From: Lukas Schauer <lukas@schauer.so>
Date: Sat, 5 Dec 2015 21:27:58 +0000 (+0100)
Subject: big portability + readability fix: use openssl base64 instead of system base64, use... 
X-Git-Tag: v0.1.0~214
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c6e6030269cd1e08966c4d966586291c52a8b6c7;p=thirdparty%2Fdehydrated.git

big portability + readability fix: use openssl base64 instead of system base64, use shasum instead of shasum, added some comments
---

diff --git a/letsencrypt.sh b/letsencrypt.sh
index 98441c5..354c478 100755
--- a/letsencrypt.sh
+++ b/letsencrypt.sh
@@ -8,29 +8,35 @@ set -o pipefail
 
 umask 077 # paranoid umask, we're creating private keys
 
+anti_newline() {
+  tr -d '\n\r'
+}
 
 urlbase64() {
-  base64 -w 0 | sed -r 's/=*$//g' | tr '+/' '-_'
+  # urlbase64: base64 encoded string with '+' replaced with '-' and '/' replaced with '_'
+  openssl base64 -e | anti_newline | sed -r 's/=*$//g' | tr '+/' '-_'
 }
 
 hex2bin() {
+  # Store hex string from stdin
   tmphex="$(cat)"
 
-  # remove spaces
+  # Remove spaces
   hex=''
   for ((i=0; i<${#tmphex}; i+=1)); do
     test "${tmphex:$i:1}" == " " || hex="${hex}${tmphex:$i:1}"
   done
 
-  # add leading zero
+  # Add leading zero
   test $((${#hex} & 1)) == 0 || hex="0${hex}"
 
-  # convert to escaped string
+  # Convert to escaped string
   escapedhex=''
   for ((i=0; i<${#hex}; i+=2)); do
     escapedhex=$escapedhex\\x${hex:$i:2}
   done
 
+  # Convert to binary data
   printf "${escapedhex}"
 }
 
@@ -48,18 +54,23 @@ _request() {
 }
 
 signed_request() {
+  # Encode payload as urlbase64
   payload64="$(printf '%s' "${2}" | urlbase64)"
 
-  # -sSf: stay silent but report errors and exit with != 0 if they occur
-  nonce="$(_request head "${CA}/directory" | grep Replay-Nonce: | awk -F ': ' '{print $2}' | tr -d '\n\r')"
+  # Retrieve nonce from acme-server
+  nonce="$(_request head "${CA}/directory" | grep Replay-Nonce: | awk -F ': ' '{print $2}' | anti_newline)"
 
+  # Build header with just our public key and algorithm information
   header='{"alg": "RS256", "jwk": {"e": "'"${pubExponent64}"'", "kty": "RSA", "n": "'"${pubMod64}"'"}}'
 
+  # Build another header which also contains the previously received nonce and encode it as urlbase64
   protected='{"alg": "RS256", "jwk": {"e": "'"${pubExponent64}"'", "kty": "RSA", "n": "'"${pubMod64}"'"}, "nonce": "'"${nonce}"'"}'
   protected64="$(printf '%s' "${protected}" | urlbase64)"
 
+  # Sign header with nonce and our payload with our private key and encode signature as urlbase64
   signed64="$(printf '%s' "${protected64}.${payload64}" | openssl dgst -sha256 -sign private_key.pem | urlbase64)"
 
+  # Send header + extended header + payload + signature to the acme-server
   data='{"header": '"${header}"', "protected": "'"${protected64}"'", "payload": "'"${payload64}"'", "signature": "'"${signed64}"'"}'
 
   _request post "${1}" "${data}"
@@ -69,22 +80,26 @@ sign_domain() {
   domain="${1}"
   altnames="${*}"
   echo "Signing domain ${1} (${*})..."
-  if [ ! -e "certs/${domain}" ]; then
-    SAN=""
-    for altname in $altnames; do
-      SAN+="DNS:${altname}, "
-    done
-    SAN="$(printf '%s' "${SAN}" | sed 's/,\s*$//g')"
 
+  # If there is no existing certificate directory we need a new private key
+  if [ ! -e "certs/${domain}" ]; then
     mkdir "certs/${domain}"
-
     echo "  + Generating private key..."
     openssl genrsa -out "certs/${domain}/privkey.pem" 4096 2> /dev/null > /dev/null
-    echo "  + Generating signing request..."
-    openssl req -new -sha256 -key "certs/${domain}/privkey.pem" -out "certs/${domain}/cert.csr" -subj "/CN=${domain}/" -reqexts SAN -config <(cat /etc/ssl/openssl.cnf <(printf "[SAN]\nsubjectAltName=%s" "${SAN}")) > /dev/null
   fi
 
