:
##########################################################################
# Title      :	rfcat - print RFC text
# Version    :	2.6
# Author     :	Heiner Steven <heiner.steven@odn.de>
# Date       :	2001-04-25
# Requires   :	wget, gzip
# Category   :	WWW
# SCCS-Id.   :	@(#) rfcat	2.6 09/10/21
##########################################################################
# Description
#    o	Prints the text of an internet standard (RFC: "Request For
#	Comments") to standard output. Tries to locate the RFC locally,
#	and retrieves it otherwise direcly from the Web.
#    o	Each RFC text file can optionally be cached after first retrieval
##########################################################################

PN=`basename "$0"`			# Program name
VER='2.6'

# A program to accept an URL as command line argument, retrieves it, and
# prints the results to standard output
: ${GETURL:=wget}
: ${GETURLFLAGS="-O- -q"}	# may be empty

: ${COMPRESS:=gzip}
: ${COMPRESSFLAGS=-f}		# may be empty

# The local directory all RFCs are contained within
: ${RFCDIR:=/usr/local/share/rfc}

# The base WWW URL for all RFCs
RFC_BASE_URL=http://www.ietf.org

# The URL of the "INDEX" page
RFC_INDEX_URL=$RFC_BASE_URL/download/rfc-index.txt

# A template for an RFC URL. The string '${no}' will be replaced by the
# RFC's number
RFC_BY_NUMBER_TEMPL="$RFC_BASE_URL/rfc/rfc\${no}.txt"

#########################################################################

Usage () {
    echo >&2 "$PN - print RFC text, $VER (stv)
usage: $PN [-fc] rfcspec [...]
   -c:	create a local copy of the file, if it does not exist already
   -f:  force retrieval of the file from the Web

An rfcspec can be a RFC number (e.g. 2100), or the symbolic name
\"INDEX\". The RFC is searched locally (RFCDIR=$RFCDIR).
If this was not successful, $PN will retrieve it from $RFC_BASE_URL."
    exit 1
}

Msg () {
    for MsgLine
    do echo "$PN: $MsgLine" >&2
    done
}

Fatal () { Msg "$@"; exit 1; }

#########################################################################
# rfc2path - convert RFC specification to local path name of file
#########################################################################

rfc2path () {
    [ $# -eq 1 ] || Fatal "INTERNAL ERROR: rfc2path needs one argument"

    _rfcspec=$1; shift

    case "$_rfcspec" in
    	INDEX)
	    _url=$RFC_INDEX_URL;;
	*)
	    no=$_rfcspec
	    eval _url="$RFC_BY_NUMBER_TEMPL";
    esac
    echo $RFCDIR/rfc$_rfcspec
}

#########################################################################
# rfc2url - convert RFC specification to URL of file
#########################################################################

rfc2url () {
    [ $# -eq 1 ] || Fatal "INTERNAL ERROR: rfc2url needs one argument"

    _rfcspec=$1; shift

    case "$_rfcspec" in
    	INDEX)
	    _url=$RFC_INDEX_URL;;
	*)
	    no=$_rfcspec
	    eval _url="$RFC_BY_NUMBER_TEMPL";
    esac
    echo "$_url"
}

#########################################################################

set -- `getopt cfh "$@"` || Usage
[ $# -lt 1 ] && Usage			# "getopt" detected an error

CacheFile=false
ForceRetrieval=false
while [ $# -gt 0 ]
do
    case "$1" in
    	-c)	CacheFile=true;;
    	-f)	ForceRetrieval=true;;
	--)	shift; break;;
	-h)	Usage;;
	-*)	Usage;;
	*)	break;;			# First file name
    esac
    shift
done

[ $# -lt 1 ] && Usage

errors=0
for rfc
do
    rfc=`echo "$rfc" | sed 's/^00*//g'`	# remove leading zeroes

    #
    # Search RFC locally
    #

    file=`rfc2path "$rfc"`
    if [ -n "$file" ] && [ $ForceRetrieval = false ]
    then
	for ext in "" .gz .Z .z .txt.gz .txt.Z .txt.z
	do
	    [ -r "$file$ext" ] || continue
	    case "$ext" in
		"") 	cat "$file$ext" ;;
		*.gz )	gunzip -c "$file$ext";;
		*.Z )	zcat "$file$ext";;
		*.z )	unpack "$file$ext";;
	    esac
	    [ $? -eq 0 ] || errors=`expr $errors + 1`
	    continue 2			# Next RFC
	done
    fi

    #
    # No local file. Try to retrieve the RFC via URL
    #

    url=`rfc2url "$rfc"`
    if [ -n "$url" ]
    then
    	# Get the RFC using the Web.
	# XXX: This page could be cached locally using
	#	... | tee $RFCDIR/...

	if [ $CacheFile = true ]
	then
	    # Retrieve file, and create a local copy.

	    # Ignore keyboard signals, because they could cause the local copy
	    # to be incomplete

	    trap '' 1 2 3 13 15
	    $GETURL $GETURLFLAGS "$url" | tee "$file"
	    trap 1 2 3 13 15
	    if [ -s "$file" ]
	    then "$COMPRESS" $COMPRESSFLAGS "$file"
	    else rm -f "$file"			# remove empty file
	    fi
	else
	    $GETURL $GETURLFLAGS "$url"
	fi
	[ $? -ne 0 ] && errors=`expr $errors + 1`

    fi
done
exit $errors