Generalized contract_info TLV (#130)

* Updated TLVs to allow support for numeric outcome and multiple oracle DLCs

* Added threshold field to multi-oracle oracle_infos

* Responded to review

* Some more review

Author: nkohen

Messaging.md

@@ -15,8 +15,18 @@ All data fields are unsigned big-endian unless otherwise specified.
   * [DLC Specific Types](#dlc-specific-types)
     * [The `contract_info` Type](#the-contract_info-type)
       * [Version 0 `contract_info`](#version-0-contract_info)
+    * [The `contract_descriptor` Type](#the-contract_descriptor-type)
+      * [Version 0 `contract_descriptor`](#version-0-contract_descriptor)
+      * [Version 1 `contract_descriptor`](#version-1-contract_descriptor)
     * [The `oracle_info` Type](#the-oracle_info-type)
       * [Version 0 `oracle_info`](#version-0-oracle_info)
+      * [Version 1 `oracle_info`](#version-1-oracle_info)
+      * [Version 2 `oracle_info`](#version-2-oracle_info)
+    * [The `oracle_params` Type](#the-oracle_params-type)
+      * [Version 0 `oracle_params`](#version-0-oracle_params)
+    * [The `negotiation_fields` Type](#the-negotiation_fields-type)
+      * [Version 0 `negotiation_fields`](#version-0-negotiation_fields)
+      * [Version 1 `negotiation_fields`](#version-1-negotiation_fields)
     * [The `funding_input` Type](#the-funding_input-type)
       * [Version 0 `funding_input`](#version-0-funding_input)
     * [The `cet_adaptor_signatures` Type](#the-cet_adaptor_signatures-type)
@@ -87,33 +97,130 @@ The following DLC-specific types are used throughout the specification. All type
 
 ### The `contract_info` Type
 
-This type contains information about a contracts outcomes and their corresponding payouts. To save space, only one side's POV is included in this message as the other can be derived using `remote_payout = total_collateral - local_payout`.
+This type contains information about a contract's outcomes, their corresponding payouts, and the oracles to be used.
 
 #### Version 0 `contract_info`
 
-1. type: 42768 (`contract_info_v0`)
+1. type: 55342 (`contract_info_v0`)
 2. data:
-   * [`bigsize`:`nb_outcomes`]
-   * [`sha256`:`outcome_1`]
-   * [`u64`:`outcome_1_local_payout`]
+   * [`u64`:`total_collateral`]
+   * [`contract_descriptor`:`contract_descriptor`]
+   * [`oracle_info`:`oracle_info`]
+
+`total_collateral` is the Satoshi-denominated value of the sum of all party's collateral.
+
+### The `contract_descriptor` Type
+
+This type contains information about a contract's outcomes and their corresponding payouts.
+
+To save space, only the offerer's payouts are included in this message as the accepter's can be derived using
+`accept_payout = total_collateral - offer_payout`.
+
+#### Version 0 `contract_descriptor`
+
+1. type: 42768 (`contract_descriptor_v0`)
+2. data:
+   * [`bigsize`:`num_outcomes`]
+   * [`string`:`outcome_1`]
+   * [`u64`:`payout_1`]
    * ...
-   * [`sha256`:`outcome_n`]
-   * [`u64`:`outcome_n_local_payout`]
+   * [`string`:`outcome_num_outcomes`]
+   * [`u64`:`payout_num_outcomes`]
+
+This type represents an enumerated outcome contract.
 
-This type of contract info is a simple enumeration of pairs of the hash of an outcome value with the corresponding payout for the local party.
+#### Version 1 `contract_descriptor`
+
+1. type: 42784 (`contract_descriptor_v1`)
+2. data:
+   * [`u16`:`num_digits`]
+   * [`payout_function`:`payout_function`]
+   * [`rounding_intervals`:`rounding_intervals`]
+
+This type represents a numeric outcome contract.
+
+The type `payout_function` is defined [here](PayoutCurve.md#curve-serialization).
+The type `rounding_intervals` is defined [here](NumericOutcome.md#rounding-interval-serialization).
 
 ### The `oracle_info` Type
 
-This type contains information about the oracle(s) to be used in executing a DLC, and possibly the outcomes possible if these are not specified in the corresponding `contract_info`.
+This type contains information about the oracles to be used in executing a DLC.
 
