94c7c1dbcf
Based on an original patch by Giuseppe Scrivano: there's no need to pass $0 to usage, drop that everywhere, and make it consistent. Don't exit with error on -h, --help. Suggested-by: Giuseppe Scrivano <gscrivan@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
228 lines
6.1 KiB
Bash
Executable file
228 lines
6.1 KiB
Bash
Executable file
#!/bin/sh -euf
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#
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# SPDX-License-Identifier: AGPL-3.0-or-later
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#
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# PASST - Plug A Simple Socket Transport
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# for qemu/UNIX domain socket mode
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#
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# PASTA - Pack A Subtle Tap Abstraction
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# for network namespace/tap device mode
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#
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# slirp4netns.sh - Compatibility wrapper for pasta, behaving like slirp4netns(1)
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#
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# WARNING: Draft quality, not really tested, --enable-sandbox not supported yet
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#
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# Copyright (c) 2021 Red Hat GmbH
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# Author: Stefano Brivio <sbrivio@redhat.com>
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PASTA_PID="$(mktemp)"
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PASTA_OPTS="-q --ipv4-only -a 10.0.2.0 -n 24 -g 10.0.2.2 -m 1500 --no-ndp --no-dhcpv6 --no-dhcp -P ${PASTA_PID}"
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USAGE_RET=1
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# add() - Add single option to $PASTA_OPTS
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# $1: Option name, with or without argument
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add() {
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PASTA_OPTS="${PASTA_OPTS} ${1}"
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}
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# drop() - Drop one option (without argument) from $PASTA_OPTS
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# $1: Option name
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drop() {
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old_opts="${PASTA_OPTS}"; PASTA_OPTS=
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for o in ${old_opts}; do [ "${o}" != "${1}" ] && add "${o}"; done
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}
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# sub() - Substitute option in $PASTA_OPTS, with or without argument
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# $1: Option name
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# $2: Option argument, can be empty
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sub() {
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old_opts="${PASTA_OPTS}"; PASTA_OPTS=
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next=0
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for o in ${old_opts}; do
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if [ ${next} -eq 1 ]; then
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next=0; add "${1} ${2}"; shift; shift; continue
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fi
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for r in ${@}; do [ "${o}" = "${r}" ] && next=1 && break; done
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[ "${next}" -eq 0 ] && add "${o}"
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done
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}
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# xorshift() - pseudorandom permutation of 16-bit group
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# $1: 16-bit value to shuffle
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xorshift() {
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# Adaptation of Xorshift algorithm from:
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# Marsaglia, G. (2003). Xorshift RNGs.
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# Journal of Statistical Software, 8(14), 1 - 6.
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# doi:http://dx.doi.org/10.18637/jss.v008.i14
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# with triplet (5, 3, 1), suitable for 16-bit ranges.
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n=${1}
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: $((n ^= n << 5))
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: $((n ^= n >> 3))
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: $((n ^= n << 1))
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echo ${n}
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}
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# opt() - Validate single option from getopts
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# $1: Option type
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# $@: Variable names to assign to
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opt() {
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case "${1}" in
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u32)
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if ! printf "%i" "${OPTARG}" >/dev/null 2>&1 || \
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[ "${OPTARG}" -lt 0 ]; then
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echo "${OPT} must be a non-negative integer"
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usage
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fi
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eval ${2}="${OPTARG}"
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;;
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mtu)
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if ! printf "%i" "${OPTARG}" >/dev/null 2>&1 || \
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[ "${OPTARG}" -lt 0 ] || [ "${OPTARG}" -ge 65522 ]; then
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echo "MTU must be a positive integer (< 65522)"
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usage
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fi
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eval ${2}="${OPTARG}"
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;;
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str)
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eval ${2}="${OPTARG}"
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;;
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net4)
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addr="${OPTARG%/*}"
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mask="${OPTARG##*/}"
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{ [ -z "${mask}" ] || !printf "%i" "${mask}" >/dev/null 2>&1 \
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|| [ ${mask} -gt 32 ] || ${mask} -le 0 ]; } && usage
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expr "${addr}" : \
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'[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*$' \
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>/dev/null
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[ $? -ne 0 ] && usage
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ifs="${IFS}"; IFS='.'
