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#ifndef CREDENTIAL_H
#define CREDENTIAL_H
#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,
username_from_proto:1;
char *username;
char *password;
char *protocol;
char *host;
char *path;
};
#define CREDENTIAL_INIT { \
.helpers = 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 and the function will return an
* error (even in 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 *want,
const struct credential *have);
#endif /* CREDENTIAL_H */
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