MT#61977 add oauth/JWT helpers

Change-Id: Ic8e54fb23f0f6403da638adaf5c3600f767caf90

debian/control

@@ -31,6 +31,7 @@ Build-Depends:
  libiptc-dev,
  libjson-glib-dev,
  libjson-perl,
+ libjwt-dev,
  libmnl-dev,
  libmosquitto-dev,
  libncurses-dev,

lib/.ycm_extra_conf.py

@@ -30,6 +30,7 @@ flags = [
     '-I/usr/include/glib-2.0',
     '-I/usr/include/opus',
     '-I/usr/lib/x86_64-linux-gnu/glib-2.0/include',
+    '-I/usr/include/json-glib-1.0',
     '-pthread',
     '-D_GNU_SOURCE',
     '-D__DEBUG=1',

lib/oauth.c

@@ -0,0 +1,293 @@
+#include "oauth.h"
+#include <glib.h>
+#include <curl/curl.h>
+#include <jwt.h>
+#include <json-glib/json-glib.h>
+#include "auxlib.h"
+#include "http.h"
+
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(jwt_t, jwt_free)
+
+
+// called during init
+// returns g_strdup'd error
+static char *oauth_service_account(oauth_context_t *ctx) {
+	g_autoptr(JsonParser) parser = json_parser_new();
+	g_autoptr(GError) error = NULL;
+	json_parser_load_from_file(parser, ctx->service_account_file, &error);
+	if (error)
+		return g_strdup(error->message);
+
+	const char *err;
+
+	err = "Failed to get JSON root node";
+	JsonNode *root = json_parser_get_root(parser);
+	if (!root)
+		goto err;
+	err = "JSON root node is not an object";
+	JsonObject *o = json_node_get_object(root);
+	if (!o)
+		goto err;
+
+
+	err = "No 'client_email' in service account file";
+	JsonNode *c = json_object_get_member(o, "client_email");
+	if (!c)
+		goto err;
+
+	err = "JSON 'client_email' is not a string";
+	const char *s = json_node_get_string(c);
+	if (!s)
+		goto err;
+	ctx->_iss = g_strdup(s);
+
+
+	err = "No 'token_uri' in service account file";
+	c = json_object_get_member(o, "token_uri");
+	if (!c)
+		goto err;
+
+	err = "JSON 'token_uri' is not a string";
+	s = json_node_get_string(c);
+	if (!s)
+		goto err;
+	ctx->_aud = g_strdup(s);
+
+
+	err = "No 'private_key' in service account file";
+	c = json_object_get_member(o, "private_key");
+	if (!c)
+		goto err;
+
+	err = "JSON 'private_key' is not a string";
+	s = json_node_get_string(c);
+	if (!s)
+		goto err;
+	ctx->_private_key = g_strdup(s);
+
+
+	err = "algorithm not supported by JWT library";
+	ctx->_alg = jwt_str_alg(ctx->algorithm);
+	if (ctx->_alg == JWT_ALG_INVAL)
+		goto err;
+
+
+	return NULL;
+
+err:
+	return g_strdup(err);
+}
+
+
+// lock is held
+// returns g_strdup'd token
+static char *oauth_set_token(oauth_context_t *ctx, const char *token, int64_t expires_in, time_t now) {
+	g_clear_pointer(&ctx->_token, g_free);
+	ctx->_token = g_strdup(token);
+	ctx->_expires = now + expires_in;
+
+	return g_strdup(token);
+}
+
+
+// lock is held
+// returns g_strdup'd token
+static char *oauth_decode_token(oauth_context_t *ctx, GString *json, time_t now, char **errp) {
+	g_autoptr(JsonParser) parser = json_parser_new();
+	g_autoptr(GError) error = NULL;
+	json_parser_load_from_data(parser, json->str, json->len, &error);
+	if (error) {
+		*errp = g_strdup(error->message);
+		return NULL;
+	}
+
+	const char *err;
+
+	err = "Failed to get JSON root node";
+	JsonNode *root = json_parser_get_root(parser);
+	if (!root)
+		goto err;
+	err = "JSON root node is not an object";
+	JsonObject *o = json_node_get_object(root);
+	if (!o)
+		goto err;
+
+
+	err = "No 'access_token' in OAuth response";
+	JsonNode *c = json_object_get_member(o, "access_token");
+	if (!c)
+		goto err;
+
+	err = "JSON 'access_token' is not a string";
+	const char *s = json_node_get_string(c);
+	if (!s)
+		goto err;
+
+
+	err = "No 'expires_in' in OAuth response";
+	c = json_object_get_member(o, "expires_in");
+	if (!c)
+		goto err;
+
+	err = "JSON 'expires_in' is not valid";
+	int64_t i = json_node_get_int(c);
+	if (!i)
+		goto err;
+
+
+	return oauth_set_token(ctx, s, i, now);
+
+err:
+	*errp = g_strdup(err);
+	return false;}
+
+
+// lock is held
+// returns g_strdup'd token
+static char *oauth_request(oauth_context_t *ctx, const char *jwt, time_t now, char **errp) {
+	g_autoptr(char) req = g_strdup_printf("{'grant_type': 'urn:ietf:params:oauth:grant-type:jwt-bearer', "
+			"'assertion': '%s'}", jwt);
+	size_t req_len = strlen(req);
+
+	struct curl_slist *headers = NULL;
+
+	http_add_header(&headers, "Content-type: application/json");
+	http_add_header(&headers, "Content-length: %zu", req_len);
+
+	const char *err;
+	CURLcode curl_code = CURLE_OK;
+	g_autoptr(GString) resp = g_string_new("");
+	err = "internal cURL error";
+	CURL *c = http_create_req(ctx->_aud,
+			http_download_write, resp,
+			http_upload_read,
+			&(http_upload) {.s = { .s = req, .len = req_len } },
+			headers, true, &curl_code, &err);
+
+	if (!c)
+		goto err;
+
+	// POST
+	err = "setting CURLOPT_POST";
+	if ((curl_code = curl_easy_setopt(c, CURLOPT_POST, 1L)) != CURLE_OK)
+		goto err;
+
+	err = "performing request";
+	if ((curl_code = curl_easy_perform(c)) != CURLE_OK)
+		goto err;
+
+	long code;
+	err = "getting CURLINFO_RESPONSE_CODE";
+	if ((curl_code = curl_easy_getinfo(c, CURLINFO_RESPONSE_CODE, &code)) != CURLE_OK)
+		goto err;
+
+	err = "checking response code (not 2xx)";
+	if (code < 200 || code >= 300) {
+		*errp = g_strdup_printf("Request OAuth/JWT token failed with code %ld: %s%.*s%s",
+				code, FMT_M((int) resp->len, resp->str));
+		return NULL;
+	}
+
+	return oauth_decode_token(ctx, resp, now, errp);
+
+err:
+	*errp = g_strdup_printf("Failed to request OAuth token: %s / %s", err, curl_easy_strerror(curl_code));
+	return NULL;
+}
+
+
+// lock is held
+// returns g_strdup'd token
+static char *oauth_request_token(oauth_context_t *ctx, time_t now, char **errp) {
+	const char *err;
+
+	err = "failed to create libjwt object";
+	g_autoptr(jwt_t) jwt = NULL;
+	int ret = jwt_new(&jwt);
+	if (ret)
+		goto err;
+
+	err = "failed to add 'iss' grant";
+	ret = jwt_add_grant(jwt, "iss", ctx->_iss);
+	if (ret)
+		goto err;
+
+	err = "failed to add 'scope' grant";
+	ret = jwt_add_grant(jwt, "scope", ctx->scope);
+	if (ret)
+		goto err;
+
+	err = "failed to add 'aud' grant";
+	ret = jwt_add_grant(jwt, "aud", ctx->_aud);
+	if (ret)
+		goto err;
+
+	err = "failed to add 'iat' grant";
+	ret = jwt_add_grant_int(jwt, "iat", now);
+	if (ret)
+		goto err;
+
+	time_t expiry = now + 3600;
+	err = "failed to add 'exp' grant";
+	ret = jwt_add_grant_int(jwt, "exp", expiry);
+	if (ret)
+		goto err;
+
+	err = "failed to set algorithm or key";
+	ret = jwt_set_alg(jwt, ctx->_alg, (unsigned char *) ctx->_private_key, strlen(ctx->_private_key));
+	if (ret)
+		goto err;
+
+	err = "failed encode JWT";
+	char *j = jwt_encode_str(jwt);
+	if (!j)
+		goto err;
+
+	char *token = oauth_request(ctx, j, now, errp);
+	free(j);
+
+	return token;
+
+err:
+	*errp = g_strdup(err);
+	return NULL;
+}
+
+
+// returns g_strdup'd token
+static char *oauth_get_token(oauth_context_t *ctx, char **errp) {
+	time_t now = time(NULL);
+	time_t cutoff = now - 10;
+
+	LOCK(&ctx->_lock);
+
+	if (ctx->_token && ctx->_expires > cutoff)
+		return g_strdup(ctx->_token);
+
+	return oauth_request_token(ctx, now, errp);
+}
+
+
+void oauth_add_auth(struct curl_slist **headers, oauth_context_t *ctx, char **errp) {
+	g_autoptr(char) jwt = oauth_get_token(ctx, errp);
+	if (!jwt)
+		return;
+
+	http_add_header(headers, "Authorization: Bearer %s", jwt);
+}
+
+
+char *oauth_init(oauth_context_t *ctx) {
+	mutex_init(&ctx->_lock);
+	return oauth_service_account(ctx);
+}
+
+
+void oauth_cleanup(oauth_context_t *ctx) {
+	g_clear_pointer(&ctx->_aud, g_free);
+	g_clear_pointer(&ctx->_iss, g_free);
+	g_clear_pointer(&ctx->_private_key, g_free);
+	g_clear_pointer(&ctx->_token, g_free);
+	mutex_destroy(&ctx->_lock);
+}