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for q in ${addr}; do [ ${q} -gt 255 ] && usage; done
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IFS="${ifs}"
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eval ${2}="${addr}"
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eval ${3}="${mask}"
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;;
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esac
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}
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# usage() - Print slirpnetns(1) usage and exit indicating failure
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# $1: Invalid option name, if any
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usage() {
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[ ${#} -eq 1 ] && printf "%s: invalid option -- '%s'\n" "${0}" "${1}"
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cat << EOF
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Usage: ${0} [OPTION]... PID|PATH TAPNAME
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User-mode networking for unprivileged network namespaces.
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-c, --configure bring up the interface
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-e, --exit-fd=FD specify the FD for terminating slirp4netns
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-r, --ready-fd=FD specify the FD to write to when the network is configured
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-m, --mtu=MTU specify MTU (default=1500, max=65521)
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-6, --enable-ipv6 enable IPv6 (experimental)
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-a, --api-socket=PATH specify API socket path
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--cidr=CIDR specify network address CIDR (default=10.0.2.0/24)
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--disable-host-loopback prohibit connecting to 127.0.0.1:* on the host namespace
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--netns-type=TYPE specify network namespace type ([path|pid], default=pid)
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--userns-path=PATH specify user namespace path
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--enable-sandbox create a new mount namespace (and drop all caps except CAP_NET_BIND_SERVICE if running as the root)
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--enable-seccomp enable seccomp to limit syscalls (experimental)
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-h, --help show this help and exit
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-v, --version show version and exit
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EOF
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exit ${USAGE_RET}
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}
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# version() - Print version
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version() {
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echo "slirp4netns-like wrapper for pasta"
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exit 0
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}
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# gen_addr6() - Generate pseudorandom IPv6 address, changes every second
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gen_addr6() {
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printf "fd00"
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n=$(($(xorshift $(date +%S)) % 65536))
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for i in $(seq 2 8); do
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printf ":%04x" ${n}
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n=$(($(xorshift ${n}) % 65536))
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done
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}
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# Default options
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v6=0
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get_pid=0
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MTU=1500
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A4="10.0.2.0"
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M4="255.255.255.0"
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no_map_gw=0
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EFD=0
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RFD=0
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while getopts ce:r:m:6a:hv-: OPT 2>/dev/null; do
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if [ "${OPT}" = "-" ]; then
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OPT="${OPTARG%%[= ]*}"
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OPTARG="${OPTARG#${OPT}[= ]}"
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fi
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case "${OPT}" in
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c | configure) add "--config-net" ;;
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e | exit-fd) opt u32 EFD ;;
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r | ready-fd) opt u32 RFD ;;
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m | mtu) opt mtu MTU && sub -m ${MTU} ;;
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6 | enable-ipv6) V6=1 ;;
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a | api-socket) opt str API ;;
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cidr) opt net4 A4 M4 && sub -a ${A4} -n ${M4} ;;
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disable-host-loopback) add "--no-map-gw" && no_map_gw=1 ;;
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netns-type) : Autodetected ;;
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userns-path) opt_str USERNS_NAME "${OPTARG}" ;;
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enable-sandbox) : Not supported yet ;;
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enable-seccomp) : Cannot be disabled ;;
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h | help) USAGE_RET=0 && usage ;;
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v | version) version ;;
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??*) usage "${OPT}" ;;
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?) usage "${OPT}" ;;
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esac
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done
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shift $((OPTIND - 1))
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[ ${#} -ne 2 ] && usage
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ns_spec="${1}"
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ifname="${2}"
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add "-I ${ifname}"
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if [ ${v6} -eq 1 ]; then
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drop "--ipv4-only"
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add "-a $(gen_addr6) -g fd00::2 -D fd00::3"
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fi
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./pasta ${PASTA_OPTS} ${ns_spec} 2>/dev/null && \
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[ ${RFD} -ne 0 ] && echo "1" >&${RFD}
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trap "kill $(cat ${PASTA_PID}); rm ${PASTA_PID}" INT TERM
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cat << EOF
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sent tapfd=5 for ${ifname}
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received tapfd=5
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Starting slirp
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* MTU: ${MTU}
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* Network: ${A4}
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* Netmask: ${M4}
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* Gateway: 10.0.2.2
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* DNS: 10.0.2.3
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* Recommended IP: 10.0.2.100
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EOF
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if [ ${no_map_gw} -eq 0 ]; then
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echo "WARNING: 127.0.0.1:* on the host is accessible as 10.0.2.2 (set --disable-host-loopback to prohibit connecting to 127.0.0.1:*)"
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fi
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if [ ${EFD} -ne 0 ]; then
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dd count=1 of=/dev/null 2>/dev/null <&${EFD}
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else
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while read a; do :; done
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fi
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exit 0
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