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89ceb273f5
Before this patch we used to send `double`s over the wire by just copying them. This is not portable because the internal represenation of a `double` is implementation specific. Instead of this, multiply any floating-point numbers that come from the outside (e.g. JSONs) by 1 million and round them to integers when handling them. * Introduce a new param_millionths() that expects a floating-point number and returns it multipled by 1000000 as an integer. * Replace param_double() and param_percent() with param_millionths() * Previously the riskfactor would be allowed to be negative, which must have been unintentional. This patch changes that to require a non-negative number. Changelog-None
305 lines
11 KiB
Markdown
305 lines
11 KiB
Markdown
lightning-getroute -- Command for routing a payment (low-level)
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===============================================================
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SYNOPSIS
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--------
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**getroute** *id* *msatoshi* *riskfactor* \[*cltv*\] \[*fromid*\]
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\[*fuzzpercent*\] \[*exclude*\] \[*maxhops*\]
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DESCRIPTION
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-----------
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The **getroute** RPC command attempts to find the best route for the
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payment of *msatoshi* to lightning node *id*, such that the payment will
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arrive at *id* with *cltv*-blocks to spare (default 9).
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*msatoshi* is in millisatoshi precision; it can be a whole number, or a
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whole number ending in *msat* or *sat*, or a number with three decimal
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places ending in *sat*, or a number with 1 to 11 decimal places ending
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in *btc*.
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There are two considerations for how good a route is: how low the fees
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are, and how long your payment will get stuck in a delayed output if a
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node goes down during the process. The *riskfactor* non-negative
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floating-point field controls this tradeoff; it is the annual cost of
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your funds being stuck (as a percentage).
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For example, if you thought the convenience of keeping your funds liquid
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(not stuck) was worth 20% per annum interest, *riskfactor* would be 20.
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If you didn’t care about risk, *riskfactor* would be zero.
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*fromid* is the node to start the route from: default is this node.
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The *fuzzpercent* is a non-negative floating-point number, representing a
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percentage of the actual fee. The *fuzzpercent* is used to distort
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computed fees along each channel, to provide some randomization to the
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route generated. 0.0 means the exact fee of that channel is used, while
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100.0 means the fee used might be from 0 to twice the actual fee. The
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default is 5.0, or up to 5% fee distortion.
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*exclude* is a JSON array of short-channel-id/direction (e.g. \[
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"564334x877x1/0", "564195x1292x0/1" \]) or node-id which should be excluded
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from consideration for routing. The default is not to exclude any channels
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or nodes. Note if the source or destination is excluded, the command result
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is undefined.
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*maxhops* is the maximum number of channels to return; default is 20.
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RISKFACTOR EFFECT ON ROUTING
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----------------------------
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The risk factor is treated as if it were an additional fee on the route,
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for the purposes of comparing routes.
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The formula used is the following approximation:
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risk-fee = amount x blocks-timeout x per-block-cost
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We are given a *riskfactor* expressed as a percentage. There are 52596
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blocks per year, thus *per-block-cost* is *riskfactor* divided by
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5,259,600.
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The final result is:
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risk-fee = amount x blocks-timeout x riskfactor / 5259600
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Here are the risk fees in millisatoshis, using various parameters. I
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assume a channel charges the default of 1000 millisatoshis plus 1
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part-per-million. Common to\_self\_delay values on the network at 14 and
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144 blocks.
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<table>
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<colgroup>
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<col style="width: 20%" />
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<col style="width: 20%" />
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<col style="width: 20%" />
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<col style="width: 20%" />
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<col style="width: 20%" />
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</colgroup>
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<thead>
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<tr class="header">
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<th style="text-align: left;">Amount (msat)</th>
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<th style="text-align: left;">Riskfactor</th>
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<th style="text-align: left;">Delay</th>
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<th style="text-align: left;">Risk Fee</th>
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<th style="text-align: left;">Route fee</th>
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</tr>
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</thead>
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<tbody>
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<tr class="odd">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>1</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>0</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>10</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>0</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>100</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>2</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>1000</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>26</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>1</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>2</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>10</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>26</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>100</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>266</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>1000</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>2661</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>1</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>266</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>10</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>2661</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>100</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>26617</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>1000</p></td>
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<td style="text-align: left;"><p>14</p></td>
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<td style="text-align: left;"><p>266179</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>1</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>0</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>10</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>2</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>100</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>27</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>10,000</p></td>
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<td style="text-align: left;"><p>1000</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>273</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>1</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>27</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>10</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>273</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>100</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>2737</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>1,000,000</p></td>
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<td style="text-align: left;"><p>1000</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>27378</p></td>
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<td style="text-align: left;"><p>1001</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>1</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>2737</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>10</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>27378</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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<tr class="odd">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>100</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>273785</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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<tr class="even">
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<td style="text-align: left;"><p>100,000,000</p></td>
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<td style="text-align: left;"><p>1000</p></td>
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<td style="text-align: left;"><p>144</p></td>
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<td style="text-align: left;"><p>2737850</p></td>
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<td style="text-align: left;"><p>1100</p></td>
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</tr>
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</tbody>
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</table>
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RECOMMENDED RISKFACTOR VALUES
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-----------------------------
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The default *fuzz* factor is 5%, so as you can see from the table above,
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that tends to overwhelm the effect of *riskfactor* less than about 5.
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1 is a conservative value for a stable lightning network with very few
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failures.
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1000 is an aggressive value for trying to minimize timeouts at all
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costs.
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The default for lightning-pay(7) is 10, which starts to become a major
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factor for larger amounts, and is basically ignored for tiny ones.
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RETURN VALUE
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------------
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On success, a "route" array is returned. Each array element contains
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*id* (the node being routed through), *msatoshi* (the millisatoshis
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sent), *amount\_msat* (the same, with *msat* appended), *delay* (the
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number of blocks to timeout at this node), and *style* (indicating
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the features which can be used for this hop).
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The final *id* will be the destination *id* given in the input. The
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difference between the first *msatoshi* minus the *msatoshi* given in
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the input is the fee. The first *delay* is the very worst case timeout
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for the payment failure, in blocks.
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AUTHOR
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------
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Rusty Russell <<rusty@rustcorp.com.au>> is mainly responsible.
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SEE ALSO
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--------
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lightning-pay(7), lightning-sendpay(7).
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RESOURCES
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---------
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Main web site: <https://github.com/ElementsProject/lightning>
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