#! /bin/ksh
#Set your hostname after this variable
fqdn=gopher.zcrayfish.soy
oldfqdn=zcrayfish.dyndns.org

cr=$(printf '\r')
crlf=$(printf '\r\n')
null=$(printf '')

securityheaders () {
   printf '%s\15\12' "Strict-Transport-Security: max-age=31536000;" \
       "Content-Security-Policy: default-src *.zcrayfish.soy; object-src *.zcrayfish.soy; base-uri *.zcrayfish.soy;" \
       "X-Frame-Options: DENY" \
       "X-XSS-Protection: 1; mode=block" \
       "Referrer-Policy: no-referrer"
}

error301 () {
   printf '%s\15\12' "HTTP/1.0 301 Moved Permanently" \
       "Location: https://$fqdn$obj" \
       "Content-Type: text/plain; charset=utf-8" \
       "Date: $date" \
       "Server: gopher to http gateway at $fqdn" \
       "Connection: close" \
       "" \
       "HTTP/1.0 301 Moved permanently" \
       "http://$oldfqdn$obj" \
       "Might be found at:" \
       "https://$fqdn$obj" \
       "" \
       "gopher to http gateway at $fqdn"
}

error400 () {
   printf '%s\15\12' "HTTP/1.0 400 Bad Request" \
       "Content-Type: text/plain; charset=utf-8" \
       "Allow: GET" \
       "Date: $date" \
       "Server: gopher to http gateway at $fqdn" \
       "Connection: close" \
       "" \
       "HTTP/1.0 400 Bad Request" \
       "Request could not be understood - bad syntax" \
       "" \
       "gopher to http gateway at $fqdn"
   exit
}

error404 () {
   printf '%s\15\12' "HTTP/1.0 404 Not Found" \
       "Content-Type: text/plain; charset=utf-8" \
       "Date: $date" \
       "Server: gopher to http gateway at $fqdn" \
       "Connection: close" \
       "" \
       "HTTP/1.0 404 Not Found" \
       "'$obj' doesn't exist!" \
       "This resource cannot be located." \
       "" \
       "gopher to http gateway at $fqdn"
}

error501 () {
   printf '%s\15\12' "HTTP/1.0 501 Not Implemented" \
       "Content-Type: text/plain; charset=utf-8" \
       "Allow: GET" \
       "Date: $date" \
       "Server: gopher to http gateway at $fqdn" \
       "Connection: close" \
       "" \
       "HTTP/1.0 501 Not Implemented" \
       "This error has accoured for one of the following reasons:" \
       " *This server only implements the GET method (e.g. your browser sent a HEAD or PUT)" \
       " *This server, while acting as a gateway or proxy, does not support CSO queries." \
       "" \
       "gopher to http gateway at $fqdn"
   exit
}

# Gather request
read -t 30 -r cmd obj proto badclient
#Did we time out... If so just exit, HTTP 1.0 does not have a timeout code
test "$?" != "0" && exit
# See if request is a GET, if not, throw it away
test "$cmd" != 'GET' && error501 && exit
# Likewise ignore invalid gets too.
test ! -z "$badclient" && error400 && exit
# If it all looks good, find out what they want
filename="$(printf "%s" "$obj" | sed -e 's/%2c/,/' -e 's/%20/ /')"


# Gather headers, assume headers are done when we see CRLF or weird crap
while /bin/true; do
 read -t 300 -r header headervalue port
 test "$header" = "$cr" && break
 test "$header" = "$crlf" && break
 test "$header" = "$null" && break
 header=$(echo "$header" | tr '[:upper:]' '[:lower:]')
 test "$header" = "host:" && host="$headervalue"
 #header="$(printf "$header" | sed -e 's/://')"
 #declare -a $header
 #printf -v "${header}" '%s' "${headervalue}" 2> /dev/null
done

#old FQDN? Redirect them!
zdo=$(echo "$host" | grep -i zcrayfish.dyndns.org)
test ! -z "$zdo" && error301 && exit

date="$(date -u +'%a, %d %b %Y %H:%M:%S GMT')"