+  # Generate signing request config and the actual signing request
+  SAN=""
   for altname in $altnames; do
+    SAN+="DNS:${altname}, "
+  done
+  SAN="$(printf '%s' "${SAN}" | sed 's/,\s*$//g')"
+  echo "  + Generating signing request..."
+  openssl req -new -sha256 -key "certs/${domain}/privkey.pem" -out "certs/${domain}/cert.csr" -subj "/CN=${domain}/" -reqexts SAN -config <(cat /etc/ssl/openssl.cnf <(printf "[SAN]\nsubjectAltName=%s" "${SAN}")) > /dev/null
+
+  # Request and respond to challenges
+  for altname in $altnames; do
+    # Ask the acme-server for new challenge token and extract them from the resulting json block
     echo "  + Requesting challenge for ${altname}..."
     response="$(signed_request "${CA}/acme/new-authz" '{"resource": "new-authz", "identifier": {"type": "dns", "value": "'"${altname}"'"}}')"
 
@@ -96,35 +111,40 @@ sign_domain() {
       exit 1
     fi
 
+    # Challenge response consists of the challenge token and the thumbprint of our public certificate
     keyauth="${challenge_token}.${thumbprint}"
 
+    # Store challenge response in well-known location and make world-readable (so that a webserver can access it)
     printf '%s' "${keyauth}" > "${WELLKNOWN}/${challenge_token}"
     chmod a+r "${WELLKNOWN}/${challenge_token}"
 
+    # Ask the acme-server to verify our challenge and wait until it becomes valid
     echo "  + Responding to challenge for ${altname}..."
     result="$(signed_request "${challenge_uri}" '{"resource": "challenge", "keyAuthorization": "'"${keyauth}"'"}')"
 
     status="$(printf '%s\n' "${result}" | grep -Eo '"status":\s*"[^"]*"' | cut -d'"' -f4)"
-
     if [ ! "${status}" = "pending" ] && [ ! "${status}" = "valid" ]; then
       echo "  + Challenge is invalid! (${result})"
       exit 1
     fi
 
-    while [ ! "${status}" = "valid" ]; do
+    while [ "${status}" = "pending" ]; do
       status="$(_request get "${challenge_uri}" | grep -Eo '"status":\s*"[^"]*"' | cut -d'"' -f4)"
+      sleep 1
     done
 
     echo "  + Challenge is valid!"
   done
 
+  # Finally request certificate from the acme-server and store it in cert.pem
   echo "  + Requesting certificate..."
   csr64="$(openssl req -in "certs/${domain}/cert.csr" -outform DER | urlbase64)"
-  crt64="$(signed_request "${CA}/acme/new-cert" '{"resource": "new-cert", "csr": "'"${csr64}"'"}' | base64 -w 64)"
+  crt64="$(signed_request "${CA}/acme/new-cert" '{"resource": "new-cert", "csr": "'"${csr64}"'"}' | openssl base64 -e)"
   printf -- '-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----\n' "${crt64}" > "certs/${domain}/cert.pem"
   echo "  + Done!"
 }
 
+# Check if private key exists, if it doesn't exist yet generate a new one (4096bit rsa key)
 register="0"
 if [ ! -e "private_key.pem" ]; then
   echo "+ Generating account key..."
@@ -132,16 +152,19 @@ if [ ! -e "private_key.pem" ]; then
   register="1"
 fi
 
+# Get public components from private key and calculate thumbprint
 pubExponent64="$(printf "%06x" "$(openssl rsa -in private_key.pem -noout -text | grep publicExponent | head -1 | cut -d' ' -f2)" | hex2bin | urlbase64)"
 pubMod64="$(printf '%s' "$(openssl rsa -in private_key.pem -noout -modulus | cut -d'=' -f2)" | hex2bin | urlbase64)"
 
-thumbprint="$(printf '%s' "$(printf '%s' '{"e":"'"${pubExponent64}"'","kty":"RSA","n":"'"${pubMod64}"'"}' | sha256sum | awk '{print $1}')" | hex2bin | urlbase64)"
+thumbprint="$(printf '%s' "$(printf '%s' '{"e":"'"${pubExponent64}"'","kty":"RSA","n":"'"${pubMod64}"'"}' | shasum -a 256 | awk '{print $1}')" | hex2bin | urlbase64)"
 
+# If we generated a new private key in the step above we have to register it with the acme-server
 if [ "${register}" = "1" ]; then
   echo "+ Registering account key with letsencrypt..."
   signed_request "${CA}/acme/new-reg" '{"resource": "new-reg", "agreement": "https://letsencrypt.org/documents/LE-SA-v1.0.1-July-27-2015.pdf"}' > /dev/null
 fi
 
+# Generate certificates for all domains found in domain.txt (TODO: check if certificate already exists and is about to expire)
 <domains.txt sed 's/^\s*//g;s/\s*$//g' | grep -v '^#' | grep -v '^$' | while read line; do
   sign_domain $line
 done