From 4b615cb3a92fad0d65e8868408debbd82ca0f32e Mon Sep 17 00:00:00 2001 From: medmunds Date: Tue, 16 Feb 2021 14:02:09 -0800 Subject: [PATCH] Clean email headers and warn on unsupported address format Just in case, make sure CR or NL don't end up in an email header. --- notify/smtp.sh | 55 +++++++++++++++++++++++++++----------------------- 1 file changed, 30 insertions(+), 25 deletions(-) diff --git a/notify/smtp.sh b/notify/smtp.sh index 43536cd2..42c1487c 100644 --- a/notify/smtp.sh +++ b/notify/smtp.sh @@ -53,16 +53,28 @@ smtp_send() { _saveaccountconf_mutable_default SMTP_BIN "$SMTP_BIN" SMTP_FROM="$(_readaccountconf_mutable_default SMTP_FROM)" + SMTP_FROM="$(_clean_email_header "$SMTP_FROM")" if [ -z "$SMTP_FROM" ]; then _err "You must define SMTP_FROM as the sender email address." return 1 fi + if _email_has_display_name "$SMTP_FROM"; then + _err "SMTP_FROM must be only a simple email address (sender@example.com)." + _err "Change your SMTP_FROM='$SMTP_FROM' to remove the display name." + return 1 + fi _debug SMTP_FROM "$SMTP_FROM" _saveaccountconf_mutable_default SMTP_FROM "$SMTP_FROM" SMTP_TO="$(_readaccountconf_mutable_default SMTP_TO)" + SMTP_TO="$(_clean_email_header "$SMTP_TO")" if [ -z "$SMTP_TO" ]; then - _err "You must define SMTP_TO as the recipient email address." + _err "You must define SMTP_TO as the recipient email address(es)." + return 1 + fi + if _email_has_display_name "$SMTP_TO"; then + _err "SMTP_TO must be only simple email addresses (to@example.com,to2@example.com)." + _err "Change your SMTP_TO='$SMTP_TO' to remove the display name(s)." return 1 fi _debug SMTP_TO "$SMTP_TO" @@ -111,7 +123,7 @@ smtp_send() { _debug SMTP_TIMEOUT "$SMTP_TIMEOUT" _saveaccountconf_mutable_default SMTP_TIMEOUT "$SMTP_TIMEOUT" "$SMTP_TIMEOUT_DEFAULT" - SMTP_X_MAILER="${PROJECT_NAME} ${VER} --notify-hook smtp" + SMTP_X_MAILER="$(_clean_email_header "$PROJECT_NAME $VER --notify-hook smtp")" # Run with --debug 2 (or above) to echo the transcript of the SMTP session. # Careful: this may include SMTP_PASSWORD in plaintext! @@ -121,6 +133,7 @@ smtp_send() { SMTP_SHOW_TRANSCRIPT="" fi + SMTP_SUBJECT=$(_clean_email_header "$SMTP_SUBJECT") _debug SMTP_SUBJECT "$SMTP_SUBJECT" _debug SMTP_CONTENT "$SMTP_CONTENT" @@ -146,28 +159,26 @@ smtp_send() { return 0 } +# Strip CR and NL from text to prevent MIME header injection +# text +_clean_email_header() { + printf "%s" "$(echo "$1" | tr -d "\r\n")" +} + +# Simple check for display name in an email address (< > or ") +# email +_email_has_display_name() { + _email="$1" + expr "$_email" : '^.*[<>"]' >/dev/null +} + ## ## curl smtp sending ## # Send the message via curl using SMTP_* variables _smtp_send_curl() { - # curl passes --mail-from and --mail-rcpt directly to the SMTP protocol without - # additional parsing, and SMTP requires addr-spec only (no display names). - # In the future, maybe try to parse the addr-spec out for curl args (non-trivial). - if _email_has_display_name "$SMTP_FROM"; then - _err "curl smtp only allows a simple email address in SMTP_FROM." - _err "Change your SMTP_FROM='$SMTP_FROM' to remove the display name." - return 1 - fi - if _email_has_display_name "$SMTP_TO"; then - _err "curl smtp only allows simple email addresses in SMTP_TO." - _err "Change your SMTP_TO='$SMTP_TO' to remove the display name(s)." - return 1 - fi - # Build curl args in $@ - case "$SMTP_SECURE" in none) set -- --url "smtp://${SMTP_HOST}:${SMTP_PORT}" @@ -219,7 +230,8 @@ _smtp_send_curl() { echo "$raw_message" | "$SMTP_BIN" "$@" } -# Output an RFC-822 / RFC-5322 email message using SMTP_* variables +# Output an RFC-822 / RFC-5322 email message using SMTP_* variables. +# (This assumes variables have already been cleaned for use in email headers.) _smtp_raw_message() { echo "From: $SMTP_FROM" echo "To: $SMTP_TO" @@ -259,13 +271,6 @@ _rfc2822_date() { LC_TIME="$_old_lc_time" } -# Simple check for display name in an email address (< > or ") -# email -_email_has_display_name() { - _email="$1" - expr "$_email" : '^.*[<>"]' >/dev/null -} - ## ## Python smtp sending ##