HCoop / hcoop / debian / exim4.git / blame
| Commit | Line | Data |
|---|---|---|
| 2ea97746 CE |
1 | #!/bin/sh -eu |
| 2 | # | |
| 3 | # Short version of this script: | |
| 4 | # curl -f -o /var/cache/exim/opendmarc.tlds https://publicsuffix.org/list/public_suffix_list.dat | |
| 5 | # but run as Exim runtime user, writing to a place it can write to, and with | |
| 6 | # sanity checks and atomic replacement. | |
| 7 | # | |
| 8 | # For now, we deliberately leave the invalid file around for analysis | |
| 9 | # with .<pid> suffix. | |
| 10 | # | |
| 11 | # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~8< cut here >8~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
| 12 | # | |
| 13 | # Create a cron-job as the Exim run-time user to invoke this daily, with a | |
| 14 | # single parameter, 'cron'. Eg: | |
| 15 | # | |
| 16 | # 3 4 * * * /usr/local/sbin/renew-opendmarc-tlds.sh cron | |
| 17 | # | |
| 18 | # That will, at 3 minutes past the 4th hour (in whatever timezone cron is | |
| 19 | # running it) invoke this script with 'cron'; we will then sleep between 10 and | |
| 20 | # 50 seconds, before continuing. | |
| 21 | # | |
| 22 | # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~8< cut here >8~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
| 23 | # | |
| 24 | # This should be "pretty portable"; the only things it depends upon are: | |
| 25 | # * a POSIX shell which additionally implements 'local' (dash works) | |
| 26 | # * the 'curl' command; change the fetch_candidate() function to replace that | |
| 27 | # * the 'stat' command, to get the size of a file; else Perl | |
| 28 | # + change size_of() if need be; it's defined per-OS | |
| 29 | # * the 'hexdump' command and /dev/urandom existing | |
| 30 | # + used when invoked with 'cron', to avoid retrieving on a minute boundary | |
| 31 | # and contending with many other automated systems. | |
| 32 | # + with bash/zsh, can replace with: $(( 10 + ( RANDOM % 40 ) )) | |
| 33 | # + on Debian/Ubuntu systems, hexdump is in the 'bsdmainutils' package. | |
| 34 | ||
| 35 | # Consider putting an email address inside the parentheses, something like | |
| 36 | # noc@example.org or other reachable address, so that if something goes wrong | |
| 37 | # and the server operators need to step in, they can see from logs who to | |
| 38 | # contact instead of just blocking your IP: | |
| 39 | readonly CurlUserAgent='renew-opendmarc-tlds/0.1 (distributed with Exim)' | |
| 40 | ||
| 41 | # change this to your Exim run-time user (exim -n -bP exim_user) : | |
| 42 | readonly RuntimeUser='_exim' | |
| 43 | ||
| 44 | # Do not make this a directory which untrusted users can write to: | |
| 45 | readonly StateDir='/var/cache/exim' | |
| 46 | ||
| 47 | readonly URL='https://publicsuffix.org/list/public_suffix_list.dat' | |
| 48 | ||
| 49 | readonly TargetShortFile='opendmarc.tlds' | |
| 50 | ||
| 51 | # When replacing, new file must be at least this percentage the size of | |
| 52 | # the old one or it's an error: | |
| 53 | readonly MinNewSizeRation=90 | |
| 54 | ||
| 55 | # Each of these regexps must be matched by the file, or it's an error: | |
| 56 | readonly MustExistRegexps=' | |
| 57 | ^ac\.uk$ | |
| 58 | ^org$ | |
| 59 | ^tech$ | |
| 60 | ' | |
| 61 | ||
| 62 | # =======================8< end of configuration >8======================= | |
| 63 | ||
| 64 | set -eu | |
| 65 | ||
| 66 | readonly FullTargetPath="${StateDir}/${TargetShortFile}" | |
| 67 | readonly WorkingFile="${FullTargetPath}.$$" | |
| 68 | ||
| 69 | progname="$(basename "$0")" | |
| 70 | note() { printf >&2 '%s: %s\n' "$progname" "$*"; } | |
| 71 | die() { note "$@"; exit 1; } | |
| 72 | ||
| 73 | # guard against stomping on file-permissions | |
| 74 | [ ".$(id -un)" = ".${RuntimeUser:?}" ] || \ | |
| 75 | die "must be invoked as ${RuntimeUser}" | |
| 76 | ||
| 77 | fetch_candidate() { | |
| 78 | curl --user-agent "$CurlUserAgent" -fSs -o "${WorkingFile}" "${URL}" | |
| 79 | } | |
| 80 | ||
| 81 | case $(uname -s) in | |
| 82 | *BSD|Darwin) | |
| 83 | size_of() { stat -f %z "$1"; } | |
| 84 | ;; | |
| 85 | Linux) | |
| 86 | size_of() { stat -c %s "$1"; } | |
| 87 | ;; | |
| 88 | *) | |
| 89 | # why do we live in a world where Perl is the safe portable solution | |
| 90 | # to getting the size of a file? | |
| 91 | size_of() { perl -le 'print((stat($ARGV[0]))[7])' -- "$1"; } | |
| 92 | ;; | |
| 93 | esac | |
| 94 | ||
| 95 | sanity_check_candidate() { | |
| 96 | local new_size prev_size re | |
| 97 | new_size="$(size_of "$WorkingFile")" | |
| 98 | ||
| 99 | for re in $MustExistRegexps; do | |
| 100 | grep -qs "$re" -- "$WorkingFile" || \ | |
| 101 | die "regexp $re not found in $WorkingFile" | |
| 102 | done | |
| 103 | ||
| 104 | if ! prev_size="$(size_of "$FullTargetPath")"; then | |
| 105 | note "missing previous file, can't size-compare: $FullTargetPath" | |
| 106 | # We're sane by definition, probably initial fetch, and the | |
| 107 | # stat failure and this note will be printed. That's fine; if | |
| 108 | # a cron invocation is missing the file then something has gone | |
| 109 | # badly wrong. | |
| 110 | return 0 | |
| 111 | fi | |
| 112 | local ratio | |
| 113 | ratio=$(expr $new_size \* 100 / $prev_size) | |
| 114 | if [ $ratio -lt $MinNewSizeRation ]; then | |
| 115 | die "New $TargetShortFile candidate only ${ratio}% size of old; $new_size vs $prev_size" | |
| 116 | fi | |
| 117 | } | |
| 118 | ||
| 119 | if [ "${1:-.}" = "cron" ]; then | |
| 120 | shift | |
| 121 | # Don't pull on-the-minute, wait for off-cycle-peak | |
| 122 | sleep $(( ($(dd if=/dev/urandom bs=1 count=1 2>/dev/null | hexdump -e '1/1 "%u"') % 40) + 10)) | |
| 123 | fi | |
| 124 | ||
| 125 | umask 022 | |
| 126 | fetch_candidate | |
| 127 | sanity_check_candidate | |
| 128 | mv -- "$WorkingFile" "$FullTargetPath" |