{ "number": 36198, "repo": "bitcoin/bitcoin", "url": "https://github.com/bitcoin/bitcoin/pull/36198", "title": "http: Add missing LIFETIMEBOUND annotations", "author": "hodlinator", "author_association": "MEMBER", "created_at": "2026-09-09T08:06:00Z", "updated_at": "2026-09-09T08:06:15Z", "age_days": 8, "draft": false, "labels": [ "RPC/REST/ZMQ" ], "milestone": null, "base": "master", "head_sha": "0b46fc9c5935068e7068a27fa39fa11f32af7a3f", "head_ref": "2026/09/http_dangling", "head_repo": "hodlinator/bitcoin", "head_history": [], "additions": 6, "deletions": 6, "changed_files": 1, "commit_count": 1, "size_bucket": "S", "mergeable_state": "clean", "bot": { "drahtbot": { "present": true, "reviews": {}, "conflicts": [] } }, "acks_parsed": {}, "acks_tally": { "ack": 0, "stale_ack": 0, "concept_ack": 0, "approach_ack": 0, "nack": 0, "concept_nack": 0, "approach_nack": 0 }, "reviews": { "approved": 0, "changes_requested": 0, "distinct_reviewers": [] }, "signals": { "needs_rebase": false, "ci_failed": false, "mergeable_state": "clean", "last_author_activity": "2026-09-08T08:11:24Z", "last_reviewer_activity": null, "last_reviewer": null, "author_silent_days": 9, "waiting_on_author_days": 0, "days_since_update": 8 }, "refs": { "mentioned": [ 36164 ], "depends_on": [], "fixes": [], "linked_issues": [], "references": [ { "number": 36164, "type": "pull", "state": "closed", "merged": true, "merged_at": "2026-09-06", "title": "util: diagnose dangling views of temporary strings" } ], "conflicts": [] }, "stack": { "shares_commits_with": [], "based_on": [], "base_for": [] }, "review_paths": [], "body": "Helps Clang detect certain dangling reference issues, in a similar vein as #36164.\n\n### Known limitations\n\nIt doesn't catch invalidation nor brace-initialization.\n\nDiff illustrating limitations\n\n```diff\n--- a/src/test/httpserver_tests.cpp\n+++ b/src/test/httpserver_tests.cpp\n@@ -80,6 +80,15 @@ BOOST_AUTO_TEST_CASE(test_query_parameters)\n\n BOOST_AUTO_TEST_CASE(http_headers_tests)\n {\n+ auto foo = HTTPHeaders{}.FindAll(\"needle\"); // Emits warning\n+ (void)foo;\n+ auto bar{HTTPHeaders{}.FindAll(\"needle\")}; // No warning with Clang 22.1.8 :/\n+ (void)bar;\n+\n+ HTTPHeaders test;\n+ auto baz = test.FindAll(\"needle\");\n+ test.Write(\"needle\", \"mutation\"); // No warning with Clang 22.1.8 :/\n+\n {\n // Writing response headers\n HTTPHeaders headers{};\n```\n\nClang 24 has experimental invalidation detection so maybe that could be used in the far future: https://clang.llvm.org/docs/LifetimeSafety.html#use-after-invalidation-experimental\n\n### Alternative solution A)\n\nReturn by copy everywhere. Might introduce more heap activity, especially in the case of `HTTPRemoteClient::GetRequest()`.\n\n### Alternative solution B)\n\nRefactor the methods to minimize copying while still making things more memory-safe. Replacing `HTTPHeaders::FindAll()` with an `Iterate()`-function taking a lambda which gets to process each header. Gets rid of the heap activity of building a `vector` but introduces copying of `first`.\n\nDiff of httpserver.cpp/h\n\n```diff\n--- a/src/httpserver.cpp\n+++ b/src/httpserver.cpp\n@@ -272,15 +272,11 @@ std::optional HTTPHeaders::FindFirst(const std::string_view key) co\n return std::nullopt;\n }\n\n-std::vector HTTPHeaders::FindAll(const std::string_view key) const\n+void HTTPHeaders::Iterate(std::function fn) const\n {\n- std::vector ret;\n for (const auto& item : m_headers) {\n- if (CaseInsensitiveEqual(key, item.first)) {\n- ret.push_back(item.second);\n- }\n+ fn(item.first, item.second);\n }\n- return ret;\n }\n\n void