Check for NULL before calling json_object_get_string()

Fixes #2102.

Co-authored-by: Dennis van der Schagt <dennisschagt@gmail.com>

6 files changed, 150 insertions, 54 deletions

diff --git a/src/feedhqapi.cpp b/src/feedhqapi.cpp
index 382cb42e..40591803 100644
--- a/src/feedhqapi.cpp
+++ b/src/feedhqapi.cpp
@@ -136,12 +136,20 @@ std::vector<TaggedFeedUrl> FeedHqApi::get_subscribed_urls()
 		json_object* id_str{};
 		json_object_object_get_ex(sub, "id", &id_str);
 		const char* id = json_object_get_string(id_str);
+		if (id == nullptr) {
+			LOG(Level::WARN, "Skipping a subscription without an id");
+			continue;
+		}
 
 		json_object* title_str{};
 		json_object_object_get_ex(sub, "title", &title_str);
 		const char* title = json_object_get_string(title_str);
-
-		tags.push_back(std::string("~") + title);
+		if (title != nullptr) {
+			tags.push_back(std::string("~") + title);
+		} else {
+			LOG(Level::WARN, "Subscription has no title, so let's call it \"%i\"", i);
+			tags.push_back(std::string("~") + std::to_string(i));
+		}
 
 		char* escaped_id = curl_easy_escape(handle.ptr(), id, 0);
 
diff --git a/src/freshrssapi.cpp b/src/freshrssapi.cpp
index 881ed184..b8f873c3 100644
--- a/src/freshrssapi.cpp
+++ b/src/freshrssapi.cpp
@@ -135,11 +135,23 @@ std::vector<TaggedFeedUrl> FreshRssApi::get_subscribed_urls()
 		json_object* sub =
 			json_object_array_get_idx(subscription_obj, i);
 
+		json_object* id_str{};
+		json_object_object_get_ex(sub, "id", &id_str);
+		const char* id = json_object_get_string(id_str);
+		if (id == nullptr) {
+			LOG(Level::WARN, "Skipping a subscription without an id");
+			continue;
+		}
+
 		json_object* title_str{};
 		json_object_object_get_ex(sub, "title", &title_str);
 		const char* title = json_object_get_string(title_str);
-
-		tags.push_back(std::string("~") + title);
+		if (title != nullptr) {
+			tags.push_back(std::string("~") + title);
+		} else {
+			LOG(Level::WARN, "Subscription has no title, so let's call it \"%i\"", i);
+			tags.push_back(std::string("~") + std::to_string(i));
+		}
 
 		json_object* cats_obj{};
 		json_object_object_get_ex(sub, "categories", &cats_obj);
@@ -151,19 +163,19 @@ std::vector<TaggedFeedUrl> FreshRssApi::get_subscribed_urls()
 			json_object* cat_name{};
 			json_object_object_get_ex(cat, "label", &cat_name);
 			const char* category = json_object_get_string(cat_name);
+			if (category == nullptr) {
+				LOG(Level::WARN, "Skipping subscription's category whose name is a null value");
+				continue;
+			}
 			tags.push_back(category);
 		}
 
-		json_object* id_str{};
-		json_object_object_get_ex(sub, "id", &id_str);
-		const char* id = json_object_get_string(id_str);
 		char* escaped_id = curl_easy_escape(handle.ptr(), id, 0);
 		auto url = strprintf::fmt("%s%s%s",
 				cfg->get_configvalue("freshrss-url"),
 				FRESHRSS_FEED_PREFIX,
 				escaped_id);
 		urls.push_back(TaggedFeedUrl(url, tags));
-
 		curl_free(escaped_id);
 	}
 
diff --git a/src/inoreaderapi.cpp b/src/inoreaderapi.cpp
index e1e37720..1ccacd9b 100644
--- a/src/inoreaderapi.cpp
+++ b/src/inoreaderapi.cpp
@@ -133,12 +133,20 @@ std::vector<TaggedFeedUrl> InoreaderApi::get_subscribed_urls()
 
