https://hashbang.sh

#!/bin/sh
# This script first and foremost attempts to be POSIX compliant.
# Secondly, it attempts to be compatible with as many shell implementations as
# possible to provide an easy gateway for new users.

# If we're using bash, we do this
if [ "x$BASH" != "x" ]; then
    shopt -s extglob
    set -o posix
    # Bail out if any curl's fail
    set -o pipefail
fi

bail() {
    echo " "
    echo " If you think this is a bug, please report it to ";
    echo " -> https://github.com/hashbang/hashbang.sh/issues/";
    echo " ";
    echo " The installer will not continue from here...";
    echo " ";
    exit 1
}

# check if can write to file
checkutil() {
    echo -n " * Checking for $1..."
    if which "$1"; then
        printf "ok!\n";
        return 0;
    else
        printf "not found!\n";
        return 1;
    fi
}

# This function can be called with two parameters:
#
# First is obligatory, and is the "question posed".
# For instance, one may ask "is pizza your favorite meal?", to which the
# responder may answer Y (yes) or N (no).
#
# Second parameter is optional, and can be either Y or N.
# The reasoning behind this is to have a default answer to the question,
# resulting in the responder being able to simple press [enter] and skip
# pressing Y or N, giving the default answer instead.
ask() {
    while true; do
        prompt=""
        default=""

        if [ "${2}" = "Y" ]; then
            prompt="Y/n"
            default=Y
        elif [ "${2}" = "N" ]; then
            prompt="y/N"
            default=N
        else
            prompt="y/n"
            default=
        fi

        # Ask the question
        echo " "
        printf "%s [%s] " "$1" "$prompt"
        read REPLY

        # Default?
        if [ -z "$REPLY" ]; then
            REPLY=$default
        fi

        # Check if the reply is valid
        case "$REPLY" in
            Y*|y*) return 0 ;;
            N*|n*) return 1 ;;
        esac

    done
    echo " "
}

# generate ssh kypair
makekey() {
    ( checkutil ssh-keygen && checkutil ssh ) || exit 1
    if [ ! -e "$1" ]; then
        ssh-keygen -t rsa -C "#! $username" -f "$1"
        if [ ! $? ]; then
            echo " Unable to make key with that location"
        else
            chmod 600 "$1"
            echo " Successfully generated key"
            break
        fi
    else
        if ask " Unable to generate key, do you want to delete the file?" N; then
            rm -f "$1"
            if [ ! $? ]; then
                echo " Unable to delete file, resetting"
            else
                echo " File deleted"
                ssh-keygen -t rsa -C "#! $username" -f "$1"
                if [ ! $? ]; then
                    echo " Unable to generate key, resetting"
                fi
            fi
        else
            echo " Unable to make key with that path, resetting"
        fi
    fi
}

# Fetch host data for later.
# If this fails there is no point in proceeding
host_data=$(mktemp)
curl -sH 'Accept:text/plain' https://hashbang.sh/server/stats > $host_data
echo >> $host_data

clear;
echo "   _  _    __ ";
echo " _| || |_ |  |  Welcome to #!. This network has three rules:";
echo "|_  __  _||  | ";
echo " _| || |_ |  |  1. When people need help, teach. Don't do it for them";
echo "|_  __  _||__|  2. Don't use our resources for closed source projects";
echo "  |_||_|  (__)  3. Be excellent to each other";
echo " ";
echo " We are a diverse community of people who love teaching and learning.";
echo " Putting a #! at the beginning of a \"script\" style program tells a ";
echo " computer that it needs to \"do something\" or \"execute\" this file.";
echo " Likewise, we are a community of people that like to \"do stuff\".";
echo " ";
echo " If you like technology, and you want to learn to write your first";
echo " program, learn to use Linux, or even take on interesting challenges";
echo " with some of the best in the industry, you are in the right place.";
echo " ";
echo " The following will set you up with a \"shell\" account on one of our";
echo " shared systems. From here you can run IRC chat clients to talk to us,";
echo " access to personal file storage and web hosting, and a wide range of";
echo " development tools. ";
echo " ";
echo " Everything should work perfectly, unless it doesn't";
echo " ";
echo " Please report any issues here: ";
echo "   -> https://github.com/hashbang/hashbang.sh/issues/";
echo " ";
printf " If you agree with the above and wish to continue, hit [Enter] ";
read _
clear

