Module handshake

Expand description

Handshake control packet — draft-sharabayko-srt-01 §3.2.1, Figure 5, and its extension messages: Handshake Extension Message (§3.2.1.1 / Figure 6, flags in §3.2.1.1.1 / Table 6), Key Material Extension (§3.2.1.2, content is a super::KeyMaterial — §3.2.2), Stream ID Extension (§3.2.1.3 / Figure 7), and Group Membership Extension (§3.2.1.4 / Figures 8-9).

word0..0   Version (32)
word1      Encryption Field (16) | Extension Field (16)
word2      Initial Packet Sequence Number (32)
word3      Maximum Transmission Unit Size (32)
word4      Maximum Flow Window Size (32)
word5      Handshake Type (32)
word6      SRT Socket ID (32)
word7      SYN Cookie (32)
word8..11  Peer IP Address (128)
── repeated ──
           Extension Type (16) | Extension Length (16, in 4-byte blocks)
           Extension Contents (Extension Length * 4 bytes)

This module covers structure only: parsing the fixed CIF fields and walking/decoding extension blocks. The handshake exchange (caller / listener / rendezvous state machine, §4.3) is an explicit follow-up.

Structs§

GroupFlags: Group Membership Extension Flags (§3.2.1.4, Figure 9): only the M bit is defined.
GroupMembershipExtension: Group Membership Extension (§3.2.1.4, Figure 8) — the payload of an ExtensionType::Group block.
HandshakeExtensionBlock: One decoded Handshake Extension block (§3.2.1): Extension Type / Extension Length / Extension Contents. Data-carrying (borrows the raw contents) — decode the contents with Self::as_hs_ext_message, Self::as_key_material, Self::as_stream_id, or Self::as_group_membership as appropriate for Self::ext_type.
HandshakeExtensionFlags: The Extension Field (§3.2.1, Table 3) — a 16-bit bitmask on a CONCLUSION handshake, or an opaque echoed value on an INDUCTION response.
HandshakeExtensionIter: Iterator over HandshakeExtensions. See HandshakeExtensions::iter.
HandshakeExtensionMessageFlags: SRT Flags of a Handshake Extension Message (§3.2.1.1.1, Table 6).
HandshakeExtensions: A borrowed, lazily-walked list of Handshake Extension blocks — the same convention dvb-si uses for descriptor loops. Iterate with Self::iter.
HandshakePacket: Handshake control packet (§3.2.1, Figure 5).
HsExtMessage: Handshake Extension Message contents (§3.2.1.1, Figure 6) — the payload of an ExtensionType::HsReq / ExtensionType::HsRsp block.

Enums§

EncryptionField: Encryption Field: block cipher family and key size advertised in the handshake (draft-sharabayko-srt-01 §3.2.1, Table 2).
ExtensionType: Handshake Extension Extension Type (draft-sharabayko-srt-01 §3.2.1, Table 5).
GroupType: Group Membership Extension Type (draft-sharabayko-srt-01 §3.2.1.4, SRT_GTYPE_*).
HandshakeType: Handshake Type (draft-sharabayko-srt-01 §3.2.1, Table 4).

Constants§

ENCRYPTION_FIELD_AES_128: AES-128.
ENCRYPTION_FIELD_AES_192: AES-192.
ENCRYPTION_FIELD_AES_256: AES-256.
ENCRYPTION_FIELD_NONE: Encryption Field wire values (§3.2.1, Table 2).
EXT_TYPE_CONGESTION: SRT_CMD_CONGESTION.
EXT_TYPE_FILTER: SRT_CMD_FILTER.
EXT_TYPE_GROUP: SRT_CMD_GROUP.
EXT_TYPE_HSREQ: Extension Type wire values (§3.2.1, Table 5).
EXT_TYPE_HSRSP: SRT_CMD_HSRSP.
EXT_TYPE_KMREQ: SRT_CMD_KMREQ — also used as the control-packet Subtype for a Key Material message delivered as a User-Defined control packet (§3.2.2).
EXT_TYPE_KMRSP: SRT_CMD_KMRSP.
EXT_TYPE_SID: SRT_CMD_SID.
GROUP_MEMBERSHIP_EXT_LEN: Wire length of a Group Membership Extension (Figure 8).
GROUP_TYPE_BALANCING: Balancing.
GROUP_TYPE_BROADCAST: Broadcast.
GROUP_TYPE_MAIN_BACKUP: Main/backup.
GROUP_TYPE_MULTICAST: Multicast (reserved for future use).
GROUP_TYPE_UNDEFINED: Type (Group Type) wire values of the Group Membership Extension (§3.2.1.4).
HANDSHAKE_CIF_FIXED_LEN: Length in bytes of the fixed Handshake CIF core (Version through Peer IP Address, §3.2.1 Figure 5) — 12 header words.
HANDSHAKE_TYPE_AGREEMENT: AGREEMENT.
HANDSHAKE_TYPE_CONCLUSION: CONCLUSION.
HANDSHAKE_TYPE_DONE: Handshake Type wire values (§3.2.1, Table 4).
HANDSHAKE_TYPE_INDUCTION: INDUCTION.
HANDSHAKE_TYPE_WAVEHAND: WAVEHAND.
HS_EXT_FLAG_CONFIG: CONFIG.
HS_EXT_FLAG_HSREQ: Extension Field bitmask values (§3.2.1, Table 3). Only meaningful on a CONCLUSION handshake; on an INDUCTION response this 16-bit field is instead echoed back opaquely by the Listener.
HS_EXT_FLAG_KMREQ: KMREQ.
HS_EXT_MESSAGE_LEN: Wire length of a Handshake Extension Message (Figure 6).
HS_MSG_FLAG_CRYPT: CRYPT.
HS_MSG_FLAG_PACKET_FILTER: PACKET_FILTER.
HS_MSG_FLAG_PERIODICNAK: PERIODICNAK.
HS_MSG_FLAG_REXMITFLG: REXMITFLG.
HS_MSG_FLAG_STREAM: STREAM.
HS_MSG_FLAG_TLPKTDROP: TLPKTDROP.
HS_MSG_FLAG_TSBPDRCV: TSBPDRCV.
HS_MSG_FLAG_TSBPDSND: SRT Flags bitmask values of the Handshake Extension Message (§3.2.1.1.1, Table 6).

Functions§

build_extension_block: Build one Handshake Extension block’s raw bytes (Extension Type + Extension Length + Extension Contents, §3.2.1) — append the result of repeated calls to chain multiple blocks.
encode_stream_id: Encode the Stream ID extension’s 32-bit-little-endian-word storage (§3.2.1.3) from a plain UTF-8 stream id string, padding with 0x00 up to the next 4-byte boundary. Inverse of HandshakeExtensionBlock::as_stream_id.