Add CLI interface for the signing key

- 'signkey set' sets a new signing key (disables an old one if
  existing).
- 'signkey show' prints the fingerprint.
- 'signkey dump' prints the certificate of the signing key.

src/cli/cli_args.rs

@@ -33,6 +33,7 @@ pub enum HuskSubcommands {
     Daemon(DaemonCommand),
     Introducer(IntroducerCommand),
     Locals(LocalsCommand),
+    Signkey(SignkeyCommand),
 }
 
 // Daemon subcommands
@@ -76,6 +77,9 @@ pub struct IntroducerCommand {
 pub enum IntroducerSubcommand {
     Add(IntroducerAddCommand),
     Remove(IntroducerRemoveCommand),
+    #[clap(
+        about = "List introducers."
+    )]
     List
 }
 
@@ -88,7 +92,8 @@ pub struct IntroducerAddCommand {
     #[clap(
         long = "cert",
         help = "Certificate to declare as introducer.",
-        conflicts_with = "cert_file"
+        conflicts_with = "cert_file",
+        value_name = "FINGERPRINT",
     )]
     pub cert: Option<String>,
 
@@ -118,7 +123,8 @@ pub struct IntroducerAddCommand {
 pub struct IntroducerRemoveCommand {
     #[clap(
         long = "cert",
-        help = "Certificate to be removed as introducer."
+        help = "Certificate to be removed as introducer.",
+        value_name = "FINGERPRINT",
     )]
     pub cert: String,
 
@@ -149,6 +155,9 @@ pub struct LocalsCommand {
 pub enum LocalsSubcommand {
     Add(LocalsAddCommand),
     Remove(LocalsRemoveCommand),
+    #[clap(
+        about = "List locals."
+    )]
     List
 }
 
@@ -174,8 +183,59 @@ pub struct LocalsAddCommand {
 pub struct LocalsRemoveCommand {
     #[clap(
         long = "cert",
-        help = "Certificate to be removed."
+        help = "Certificate to be removed.",
+        value_name = "FINGERPRINT",
     )]
     pub cert: String,
 }
 
+// Signkey subcommands
+
+#[derive(Parser, Debug)]
+#[clap(
+    name = "signkey",
+    about = "Manage the signing key.",
+    subcommand_required = true,
+    arg_required_else_help = true,
+    disable_colored_help = true,
+    disable_version_flag = true,
+)]
+pub struct SignkeyCommand {
+    #[clap(subcommand)]
+    pub subcommand: SignkeySubcommand,
+}
+#[derive(Debug, Subcommand)]
+pub enum SignkeySubcommand {
+    Set(SignkeySetCommand),
+    #[clap(
+        about = "Show the fingerprint of the signing key."
+    )]
+    Show,
+    #[clap(
+        about = "Print the certificate of the signing key."
+    )]
+    Dump,
+}
+
+#[derive(Parser, Debug)]
+#[clap(
+    about = "Set a new signing key.",
+)]
+pub struct SignkeySetCommand {
+    #[clap(
+        long,
+        help = "Load a new signing key from <FILE>.",
+        value_name = "FILE",
+        conflicts_with = "cert"
+    )]
+    pub cert_file: Option<String>,
+
+    #[clap(
+        long = "cert",
+        help = "Certificate to declare as signing key.",
+        conflicts_with = "cert_file",
+        value_name = "FINGERPRINT",
+    )]
+    pub cert: Option<String>,
+}
+