 		json_object_object_get_ex(sub, "id", &node);
 		const char* id = json_object_get_string(node);
+		if (id == nullptr) {
+			LOG(Level::WARN, "Skipping a subscription without an id");
+			continue;
+		}
 		char* id_uenc = curl_easy_escape(handle.ptr(), id, 0);
 
 		json_object_object_get_ex(sub, "title", &node);
 		const char* title = json_object_get_string(node);
-
-		tags.push_back(std::string("~") + title);
+		if (title != nullptr) {
+			tags.push_back(std::string("~") + title);
+		} else {
+			LOG(Level::WARN, "Subscription has no title, so let's call it \"%i\"", i);
+			tags.push_back(std::string("~") + std::to_string(i));
+		}
 
 		json_object_object_get_ex(sub, "categories", &node);
 		struct array_list* categories = json_object_get_array(node);
@@ -152,6 +160,10 @@ std::vector<TaggedFeedUrl> InoreaderApi::get_subscribed_urls()
 			json_object* label_node{};
 			json_object_object_get_ex(cat, "label", &label_node);
 			const char* label = json_object_get_string(label_node);
+			if (label == nullptr) {
+				LOG(Level::WARN, "Skipping subscription's label whose name is a null value");
+				continue;
+			}
 			tags.push_back(std::string(label));
 		}
 
diff --git a/src/newsblurapi.cpp b/src/newsblurapi.cpp
index fafbf39b..ec129ab9 100644
--- a/src/newsblurapi.cpp
+++ b/src/newsblurapi.cpp
@@ -109,10 +109,21 @@ std::vector<TaggedFeedUrl> NewsBlurApi::get_subscribed_urls()
 
 		json_object* feed_json = json_object_iter_peek_value(&it);
 		json_object_object_get_ex(feed_json, "feed_title", &node);
-		current_feed.title = json_object_get_string(node);
+		const auto title = json_object_get_string(node);
+		if (title != nullptr) {
+			current_feed.title = title;
+		} else {
+			LOG(Level::WARN, "Subscription has no title, so let's call it \"%s\"", feed_id);
+			current_feed.title = feed_id;
+		}
 		json_object_object_get_ex(feed_json, "feed_link", &node);
 		if (node) {
-			current_feed.link = json_object_get_string(node);
+			const auto link = json_object_get_string(node);
+			if (link == nullptr) {
+				LOG(Level::WARN, "Skipping a subscription without a link");
+				continue;
+			}
+			current_feed.link = link;
 
 			known_feeds[feed_id] = current_feed;
 			std::string std_feed_id(feed_id);
@@ -152,6 +163,8 @@ std::map<std::string, std::vector<std::string>> NewsBlurApi::mk_feeds_to_tags(
 			continue;
 		}
 
+		// invariant: `tag_to_feed_ids` is a JSON object
+
 		json_object_object_foreach(
 			tag_to_feed_ids, key, feeds_with_tag_obj) {
 			std::string std_key(key);
@@ -163,9 +176,12 @@ std::map<std::string, std::vector<std::string>> NewsBlurApi::mk_feeds_to_tags(
 				json_object* feed_id_obj =
 					json_object_array_get_idx(
 						feeds_with_tag_obj, j);
-				std::string feed_id(
-					json_object_get_string(feed_id_obj));
-				result[feed_id].push_back(std_key);
+				const auto id = json_object_get_string(feed_id_obj);
+				if (id == nullptr) {
+					LOG(Level::WARN, "Skipping subscription's tag whose name is a null value");
+					continue;
+				}
+				result[std::string(id)].push_back(std_key);
 			}
 		}
 	}
@@ -183,7 +199,8 @@ bool request_successfull(json_object* payload)
 	if (json_object_object_get_ex(payload, "result", &result) == FALSE) {
 		return false;
 	} else {
-		return !strcmp("ok", json_object_get_string(result));
+		const auto result_str = json_object_get_string(result);
+		return result_str != nullptr && strcmp("ok", result_str) == 0;
 	}
 }
 
@@ -284,26 +301,32 @@ rsspp::Feed NewsBlurApi::fetch_feed(const std::string& id)
 
 			json_object* node{};
 
