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-rw-r--r--credential.h162
1 files changed, 161 insertions, 1 deletions
diff --git a/credential.h b/credential.h
index 6b0cd16be2b9..d99ec42b2a8c 100644
--- a/credential.h
+++ b/credential.h
@@ -3,12 +3,123 @@
 
 #include "string-list.h"
 
+/**
+ * The credentials API provides an abstracted way of gathering username and
+ * password credentials from the user.
+ *
+ * Typical setup
+ * -------------
+ *
+ * ------------
+ * +-----------------------+
+ * | Git code (C)          |--- to server requiring --->
+ * |                       |        authentication
+ * |.......................|
+ * | C credential API      |--- prompt ---> User
+ * +-----------------------+
+ * 	^      |
+ * 	| pipe |
+ * 	|      v
+ * +-----------------------+
+ * | Git credential helper |
+ * +-----------------------+
+ * ------------
+ *
+ * The Git code (typically a remote-helper) will call the C API to obtain
+ * credential data like a login/password pair (credential_fill). The
+ * API will itself call a remote helper (e.g. "git credential-cache" or
+ * "git credential-store") that may retrieve credential data from a
+ * store. If the credential helper cannot find the information, the C API
+ * will prompt the user. Then, the caller of the API takes care of
+ * contacting the server, and does the actual authentication.
+ *
+ * C API
+ * -----
+ *
+ * The credential C API is meant to be called by Git code which needs to
+ * acquire or store a credential. It is centered around an object
+ * representing a single credential and provides three basic operations:
+ * fill (acquire credentials by calling helpers and/or prompting the user),
+ * approve (mark a credential as successfully used so that it can be stored
+ * for later use), and reject (mark a credential as unsuccessful so that it
+ * can be erased from any persistent storage).
+ *
+ * Example
+ * ~~~~~~~
+ *
+ * The example below shows how the functions of the credential API could be
+ * used to login to a fictitious "foo" service on a remote host:
+ *
+ * -----------------------------------------------------------------------
+ * int foo_login(struct foo_connection *f)
+ * {
+ * 	int status;
+ * 	// Create a credential with some context; we don't yet know the
+ * 	// username or password.
+ *
+ * struct credential c = CREDENTIAL_INIT;
+ * c.protocol = xstrdup("foo");
+ * c.host = xstrdup(f->hostname);
+ *
+ * // Fill in the username and password fields by contacting
+ * // helpers and/or asking the user. The function will die if it
+ * // fails.
+ * credential_fill(&c);
+ *
+ * // Otherwise, we have a username and password. Try to use it.
+ *
+ * status = send_foo_login(f, c.username, c.password);
+ * switch (status) {
+ * case FOO_OK:
+ * // It worked. Store the credential for later use.
+ * credential_accept(&c);
+ * break;
+ * case FOO_BAD_LOGIN:
+ * // Erase the credential from storage so we don't try it again.
+ * credential_reject(&c);
+ * break;
+ * default:
+ * // Some other error occurred. We don't know if the
+ * // credential is good or bad, so report nothing to the
+ * // credential subsystem.
+ * }
+ *
+ * // Free any associated resources.
+ * credential_clear(&c);
+ *
+ * return status;
+ * }
+ * -----------------------------------------------------------------------
+ */
+
+
+/**
+ * This struct represents a single username/password combination
+ * along with any associated context. All string fields should be
+ * heap-allocated (or NULL if they are not known or not applicable).
+ * The meaning of the individual context fields is the same as
+ * their counterparts in the helper protocol.
+ *
+ * This struct should always be initialized with `CREDENTIAL_INIT` or
+ * `credential_init`.
+ */
 struct credential {
+
+	/**
+	 * A `string_list` of helpers. Each string specifies an external
+	 * helper which will be run, in order, to either acquire or store
+	 * credentials. This list is filled-in by the API functions
+	 * according to the corresponding configuration variables before
+	 * consulting helpers, so there usually is no need for a caller to
+	 * modify the helpers field at all.
+	 */
 	struct string_list helpers;
+
 	unsigned approved:1,
 		 configured:1,
 		 quit:1,
-		 use_http_path:1;
+		 use_http_path:1,
+		 username_from_proto:1;
 
 	char *username;
 	char *password;
@@ -19,16 +130,65 @@ struct credential {
 
 #define CREDENTIAL_INIT { STRING_LIST_INIT_DUP }
 
+/* Initialize a credential structure, setting all fields to empty. */
 void credential_init(struct credential *);
+
+/**
+ * Free any resources associated with the credential structure, returning
+ * it to a pristine initialized state.
+ */
 void credential_clear(struct credential *);
 
+/**
+ * Instruct the credential subsystem to fill the username and
+ * password fields of the passed credential struct by first
+ * consulting helpers, then asking the user. After this function
+ * returns, the username and password fields of the credential are
+ * guaranteed to be non-NULL. If an error occurs, the function will
+ * die().
+ */
 void credential_fill(struct credential *);
+
+/**
+ * Inform the credential subsystem that the provided credentials
+ * were successfully used for authentication.  This will cause the
+ * credential subsystem to notify any helpers of the approval, so
+ * that they may store the result to be used again.  Any errors
+ * from helpers are ignored.
+ */
 void credential_approve(struct credential *);
+
+/**
+ * Inform the credential subsystem that the provided credentials
+ * have been rejected. This will cause the credential subsystem to
+ * notify any helpers of the rejection (which allows them, for
+ * example, to purge the invalid credentials from storage). It
+ * will also free() the username and password fields of the
+ * credential and set them to NULL (readying the credential for
+ * another call to `credential_fill`). Any errors from helpers are
+ * ignored.
+ */
 void credential_reject(struct credential *);
 
 int credential_read(struct credential *, FILE *);
 void credential_write(const struct credential *, FILE *);
+
+/*
+ * Parse a url into a credential struct, replacing any existing contents.
+ *
+ * If the url can't be parsed (e.g., a missing "proto://" component), the
+ * resulting credential will be empty but we'll still return success from the
+ * "gently" form.
+ *
+ * If we encounter a component which cannot be represented as a credential
+ * value (e.g., because it contains a newline), the "gently" form will return
+ * an error but leave the broken state in the credential object for further
+ * examination.  The non-gentle form will issue a warning to stderr and return
+ * an empty credential.
+ */
 void credential_from_url(struct credential *, const char *url);
+int credential_from_url_gently(struct credential *, const char *url, int quiet);
+
 int credential_match(const struct credential *have,
 		     const struct credential *want);