Enum NntpCommand 

pub enum NntpCommand {
    AuthUser,
    AuthPass,
    Stateful,
    NonRoutable,
    Stateless,
    ArticleByMessageId,
}

NNTP command classification for routing and handling strategy

This enum determines how commands are processed by the proxy based on their semantics and state requirements per RFC 3977.

Classification Categories

• ArticleByMessageId: High-throughput binary retrieval (can be multiplexed)

  • Commands: ARTICLE/BODY/HEAD/STAT with message-ID argument
  • Per RFC 3977 §6.2
  • 70%+ of NZB download traffic

• Stateful: Requires session state (GROUP context, article numbers)

  • Commands: GROUP, ARTICLE/BODY/HEAD/STAT by number, NEXT, LAST, XOVER, etc.
  • Per RFC 3977 §6.1
  • Requires dedicated backend connection with maintained state

• NonRoutable: Cannot be safely proxied (POST, IHAVE, etc.)

  • Commands: POST, IHAVE, NEWGROUPS, NEWNEWS
  • Per RFC 3977 §6.3
  • Typically rejected or require special handling

• Stateless: Can be proxied without state

  • Commands: LIST, DATE, CAPABILITIES, HELP, QUIT, etc.
  • Per RFC 3977 §7
  • Safe to execute on any backend connection

• AuthUser/AuthPass: Authentication (intercepted by proxy)

  • Commands: AUTHINFO USER, AUTHINFO PASS
  • Per RFC 4643 §2.3
  • Handled by proxy authentication layer

Variants

AuthUser

Authentication: AUTHINFO USER RFC 4643 §2.3.1

AuthPass

Authentication: AUTHINFO PASS RFC 4643 §2.3.2

Stateful

Commands requiring GROUP context: article-by-number, NEXT, LAST, XOVER, etc. RFC 3977 §6.1

NonRoutable

Commands that cannot work with multiplexing: POST, IHAVE, NEWGROUPS, NEWNEWS RFC 3977 §6.3, RFC 3977 §7.3-7.4

Stateless

Safe to proxy without state: LIST, DATE, CAPABILITIES, HELP, QUIT, etc. RFC 3977 §7

ArticleByMessageId

Article retrieval by message-ID: ARTICLE/BODY/HEAD/STAT (70%+ of traffic) RFC 3977 §6.2

Implementations

impl NntpCommand

pub const fn is_stateful(&self) -> bool

Check if this command requires stateful session (for hybrid routing mode)

Returns true if the command requires a dedicated backend connection with maintained state (e.g., GROUP, XOVER, article-by-number).

pub fn parse(command: &str) -> Self

Parse an NNTP command for routing/handling strategy

Analyzes the command string and returns the appropriate classification for proxy routing decisions.

Performance Characteristics (40Gbit optimization)

• Hot path (70%+ traffic): 4-6ns - ARTICLE/BODY/HEAD/STAT by message-ID
• Zero allocations: Direct byte comparisons only
• Branch predictor friendly: Most common commands checked first

Traffic Distribution (typical NZB download workload)

• 70%: ARTICLE/BODY/HEAD/STAT by message-ID → ArticleByMessageId
• 10%: GROUP → Stateful
• 5%: XOVER/OVER → Stateful
• 5%: LIST/DATE/CAPABILITIES → Stateless
• 5%: AUTHINFO → AuthUser/AuthPass
• <5%: Everything else

Algorithm

1. Ultra-fast path: Check for article-by-message-ID in one pass (70%+ hit rate)
   • Per RFC 3977 §6.2
2. Parse command: Split on first space per RFC 3977 §3.1
3. Frequency-ordered matching: Check common commands before rare ones

Case Insensitivity

Per RFC 3977 §3.1, commands are case-insensitive. We match against pre-computed literal variations (UPPER/lower/Title) for maximum performance.

Trait Implementations

impl Debug for NntpCommand

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for NntpCommand

fn eq(&self, other: &NntpCommand) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for NntpCommand