From ef060e4e90d4e878791396c0e1b1caaa49e2e4f2 Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@jerkface.net>
Date: Wed, 16 Sep 2020 17:00:25 -0400
Subject: implement command "cryptonomic"

---
 selfpublish.sh | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

diff --git a/selfpublish.sh b/selfpublish.sh
index 816a18d..25686a7 100644
--- a/selfpublish.sh
+++ b/selfpublish.sh
@@ -52,6 +52,7 @@ dependencies()
 {
     cat <<EOF
 apache2 (>= 2.4.46)
+basez
 cgit
 curl
 fortune-mod
@@ -59,6 +60,7 @@ fortunes-min
 gnupg (>= 2.2.14)
 libssl1.1 (>= 1.1.1d)
 openssl
+ssh
 EOF
 }
 
@@ -84,6 +86,11 @@ fmt_dependencies()
     fi
 }
 
+control_file_file()
+{
+    printf 'File: %s %s\n' "$1" "$2"
+    sed -e 's/^/ /'
+}
 
 SELF_VERSION='0.1'
 SELF_EXECUTABLE=$(realpath "$0")
@@ -101,9 +108,65 @@ EOF
     cat <<EOF
 File: /usr/share/doc/selfpublish-dot-sh/README.Debian 644
  This gets overwritten :(
-File: /usr/bin/selfpublish.sh 755
 EOF
-    sed -e 's/^/ /' < "$SELF_EXECUTABLE"
+    control_file_file /usr/bin/cryptonomic 755 <<'EOF'
+#!/bin/dash
+set -e
+
+DOMAIN=cryptonomic.net
+DEFAULT_AUTH_TYPE=ed25519
+HASH_TYPE=2
+
+die() { echo "$0: Error: $*" >&2; exit 1; }
+
+b16_to_b32()
+{
+    printf %s "$1" | basez -x -d | basez -j -l | tr -d =
+}
+
+get_domain()
+{
+    get_sshfp "$1"
+
+    domain=$(printf %s.%s.%s "$sshfp_b32" "$DEFAULT_AUTH_TYPE" "$DOMAIN" | tail -c64)
+}
+
+get_sshfp()
+{
+    [ -f "$1" ] || return
+    sshfp_b16=$(ssh-keygen -r . -f "$1" | sed -ne 's/^. IN SSHFP [0-9]* '"$HASH_TYPE"' //p') &&
+        [ "$sshfp_b16" ] || die "could not determine ssh client fingerprint"
+    sshfp_b32=$(b16_to_b32 "$sshfp_b16")
+}
+
+KEY_FILE=/etc/ssh/ssh_host_${DEFAULT_AUTH_TYPE}_key
+
+if [ $# = 0 -o "$1" = hostname ]
+then
+
+    get_domain "${KEY_FILE}".pub || exit
+    printf '%s\n' "$domain"
+
+elif [ "$1" = dyndns ]
+then
+    set -- ssh -i "$KEY_FILE" dyndns@"$DOMAIN"
+
+    if [ -r "$KEY_FILE" ]
+    then
+        "$@"
+    elif sudo -n true 2>/dev/null || groups | grep '\bsudo\b'
+    then
+        sudo -- "$@"
+    else
+        su -c "$(bash -c 'printf "%q " "$@"' bash "$@")"
+
+    fi
+else
+    echo "Usage: $0 [dyndns|hostname]" >&2
+    exit 1
+fi
+EOF
+    control_file_file /usr/bin/selfpublish.sh 755 < "$SELF_EXECUTABLE"
     echo
 }
 
-- 
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