while [ $# -gt 0 ]; do
  case "$1" in
    --vk) ;;
    --name) NAME=$2; shift ;;
    --days) DAYS=$2; shift ;;
    --out) OUT=$2; shift ;;
    --pfx) PFX=1 ;;
    -h|--help) sed -n 2,5p "$0"; exit 0 ;;
    --operator) fail "The manual approval queue works only inside the LAN (request-cert.sh)." ;;
    *) fail "unknown option $1" ;;
  esac
  shift
done
[ -n "$NAME" ] && INTERACTIVE=""
command -v openssl >/dev/null && command -v curl >/dev/null || fail "openssl and curl are required."
# Schannel builds of curl (Windows) may stall on revocation lookups; the server key is pinned anyway.
NOREVOKE=""; curl --ssl-no-revoke --version >/dev/null 2>&1 && NOREVOKE=--ssl-no-revoke

BASE=${OUT:-$HOME/alagezia-certs}
mkdir -p "$BASE"
W=$(mktemp -d); trap 'rm -rf "$W"' EXIT
ROOT=$BASE/alagezia-root.crt
cat > "$ROOT" <<'EOF'
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
EOF
der_sha() { openssl x509 -in "$1" -outform DER 2>/dev/null | openssl dgst -sha256 | awk '{print $NF}'; }
[ "$(der_sha "$ROOT")" = "$ROOT_SHA256" ] || fail "The built-in root certificate does not match its own fingerprint: this copy of the script is damaged."
API="https://$EXT_HOST"

printf '\n'; say 'Alagezia PKI - certificate request from outside the LAN'
say 'The key is created on this host and never leaves it. Nothing is installed.'; printf '\n'

# ---------------------------------------------------------------- helpers
api() {  # api METHOD PATH [BODYFILE] [SECRET] -> body in $W/resp, prints the HTTP status ("000" = no answer)
  # never exits by itself: it runs inside $(...), where exit would end only the subshell
  _m=$1; _p=$2; _b=${3:-}; _s=${4:-}
  : > "$W/resp"
  # system CA store for the name (Let's Encrypt) + the pinned key of the CA host
  set -- curl -sS -o "$W/resp" -w '%{http_code}' --connect-timeout 10 --max-time 30 --proto =https --tlsv1.2 \
    --pinnedpubkey "$PIN" -X "$_m"
  [ -n "$NOREVOKE" ] && set -- "$@" "$NOREVOKE"
  [ -n "$_b" ] && set -- "$@" -H 'Content-Type: application/json' --data-binary "@$_b"
  [ -n "$_s" ] && set -- "$@" -H "X-Ticket-Secret: $_s"
  "$@" "$API/ca/ext/$_p" 2>"$W/err" || true
}
jget() {  # value of a top-level key of the CA's JSON (one key per line), unescaped
  awk -v k="\"$2\": " 'index($0, k) {
      v = substr($0, index($0, k) + length(k)); sub(/,[ \t\r]*$/, "", v)
      if (v ~ /^"/) v = substr(v, 2, length(v) - 2)
      gsub(/\\n/, "\n", v); gsub(/\\"/, "\"", v); if (v == "null") v = ""; print v; exit }' "$1"
}
refusal() {
  if [ "${1:-000}" = 000 ]; then
    if grep -qi 'pinned\|pubkey' "$W/err" 2>/dev/null; then
      fail "The server at $API did not show the CA host's key: someone on the way answers instead of it, or this script is outdated - get a fresh copy from https://$EXT_HOST/ ($(tail -1 "$W/err"))."
    fi
    fail "Cannot reach the Alagezia CA at $API ($(tail -1 "$W/err" 2>/dev/null))."
  fi
  e=$(jget "$W/resp" error); m=$(jget "$W/resp" message); fail "The CA refused: ${e:-HTTP $1}${m:+ - $m}"
}
transient() { case "$1" in 000|429|5??) return 0 ;; esac; return 1; }
key_fp() { openssl pkey -in "$1" -pubout -outform DER | openssl dgst -sha256 | awk '{h=toupper($NF); print substr(h,1,4)" "substr(h,5,4)" "substr(h,9,4)" "substr(h,13,4)}'; }
new_key() {  # new_key DIR FILE CN
  ( umask 077; openssl ecparam -name prime256v1 -genkey -noout -out "$1/$2.key" )
  # MSYS (Git-bash on Windows) would rewrite the leading "/" of -subj as a Windows path; only that argument is
  # excluded (the file paths still need the conversion). Elsewhere the variable does nothing.
  MSYS2_ARG_CONV_EXCL='/O=' openssl req -new -key "$1/$2.key" -subj "/O=Alagezia/CN=$3" -out "$1/$2.csr"
}
save() {  # save DIR FILE CHAINFILE
  cp "$3" "$1/$2.chain.pem"
  openssl x509 -in "$1/$2.chain.pem" -out "$1/$2.crt"
  openssl verify -CAfile "$ROOT" -untrusted "$1/$2.chain.pem" "$1/$2.crt" >/dev/null || fail "The received certificate does not verify."
  [ "$(openssl x509 -in "$1/$2.crt" -noout -pubkey | openssl pkey -pubin -outform DER | openssl dgst -sha256)" = \
    "$(openssl pkey -in "$1/$2.key" -pubout -outform DER | openssl dgst -sha256)" ] || fail "The received certificate is not for the key made here."
  printf '\n'; say "Issued: $(openssl x509 -in "$1/$2.crt" -noout -subject -nameopt RFC2253 | sed 's/^subject=//')"
  say "$(openssl x509 -in "$1/$2.crt" -noout -enddate -serial | tr '\n' ' ')"
  if [ -n "$PFX" ]; then
    openssl pkcs12 -export -inkey "$1/$2.key" -in "$1/$2.crt" -certfile "$1/$2.chain.pem" -name "$2" -out "$1/$2.pfx"
  fi
  printf '\n'; say "Files: $1"; for f in "$1"/*; do say "  $(basename "$f")"; done
}

