https://gitlab.synchro.net/main/sbbs/-/commit/5bc9f14f1408ea6564e5d591
Modified Files:
src/sbbs3/js_msgbase.cpp mailsrvr.cpp src/smblib/smblib.c smblib.h src/smblib/tests/smbidxtest.c
Log Message:
smblib: add smb_getmsghdr_for_idx() to refuse another message's header

smb_getmsghdr() reads whatever header is at msg->idx.offset and checks
only its ID and version. A caller that has just looked the message up in
the index therefore got no error when the index record pointed at some
other message's header (a damaged index, or a header relocated between
the lookup and the read) and went on to use that header's content.
On the mail base that means one user being sent, or deleting, another
user's message, since the index decides whose mailbox a message is in.

smb_getmsghdr_for_idx() reads the header the same way, then fails with
the new SMB_ERR_HDR_NUMBER when the header's message number is not the
index record's. smb_getmsghdr() is unchanged, for the callers that have
only an offset (the base-scanning utilities, and the terminal server,
which compares the number itself in sbbs_t::loadmsg()).

Use it where an index lookup is followed directly by a header read:

- mail server: the POP3 size scan at login, RSET, LIST, UIDL, RETR, TOP
and DELE, and the send-mail thread
- JS MsgBase: get_msg_header(), get_all_msg_headers(), put_msg_header(),
remove_msg() and the body/tail readers

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

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