[PATCH 8/8] http: set specific auth scheme depending on credential

["Matthew John Cheetham via GitGitGadget" <gitgitgadget@gmail.com>]

From: Matthew John Cheetham <mjcheetham@outlook.com>

Introduce a new credential field `authtype` that can be used by
credential helpers to indicate the type of the credential or
authentication mechanism to use for a request.

Modify http.c to now specify the correct authentication scheme or
credential type when authenticating the curl handle. If the new
`authtype` field in the credential structure is `NULL` or "Basic" then
use the existing username/password options. If the field is "Bearer"
then use the OAuth bearer token curl option. Otherwise, the `authtype`
field is the authentication scheme and the `password` field is the
raw, unencoded value.

Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com>
---
 Documentation/git-credential.txt |  9 +++++++++
 credential.c                     |  5 +++++
 credential.h                     |  1 +
 git-curl-compat.h                |  7 +++++++
 http.c                           | 24 +++++++++++++++++++++---
 5 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-credential.txt b/Documentation/git-credential.txt
index 7d4a788c63d..3b6ef6f4906 100644
--- a/Documentation/git-credential.txt
+++ b/Documentation/git-credential.txt
@@ -152,6 +152,15 @@ Git understands the following attributes:
 	`protocol=https` and `host=example.com` had been provided). This
 	can help callers avoid parsing URLs themselves.
 
+`authtype`::
+
+	Indicates the type of authentication scheme used. If this is not
+	present the default is "Basic".
+	Known values include "Basic", "Digest", and "Bearer".
+	If an unknown value is provided, this is taken as the authentication
+	scheme for the `Authorization` header, and the `password` field is
+	used as the raw unencoded authorization parameters of the same header.
+
 `wwwauth[n]`::
 
 	When an HTTP response is received that includes one or more
diff --git a/credential.c b/credential.c
index 4ad40323fc7..9d4a0f3fd51 100644
--- a/credential.c
+++ b/credential.c
@@ -21,6 +21,7 @@ void credential_clear(struct credential *c)
 	free(c->path);
 	free(c->username);
 	free(c->password);
+	free(c->authtype);
 	string_list_clear(&c->helpers, 0);
 	strvec_clear(&c->wwwauth_headers);
 
@@ -235,6 +236,9 @@ int credential_read(struct credential *c, FILE *fp)
 		} else if (!strcmp(key, "path")) {
 			free(c->path);
 			c->path = xstrdup(value);
+		} else if (!strcmp(key, "authtype")) {
+			free(c->authtype);
+			c->authtype = xstrdup(value);
 		} else if (!strcmp(key, "url")) {
 			credential_from_url(c, value);
 		} else if (!strcmp(key, "quit")) {
@@ -281,6 +285,7 @@ void credential_write(const struct credential *c, FILE *fp)
 	credential_write_item(fp, "path", c->path, 0);
 	credential_write_item(fp, "username", c->username, 0);
 	credential_write_item(fp, "password", c->password, 0);
+	credential_write_item(fp, "authtype", c->authtype, 0);
 	credential_write_strvec(fp, "wwwauth", &c->wwwauth_headers);
 }
 
diff --git a/credential.h b/credential.h
index 6a9d4e3de07..a6572aacf1d 100644
--- a/credential.h
+++ b/credential.h
@@ -135,6 +135,7 @@ struct credential {
 	char *protocol;
 	char *host;
 	char *path;
+	char *authtype;
 };
 
 #define CREDENTIAL_INIT { \
diff --git a/git-curl-compat.h b/git-curl-compat.h
index 56a83b6bbd8..74732500a9f 100644
--- a/git-curl-compat.h
+++ b/git-curl-compat.h
@@ -126,4 +126,11 @@
 #define GIT_CURL_HAVE_CURLSSLSET_NO_BACKENDS
 #endif
 
+/**
+ * CURLAUTH_BEARER was added in 7.61.0, released in July 2018.
+ */
+#if LIBCURL_VERSION_NUM >= 0x073D00
+#define GIT_CURL_HAVE_CURLAUTH_BEARER
+#endif
+
 #endif
diff --git a/http.c b/http.c
index 8e107ff19b8..d8913b2c641 100644
--- a/http.c
+++ b/http.c
@@ -516,7 +516,8 @@ static int curl_empty_auth_enabled(void)
 
 static void init_curl_http_auth(struct active_request_slot *slot)
 {
-	if (!http_auth.username || !*http_auth.username) {
+	if (!http_auth.authtype &&
+		(!http_auth.username || !*http_auth.username)) {
 		if (curl_empty_auth_enabled())
 			curl_easy_setopt(slot->curl, CURLOPT_USERPWD, ":");
 		return;
@@ -524,8 +525,25 @@ static void init_curl_http_auth(struct active_request_slot *slot)
 
 	credential_fill(&http_auth);
 
-	curl_easy_setopt(slot->curl, CURLOPT_USERNAME, http_auth.username);
-	curl_easy_setopt(slot->curl, CURLOPT_PASSWORD, http_auth.password);
+	if (!http_auth.authtype || !strcasecmp(http_auth.authtype, "basic")
+				|| !strcasecmp(http_auth.authtype, "digest")) {
+		curl_easy_setopt(slot->curl, CURLOPT_USERNAME,
+			http_auth.username);
+		curl_easy_setopt(slot->curl, CURLOPT_PASSWORD,
+			http_auth.password);
+#ifdef GIT_CURL_HAVE_CURLAUTH_BEARER
+	} else if (!strcasecmp(http_auth.authtype, "bearer")) {
+		curl_easy_setopt(slot->curl, CURLOPT_HTTPAUTH, CURLAUTH_BEARER);
+		curl_easy_setopt(slot->curl, CURLOPT_XOAUTH2_BEARER,
+			http_auth.password);
+#endif
+	} else {
+		struct strbuf auth = STRBUF_INIT;
+		strbuf_addf(&auth, "Authorization: %s %s",
+			http_auth.authtype, http_auth.password);
+		slot->headers = curl_slist_append(slot->headers, auth.buf);
+		strbuf_release(&auth);
+	}
 }
 
 /* *var must be free-able */
-- 
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