# ================================================================ VK confirmation
while :; do
  if [ -z "$NAME" ]; then
    printf '\n'; say 'Certificate name: one word (a-z 0-9 -) gives <word>.external.alagezia.internal;'
    say 'a full name (host.alagezia.internal) works only if it is reserved for your VK account.'
    ask 'Name: '; NAME=$(printf '%s' "$REPLY" | tr 'A-Z' 'a-z')
  fi
  case "$NAME" in *[!a-z0-9.-]*|'') say 'Name: a-z 0-9 . - only.'; NAME=""; [ -n "$INTERACTIVE" ] || exit 1; continue ;; esac
  case "$DAYS" in ''|*[!0-9]*) d=null ;; *) d=$DAYS ;; esac
  printf '{"name":"%s","days":%s}' "$NAME" "$d" > "$W/hello.json"
  st=$(api POST hello "$W/hello.json")
  [ "$st" = 200 ] && break
  { [ -n "$INTERACTIVE" ] && ! transient "$st"; } || refusal "$st"
  say "Not accepted: $(jget "$W/resp" message)"; NAME=""; DAYS=""
done
CN=$(jget "$W/resp" cn); say "Name: $CN"
[ "$(jget "$W/resp" bot)" = online ] || fail "The VK confirmation service is offline right now: a code could not be confirmed. Try again later."
if [ -z "$DAYS" ]; then
  DAYS=$(jget "$W/resp" days)
  if [ -n "$INTERACTIVE" ]; then ask "Days (1-$(jget "$W/resp" max_days)) [$DAYS]: "; case "$REPLY" in ''|*[!0-9]*) ;; *) DAYS=$REPLY ;; esac; fi
fi
D=$BASE/$CN; mkdir -p "$D"
new_key "$D" "$CN" "$CN"
FP=$(key_fp "$D/$CN.key")
csr=$(awk '{printf "%s\\n", $0}' "$D/$CN.csr")
printf '{"name":"%s","days":%s,"csr":"%s"}' "$CN" "$DAYS" "$csr" > "$W/open.json"
st=$(api POST open "$W/open.json"); [ "$st" = 201 ] || refusal "$st"
cp "$W/resp" "$W/ticket"
ID=$(jget "$W/ticket" id); SECRET=$(jget "$W/ticket" secret); CODE=$(jget "$W/ticket" code)
if [ "$(jget "$W/ticket" key_fp)" != "$FP" ]; then
  api POST "cancel/$ID" "" "$SECRET" >/dev/null
  fail "The CA saw a different key ($(jget "$W/ticket" key_fp)) than this host made ($FP): the request was altered on the way. Cancelled."
fi
DONE=""
cancel() { [ -n "$DONE" ] || { api POST "cancel/$ID" "" "$SECRET" >/dev/null 2>&1 || true; printf '\n'; say 'Request cancelled.'; }; }
trap 'cancel; rm -rf "$W"; exit 130' INT TERM
printf '\n'; say '=================================================='
say "  Confirmation code:  $(printf '%s' "$CODE" | cut -c1-4) $(printf '%s' "$CODE" | cut -c5-8)"
say "  Key fingerprint:    $FP"
say '=================================================='
say "In a PRIVATE chat with the VK community Alagezia: $VK_GROUP"
say "(direct link to the chat: $VK_CHAT) open"
say '"Sertifikaty" -> "Vypustit sertifikat" (certificates -> issue) and send the code there'
say 'within 5 minutes. A code sent anywhere else is ignored, group chats included.'
say 'The reply shows a key fingerprint: it must be exactly the one above - otherwise press "Cancel" there.'
say 'Ctrl+C here cancels the request.'; printf '\n'
LAST=""; TROUBLE=""; END=$(( $(date +%s) + 660 ))
while [ "$(date +%s)" -lt "$END" ]; do
  st=$(api GET "t/$ID" "" "$SECRET")
  # temporary trouble (no network, rate limit shared with neighbours behind one address, CA restarting)
  # must not cost the request: the code may already be on its way in VK. Only a final answer ends the wait.
  if transient "$st"; then
    [ -n "$TROUBLE" ] || say "Connection problem (HTTP $st), retrying..."; TROUBLE=1; sleep 10; continue
  fi
  [ "$st" = 200 ] || { cancel; refusal "$st"; }
  [ -z "$TROUBLE" ] || { say 'Connection restored.'; TROUBLE=""; }
  S=$(jget "$W/resp" state)
  if [ "$S" != "$LAST" ]; then
    case "$S" in
      open)     say 'Waiting for the code in VK...' ;;
      claimed)  say "Code received from VK id $(jget "$W/resp" vk_id). Waiting for 'issue' in VK..." ;;
      issuing)  say 'Issuing...' ;;
      rejected) DONE=1; fail 'The request was cancelled.' ;;
      expired)  DONE=1; fail 'Time is up - run the script again for a new code.' ;;
      failed)   DONE=1; fail 'The CA could not issue the certificate.' ;;
    esac
    LAST=$S
  fi
  [ "$S" = issued ] && { DONE=1; break; }
  sleep 5
done
[ -n "$DONE" ] || { cancel; fail 'Time is up - run the script again for a new code.'; }
jget "$W/resp" chain > "$W/chain.pem"
save "$D" "$CN" "$W/chain.pem"
printf '\n'; say 'Services: https://hanei-no-choten.com/'
exit 0