🐛 Fixed credential retrieval for SSH without username to work correct…

…ly (#45)

* Fixed credential retrieval for SSH without username to work correctly

Fixes #44

* Retrieve SSH username from ssh_config

Fixes #42

* Comment out the debug assertion

Address the review comment: #45 (comment)

* Change the local variable name to reflect function modificatio

Address the review comment: #45 (comment)

src/lib.rs

@@ -35,10 +35,10 @@ pub mod ui4dialoguer;
 use std::error::Error;
 
 pub struct CredentialHandler {
-    usernames: Vec<String>,
+    username_attempts_count: usize,
+    username_candidates: Vec<String>,
     ssh_attempts_count: usize,
     ssh_key_candidates: Vec<std::path::PathBuf>,
-    username_attempts_count: usize,
     cred_helper_bad: Option<bool>,
     cfg: git2::Config,
     ui: Box<dyn CredentialUI>,
@@ -56,22 +56,11 @@ impl CredentialHandler {
     }
 
     pub fn new_with_ui(cfg: git2::Config, ui: Box<dyn CredentialUI>) -> Self {
-        let mut usernames = vec!["".to_string(), "git".to_string()];
-        if let Ok(s) = std::env::var("USER").or_else(|_| std::env::var("USERNAME")) {
-            usernames.push(s);
-        }
-
-        // let mut cred_helper = git2::CredentialHelper::new(url);
-        // cred_helper.config(cfg);
-        // if let Some(ref s) = cred_helper.username {
-        //     usernames.push(s.clone());
-        // }
-
         CredentialHandler {
-            usernames,
+            username_attempts_count: 0,
+            username_candidates: vec![],
             ssh_attempts_count: 0,
             ssh_key_candidates: vec![],
-            username_attempts_count: 0,
             cred_helper_bad: None,
             cfg,
             ui,
@@ -137,11 +126,12 @@ impl CredentialHandler {
             // debug_assert!(username.is_none());
             let idx = self.username_attempts_count;
             self.username_attempts_count += 1;
-            return match self.usernames.get(idx).map(|s| &s[..]) {
-                Some("") if username.is_none() => {
-                    Err(git2::Error::from_str("gonna try usernames later"))
-                }
-                Some("") => git2::Cred::username(username.unwrap_or("")),
+            if idx == 0 {
+                let maybe_host = extract_host(url)?;
+                self.username_candidates =
+                    ssh_config::find_username_candidates(maybe_host.as_deref())?;
+            }
+            return match self.username_candidates.get(idx).map(|s| &s[..]) {
                 Some(s) => git2::Cred::username(s),
                 _ => Err(git2::Error::from_str("no more username to try")),
             };

src/ssh_config.rs

@@ -12,6 +12,13 @@ use std::path;
 #[allow(dead_code)]
 pub struct SSHConfigParser;
 
+fn find_username_in_ssh_config(host: &str) -> Result<Option<String>, git2::Error> {
+    match read_ssh_config_as_string()? {
+        Some(content) => find_username_for_host_in_config(host, &content),
+        _ => Ok(None),
+    }
+}
+
 fn find_ssh_key_in_ssh_config(host: &str) -> Result<Option<String>, git2::Error> {
     match read_ssh_config_as_string()? {
         Some(content) => find_ssh_key_for_host_in_config(host, &content),
@@ -49,9 +56,24 @@ fn read_ssh_config_as_string() -> Result<Option<String>, git2::Error> {
         .unwrap_or(Ok(None))
 }
 
+fn find_username_for_host_in_config(
+    host: &str,
+    ssh_config_str: &str,
+) -> Result<Option<String>, git2::Error> {
+    find_entry_for_host_in_config(host, ssh_config_str, "User")
+}
+
 fn find_ssh_key_for_host_in_config(
     host: &str,
     ssh_config_str: &str,
+) -> Result<Option<String>, git2::Error> {
+    find_entry_for_host_in_config(host, ssh_config_str, "IdentityFile")
+}
+
+fn find_entry_for_host_in_config(
+    host: &str,
+    ssh_config_str: &str,
+    name: &str,
 ) -> Result<Option<String>, git2::Error> {
     // trace!("parsing {:?} to find host {}", ssh_config_path, host);
 
@@ -106,11 +128,11 @@ fn find_ssh_key_for_host_in_config(
                             ))
                         })?;
 
-                    if key.as_str().eq_ignore_ascii_case("IdentityFile") {
-                        let path = value.as_str().to_string();
+                    if key.as_str().eq_ignore_ascii_case(name) {
+                        let found_value = value.as_str().to_string();
 
-                        // trace!("found IdentityFile option with value {:?}", path);
-                        return Ok(Some(path));
+                        // trace!("found IdentityFile option with value {:?}", found_value);
+                        return Ok(Some(found_value));
                     }
                 }
             }
@@ -120,6 +142,24 @@ fn find_ssh_key_for_host_in_config(
     Ok(None)
 }
 
+pub(crate) fn find_username_candidates(host: Option<&str>) -> Result<Vec<String>, git2::Error> {
+    // candidates in the same order than the list from IdentityFile in ssh_config man page.
+    let mut candidates = vec![];
+    // first the candidates from .ssh/config for the target host
+    if let Some(host) = host {
+        if let Some(username_host) = find_username_in_ssh_config(host)? {
+            candidates.push(username_host);
+        }
+    }
+    // push default candidates
+    candidates.push("git".to_string());
+    if let Ok(s) = std::env::var("USER").or_else(|_| std::env::var("USERNAME")) {
+        candidates.push(s);
+    }
+
+    Ok(candidates)
+}
+
 pub(crate) fn find_ssh_key_candidates(
     host: Option<&str>,
 ) -> Result<Vec<path::PathBuf>, git2::Error> {