-			if (json_object_object_get_ex(
-					item_obj, "story_title", &node) == TRUE) {
-				item.title = json_object_get_string(node);
+			if (json_object_object_get_ex(item_obj, "story_title", &node) == TRUE) {
+				const auto title = json_object_get_string(node);
+				if (title != nullptr) {
+					item.title = title;
+				}
 			}
 
-			if (json_object_object_get_ex(
-					item_obj, "story_authors", &node) == TRUE) {
-				item.author = json_object_get_string(node);
+			if (json_object_object_get_ex(item_obj, "story_authors", &node) == TRUE) {
+				const auto author = json_object_get_string(node);
+				if (author != nullptr) {
+					item.author = author;
+				}
 			}
 
-			if (json_object_object_get_ex(item_obj,
-					"story_permalink",
-					&node) == TRUE) {
-				item.link = json_object_get_string(node);
+			if (json_object_object_get_ex(item_obj, "story_permalink", &node) == TRUE) {
+				const auto link = json_object_get_string(node);
+				if (link != nullptr) {
+					item.link = link;
+				}
 			}
 
-			if (json_object_object_get_ex(
-					item_obj, "story_content", &node) == TRUE) {
-				item.content_encoded =
-					json_object_get_string(node);
+			if (json_object_object_get_ex(item_obj, "story_content", &node) == TRUE) {
+				const auto content_encoded = json_object_get_string(node);
+				if (content_encoded != nullptr) {
+					item.content_encoded = content_encoded;
+				}
 			}
 
 			const char* article_id{};
@@ -325,11 +348,13 @@ rsspp::Feed NewsBlurApi::fetch_feed(const std::string& id)
 				}
 			}
 
-			if (json_object_object_get_ex(
-					item_obj, "story_date", &node) == TRUE) {
-				const char* pub_date =
-					json_object_get_string(node);
-				item.pubDate_ts = parse_date(pub_date);
+			if (json_object_object_get_ex(item_obj, "story_date", &node) == TRUE) {
+				const char* pub_date = json_object_get_string(node);
+				if (pub_date != nullptr) {
+					item.pubDate_ts = parse_date(pub_date);
+				} else {
+					item.pubDate_ts = ::time(nullptr);
+				}
 
 				item.pubDate = utils::mt_strf_localtime(
 						"%a, %d %b %Y %H:%M:%S %z",
diff --git a/src/ocnewsapi.cpp b/src/ocnewsapi.cpp
index 59f7adac..3c43275b 100644
--- a/src/ocnewsapi.cpp
+++ b/src/ocnewsapi.cpp
@@ -82,7 +82,11 @@ std::vector<TaggedFeedUrl> OcNewsApi::get_subscribed_urls()
 		long folder_id = json_object_get_int(node);
 
 		json_object_object_get_ex(folder, "name", &node);
-		folders_map[folder_id] = json_object_get_string(node);
+		const auto name = json_object_get_string(node);
+
+		if (name != nullptr) {
+			folders_map[folder_id] = name;
+		}
 	}
 
 	rsspp::Feed starred;
@@ -111,10 +115,19 @@ std::vector<TaggedFeedUrl> OcNewsApi::get_subscribed_urls()
 		long feed_id = json_object_get_int(node);
 
 		json_object_object_get_ex(feed, "title", &node);
-		current_feed.title = json_object_get_string(node);
+		const auto title = json_object_get_string(node);
+		if (title != nullptr) {
+			current_feed.title = title;
+		} else {
+			LOG(Level::WARN, "Subscription has no title, so let's call it \"%i\"", i);
+			current_feed.title = std::string("~") + std::to_string(i);
+		}
 
 		json_object_object_get_ex(feed, "url", &node);
-		current_feed.link = json_object_get_string(node);
+		const auto link = json_object_get_string(node);
+		if (link != nullptr) {
+			current_feed.link = link;
+		}
 
 		while (known_feeds.find(current_feed.title) !=
 			known_feeds.end()) {
@@ -246,18 +259,28 @@ rsspp::Feed OcNewsApi::fetch_feed(const std::string& feed_id)
 		rsspp::Item item;
 
