cred: separate public interface from low-level details

Author: tiennou

docs/changelog.md

@@ -1,6 +1,14 @@
 v0.28 + 1
 ---------
 
+### Breaking API changes
+
+* The "private" implementation details of the `git_cred` structure have been
+  moved to a dedicated `git2/sys/cred.h` header, to clarify that the underlying
+  structures are only provided for custom transport implementers.
+  The breaking change is that the `username` member of the underlying struct
+  is now hidden, and a new `git_cred_get_username` function has been provided.
+
 ### Breaking CMake configuration changes
 
 * The CMake option to use a system http-parser library, instead of the

include/git2.h

@@ -21,6 +21,7 @@
 #include "git2/commit.h"
 #include "git2/common.h"
 #include "git2/config.h"
+#include "git2/cred.h"
 #include "git2/deprecated.h"
 #include "git2/describe.h"
 #include "git2/diff.h"

include/git2/cred.h

@@ -0,0 +1,308 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_cred_h__
+#define INCLUDE_git_cred_h__
+
+#include "common.h"
+
+/**
+ * @file git2/cred.h
+ * @brief Git authentication & credential management
+ * @defgroup git_cred Authentication & credential management
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Supported credential types
+ *
+ * This represents the various types of authentication methods supported by
+ * the library.
+ */
+typedef enum {
+	/**
+	 * A vanilla user/password request
+	 * @see git_cred_userpass_plaintext_new
+	 */
+	GIT_CREDTYPE_USERPASS_PLAINTEXT = (1u << 0),
+
+	/**
+	 * An SSH key-based authentication request
+	 * @see git_cred_ssh_key_new
+	 */
+	GIT_CREDTYPE_SSH_KEY = (1u << 1),
+
+	/**
+	 * An SSH key-based authentication request, with a custom signature
+	 * @see git_cred_ssh_custom_new
+	 */
+	GIT_CREDTYPE_SSH_CUSTOM = (1u << 2),
+
+	/**
+	 * An NTLM/Negotiate-based authentication request.
+	 * @see git_cred_default
+	 */
+	GIT_CREDTYPE_DEFAULT = (1u << 3),
+
+	/**
+	 * An SSH interactive authentication request
+	 * @see git_cred_ssh_interactive_new
+	 */
+	GIT_CREDTYPE_SSH_INTERACTIVE = (1u << 4),
+
+	/**
+	 * Username-only authentication request
+	 *
+	 * Used as a pre-authentication step if the underlying transport
+	 * (eg. SSH, with no username in its URL) does not know which username
+	 * to use.
+	 *
+	 * @see git_cred_username_new
+	 */
+	GIT_CREDTYPE_USERNAME = (1u << 5),
+
+	/**
+	 * An SSH key-based authentication request
+	 *
+	 * Allows credentials to be read from memory instead of files.
+	 * Note that because of differences in crypto backend support, it might
+	 * not be functional.
+	 *
+	 * @see git_cred_ssh_key_memory_new
+	 */
+	GIT_CREDTYPE_SSH_MEMORY = (1u << 6),
+} git_credtype_t;
+
+/**
+ * The base structure for all credential types
+ */
+typedef struct git_cred git_cred;
+
+typedef struct git_cred_userpass_plaintext git_cred_userpass_plaintext;
+
+/** Username-only credential information */
+typedef struct git_cred_username git_cred_username;
+
+/** A key for NTLM/Kerberos "default" credentials */
+typedef struct git_cred git_cred_default;
+
+/**
+ * A ssh key from disk
+ */
+typedef struct git_cred_ssh_key git_cred_ssh_key;
+
+/**
+ * Keyboard-interactive based ssh authentication
+ */
+typedef struct git_cred_ssh_interactive git_cred_ssh_interactive;
+
+/**
+ * A key with a custom signature function
+ */
+typedef struct git_cred_ssh_custom git_cred_ssh_custom;
+
+/**
+ * Credential acquisition callback.
+ *
+ * This callback is usually involved any time another system might need
+ * authentication. As such, you are expected to provide a valid git_cred
+ * object back, depending on allowed_types (a git_credtype_t bitmask).
+ *
+ * Note that most authentication details are your responsibility - this
+ * callback will be called until the authentication succeeds, or you report
+ * an error. As such, it's easy to get in a loop if you fail to stop providing
+ * the same incorrect credentials.
+ *
+ * @param cred The newly created credential object.
+ * @param url The resource for which we are demanding a credential.
+ * @param username_from_url The username that was embedded in a "user\@host"
+ *                          remote url, or NULL if not included.
+ * @param allowed_types A bitmask stating which cred types are OK to return.
+ * @param payload The payload provided when specifying this callback.
+ * @return 0 for success, < 0 to indicate an error, > 0 to indicate
+ *       no credential was acquired
+ */
+typedef int GIT_CALLBACK(git_cred_acquire_cb)(
+	git_cred **cred,
+	const char *url,
+	const char *username_from_url,
+	unsigned int allowed_types,
+	void *payload);
+
+/**
+ * Free a credential.
+ *
+ * This is only necessary if you own the object; that is, if you are a
+ * transport.
+ *
+ * @param cred the object to free
+ */
+GIT_EXTERN(void) git_cred_free(git_cred *cred);
+
+/**
+ * Check whether a credential object contains username information.
+ *
+ * @param cred object to check
+ * @return 1 if the credential object has non-NULL username, 0 otherwise
+ */
+GIT_EXTERN(int) git_cred_has_username(git_cred *cred);
+
+/**
+ * Return the username associated with a credential object.
+ *
+ * @param cred object to check
+ * @return the credential username, or NULL if not applicable
