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# Copyright (c) 2007-2008 Roy Marples <roy@marples.name> |
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# Copyright (c) 2007-2008 Roy Marples <roy@marples.name> |
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# Released under the 2-clause BSD license. |
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# Released under the 2-clause BSD license. |
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# shellcheck shell=sh disable=SC1008 |
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apipa_depend() |
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apipa_depend() |
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{ |
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{ |
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program /sbin/arping /bin/arping |
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program /sbin/arping /bin/arping |
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} |
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} |
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_random() |
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_random_bytes_as_int() |
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{ |
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{ |
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local r=${RANDOM} # checkbashisms: false positive, we handle it AFTERWARDS |
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local hex num_bytes="$1" |
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if [ -n "${r}" ]; then |
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echo "${r}" |
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# While POSIX does not require that /dev/urandom exist, it is a |
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else |
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# de-facto standard. Therefore, the following approach should be |
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uuidgen | sed -n -e 's/[^[:digit:]]//g' -e 's/\(^.\{1,7\}\).*/\1/p' |
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# highly portable in practice. In the case of Linux, and unlike BSD |
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fi |
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# this interface does not block in the event that the CSRNG has not |
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# yet been seeded. Still, this is acceptable because we do not |
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# require a guarantee that the entropy be cryptographically secure. |
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# It's also worth noting that Linux >=5.4 is faster at seeding in |
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# the absence of RDRAND/RDSEED than previous versions were. |
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test -e /dev/urandom && |
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hex=$( |
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LC_ALL=C tr -dc '[:xdigit:]' < /dev/urandom | |
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dd bs="$(( num_bytes * 2 ))" count=1 2>/dev/null) && |
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test "${#hex}" = "$(( num_bytes * 2 ))" && |
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printf '%d\n' "0x${hex}" |
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} |
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_random_apipa_octets() |
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{ |
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local seed |
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# Obtain a highly random 16-bit seed for use by awk's RNG. In the |
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# unlikely event that the seed ends up being empty, awk will seed |
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# based on the time of day, with a granularity of one second. |
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seed=$(_random_bytes_as_int 2) |
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# For APIPA (RFC 3927), the 169.254.0.0/16 address block is |
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# reserved. This provides 65534 addresses, having accounted for the |
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# network and broadcast address. Note that we must count from 1. |
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awk "BEGIN { |
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srand($seed) |
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for (i=1; i<65535; i++) print rand() \" \" i |
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}" | |
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sort -k 1,1 -n | |
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POSIXLY_CORRECT=1 awk '{ |
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hex = sprintf("%04x",$2) |
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printf("%d %d\n", "0x" substr(hex,1,2), "0x" substr(hex,3,2)) |
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}' |
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} |
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} |
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apipa_start() |
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apipa_start() |
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{ |
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{ |
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local iface="$1" i1= i2= addr= i=0 |
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local addr rc |
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_exists true || return 1 |
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_exists || return |
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einfo "Searching for free addresses in 169.254.0.0/16" |
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einfo "Searching for free addresses in 169.254.0.0/16" |
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eindent |
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eindent |
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while [ ${i} -lt 64516 ]; do |
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exec 3>&1 |
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: $(( i1 = (_random % 255) + 1 )) |
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addr=$( |
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: $(( i2 = (_random % 255) + 1 )) |
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_random_apipa_octets | |
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{ |
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addr="169.254.${i1}.${i2}" |
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while read -r i1 i2; do |
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vebegin "${addr}/16" |
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addr="169.254.${i1}.${i2}" |
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if ! arping_address "${addr}"; then |
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vebegin "${addr}/16" >&3 |
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eval config_${config_index}="\"${addr}/16 broadcast 169.254.255.255\"" |
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if ! arping_address "${addr}" >&3; then |
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: $(( config_index -= 1 )) |
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printf '%s\n' "${addr}" |
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veend 0 |
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exit 0 |
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eoutdent |
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fi |
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return 0 |
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done |
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fi |
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exit 1 |
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} |
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) |
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rc=$? |
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exec 3>&- |
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: $(( i += 1 )) |
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if [ "$rc" = 0 ]; then |
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done |
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eval "config_${config_index}=\"\${addr}/16 broadcast 169.254.255.255\"" |
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: $(( config_index -= 1 )) |
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veend 0 |
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else |
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eerror "No free address found!" |
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fi |
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eerror "No free address found!" |
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eoutdent |
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eoutdent |
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return 1 |
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return "$rc" |
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} |
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} |
