Difference between revisions of "Satoshi Client Transaction Exchange"

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Transactions are exchanged only if they are [[IsStandard|standard]] and [[Invalid block|valid]].
 
Transactions are exchanged only if they are [[IsStandard|standard]] and [[Invalid block|valid]].
 
  
 
== Wallet Send ==
 
== Wallet Send ==
Line 19: Line 18:
 
Transactions are only rebroadcast if they have a timestamp at least
 
Transactions are only rebroadcast if they have a timestamp at least
 
5 minutes older than the last block was received. They are sorted
 
5 minutes older than the last block was received. They are sorted
and sent oldest first.[1]
+
and sent oldest first.<ref>See: <code>CWallet::ResendWalletTransactions</code> in wallet.cpp.</ref>
  
 
== Periodic Advertisement ==
 
== Periodic Advertisement ==
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determines if a message should be sent to a remote node.
 
determines if a message should be sent to a remote node.
 
For each message processing iteration, one node is chosen as the
 
For each message processing iteration, one node is chosen as the
"trickle node".[2]  This node is the only one chosen to receive
+
"trickle node".<ref>See: <br><code>pnodeTrickle = vNodesCopy[GetRand(vNodesCopy.size())];</code><br>
an "addr" message, if appropriate.[3]
+
and <br><code>SendMessages(pnode, pnode == pnodeTrickle);</code><br> in ThreadMessageHandler2() in net.cpp.</ref> This node is the only one chosen to receive
 +
an "addr" message, if appropriate.<ref>See:<br><code>
 +
        //<br>
 +
        // Message: addr<br>
 +
        //<br>
 +
        if (fSendTrickle)<br>
 +
        {  </code><br>
 +
in SendMessages() in main.cpp.</ref>
  
 
In the section for inventory, the client sends 1/4 of the transaction
 
In the section for inventory, the client sends 1/4 of the transaction
inventory, determined randomly [4], UNLESS they are the trickle node,
+
inventory, determined randomly<ref>See: <br><code>bool fTrickleWait = ((hashRand & 3) != 0);</code><br>
in which case they receive ALL transactions.[5] Yes that seems reversed,
+
in SendMessages() in main.cpp.</ref>, UNLESS they are the trickle node,
 +
in which case they receive ALL transactions.<ref>See:<br><code>
 +
        // trickle out tx inv to protect privacy<br>
 +
        if (inv.type == MSG_TX && !fSendTrickle)<br>
 +
        {  </code><br>
 +
in SendMessages() in main.cpp.</ref> Yes, that seems reversed,
 
but it is what it is. If the node is to receive 1/4 (not all), then the
 
but it is what it is. If the node is to receive 1/4 (not all), then the
 
code also avoids sending any transactions that came from the local
 
code also avoids sending any transactions that came from the local
wallet.[6] The comments indicate this is intended to increase privacy.
+
wallet.<ref>See:<br><code>
 
+
        // always trickle our own transactions<br>
 
+
        if (!fTrickleWait)<br>
 +
        {  <br>
 +
            CWalletTx wtx;<br>
 +
            if (GetTransaction(inv.hash, wtx))<br>
 +
              if (wtx.fFromMe)<br>
 +
                  fTrickleWait = true;<br>
 +
        }</code><br>
 +
in SendMessages() in main.cpp.</ref> The comments indicate this is intended to increase privacy.
  
 
== Relay ==
 
== Relay ==
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When the client receives a transaction via a "tx" messages,
 
When the client receives a transaction via a "tx" messages,
 
it calls RelayMessage, which calls RelayInventory, which queues the
 
it calls RelayMessage, which calls RelayInventory, which queues the
inventory to be sent to all other nodes.[7]
+
inventory to be sent to all other nodes.<ref>Both RelayMessage and RelayInventory in net.h.</ref>
 
 
 
 
 
 
==Footnotes==
 
 
 
1. See CWallet::ResendWalletTransactions in wallet.cpp.
 
 
 
2. See:
 
      pnodeTrickle = vNodesCopy[GetRand(vNodesCopy.size())];
 
and
 
      SendMessages(pnode, pnode == pnodeTrickle);
 
in ThreadMessageHandler2() in net.cpp.
 
