Fix null key dereference in post_iterator (#375)#376
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MHD may invoke the post iterator with a null key on a continuation chunk (off > 0): the field name is supplied only on the first call and not repeated. handle_post_form_arg passed the raw key pointer straight into std::string (via set_arg / grow_last_arg), which throws std::logic_error on null. Because the throw escapes the C post-iterator callback, it propagates as an uncaught exception and aborts the process via std::terminate. Guard key for null before constructing std::string: with no field name there is nothing to store the value under, so accept and silently skip the chunk (MHD_YES keeps the request alive; MHD_NO would abort it). Same class of bug as the null-uri fix in uri_log (#371). Adds unit/post_iterator_null_key_test.cpp pinning the regression (the test terminates without the guard) plus the happy-path initial and continuation-append cases. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Rkuh4aSmrD8m2f2vYqakb6
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Fixes #375 on the v2.0 integration branch.
Problem
MHD may invoke
webserver_impl::post_iteratorwith a nullkeyon a continuation chunk (off > 0) — the field name is supplied only on the first callback and not repeated when a field is split across callbacks (the large-field path introduced in #337 / commit1b5fe8f).handle_post_form_argpassed the rawkeypointer straight intostd::string(viaset_arg/grow_last_arg), which throwsstd::logic_erroron null. Because the throw escapes the C post-iterator callback, it propagates as an uncaught exception and aborts the process viastd::terminate.Fix
Guard
keyfor null before constructing astd::string. With no field name there is nothing to store the value under, so accept and silently skip the chunk:MHD_YEStells MHD to continue (MHD_NOwould abort the whole request). This is the same class of bug — and the same fix shape — as the null-uriguard inuri_log(#371).Test
test/unit/post_iterator_null_key_test.cpp:null_key_continuation_does_not_throw/null_key_initial_does_not_throw— regression cases; without the guard the test process terminates (verified locally).valid_key_stores_arg/valid_key_continuation_appends— happy paths proving normal form handling and the large-field append are unaffected.All 4 tests / 11 checks pass; related
create_test_requestanduri_logsuites stay green.🤖 Generated with Claude Code
https://claude.ai/code/session_01Rkuh4aSmrD8m2f2vYqakb6