Add mosh, a tool for a more stable remote connection

see https://mosh.org/ for details

tools/mosh/Dockerfile

@@ -0,0 +1,103 @@
+ARG HOST_ARCH=i686
+ARG TARGET_TRIPLE=armv7l-linux-musleabihf
+
+FROM muslcc/$HOST_ARCH:$TARGET_TRIPLE
+
+ARG VERSION=1.4.0
+ARG TARGET_ARCH=armv7l-linux
+
+USER root:root
+
+WORKDIR /root/
+
+RUN apk add --no-cache build-base ncurses-dev ncurses-libs python3 autoconf automake linux-headers git
+
+# https://gitlab.alpinelinux.org/alpine/aports/-/issues/8626
+ENV CFLAGS=-U_FORTIFY_SOURCE
+ENV CFLAGS_host=-U_FORTIFY_SOURCE
+ENV CXXFLAGS=-U_FORTIFY_SOURCE
+ENV CXXFLAGS_host=-U_FORTIFY_SOURCE
+
+ENV CC=/bin/gcc
+ENV CXX=/bin/g++
+ENV AR=/bin/ar
+ENV NM=/bin/nm
+ENV READELF=/bin/readelf
+ENV STRIP=/bin/strip
+
+ENV CC_host=/usr/bin/gcc
+ENV CXX_host=/usr/bin/g++
+ENV AR_host=/usr/bin/ar
+ENV NM_host=/usr/bin/nm
+ENV READELF_host=/usr/bin/readelf
+
+ADD "https://invisible-mirror.net/archives/ncurses/ncurses-6.3.tar.gz" /root/ncurses/ncurses.tar.gz
+
+WORKDIR /root/ncurses/
+
+RUN tar xf ./ncurses.tar.gz
+
+WORKDIR /root/ncurses/ncurses-6.3/
+
+RUN ./configure --with-normal --host=${TARGET_ARCH} --with-terminfo-dirs="/etc/terminfo:/usr/share/terminfo:/lib/terminfo:/usr/lib/terminfo"  --without-tests --without-ada
+
+RUN make -j4
+
+ENV CFLAGS="-I/root/ncurses/ncurses-6.3/include -I/root/deps/usr/include/ $CFLAGS"
+ENV CPPFLAGS="-I/root/ncurses/ncurses-6.3/include -I/root/deps/usr/include/ $CFLAGS"
+ENV LDFLAGS="-L/root/ncurses/ncurses-6.3/lib -L/root/deps/lib/ -L/root/deps/usr/lib/ $LDFLAGS"
+
+WORKDIR /root/mosh
+
+ADD "https://mosh.org/mosh-${VERSION}.tar.gz" ./mosh.tar.gz
+
+RUN tar xf ./mosh.tar.gz
+
+WORKDIR /root/mosh/mosh-${VERSION}
+
+ENV ARM_DEPS=/root/deps/
+
+RUN mkdir -p $ARM_DEPS/etc/apk/
+
+RUN cp /etc/apk/repositories $ARM_DEPS/etc/apk/
+
+# *target* side libraries
+# use nettle instead of openssl to save space
+RUN apk -p $ARM_DEPS --allow-untrusted --arch armv7 add --initdb nettle-dev nettle-static protobuf-dev zlib-dev zlib-static
+
+# *host* side protoc, needed during compilation
+RUN apk add --no-cache protoc
+
+# adjust PKG_CONFIG so it *does not* look up *host side* stuff
+ENV PKG_CONFIG_SYSROOT_DIR=${ARM_DEPS}
+ENV PKG_CONFIG_LIBDIR=${ARM_DEPS}/usr/lib/pkgconfig
+ENV PKG_CONFIG_PATH=
+
+# GC sections: Saves around 400 KB (1.4 MB --> 1.0 MB)
+ENV CFLAGS="$CFLAGS -static -Os -ffunction-sections -fdata-sections"
+ENV CPPFLAGS="$CPPFLAGS -static -Os -ffunction-sections -fdata-sections"
+ENV LDFLAGS="$LDFLAGS -static -Os -Wl,--gc-sections"
+
+# not needed, unless we want to adjust configure.ac
+# RUN ./autogen.sh
+
+RUN ./configure --disable-client --enable-static-libraries  --host=${TARGET_ARCH} --without-utempter --with-ncurses --without-ncursesw --disable-hardening --with-crypto-library=nettle --with-curses=/root/ncurses/ncurses-6.3/
+
+# fix bug (?) in mosh build env: If pkg-config is not available, the generated config.h is wrong
+RUN sed -i.bak -e '/HAVE_CURSES_H/ a#define HAVE_CURSES_H 1' src/include/config.h
+
+# less drastic option: Only in mosh-server Makefile
+# (alt: Remove in configure.ac and rerun autogen.sh)
+# For some reason, the presence of -Wl,-Bdynamic as trailing argument in the
+# Make link recipe makes the executable a dynamically-linked executable.
+# get rid of these altogether.
+RUN sed -i.bak -e 's|-Wl,-Bdynamic||g' ./src/frontend/Makefile
+
+RUN make -j4
+
+RUN /bin/strip ./src/frontend/mosh-server
+
+# output checking if it's a statically linked executable.
+#RUN file ./src/frontend/mosh-server
+
+# #RUN upx --brute ./src/frontend/mosh-server

tools/mosh/wrapper.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+if [[ "$#" -ne "2" ]]; then
+	echo "Use: $0 <user> <ssh-server>" >&2
+	exit 1
+fi
+
+#server_side_mosh=/tmp/mosh-server
+vars=$(ssh "${1}@${2}" "${MOSH_SERVER:-mosh-server}" | sed -n '/MOSH CONNECT/ p')
+port=$(echo "${vars}"  | awk '{ print $3; }')
+key=$(echo "${vars}"  | awk '{ print $4; }')
+
+ip=$(dig +short "$2")
+
+if [[ -n "${key}" && -n "${port}" && -n "$ip" ]]; then
+	echo "MOSH_KEY=${key} mosh-client ${ip} ${port}"
+	MOSH_KEY="${key}" mosh-client "${ip}" "${port}"
+else
+	echo "Something went wrong getting key / port / ip:"
+	echo "${key} / ${port} / ${ip}"
+fi