lib/oauth.h

@@ -0,0 +1,35 @@
+#ifndef _OAUTH_H_
+#define _OAUTH_H_
+
+#include <jwt.h>
+#include <stdbool.h>
+#include <curl/curl.h>
+#include "auxlib.h"
+
+
+typedef struct {
+	const char *service_account_file;
+	const char *scope; // https://www.googleapis.com/auth/cloud-platform
+	const char *algorithm; // RS256
+
+	// fields below here get filled in and are private,
+	// but must be initialised to zero
+
+	jwt_alg_t _alg;
+	char *_iss; // client_email
+	char *_aud; // token_uri
+	char *_private_key; // PEM
+
+	mutex_t _lock;
+	char *_token;
+	time_t _expires;
+} oauth_context_t;
+
+
+char *oauth_init(oauth_context_t *);
+void oauth_cleanup(oauth_context_t *);
+
+void oauth_add_auth(struct curl_slist **headers, oauth_context_t *ctx, char **errp);
+
+
+#endif

recording-daemon/.ycm_extra_conf.py

@@ -20,6 +20,7 @@ flags = [
     '-fno-strict-aliasing',
     '-I/usr/include/glib-2.0',
     '-I/usr/lib/x86_64-linux-gnu/glib-2.0/include',
+    '-I/usr/include/json-glib-1.0',
     '-I/usr/include/mysql',
     '-I.',
     '-I../lib/',