feat: client requires an HTTPS URL for server

2 files changed, 31 insertions, 1 deletions

diff --git a/obnam.md b/obnam.md
index 6e9085c..47839c7 100644
--- a/obnam.md
+++ b/obnam.md
@@ -1001,6 +1001,25 @@ server_url: https://backup.example.com
 ~~~
 
 
+## Client requires https
+
+This scenario verifies that the client rejects a configuration with a
+server URL using `http:` instead of `https:`.
+
+
+~~~scenario
+given an installed obnam
+and file http.yaml
+when I try to run obnam --config http.yaml config
+then command fails
+then stderr contains "https:"
+~~~
+
+~~~{#http.yaml .file .yaml .numberLines}
+root: live
+server_url: http://backup.example.com
+~~~
+
 # Acceptance criteria for Obnam as a whole
 
 The scenarios in this chapter apply to Obnam as a whole: the client
diff --git a/src/client.rs b/src/client.rs
index e8e20eb..3d3b2a5 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -26,6 +26,9 @@ pub struct ClientConfig {
 
 #[derive(Debug, thiserror::Error)]
 pub enum ClientConfigError {
+    #[error("server URL doesn't use https: {0}")]
+    NotHttps(String),
+
     #[error(transparent)]
     IoError(#[from] std::io::Error),
 
@@ -39,9 +42,17 @@ impl ClientConfig {
     pub fn read_config(filename: &Path) -> ClientConfigResult<Self> {
         trace!("read_config: filename={:?}", filename);
         let config = std::fs::read_to_string(filename)?;
-        let config = serde_yaml::from_str(&config)?;
+        let config: ClientConfig = serde_yaml::from_str(&config)?;
+        config.check()?;
         Ok(config)
     }
+
+    fn check(&self) -> Result<(), ClientConfigError> {
+        if !self.server_url.starts_with("https://") {
+            return Err(ClientConfigError::NotHttps(self.server_url.to_string()));
+        }
+        Ok(())
+    }
 }
 
 #[derive(Debug, thiserror::Error)]