 
 
3. See:
 
        //
 
        // Message: addr
 
        //
 
        if (fSendTrickle)
 
        { 
 
in SendMessages() in main.cpp.
 
 
 
4. See:
 
      bool fTrickleWait = ((hashRand & 3) != 0);
 
in SendMessages() in main.cpp.
 
 
 
5. See:
 
        // trickle out tx inv to protect privacy
 
        if (inv.type == MSG_TX && !fSendTrickle)
 
        { 
 
in SendMessages() in main.cpp.
 
 
 
6. See:
 
        // always trickle our own transactions
 
        if (!fTrickleWait)
 
        { 
 
            CWalletTx wtx;
 
            if (GetTransaction(inv.hash, wtx))
 
              if (wtx.fFromMe)
 
                  fTrickleWait = true;
 
        }
 
in SendMessages() in main.cpp.
 
 
 
7. Both RelayMessage and RelayInventory in net.h.
 
  
 
==See Also==
 
==See Also==
 
[[Transaction_broadcasting | Transaction broadcasting]]
 
[[Transaction_broadcasting | Transaction broadcasting]]
  
 +
==Footnotes==
 
[[Category:Developer]]
 
[[Category:Developer]]
 
[[Category:Technical]]
 
[[Category:Technical]]

Latest revision as of 14:24, 18 September 2015

Overview

The Satoshi client advertises locally generated transactions and relays transactions from other nodes. This article describes the operations that deal with this exchange of transactions.

Transactions are exchanged only if they are standard and valid.

Wallet Send

The client periodically calls SendMessages() (in main.cpp) which calls ResendWalletTransactions to send transactions generated locally. This routine looks to see if there has been a new block since last time, and if so, and the local transaction are still not in a block, then the transactions are sent to all nodes. This is done only about every 30 minutes.

Transactions are only rebroadcast if they have a timestamp at least 5 minutes older than the last block was received. They are sorted and sent oldest first.[1]

Periodic Advertisement

The client periodically calls SendMessages() (in main.cpp) which determines if a message should be sent to a remote node. For each message processing iteration, one node is chosen as the "trickle node".[2] This node is the only one chosen to receive an "addr" message, if appropriate.[3]

In the section for inventory, the client sends 1/4 of the transaction inventory, determined randomly[4], UNLESS they are the trickle node, in which case they receive ALL transactions.[5] Yes, that seems reversed, but it is what it is. If the node is to receive 1/4 (not all), then the code also avoids sending any transactions that came from the local wallet.[6] The comments indicate this is intended to increase privacy.

Relay

When the client receives a transaction via a "tx" messages, it calls RelayMessage, which calls RelayInventory, which queues the inventory to be sent to all other nodes.[7]

See Also

Transaction broadcasting

Footnotes

  1. See: CWallet::ResendWalletTransactions in wallet.cpp.
  2. See:
    pnodeTrickle = vNodesCopy[GetRand(vNodesCopy.size())];
    and
    SendMessages(pnode, pnode == pnodeTrickle);
    in ThreadMessageHandler2() in net.cpp.
  3. See:
    //
    // Message: addr
    //
    if (fSendTrickle)
    {

    in SendMessages() in main.cpp.
  4. See:
    bool fTrickleWait = ((hashRand & 3) != 0);
    in SendMessages() in main.cpp.
  5. See:
    // trickle out tx inv to protect privacy
    if (inv.type == MSG_TX && !fSendTrickle)
    {

    in SendMessages() in main.cpp.
  6. See:
    // always trickle our own transactions
    if (!fTrickleWait)
    {
    CWalletTx wtx;
    if (GetTransaction(inv.hash, wtx))
    if (wtx.fFromMe)
    fTrickleWait = true;
    }

    in SendMessages() in main.cpp.
  7. Both RelayMessage and RelayInventory in net.h.