echo " ";
echo " ";
printf -- ' %72s\n' | tr ' ' -;
echo " ";

echo " First, your system must be properly configured with the required";
echo " utilities and executables.";
echo " We will perform a short check for those now.";
echo " NOTE: If you see this message, it is likely because something is";
echo " not installed. Check the list below, and install any";
echo " missing applications.";

checkutil expr || exit 1
checkutil gpg || exit 1
( checkutil ssh-keygen && checkutil ssh ) || exit 1
checkutil curl || exit 1
clear;

echo " ";
echo " ";
printf -- ' %72s\n' | tr ' ' -;
echo " ";


echo " To create your account we first need a username.";
echo " ";
echo " A valid username must:";
echo "  * be between between 1-31 characters long";
echo "  * consist of only 0-9 and a-z (lowercase only)";
echo "  * begin with a letter";
echo " ";
echo " Traditional unix usernames are first initial, optional middle initial,";
echo " and the first 6 characters of the last name, but feel free to use ";
echo " whatever you want";
echo " ";

while [ "x$username" = "x" ]; do
    printf " Username: ";
    read input;
    if echo "$input" | grep -E "^[a-z][a-z0-9]{0,30}$" >/dev/null; then
        username="$input"
    else
        echo " ";
        echo " \"$input\" is not a valid username."
        echo " Please read the instructions and try again"
        echo " ";
    fi
done

echo " ";
printf -- ' %72s\n' | tr ' ' -;
echo " ";
echo " Now we will need an SSH Public Key."
echo " ";
echo " SSH Keys are a type of public/private key system that let you identify";
echo " yourself to systems like this one without ever sending your password ";
echo " over the internet, and thus by nature we won't even know what it is";

for keytype in id_rsa id_dsa id_ecdsa id_ed25519; do
    if [ -e ~/.ssh/${keytype}.pub ] && [ -e ~/.ssh/${keytype} ]; then
        if ask " We found a public key in [ ~/.ssh/${keytype}.pub ]. Use this key?" Y; then
            private_keyfile="~/.ssh/${keytype}"
            public_key="$(cat ~/.ssh/${keytype}.pub)"
            break
        fi
    fi
done

if [ "x$public_key" = "x" ]; then
    echo " No SSH key for login to server found, attempting to generate one"
    while true; do
        echo " "
        echo -n " Path to new or existing connection key (~/.ssh/id_rsa): ";
        read private_keyfile
        if [ "x$private_keyfile" = "x" ]; then
            private_keyfile="$HOME/.ssh/id_rsa"
        fi
        private_keyfile=$(echo "$private_keyfile" | sed "s@~@$HOME@")
        echo " "
        if [ ! -e "$private_keyfile" ] && [ ! -e "$private_keyfile.pub" ]; then
            if ask " Do you want us to generate a key for you?" Y; then
                if [ -e "$private_keyfile" ]; then
                    if ask " File exists: $private_keyfile - delete?" Y; then
                        rm "$private_keyfile"
                        if [ -e "${private_keyfile}.pub" ]; then
                            rm "${private_keyfile}.pub"
                        fi
                        makekey "$private_keyfile"
                    fi
                else
                    makekey "$private_keyfile"
                fi
                public_key=$(cat "${privat_keyfile}.pub")
            fi
        elif [ ! -e "$private_keyfile" ] && [ -e "${private_keyfile}.pub" ]; then
            if ask " Found public keyfile, missing private. Do you wish to continue?" N; then
                echo " Using public key ${private_keyfile}.pub"
                break
            else
                echo " Resetting"
            fi
        elif [ ! -e "${private_keyfile}.pub" ]; then
            echo " Unable to find public key ${private_keyfile}.pub"
        else
            echo " Using public key ${private_keyfile}.pub"
            break
        fi
    done
    public_key=$(cat "${private_keyfile}.pub")
fi