+ */
+GIT_EXTERN(const char *) git_cred_get_username(git_cred *cred);
+
+/**
+ * Create a new plain-text username and password credential object.
+ * The supplied credential parameter will be internally duplicated.
+ *
+ * @param out The newly created credential object.
+ * @param username The username of the credential.
+ * @param password The password of the credential.
+ * @return 0 for success or an error code for failure
+ */
+GIT_EXTERN(int) git_cred_userpass_plaintext_new(
+	git_cred **out,
+	const char *username,
+	const char *password);
+
+/**
+ * Create a "default" credential usable for Negotiate mechanisms like NTLM
+ * or Kerberos authentication.
+ *
+ * @return 0 for success or an error code for failure
+ */
+GIT_EXTERN(int) git_cred_default_new(git_cred **out);
+
+/**
+ * Create a credential to specify a username.
+ *
+ * This is used with ssh authentication to query for the username if
+ * none is specified in the url.
+ */
+GIT_EXTERN(int) git_cred_username_new(git_cred **cred, const char *username);
+
+/**
+ * Create a new passphrase-protected ssh key credential object.
+ * The supplied credential parameter will be internally duplicated.
+ *
+ * @param out The newly created credential object.
+ * @param username username to use to authenticate
+ * @param publickey The path to the public key of the credential.
+ * @param privatekey The path to the private key of the credential.
+ * @param passphrase The passphrase of the credential.
+ * @return 0 for success or an error code for failure
+ */
+GIT_EXTERN(int) git_cred_ssh_key_new(
+	git_cred **out,
+	const char *username,
+	const char *publickey,
+	const char *privatekey,
+	const char *passphrase);
+
+/**
+ * Create a new ssh key credential object reading the keys from memory.
+ *
+ * @param out The newly created credential object.
+ * @param username username to use to authenticate.
+ * @param publickey The public key of the credential.
+ * @param privatekey The private key of the credential.
+ * @param passphrase The passphrase of the credential.
+ * @return 0 for success or an error code for failure
+ */
+GIT_EXTERN(int) git_cred_ssh_key_memory_new(
+	git_cred **out,
+	const char *username,
+	const char *publickey,
+	const char *privatekey,
+	const char *passphrase);
+
+/*
+ * If the user hasn't included libssh2.h before git2.h, we need to
+ * define a few types for the callback signatures.
+ */
+#ifndef LIBSSH2_VERSION
+typedef struct _LIBSSH2_SESSION LIBSSH2_SESSION;
+typedef struct _LIBSSH2_USERAUTH_KBDINT_PROMPT LIBSSH2_USERAUTH_KBDINT_PROMPT;
+typedef struct _LIBSSH2_USERAUTH_KBDINT_RESPONSE LIBSSH2_USERAUTH_KBDINT_RESPONSE;
+#endif
+
+typedef void GIT_CALLBACK(git_cred_ssh_interactive_cb)(
+	const char *name,
+	int name_len,
+	const char *instruction, int instruction_len,
+	int num_prompts, const LIBSSH2_USERAUTH_KBDINT_PROMPT *prompts,
+	LIBSSH2_USERAUTH_KBDINT_RESPONSE *responses,
+	void **abstract);
+
+
+/**
+ * Create a new ssh keyboard-interactive based credential object.
+ * The supplied credential parameter will be internally duplicated.
+ *
+ * @param username Username to use to authenticate.
+ * @param prompt_callback The callback method used for prompts.
+ * @param payload Additional data to pass to the callback.
+ * @return 0 for success or an error code for failure.
+ */
+GIT_EXTERN(int) git_cred_ssh_interactive_new(
+	git_cred **out,
+	const char *username,
+	git_cred_ssh_interactive_cb prompt_callback,
+	void *payload);
+
+/**
+ * Create a new ssh key credential object used for querying an ssh-agent.
+ * The supplied credential parameter will be internally duplicated.
+ *
+ * @param out The newly created credential object.
+ * @param username username to use to authenticate
+ * @return 0 for success or an error code for failure
+ */
+GIT_EXTERN(int) git_cred_ssh_key_from_agent(
+	git_cred **out,
+	const char *username);
+
+typedef int GIT_CALLBACK(git_cred_sign_cb)(
+	LIBSSH2_SESSION *session,
+	unsigned char **sig, size_t *sig_len,
+	const unsigned char *data, size_t data_len,
+	void **abstract);
+
+/**
+ * Create an ssh key credential with a custom signing function.
+ *
+ * This lets you use your own function to sign the challenge.
+ *
+ * This function and its credential type is provided for completeness
+ * and wraps `libssh2_userauth_publickey()`, which is undocumented.
+ *
+ * The supplied credential parameter will be internally duplicated.
+ *
+ * @param out The newly created credential object.
+ * @param username username to use to authenticate
+ * @param publickey The bytes of the public key.
+ * @param publickey_len The length of the public key in bytes.
+ * @param sign_callback The callback method to sign the data during the challenge.
+ * @param payload Additional data to pass to the callback.
+ * @return 0 for success or an error code for failure
+ */
+GIT_EXTERN(int) git_cred_ssh_custom_new(
+	git_cred **out,
+	const char *username,
+	const char *publickey,
+	size_t publickey_len,
+	git_cred_sign_cb sign_callback,
+	void *payload);
+
+/** @} */
+GIT_END_DECL
+#endif

include/git2/proxy.h

@@ -8,7 +8,7 @@
 #define INCLUDE_git_proxy_h__
 
 #include "common.h"
-#include "transport.h"
+#include "cred.h"
 
 GIT_BEGIN_DECL