Strips sender details (IP, client, user agent) when sending (#91)

* Strips sender's IP, client, and user agent headers

* Bumping patch verison number

Dockerfile

@@ -21,6 +21,7 @@ RUN apk add --update --no-cache \
         openssl \
         postsrsd \
         postfix \
+        postfix-pcre \
         syslog-ng \
         tzdata \
     \
@@ -41,7 +42,7 @@ COPY install/main.dist.cf /etc/postfix/main.cf
 COPY install/master.dist.cf /etc/postfix/master.cf
 COPY install/syslog-ng.conf /etc/syslog-ng/syslog-ng.conf
 COPY install/opendkim.conf /etc/opendkim/opendkim.conf
-
+COPY install/sender_header_filter.pcre /etc/postfix/sender_header_filter.pcre
 RUN cat /dev/null > /etc/postfix/aliases && newaliases \
     && echo simple-mail-forwarder.com > /etc/hostname \
     && mkdir -p /run/opendkim && chown opendkim:opendkim /run/opendkim \

README.md

@@ -241,6 +241,11 @@ It is highly advised to mount `/var/db/dkim/` folder to host, so generated keypa
 docker run -e SMF_CONFIG="$SMF_CONFIG" -p 25:25 -v $(pwd)/dkim:/var/db/dkim/ zixia/simple-mail-forwarder
 ```
 
+Stripping sender details
+------------------------
+
+SMF will strip the sender's IP, client, and user agent headers when the `SMF_SENDERPRIVACY` environment variable is defined.
+
 Helper Scripts
 --------------------
 

VERSION

@@ -1 +1 @@
-1.4.0
+1.4.1

entrypoint.sh

@@ -19,6 +19,7 @@ Environment Variables:
     SMF_CONFIG - mail forward addresses mapping list.
     SMF_MYNETWORKS - configure relaying from trusted IPs, see http://www.postfix.org/postconf.5.html#mynetworks
     SMF_RELAYHOST - configure a relayhost
+    SMF_SENDERPRIVACY - strips sender's IP, client, and user agent.
 
 this creates a new smtp server which listens on port 25,
 forward all email from
@@ -188,6 +189,12 @@ function start_postfix {
         postconf -e smtp_tls_CAfile=/etc/ssl/certs/ca-certificates.crt
     fi
 
+    if [ "$SMF_SENDERPRIVACY" != "" ]
+    then
+        echo "Stripping sender's IP, client, and user agent."
+        postconf -e smtp_header_checks=pcre:/etc/postfix/sender_header_filter.pcre
+    fi
+
     postfix start
 
     # migrating older single-domain DKIM (/var/db/dkim/default.*) to /var/db/dkim/$HOSTNAME/default.*

install/sender_header_filter.pcre

@@ -0,0 +1,5 @@
+/^(Received: from)[^\n]*(.*)/ REPLACE $1 127.0.0.1 (localhost [127.0.0.1])$2
+/^User-Agent/ IGNORE
+/^X-Originating-IP/ IGNORE
+/^X-Mailer:/            IGNORE
+/^Mime-Version:/        IGNORE