codec::akamai

seleniumbase_rs_codec::akamai parses and renders Akamai HTTP/2 fingerprint strings, in the format of Akamai’s public whitepaper on passive HTTP/2 fingerprinting: four sections separated by |.

SETTINGS | WINDOW_UPDATE | PRIORITY | pseudo-header order1:4096;2:0;4:1048576|983041|3:0:0:201,5:1:3:16|m,a,s,p

• SETTINGS is id:value pairs joined by ;, in the order the frame carried them.
• WINDOW_UPDATE is the connection-level increment, or 0 when no frame was sent.
• PRIORITY is stream:exclusive:depends_on:weight entries joined by ,, or 0 for none. The weight is the protocol weight, 1 to 256 (the wire byte plus one).
• The pseudo-header order is a permutation of m,a,s,p (:method, :authority, :scheme, :path).

Parsing is strict about what can exist on the wire: canonical decimal numbers only, each SETTINGS id once, weights in 1 to 256, stream ids below 2^31. What a given client stack can emit is a separate question, answered by H2Spec.

Akamai#

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]pub struct Akamai {    pub settings: Vec<(u16, u32)>,    pub window_update: u32,    pub priority_frames: Vec<PriorityFrame>,    pub pseudo_order: [Pseudo; 4],}

A parsed Akamai HTTP/2 fingerprint. The fields are public so a caller can build one directly; Akamai::parse is the validating constructor, and H2Spec::with_akamai checks again whatever it is given. Display writes the canonical string and FromStr parses, so a canonical string round-trips.

Akamai::parse#

pub fn parse(text: &str) -> Result<Self, AkamaiError>

Parses an Akamai fingerprint string. Leading and trailing whitespace is ignored; nothing inside the string is. Returns an AkamaiError naming the section and entry that is malformed.

PriorityFrame#

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]pub struct PriorityFrame {    pub stream_id: u32,    pub exclusive: bool,    pub depends_on: u32,    pub weight: u16,}

One PRIORITY frame, in the Akamai notation stream:exclusive:depends_on:weight (its Display, with exclusive written 0 or 1).

Pseudo#

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]#[serde(rename_all = "lowercase")]pub enum Pseudo {    Method,    Authority,    Scheme,    Path,}impl Pseudo {    pub const ALL: [Pseudo; 4] = [Pseudo::Method, Pseudo::Authority, Pseudo::Scheme, Pseudo::Path];    pub const fn letter(self) -> char;    pub const fn header_name(self) -> &'static str;    pub fn from_letter(letter: char) -> Option<Self>;    pub fn from_header_name(name: &str) -> Option<Self>;}

A request pseudo-header, as named in the pseudo-header order section. This is the complete set of pseudo-headers of a plain request, so the enum is not non_exhaustive: a pseudo-header order is a permutation of exactly these four. In JSON it is written in lower case ("method", "authority", …).

ALL is the order m,a,s,p. letter and header_name give the letter and the header name (:method); from_letter accepts lowercase letters only, and from_header_name the exact name.

AkamaiError#

#[derive(Debug, Clone, PartialEq, Eq, Error)]#[non_exhaustive]pub enum AkamaiError {    TooLong,    Sections(usize),    Setting { index: usize, token: String },    DuplicateSetting(u16),    TooManySettings,    WindowUpdate(String),    PriorityFrame { index: usize, token: String },    TooManyPriorityFrames,    PseudoOrder(String),}

Why an Akamai string was refused. index is the zero-based position of the entry and token the offending text.

Constants#

pub const MAX_STREAM_ID: u32 = 0x7fff_ffff;pub const MIN_WEIGHT: u16 = 1;pub const MAX_WEIGHT: u16 = 256;pub const MAX_AKAMAI_LEN: usize = 4096;pub const MAX_SETTINGS: usize = 32;pub const MAX_PRIORITY_FRAMES: usize = 64;

The largest stream id, dependency id or window increment (2^31 - 1, the top bit is reserved); the smallest and largest protocol weight (the wire byte is one less); the longest string accepted, in bytes; and the most SETTINGS and PRIORITY entries in one string.

Related#