 		json_object_object_get_ex(item_j, "title", &node);
-		item.title = json_object_get_string(node);
+		const auto title = json_object_get_string(node);
+		if (title != nullptr) {
+			item.title = title;
+		}
 
 		json_object_object_get_ex(item_j, "url", &node);
-		if (node) {
-			item.link = json_object_get_string(node);
+		const auto link = json_object_get_string(node);
+		if (link != nullptr) {
+			item.link = link;
 		}
 
 		json_object_object_get_ex(item_j, "author", &node);
-		item.author = json_object_get_string(node);
+		const auto author = json_object_get_string(node);
+		if (author != nullptr) {
+			item.author = author;
+		}
 
 		json_object_object_get_ex(item_j, "body", &node);
-		item.content_encoded = json_object_get_string(node);
+		const auto content_encoded = json_object_get_string(node);
+		if (content_encoded != nullptr) {
+			item.content_encoded = content_encoded;
+		}
 
 		{
 			json_object* type_obj;
@@ -267,13 +290,14 @@ rsspp::Feed OcNewsApi::fetch_feed(const std::string& feed_id)
 			json_object_object_get_ex(
 				item_j, "enclosureLink", &node);
 
-			if (type_obj && node) {
-				const std::string type =
-					json_object_get_string(type_obj);
-				if (utils::is_valid_podcast_type(type)) {
-					item.enclosure_url =
-						json_object_get_string(node);
-					item.enclosure_type = std::move(type);
+			const auto type_ptr = json_object_get_string(type_obj);
+			const auto url_ptr = json_object_get_string(node);
+
+			if (type_ptr != nullptr) {
+				const std::string type = type_ptr;
+				if (utils::is_valid_podcast_type(type) && url_ptr != nullptr) {
+					item.enclosure_url = url_ptr;
+					item.enclosure_type = type;
 				}
 			}
 		}
@@ -285,8 +309,9 @@ rsspp::Feed OcNewsApi::fetch_feed(const std::string& feed_id)
 		long f_id = json_object_get_int(node);
 
 		json_object_object_get_ex(item_j, "guid", &node);
+		const auto guid = json_object_get_string(node);
 		item.guid = std::to_string(id) + ":" + std::to_string(f_id) +
-			"/" + json_object_get_string(node);
+			"/" + (guid ? std::string(guid) : std::to_string(i));
 
 		json_object_object_get_ex(item_j, "unread", &node);
 		bool unread = json_object_get_boolean(node);
diff --git a/src/oldreaderapi.cpp b/src/oldreaderapi.cpp
index 3f262b79..b8488af8 100644
--- a/src/oldreaderapi.cpp
+++ b/src/oldreaderapi.cpp
@@ -136,9 +136,20 @@ std::vector<TaggedFeedUrl> OldReaderApi::get_subscribed_urls()
 
 		json_object_object_get_ex(sub, "id", &node);
 		const char* id = json_object_get_string(node);
+		if (id == nullptr) {
+			LOG(Level::WARN, "Skipping a subscription without an id");
+			continue;
+		}
 
 		json_object_object_get_ex(sub, "title", &node);
-		const char* title = json_object_get_string(node);
+		const char* title_ptr = json_object_get_string(node);
+		std::string title;
+		if (title_ptr != nullptr) {
+			title = title_ptr;
+		} else {
+			LOG(Level::WARN, "Subscription has no title, so let's call it \"%i\"", i);
+			title = std::to_string(i);
+		}
 
 		// Ignore URLs where ID start with given prefix - those never
 		// load, always returning 404 and annoying people
@@ -161,8 +172,11 @@ std::vector<TaggedFeedUrl> OldReaderApi::get_subscribed_urls()
 				json_object* label_node{};
 				json_object_object_get_ex(
 					cat, "label", &label_node);
-				const char* label =
-					json_object_get_string(label_node);
+				const char* label = json_object_get_string(label_node);
+				if (label == nullptr) {
+					LOG(Level::WARN, "Skipping subscription's label whose name is a null value");
+					continue;
+				}
 				tags.push_back(std::string(label));
 			}