source: locker/bin/webaccess @ 208

#!/bin/bash

# webaccess
# Manage access control for scripts.mit.edu in .htaccess and .htpasswd files.
# Anders Kaseorg <andersk@mit.edu>

set -e

on_exit=
trap 'eval "$on_exit"' EXIT

dir="$(pwd)"
htaccess=$dir/.htaccess
authuserfile=$dir/.htpasswd

add_users=
del_users=
enable_auth=1
def_authname=\"Private\"

begin_section="### BEGIN webaccess directives"
end_section="### END webaccess directives"

usage () {
    cat <<EOF >&2
usage:
  webaccess -a <user>   Allow access from <user> and set password.
  webaccess -d <user>   Deny access from <user>.
  webaccess -r          Reset default access control.
EOF
    exit 1
}

getpass () {
    user=$1
    (
        echo -n "New password for $user: " >/dev/tty
        trap 'stty echo; echo >/dev/tty' EXIT
        stty -echo
        perl -e 'chop($_ = <>); print crypt($_, "\$1\$" . join "", (".", "/", "0".."9", "A".."Z", "a".."z") [rand 64, rand 64, rand 64, rand 64, rand 64, rand 64, rand 64, rand 64])' </dev/tty
    )
}

if [ $# -eq 0 ]; then usage; fi

while [ $# -gt 0 ]; do
    arg="$1"; shift
    case "$arg" in
        -a*)
            user="${arg#-a}"
            if [ -z "$user" ]; then user=$1; shift; fi
            if [ -z "$user" ]; then usage; fi
            add_users=$add_users\ $user
            ;;
        allow)
            user="$1"; shift
            if [ -z "$user" ]; then usage; fi
            add_users=$add_users\ $user
            ;;
        -d*)
            user="${arg#-d}"
            if [ -z "$user" ]; then user=$1; shift; fi
            if [ -z "$user" ]; then usage; fi
            del_users=$del_users\ $user
            ;;
        remove)
            user="$1"; shift
            if [ -z "$user" ]; then usage; fi
            del_users=$del_users\ $user
            ;;
        -r|reset)
            enable_auth=0
            ;;
        -n*)
            authname="${arg#-n}"
            if [ -z "$authname" ]; then authname=\"$1\"; shift; fi
            if [ -z "$authname" ]; then usage; fi
            ;;
        *)
            usage
            ;;
    esac
done

tmp_htaccess=$htaccess.webaccess-new
trap 'rm -f "$tmp_htaccess"' EXIT
exec 3>"$tmp_htaccess"

config_written=0
write_config () {
    if [ $config_written -eq 1 ]; then return 0; fi
    config_written=1
    if [ $enable_auth -eq 1 ]; then
        echo "$begin_section" >&3
        echo "# See http://scripts.mit.edu/faq/23" >&3
        echo "AuthUserFile $authuserfile" >&3
        echo "AuthName ${authname:-$def_authname}" >&3
        echo "AuthType Basic" >&3
        echo "Require valid-user" >&3
        echo "$end_section" >&3
    fi
}

if [ -e "$htaccess" ]; then
    exec 4<"$htaccess"
    
    oldconfig_state=0
    oldconfig_buffer=__END__
    
    while read -r line <&4; do
        oldconfig_newstate=0
        case "$line" in
            "AuthUserFile "*)     oldconfig_newstate=1 ;;
            "AuthName "*)         oldconfig_newstate=2; oldconfig_authname=${line#AuthName } ;;
            "AuthType Basic")     oldconfig_newstate=3 ;;
            "<Limit GET>")        oldconfig_newstate=4 ;;
            "require valid-user") oldconfig_newstate=5 ;;
            "</Limit>")           oldconfig_newstate=6 ;;
        esac
        
        if [ $oldconfig_newstate -ne $(($oldconfig_state + 1)) ]; then
            if [ $oldconfig_state -ne 0 ]; then
                echo "${oldconfig_buffer%
__END__}" >&3
                oldconfig_state=0
                oldconfig_buffer=__END__
            fi
        fi
        
        if [ "$line" = "$begin_section" ]; then
            while read -r line <&4 && [ "$line" != "$end_section" ]; do
                case "$line" in
                    "AuthName "*)
                        def_authname=${line#AuthName }
                        ;;
                esac
            done
            write_config
        elif [ $oldconfig_newstate -eq $(($oldconfig_state + 1)) ]; then
            oldconfig_buffer=$(echo "${oldconfig_buffer%__END__}$line"; echo __END__)
            oldconfig_state=$oldconfig_newstate
            if [ $oldconfig_state -eq 6 ]; then
                echo "Replacing obsolete webaccess configuration." >&2
                oldconfig_state=0
                oldconfig_buffer=__END__
                def_authname=$oldconfig_authname
            fi
        else
            echo "$line" >&3
        fi
    done
    
    if [ $oldconfig_state -ne 0 ]; then
        echo "${oldconfig_buffer%
__END__}"
        oldconfig_state=0
        oldconfig_buffer=__END__
    fi
    
    exec 4<&-
fi

write_config

exec 3>&-
if ! cmp -s "$htaccess" "$tmp_htaccess"; then
    if [ -s "$tmp_htaccess" ]; then
        echo "Updating $htaccess" >&2
        chmod 777 "$tmp_htaccess"
        mv -f "$tmp_htaccess" "$htaccess"
    else
        if [ -e "$htaccess" ]; then
            echo "Deleting $htaccess" >&2
            rm -f "$htaccess"
        fi
        rm -f "$tmp_htaccess"
    fi
fi
trap - EXIT

if [ $enable_auth -eq 1 ]; then
    if [ ! -e "$authuserfile" ]; then touch "$authuserfile"; fi
    chmod 777 "$authuserfile"
    
    tmp_authuserfile=$authuserfile.webaccess-new
    trap 'rm -f "$tmp_authuserfile"' EXIT
    exec 3>"$tmp_authuserfile"

    exec 4<"$authuserfile"
    while IFS=: read user pass <&4; do
        for del_user in $del_users; do
            if [ "$del_user" = "$user" ]; then
                echo "Deleting user $del_user:" >&2
                pass=
            fi
        done
        new_add_users=
        for add_user in $add_users; do
            if [ "$add_user" = "$user" ]; then
                pass=$(getpass "$user")
            else
                new_add_users=$new_add_users\ $add_user
            fi
        done
        add_users=$new_add_users
        if [ -n "$pass" ]; then
            echo "$user:$pass" >&3
        fi
    done
    exec 4<&-
    
    for add_user in $add_users; do
        pass=$(getpass "$add_user")
        echo "$add_user:$pass" >&3
    done
    
    exec 3>&-
    chmod 777 "$tmp_authuserfile"
    mv -f "$tmp_authuserfile" "$authuserfile"
    trap - EXIT
    
    echo "Done.  New list of valid users:" >&2
    sed -n 's/^\([^:]*\):.*$/  \1/ p' "$authuserfile"
else
    rm -f "$authuserfile"
fi