n=0
echo
printf -- ' %72s\n' | tr ' ' -;
echo
echo " Please choose a server to create your account on."
echo
printf -- ' %72s\n' | tr ' ' -;
printf "  %-1s | %-4s | %-36s | %-8s | %-8s\n" \
    "#" "Host" "Location" "Users" "Latency"
printf -- ' %72s\n' | tr ' ' -;
while IFS="|" read host ip location current_users max_users; do
    host=$(echo $host | sed 's/\([a-z0-9]\+\)\..*/\1/g')
    latency=$(ping -c1 ${host}.hashbang.sh | head -n2 | tail -n1 | sed 's/.*=//g')
    n=$((n+1))
    printf "  %-1s | %-4s | %-36s | %8s | %-8s\n" \
        "$n" \
        "$host" \
        "$location" \
        "$current_users/$max_users" \
        "$latency"
done < $host_data
printf -- ' %72s\n' | tr ' ' -;

echo
while true; do
    echo -n " Enter Number 1-$n : "
    read choice
    number=$(echo "$choice" | awk '$0 ~/[^0-9]/ { print "no" }')
    if [ "$number" != "no" ] && \
       [ "$choice" -ge 1 ] && \
       [ "$choice" -le $n ]; then
        break;
    fi
done
host=$(cat $host_data | head -n $choice | tail -n1 | cut -d '|' -f1)

if [ "x$public_key" != "x" -a "x$username" != "x" ]; then
    echo " ";
    printf -- ' %72s\n' | tr ' ' -;
    echo " ";
    echo " We are going to create an account with the following information";
    echo " ";
    echo " Username: $username";
    echo " Public Key: ${private_keyfile}.pub";
    echo " Host: $host";
    echo " ";
    if ask " Does this look correct?" Y ; then

        echo " ";
        echo -n " Creating your account... ";
        headers=$(mktemp)
        format="{\"user\":\"$username\",\"key\":\"$public_key\",\"host\":\"$host\"}"
        output="$(curl -H 'Content-Type: application/json' -d '$format' https://hashbang.sh/user/create -D $headers )"
        status="$(cat $headers | awk '{print \$1}' | head -n 1)"
        if [ "$status" -eq 200 ]; then
            echo " Account Created!"
        else
            echo " Account creation failed: $(echo $output | sed -e 's/.*\"message\": \?\"\([^"]\+\)\".*/\1/')";
            bail
        fi

        if ask " Would you like to add trusted/signed keys for our servers to your .ssh/known_hosts?" Y ; then
            echo " Downloading GPG keys"
            echo " "
            gpg --recv-keys 0xD2C4C74D8FAA96F5
            echo " "
            echo " Downloading key list"
            echo " "
            data="$(curl -s https://hashbang.sh/static/known_hosts.asc)"
            printf %s "$data" | gpg --verify
            if [ ! $? -eq 0 ]; then
                echo " "
                echo " Unable to verify keys"
                bail
            fi
            printf %s "$data" | grep "hashbang.sh" >> ~/.ssh/known_hosts
            echo " "
            echo " Key scanned and saved"
        fi

        if ask " Would you like an alias (shortcut) added to your .ssh/config?" Y ; then
            printf "\nHost hashbang\n  HostName ${host}\n  IdentitiesOnly yes\n  User %s\n  IdentityFile %s\n" \
                            "$username" "$private_keyfile" \
            >> ~/.ssh/config
            echo " You can now connect any time by entering the command:";
            echo " ";
            echo " > ssh hashbang";
        else
            echo " You can now connect any time by entering the command:";
            echo " ";
            echo " > ssh ${username}@${host}.hashbang.sh";
        fi

    else
        echo " Please re-run script to make corrections.";
        bail
    fi

    if ask " Do you want us to log you in now?" Y; then
        if [ -e $private_keyfile ]; then
            ssh ${username}@${host}.hashbang.sh -i "$private_keyfile"
        else
            ssh ${username}@${host}.hashbang.sh
        fi
    fi
fi

# exit [n]. if [n] is not specified, then exit shall use the return code of the
# last command.
exit 0