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sendheaders message

BIP 130. Suhas Daftuar.

BIP 130, sendheaders message. Add a new message, "sendheaders", which indicates that a node prefers to receive new block announcements via a "headers" message rather than an "inv".

Status in the source: Deployed. A reading of the public specification, not a copy of it and not a certification.

sendheaders message is worth reading for the rule it actually adds: Add a new message, "sendheaders", which indicates that a node prefers to receive new block announcements via a "headers" message rather than an "inv".
Evidence
Primary paper
Re-measured
No
Assumptions
3
Records linked
4

Code

Source, repository, and what is actually hosted

  • BIP 130https://bips.dev/130
  • The source URL is not a GitHub repository. No code remote is invented.
  • Full text is not mirrored. Public availability is not a licence to copy the file onto this site.
  • Add to a reading list

01 Claim ledger

What the paper is allowed to say

Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.

  1. Claim 01 · Paper model

    The rule

    Add a new message, "sendheaders", which indicates that a node prefers to receive new block announcements via a "headers" message rather than an "inv".

  2. Claim 02 · Paper model

    What was already failing

    A node that cannot fetch, filter, or relay the data it is supposed to validate is not a peer of the network the paper describes.

  3. Claim 03 · Paper model

    What the number does not mean

    The source marks this deployed. That is a statement about the text, not a promise that every wallet or node has shipped it.

  4. Claim 04 · Paper model

    What a builder should be able to point at

    An implementation either constrains sendheaders message or it is a different design.

02 Three cuts

Observation, model, falsifier

A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.

  1. 01 The rule

    Observation

    What the study says

    Add a new message, "sendheaders", which indicates that a node prefers to receive new block announcements via a "headers" message rather than an "inv".

    Model

    What has to hold

    The object that has to change is sendheaders message. A neighbouring document with a similar name is not this one.

    Falsifier

    What would retire it

    Which message does sendheaders message add, and which old peer must still be answered?

  2. 02 What was already failing

    Observation

    What the study says

    A node that cannot fetch, filter, or relay the data it is supposed to validate is not a peer of the network the paper describes.

    Model

    What has to hold

    The object that has to change is sendheaders message. A neighbouring document with a similar name is not this one.

    Falsifier

    What would retire it

    What does a node do when the short form fails and the full object is required?

  3. 03 What the number does not mean

    Observation

    What the study says

    The source marks this deployed. That is a statement about the text, not a promise that every wallet or node has shipped it.

    Model

    What has to hold

    You are implementing BIP 130 at the status the text itself states: Deployed.

    Falsifier

    What would retire it

    Which names are normative: sendheaders message?

  4. 04 What a builder should be able to point at

    Observation

    What the study says

    An implementation either constrains sendheaders message or it is a different design.

    Model

    What has to hold

    The object that has to change is sendheaders message. A neighbouring document with a similar name is not this one.

    Falsifier

    What would retire it

    Which message does sendheaders message add, and which old peer must still be answered?

03 Sequence

One action, as an operating tape

  1. 01Open BIP 130 and read the status line before the examples.
  2. 02Write down the rule in one sentence. A fair version of that sentence is: Add a new message, "sendheaders", which indicates that a node prefers to receive new block announcements via a "headers" message rather than an "inv".
  3. 03Name the object that changes: sendheaders message.
  4. 04Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.

04 Load-bearing

The argument, and where a pitch drops it

  1. What the text is allowed to settle

    The cut

    Bitcoin Improvement Proposal 130 can settle the shape of sendheaders message. It cannot settle whether a later client, a later fork, or a later wallet still does this.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    A peer protocol is not a consensus rule. A peer can disconnect. A block is still valid or not on its own.

  2. What this page will not pretend

    The cut

    There is no benchmark, no adoption number, and no claim that the mechanism is safe outside the assumptions written in the source.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    The source marks this deployed. That is a statement about the text, not a promise that every wallet or node has shipped it.

05 Register

What has to be true

  • Model · Not re-measured

    You are implementing BIP 130 at the status the text itself states: Deployed.

  • Network · Not re-measured

    The object that has to change is sendheaders message. A neighbouring document with a similar name is not this one.

  • Network · Not re-measured

    Measurements of delay in one year do not travel with the specification.

06 Divergence

What happened after the paper

The source marks this deployed. That is a statement about the text, not a promise that every wallet or node has shipped it. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.

07 Pre-mortem

What to check before you use the idea

  4. 0 of 3 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.

08 Anatomy

The paper, in the order a builder needs

The problem it names

A node that cannot fetch, filter, or relay the data it is supposed to validate is not a peer of the network the paper describes.

What the design proposes

  • Add a new message, "sendheaders", which indicates that a node prefers to receive new block announcements via a "headers" message rather than an "inv".
  • Since the introduction of "headers-first" downloading of blocks in 0.10, blocks will not be processed unless they are able to connect to a (valid) headers chain.
  • Consequently, block relay generally works as follows: # A node (N) announces the new tip with an "inv" message, containing the block hash # A peer (P) responds to the "inv" with a "getheaders" message (to request headers up to the new tip) and a "getdata" message for the new tip itself # N responds with a "headers" message (with the header for the new block along with any preceding headers unknown to P) and a "block" message containing the new block However, in the case where a new block is being announced that builds on the tip, it would be generally more efficient if the node N just announced the block header for the new block, rather than just the block hash, and saved the peer from generating and transmitting the getheaders message (and the required block locator).

How the mechanism is specified

  • Taken from the specification, the next constraint is: Since the introduction of "headers-first" downloading of blocks in 0.10, blocks will not be processed unless they are able to connect to a (valid) headers chain.
  • Locate sendheaders message in BIP 130 and apply it to one transaction or call.
  • Then check the failure the class of rule always has: a node that did not upgrade, a reverted call, a replayed signature, or a peer that does not speak the message.

What this page does not treat as proven

  • A peer protocol is not a consensus rule. A peer can disconnect. A block is still valid or not on its own.
  • Measurements of delay in one year do not travel with the specification.
  • The source marks this deployed. That is a statement about the text, not a promise that every wallet or node has shipped it.

Why the desk still reads it

Use BIP 130 when a pitch says 'sendheaders message' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.

09 Lexicon

Terms, opened into the record

BIP 130
The public text titled sendheaders message.
Deployed
The document's own label for how finished the text is. It is not a market fact.

10 Repository

Every linked record on this page

Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.

Protocols

This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.

Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.