 #### Version 0 `oracle_info`
 
 1. type: 42770 (`oracle_info_v0`)
 2. data:
-   * [`x_point`:`oracle_public_key`]
-   * [`x_point`:`oracle_nonce`]
+   * [`oracle_announcement`:`oracle_announcement`]
+
+This type of oracle info is for single-oracle events.
+
+#### Version 1 `oracle_info`
+
+1. type: 42786 (`oracle_info_v1`)
+2. data:
+   * [`u16`:`threshold`]
+   * [`u16`:`num_oracles`]
+   * [`oracle_announcement`:`oracle_announcement_1`]
+   * ...
+   * [`oracle_announcment`:`oracle_announcement_num_oracles`]
+
+This type of oracle info is for multi-oracle events where all oracles are signing messages chosen
+from a set of messages that exactly corresponds to the set of messages being signed by the other oracles,
+and any `threshold` oracles must sign (exactly) corresponding messages for execution to happen.
+
+#### Version 2 `oracle_info`
+
+1. type: 55340 (`oracle_info_v2`)
+2. data:
+   * [`u16`:`threshold`]
+   * [`u16`:`num_oracles`]
+   * [`oracle_announcement`:`oracle_announcement_1`]
+   * ...
+   * [`oracle_announcment`:`oracle_announcement_num_oracles`]
+   * [`oracle_params`:`oracle_params`]
+
+The order of the oracle announcements represents a total ordering of preference on the oracles.
+
+This type of oracle info is for multi-oracle numeric events where allowed differences in the values
+signed by oracles is specified in `oracle_params`.
+
+### The `oracle_params` Type
+
+Contains information about how oracle information is used in a given contract.
+
+#### Version 0 `oracle_params`
+
+1. type: 55338 (`oracle_params_v0`)
+2. data
+   * [`u16`:`maxErrorExp`]
+   * [`u16`:`minFailExp`]
+   * [`bool`:`maximize_coverage`]
+
+This type is used when the error bound requirements for any set of oracles `threshold` oracles in a
+multi-oracle numeric outcome DLC with allowed error is the same.
+
+### The `negotiation_fields` Type
+
+This type contains preferences of the accepter of a DLC which are taken into account during DLC construction.
+
+#### Version 0 `negotiation_fields`
+
+1. type: 55334 (`negotiation_fields_v0`)
+2. data:
+   * (empty)
+
+This type signifies that the accepter has no negotiation fields.
+
+#### Version 1 `negotiation_fields`
+
+1. type: 55336 (`negotiation_fields_v1`)
+2. data
+   * [`rounding_intervals`: `rounding_intervals`]
+
+`rounding_intervals` represents the maximum amount of allowed rounding at any possible oracle outcome
+in a numeric outcome DLC.
 
-This type of oracle info is for single-oracle, single signature (and hence single nonce) events.
+The type `rounding_intervals` is defined [here](NumericOutcome.md#rounding-interval-serialization).
 
 ### The `funding_input` Type
 

Protocol.md

@@ -68,7 +68,6 @@ the funding transaction and CETs.
    * [`byte`:`contract_flags`]
    * [`chain_hash`:`chain_hash`]
    * [`contract_info`:`contract_info`]
-   * [`oracle_info`:`oracle_info`]
    * [`point`:`funding_pubkey`]
    * [`spk`:`payout_spk`]
    * [`u64`:`total_collateral_satoshis`]
@@ -87,8 +86,7 @@ The existence of the `chain_hash` allows nodes to open contracts
 across many distinct blockchains as well as have contracts within multiple
 blockchains opened to the same peer (if it supports the target chains).
 
-`contract_info` specifies the sender's payouts for all events. `oracle_info`
-specifies the oracle(s) to be used as well as their commitments to events.
+`contract_info` specifies the contract to be constructed and the oracles to be used.
 
 `funding_pubkey` is the public key in the 2-of-2 multisig script of
 the funding transaction output. `payout_spk` specifies the script
@@ -133,7 +131,7 @@ The receiving node MAY reject the contract if:
 
   - it does not agree to the terms in `contract_info`.
   - the `contract_info` is missing relevant events.
-  - it does not want to use the oracle(s) specified in `oracle_info`.
+  - it does not want to use the oracle(s) specified in `contract_info`.
   - `total_collateral_satoshis` is too small.
   - `feerate_per_vb` is too small.
   - `feerate_per_vb` is too large.
@@ -142,7 +140,7 @@ The receiving node MUST reject the contract if:
 
   - the `chain_hash` value is set to a hash of a chain that is unknown to the receiver.
   - the `contract_info` refers to events unknown to the receiver.
-  - the `oracle_info` refers to an oracle unknown or inaccessible to the receiver.
+  - the `contract_info` refers to an oracle unknown or inaccessible to the receiver.
   - it considers `feerate_per_vb` too small for timely processing or unreasonably large.
   - `funding_pubkey` is not a valid secp256k1 pubkey in compressed format.
   - `funding_inputs` do not contribute at least `total_collateral_satoshis` plus full [fee payment](Transactions.md#fee-payment).
@@ -165,6 +163,7 @@ and closing transactions.
    * [`spk`:`change_spk`]
    * [`cet_adaptor_signatures`:`cet_adaptor_signatures`]
    * [`signature`:`refund_signature`]
+   * [`negotiation_fields`:`negotiation_fields`]
 
 #### Requirements