IMAP protocol parser, logger and sticky buffers v7#15617
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This introduces a parser for IMAP protocol.
An IMAP transaction has two states driven by the 'complete' field:
- Open (complete = false): waiting for a matching tagged response.
- Complete (complete = true): tagged response received, or special
conditions met (BYE, server greeting).
Completion logic (is_complete):
- If a tagged request exists: requires a matching tagged response.
- No tagged request + BYE: complete (server closing).
- No tagged request + any response: complete (server greeting).
Transactions are created in three places:
1. Request parser: every parsed command creates a new tx.
2. Response parser (tagged, no matching request): midstream/async;
orphan tagged response gets its own tx.
3. Response parser (untagged, no incomplete tx): server greeting or
unsolicited response.
Once open, messages accumulate:
- Request side: continuation and literal data attach to the most
recent incomplete tx.
- Response side: untagged responses attach to the most recent
incomplete tx; tagged responses attach via find_request(tag).
Email extraction happens at most once per tx:
- From literal data in APPEND commands (request side).
- From FETCH response data (response side).
Six hard limits prevent unbounded growth:
- IMAP_MAX_TX (256, configurable): total transactions. Exceeded:
all incomplete txs force-completed with TooManyTransactions event.
- IMAP_MAX_MSGS_PER_TX (512): requests/responses per tx. Exceeded:
message silently dropped.
- IMAP_MAX_LINES (512): request/response lines per tx. Exceeded:
line silently dropped.
- IMAP_MAX_HEADERS (512): headers in ImapParsedEmail. Exceeded:
TooManyHeaders event.
- IMAP_MAX_BODY_SIZE (10 MB): email body in ImapParsedEmail.
Exceeded: body truncated, BodyTooLarge event.
- Literal size (u32): bounded by declared size in {N} specifier.
IMAP_MAX_TX is the only configurable limit, via
app-layer.protocols.imap.max-tx.
Ticket OISF#8276
This introduces a logger for IMAP protocol. Ticket OISF#8276
This implements the following sticky buffers for IMAP protocol: - imap.request - imap.response The following frames have been added: - imap.body - imap.headers - imap.pdu The following email sticky buffers have been updated to work with IMAP: - email.from - email.subject - email.to - email.cc - email.date - email.message_id - email.x_mailer The following email sticky buffers have been added and are supported only for IMAP: - email.command - email.body - email.header - email.header.name - email.header.value Ticket OISF#8276
glongo
requested review from
a team,
jasonish,
jufajardini and
victorjulien
as code owners
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Information: QA ran without warnings. Pipeline = 31997 |
Codecov Report❌ Patch coverage is Additional details and impacted files@@ Coverage Diff @@
## main #15617 +/- ##
==========================================
- Coverage 82.89% 82.83% -0.07%
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Files 1006 1009 +3
Lines 273487 276035 +2548
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+ Hits 226710 228654 +1944
- Misses 46777 47381 +604
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Replaced with #15648 |
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Changes:
email.body_md5compatible with IMAPLink to ticket: https://redmine.openinfosecfoundation.org/issues/8276
Previous PR: #15400
SV_BRANCH=OISF/suricata-verify#2908