   #Step4
   case "$filename" in
       /favicon.ico)
           error404
           ;;
       /sitemap*|/robots.txt|/.well-known*)
           printf '%s\15\12' "HTTP/1.0 200 OK" \
               "Date: $date" \
               "Server: gopher to http gateway at $fqdn" \
               "Connection: close" \
               ""
           lynx -anonymous -source "gopher://$fqdn:70/0/$filename"
           ;;
       /2*)
           error501
           ;;
       /7*)
           printf '%s\15\12' "HTTP/1.0 200 OK" \
               "Content-Type: text/html; charset=utf-8" \
               "Date: $date" \
               "Server: gopher to http gateway at $fqdn" \
               "Connection: close" \
               "" \
               '<!DOCTYPE html PUBLIC "-//IETF//DTD HTML 2.0//EN">' \
               '<title></title>' \
               "<form action='$fqdn$filename' method='get'>" \
               '<p>This is a searchable gopher index. Enter search keywords:<input type="text" name="httpsearch"></p></form>'
           ;;
       /debug*)
           printf '%s\15\12' "HTTP/1.0 200 OK" \
               "Content-Type: text/plain" \
               ""
           set
           ;;
       ###START OF DUMB / NON-INTELLIGENT GOPHER TYPES###
       /[04569IMPdghps]*)
           printf '%s\15\12' "HTTP/1.0 200 OK"
           case "$filename" in
               /0/stylesheet.css)
                   printf '%s\15\12' "Content-Type: text/css" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /0*)
                   printf '%s\15\12' "Content-Type: text/plain" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /4*)
                   printf '%s\15\12' "Content-Type: application/mac-binhex40" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /5*)
                   printf '%s\15\12' "Content-Type: application/octet-stream" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /6*)
                   printf '%s\15\12' "Content-Type: message/rfc822" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /9*)
                   printf '%s\15\12' "Content-Type: application/octet-stream" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /I*)
                   printf '%s\15\12' "Content-Type: image/jpeg" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /M*)
                   printf '%s\15\12' "Content-Type: message/rfc822" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /P*)
                   printf '%s\15\12' "Content-Type: application/pdf" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /d*)
                   printf '%s\15\12' "Content-Type: application/pdf"
                       "X-Content-Type-Options: nosniff" \
                   ;;
               /g*)
                   printf '%s\15\12' "Content-Type: image/gif" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /h*)
                   printf '%s\15\12' "Content-Type: text/html" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /p*)
                   printf '%s\15\12' "Content-Type: image/png" \
                       "X-Content-Type-Options: nosniff"
                   ;;
               /s*)
                   printf '%s\15\12' "Content-Type: application/octet-stream"
                   ;;
           esac
           securityheaders
           printf '%s\15\12' "Date: $date" \
               "Server: gopher to http gateway at $fqdn" \
               "Connection: close" \
               ""
           lynx -anonymous -dump -source "gopher://$fqdn:70$filename"
           ;;
       ###END OF DUMB / NON-INTELLIGENT GOPHER TYPES###
       *)
           printf '%s\15\12' 'HTTP/1.0 200 OK' \
               'Content-Type: text/html; charset=utf-8' \
               "Date: $date" \
               "Server: gopher to http gateway at $fqdn"
           securityheaders
           printf '%s\15\12' 'Connection: close' \
               'X-Content-Type-Options: nosniff' \
               '' \
               '<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Strict Level 1//EN">'
#               '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">'
           lynx -anonymous -dump -source "gopher://$fqdn:70$filename" | \
               tidy -in -w 0 -cn --doctype omit --show-errors 0 --show-warnings 0 --quiet 1 --uppercase-tags 1 --uppercase-attributes 1 --char-encoding utf8 | \
#               sed -e 's/<A HREF="\/\/'$fqdn':70/<A HREF="\/\/'$fqdn'/g'
               sed -e 's/<A HREF="\/\//<A HREF="gopher:\/\//g' -e 's/<A HREF="gopher:\/\/'$fqdn':70/<A HREF="\/\/'$fqdn'/g' -e '/<HEAD>/a <LINK REL="STYLESHEET" HREF="//gopher.zcrayfish.soy/0/stylesheet.css">'
#               sed -e 's/<A HREF="\/\/'$fqdn':70/<A HREF="http:\/\/'$fqdn'/g' -e 's/<A HREF="\/\//<A HREF="gopher:\/\//g'
                   ;;
   esac
exit

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