HTTPHeaders::Write(std::string&& key, std::string&& value)\n@@ -504,18 +500,21 @@ bool HTTPRequest::LoadBody(LineReader& reader)\n // We read all the chunks but never got the last chunk, wait for client to send more\n return false;\n } else {\n+ std::optional first;\n+ m_headers.Iterate([&first] (const std::string& key, const std::string& value) {\n+ if (!CaseInsensitiveEqual(key, \"Content-Length\")) return;\n+ if (!first.has_value()) {\n+ first = value;\n+ } else if (first != value) {\n+ // Duplicate Content-Length headers are allowed only if they all have the same value\n+ // https://www.rfc-editor.org/rfc/rfc7230#section-3.3.3\n+ throw std::runtime_error(\"Differing Content-Length values\");\n+ }\n+ });\n // No Content-length or Transfer-Encoding header means no body, see libevent evhttp_get_body()\n- auto content_length_values{m_headers.FindAll(\"Content-Length\")};\n- if (content_length_values.empty()) return true;\n-\n- // Duplicate Content-Length headers are allowed only if they all have the same value\n- // https://www.rfc-editor.org/rfc/rfc7230#section-3.3.3\n- const auto& first_content_length_value{content_length_values[0]};\n- for (size_t i = 1; i < content_length_values.size(); ++i) {\n- if (content_length_values[i] != first_content_length_value) throw std::runtime_error(\"Differing Content-Length values\");\n- }\n+ if (!first.has_value()) return true;\n\n- const auto content_length{ToIntegral(first_content_length_value)};\n+ const auto content_length{ToIntegral(first.value())};\n if (!content_length) throw std::runtime_error(\"Cannot parse Content-Length value\");\n\n if (*content_length > MAX_BODY_SIZE) throw ContentTooLargeError(\"Max body size exceeded\");\n--- a/src/httpserver.h\n+++ b/src/httpserver.h\n@@ -97,10 +97,9 @@ public:\n */\n std::optional FindFirst(std::string_view key) const;\n /**\n- * @param[in] key The field-name of the header to search for\n- * @returns Views into all values matching the provided key (valid while this object is alive)\n+ * @param[in] fn Receives each header as they are iterated through.\n */\n- std::vector FindAll(std::string_view key) const LIFETIMEBOUND;\n+ void Iterate(std::function fn) const;\n void Write(std::string&& key, std::string&& value);\n /**\n * @param[in] key The field-name of the header to search for and delete\n```\n\n### Rationale\n\nThe methods are not called in many places so risk of misuse is low, and we avoid any risk of performance degradation (such as the one found in https://github.com/bitcoin/bitcoin/pull/35182#discussion_r3266022600). Return copies without adding mutexes or other thread safety measures does not considerably increase thread-safety.", "commits": [ { "sha": "0b46fc9c5935068e7068a27fa39fa11f32af7a3f", "date": "2026-09-08T08:11:24Z", "message": "http: Add missing LIFETIMEBOUND annotations\n\nDecreases footguns without any hit to runtime performance." } ], "timeline": [], "labels_log": [ { "t": "2026-09-09T08:06:04Z", "action": "labeled", "label": "RPC/REST/ZMQ", "who": "DrahtBot" } ], "state_log": [], "text_chars": 5286, "text_tokens_estimate": 1321, "changed_paths": [ "src/httpserver.h" ], "files": [ { "path": "src/httpserver.h", "add": 6, "del": 6 } ], "test_lines": 0, "git": { "head": "0b46fc9c5935068e7068a27fa39fa11f32af7a3f", "head_matches_backup": true, "base": "013b0b2de48153b7481c036a353b81a411f1da8f", "commits": [ { "sha": "0b46fc9c59", "subject": "http: Add missing LIFETIMEBOUND annotations", "files": 1, "add": 6, "del": 6 } ], "patch_truncated": false }, "input_hash": "f3862c53fe0d3bfc", "extracted_at": "2026-09-17T16:15:31+00:00" }