From f753effce86dc79a372dc405aaadaf246b467a7c Mon Sep 17 00:00:00 2001 From: tmsdkeys <98807841+tmsdkeys@users.noreply.github.com> Date: Tue, 19 Jul 2022 15:20:55 +0200 Subject: [PATCH] Thomas/1584 update docs apps (#1675) * restructure content according to outline, fix image and syntax highlighting, fix titles and prepare for content updates * rewrite bind port section * restructure applications doc into folder structure * add keeper section, make some minor corrections in bind ports, custom packet and implmenent IBC module sections * update ibcmodule interface to encorporate the simpliefied handshake callbacks and version negotiation * fix broken links * fix remaining broken link * fix some nits, correct for removal of crossing hellos and add some more explanation on portIDs * update middleware docs to resolve merge confilicts (cherry picked from commit d1649c029cbbd7b380eafd82d94ad3f8eea34398) --- docs/.vuepress/config.js | 283 +++++++++++++++------------ docs/ibc/apps/apps.md | 51 +++++ docs/ibc/apps/bindports.md | 114 +++++++++++ docs/ibc/apps/ibcmodule.md | 342 +++++++++++++++++++++++++++++++++ docs/ibc/apps/keeper.md | 88 +++++++++ docs/ibc/apps/packets_acks.md | 99 ++++++++++ docs/ibc/apps/routing.md | 36 ++++ docs/ibc/integration.md | 6 +- docs/ibc/middleware/develop.md | 23 ++- 9 files changed, 902 insertions(+), 140 deletions(-) create mode 100644 docs/ibc/apps/apps.md create mode 100644 docs/ibc/apps/bindports.md create mode 100644 docs/ibc/apps/ibcmodule.md create mode 100644 docs/ibc/apps/keeper.md create mode 100644 docs/ibc/apps/packets_acks.md create mode 100644 docs/ibc/apps/routing.md diff --git a/docs/.vuepress/config.js b/docs/.vuepress/config.js index a15407fd54a..a5841915b3b 100644 --- a/docs/.vuepress/config.js +++ b/docs/.vuepress/config.js @@ -3,19 +3,48 @@ module.exports = { title: "IBC-Go", locales: { "/": { - lang: "en-US" + lang: "en-US", }, }, base: process.env.VUEPRESS_BASE || "/", head: [ - ['link', { rel: "apple-touch-icon", sizes: "180x180", href: "/apple-touch-icon.png" }], - ['link', { rel: "icon", type: "image/png", sizes: "32x32", href: "/favicon-32x32.png" }], - ['link', { rel: "icon", type: "image/png", sizes: "16x16", href: "/favicon-16x16.png" }], - ['link', { rel: "manifest", href: "/site.webmanifest" }], - ['meta', { name: "msapplication-TileColor", content: "#2e3148" }], - ['meta', { name: "theme-color", content: "#ffffff" }], - ['link', { rel: "icon", type: "image/svg+xml", href: "/favicon-svg.svg" }], - ['link', { rel: "apple-touch-icon-precomposed", href: "/apple-touch-icon-precomposed.png" }], + [ + "link", + { + rel: "apple-touch-icon", + sizes: "180x180", + href: "/apple-touch-icon.png", + }, + ], + [ + "link", + { + rel: "icon", + type: "image/png", + sizes: "32x32", + href: "/favicon-32x32.png", + }, + ], + [ + "link", + { + rel: "icon", + type: "image/png", + sizes: "16x16", + href: "/favicon-16x16.png", + }, + ], + ["link", { rel: "manifest", href: "/site.webmanifest" }], + ["meta", { name: "msapplication-TileColor", content: "#2e3148" }], + ["meta", { name: "theme-color", content: "#ffffff" }], + ["link", { rel: "icon", type: "image/svg+xml", href: "/favicon-svg.svg" }], + [ + "link", + { + rel: "apple-touch-icon-precomposed", + href: "/apple-touch-icon-precomposed.png", + }, + ], ], themeConfig: { repo: "cosmos/ibc-go", @@ -32,109 +61,109 @@ module.exports = { //}, versions: [ { - "label": "main", - "key": "main" + label: "main", + key: "main", }, { - "label": "v1.1.0", - "key": "v1.1.0" + label: "v1.1.0", + key: "v1.1.0", }, { - "label": "v1.2.0", - "key": "v1.2.0" + label: "v1.2.0", + key: "v1.2.0", }, { - "label": "v1.3.0", - "key": "v1.3.0" + label: "v1.3.0", + key: "v1.3.0", }, { - "label": "v1.5.0", - "key": "v1.5.0" + label: "v1.5.0", + key: "v1.5.0", }, { - "label": "v1.4.0", - "key": "v1.4.0" + label: "v1.4.0", + key: "v1.4.0", }, { - "label": "v2.0.0", - "key": "v2.0.0" - } , + label: "v2.0.0", + key: "v2.0.0", + }, { - "label": "v2.1.0", - "key": "v2.1.0" - }, - { - "label": "v2.2.0", - "key": "v2.2.0" + label: "v2.1.0", + key: "v2.1.0", }, - { - "label": "v2.3.0", - "key": "v2.3.0" + { + label: "v2.2.0", + key: "v2.2.0", }, { - "label": "v3.0.0", - "key": "v3.0.0" + label: "v2.3.0", + key: "v2.3.0", }, { - "label": "v3.1.0", - "key": "v3.1.0" - } + label: "v3.0.0", + key: "v3.0.0", + }, + { + label: "v3.1.0", + key: "v3.1.0", + }, ], topbar: { - banner: true + banner: true, }, - sidebar: { + sidebar: { auto: false, nav: [ - { + { title: "Using IBC-Go", children: [ { title: "Overview", directory: false, - path: "/ibc/overview.html" - }, + path: "/ibc/overview.html", + }, { title: "Integration", directory: false, - path: "/ibc/integration.html" + path: "/ibc/integration.html", }, { title: "Applications", - directory: false, - path: "/ibc/apps.html" + directory: true, + path: "/ibc/apps", }, { title: "Middleware", directory: true, - path: "/ibc/middleware" + path: "/ibc/middleware", }, { title: "Upgrades", directory: true, - path: "/ibc/upgrades" + path: "/ibc/upgrades", }, { title: "Governance Proposals", directory: false, - path: "/ibc/proposals.html" + path: "/ibc/proposals.html", }, { title: "Relayer", directory: false, - path: "/ibc/relayer.html" + path: "/ibc/relayer.html", }, { title: "Protobuf Documentation", directory: false, - path: "/ibc/proto-docs.html" + path: "/ibc/proto-docs.html", }, { title: "Roadmap", directory: false, - path: "/roadmap/roadmap.html" + path: "/roadmap/roadmap.html", }, - ] + ], }, { title: "IBC Application Modules", @@ -147,34 +176,34 @@ module.exports = { { title: "Overview", directory: false, - path: "/apps/interchain-accounts/overview.html" - }, + path: "/apps/interchain-accounts/overview.html", + }, { title: "Authentication Modules", directory: false, - path: "/apps/interchain-accounts/auth-modules.html" + path: "/apps/interchain-accounts/auth-modules.html", }, { title: "Active Channels", directory: false, - path: "/apps/interchain-accounts/active-channels.html" + path: "/apps/interchain-accounts/active-channels.html", }, { title: "Integration", directory: false, - path: "/apps/interchain-accounts/integration.html" + path: "/apps/interchain-accounts/integration.html", }, { title: "Parameters", directory: false, - path: "/apps/interchain-accounts/parameters.html" + path: "/apps/interchain-accounts/parameters.html", }, { title: "Transactions", directory: false, - path: "/apps/interchain-accounts/transactions.html" + path: "/apps/interchain-accounts/transactions.html", }, - ] + ], }, { title: "Transfer", @@ -184,41 +213,41 @@ module.exports = { { title: "Overview", directory: false, - path: "/apps/transfer/overview.html" - }, + path: "/apps/transfer/overview.html", + }, { title: "State", directory: false, - path: "/apps/transfer/state.html" + path: "/apps/transfer/state.html", }, { title: "State Transitions", directory: false, - path: "/apps/transfer/state-transitions.html" + path: "/apps/transfer/state-transitions.html", }, { title: "Messages", directory: false, - path: "/apps/transfer/messages.html" + path: "/apps/transfer/messages.html", }, { title: "Events", directory: false, - path: "/apps/transfer/events.html" + path: "/apps/transfer/events.html", }, { title: "Metrics", directory: false, - path: "/apps/transfer/metrics.html" + path: "/apps/transfer/metrics.html", }, { title: "Params", directory: false, - path: "/apps/transfer/params.html" + path: "/apps/transfer/params.html", }, - ] + ], }, - ] + ], }, { title: "IBC Middleware Modules", @@ -231,77 +260,78 @@ module.exports = { { title: "Overview", directory: false, - path: "/middleware/ics29-fee/overview.html" - }, + path: "/middleware/ics29-fee/overview.html", + }, { title: "Integration", directory: false, - path: "/middleware/ics29-fee/integration.html" + path: "/middleware/ics29-fee/integration.html", }, { title: "End Users", directory: false, - path: "/middleware/ics29-fee/end-users.html" + path: "/middleware/ics29-fee/end-users.html", }, { title: "Fee Messages", directory: false, - path: "/middleware/ics29-fee/msgs.html" + path: "/middleware/ics29-fee/msgs.html", }, { title: "Fee Distribution", directory: false, - path: "/middleware/ics29-fee/fee-distribution.html" + path: "/middleware/ics29-fee/fee-distribution.html", }, { title: "Events", directory: false, - path: "/middleware/ics29-fee/events.html" + path: "/middleware/ics29-fee/events.html", }, - ] + ], }, - ] + ], }, { title: "Migrations", children: [ { - title: "Support transfer of coins whose base denom contains slashes", + title: + "Support transfer of coins whose base denom contains slashes", directory: false, - path: "/migrations/support-denoms-with-slashes.html" + path: "/migrations/support-denoms-with-slashes.html", }, { title: "SDK v0.43 to IBC-Go v1", directory: false, - path: "/migrations/sdk-to-v1.html" + path: "/migrations/sdk-to-v1.html", }, { title: "IBC-Go v1 to v2", directory: false, - path: "/migrations/v1-to-v2.html" + path: "/migrations/v1-to-v2.html", }, { title: "IBC-Go v2 to v3", directory: false, - path: "/migrations/v2-to-v3.html" + path: "/migrations/v2-to-v3.html", }, { title: "IBC-Go v3 to v4", directory: false, - path: "/migrations/v3-to-v4.html" + path: "/migrations/v3-to-v4.html", }, - ] + ], }, { title: "Resources", children: [ { title: "IBC Specification", - path: "https://github.com/cosmos/ibc" + path: "https://github.com/cosmos/ibc", }, - ] - } - ] + ], + }, + ], }, gutter: { title: "Help & Support", @@ -310,46 +340,46 @@ module.exports = { title: "Discord", text: "Chat with IBC developers on Discord.", url: "https://discordapp.com/channels/669268347736686612", - bg: "linear-gradient(225.11deg, #2E3148 0%, #161931 95.68%)" + bg: "linear-gradient(225.11deg, #2E3148 0%, #161931 95.68%)", }, github: { title: "Found an Issue?", - text: "Help us improve this page by suggesting edits on GitHub." - } + text: "Help us improve this page by suggesting edits on GitHub.", + }, }, footer: { question: { - text: "Chat with IBC developers in Discord." + text: "Chat with IBC developers in Discord.", }, textLink: { text: "ibcprotocol.org", - url: "https://ibcprotocol.org" + url: "https://ibcprotocol.org", }, services: [ { service: "medium", - url: "https://blog.cosmos.network/" + url: "https://blog.cosmos.network/", }, { service: "twitter", - url: "https://twitter.com/cosmos" + url: "https://twitter.com/cosmos", }, { service: "linkedin", - url: "https://www.linkedin.com/company/interchain-gmbh" + url: "https://www.linkedin.com/company/interchain-gmbh", }, { service: "reddit", - url: "https://reddit.com/r/cosmosnetwork" + url: "https://reddit.com/r/cosmosnetwork", }, { service: "telegram", - url: "https://t.me/cosmosproject" + url: "https://t.me/cosmosproject", }, { service: "youtube", - url: "https://www.youtube.com/c/CosmosProject" - } + url: "https://www.youtube.com/c/CosmosProject", + }, ], smallprint: "The development of IBC-Go is led primarily by [Interchain GmbH](https://interchain.berlin/). Funding for this development comes primarily from the Interchain Foundation, a Swiss non-profit.", @@ -359,64 +389,63 @@ module.exports = { children: [ { title: "Cosmos SDK", - url: "https://docs.cosmos.network" + url: "https://docs.cosmos.network", }, { title: "Cosmos Hub", - url: "https://hub.cosmos.network" + url: "https://hub.cosmos.network", }, { title: "Tendermint Core", - url: "https://docs.tendermint.com" - } - ] + url: "https://docs.tendermint.com", + }, + ], }, { title: "Community", children: [ { title: "Cosmos blog", - url: "https://blog.cosmos.network" + url: "https://blog.cosmos.network", }, { title: "Forum", - url: "https://forum.cosmos.network" + url: "https://forum.cosmos.network", }, { title: "Chat", - url: "https://discord.gg/W8trcGV" - } - ] + url: "https://discord.gg/W8trcGV", + }, + ], }, { title: "Contributing", children: [ { title: "Contributing to the docs", - url: - "https://github.com/cosmos/ibc-go/blob/main/docs/DOCS_README.md" + url: "https://github.com/cosmos/ibc-go/blob/main/docs/DOCS_README.md", }, { title: "Source code on GitHub", - url: "https://github.com/cosmos/ibc-go/" - } - ] - } - ] - } + url: "https://github.com/cosmos/ibc-go/", + }, + ], + }, + ], + }, }, plugins: [ [ "@vuepress/google-analytics", { - ga: "UA-51029217-2" - } + ga: "UA-51029217-2", + }, ], [ "sitemap", { - hostname: "https://ibc.cosmos.network" - } - ] - ] + hostname: "https://ibc.cosmos.network", + }, + ], + ], }; diff --git a/docs/ibc/apps/apps.md b/docs/ibc/apps/apps.md new file mode 100644 index 00000000000..a24032168aa --- /dev/null +++ b/docs/ibc/apps/apps.md @@ -0,0 +1,51 @@ + + +# IBC Applications + +Learn how to build custom IBC application modules that enable packets to be sent to and received from other IBC-enabled chains. {synopsis} + +This document serves as a guide for developers who want to write their own Inter-blockchain Communication Protocol (IBC) applications for custom use cases. + +Due to the modular design of the IBC protocol, IBC application developers do not need to concern themselves with the low-level details of clients, connections, and proof verification. Nevertheless, an overview of these low-level concepts can be found in [the Overview section](../overview.md). +The document goes into detail on the abstraction layer most relevant for application developers (channels and ports), and describes how to define your own custom packets, `IBCModule` callbacks and more to make an application module IBC ready. + +**To have your module interact over IBC you must:** + +- implement the `IBCModule` interface, i.e.: + - channel (opening) handshake callbacks + - channel closing handshake callbacks + - packet callbacks +- bind to a port(s) +- add keeper methods +- define your own packet data and acknowledgement structs as well as how to encode/decode them +- add a route to the IBC router + +The following sections provide a more detailed explanation of how to write an IBC application +module correctly corresponding to the listed steps. + +## Pre-requisites Readings + +- [IBC Overview](../overview.md)) {prereq} +- [IBC default integration](../integration.md) {prereq} + +## Working example + +For a real working example of an IBC application, you can look through the `ibc-transfer` module +which implements everything discussed in this section. + +Here are the useful parts of the module to look at: + +[Binding to transfer +port](https://github.com/cosmos/ibc-go/blob/main/modules/apps/transfer/keeper/genesis.go) + +[Sending transfer +packets](https://github.com/cosmos/ibc-go/blob/main/modules/apps/transfer/keeper/relay.go) + +[Implementing IBC +callbacks](https://github.com/cosmos/ibc-go/blob/main/modules/apps/transfer/ibc_module.go) + +## Next {hide} + +Learn about [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/intro.md) {hide} diff --git a/docs/ibc/apps/bindports.md b/docs/ibc/apps/bindports.md new file mode 100644 index 00000000000..c0cfa703191 --- /dev/null +++ b/docs/ibc/apps/bindports.md @@ -0,0 +1,114 @@ + + +# Bind ports + +Learn what changes to make to bind modules to their ports on initialization. {synopsis} + +## Pre-requisites Readings + +- [IBC Overview](../overview.md)) {prereq} +- [IBC default integration](../integration.md) {prereq} + +Currently, ports must be bound on app initialization. In order to bind modules to their respective ports on initialization, the following needs to be implemented: + +> Note that `portID` does not refer to a certain numerical ID, like `localhost:8080` with a `portID` 8080. Rather it refers to the application module the port binds. For IBC Modules built with the Cosmos SDK, it defaults to the module's name and for Cosmwasm contracts it defaults to the contract address. + +1. Add port ID to the `GenesisState` proto definition: + + ```protobuf + message GenesisState { + string port_id = 1; + // other fields + } + ``` + +1. Add port ID as a key to the module store: + + ```go + // x//types/keys.go + const ( + // ModuleName defines the IBC Module name + ModuleName = "moduleName" + + // Version defines the current version the IBC + // module supports + Version = "moduleVersion-1" + + // PortID is the default port id that module binds to + PortID = "portID" + + // ... + ) + ``` + +1. Add port ID to `x//types/genesis.go`: + + ```go + // in x//types/genesis.go + + // DefaultGenesisState returns a GenesisState with "transfer" as the default PortID. + func DefaultGenesisState() *GenesisState { + return &GenesisState{ + PortId: PortID, + // additional k-v fields + } + } + + // Validate performs basic genesis state validation returning an error upon any + // failure. + func (gs GenesisState) Validate() error { + if err := host.PortIdentifierValidator(gs.PortId); err != nil { + return err + } + //addtional validations + + return gs.Params.Validate() + } + ``` + +1. Bind to port(s) in the module keeper's `InitGenesis`: + + ```go + // InitGenesis initializes the ibc-module state and binds to PortID. + func (k Keeper) InitGenesis(ctx sdk.Context, state types.GenesisState) { + k.SetPort(ctx, state.PortId) + + // ... + + // Only try to bind to port if it is not already bound, since we may already own + // port capability from capability InitGenesis + if !k.IsBound(ctx, state.PortId) { + // transfer module binds to the transfer port on InitChain + // and claims the returned capability + err := k.BindPort(ctx, state.PortId) + if err != nil { + panic(fmt.Sprintf("could not claim port capability: %v", err)) + } + } + + // ... + } + ``` + + With: + + ```go + // IsBound checks if the module is already bound to the desired port + func (k Keeper) IsBound(ctx sdk.Context, portID string) bool { + _, ok := k.scopedKeeper.GetCapability(ctx, host.PortPath(portID)) + return ok + } + + // BindPort defines a wrapper function for the port Keeper's function in + // order to expose it to module's InitGenesis function + func (k Keeper) BindPort(ctx sdk.Context, portID string) error { + cap := k.portKeeper.BindPort(ctx, portID) + return k.ClaimCapability(ctx, cap, host.PortPath(portID)) + } + ``` + + The module binds to the desired port(s) and returns the capabilities. + + In the above we find reference to keeper methods that wrap other keeper functionality, in the next section the keeper methods that need to be implemented will be defined. diff --git a/docs/ibc/apps/ibcmodule.md b/docs/ibc/apps/ibcmodule.md new file mode 100644 index 00000000000..d5864435700 --- /dev/null +++ b/docs/ibc/apps/ibcmodule.md @@ -0,0 +1,342 @@ + + +# Implement `IBCModule` interface and callbacks + +Learn how to implement the `IBCModule` interface and all of the callbacks it requires. {synopsis} + +The Cosmos SDK expects all IBC modules to implement the [`IBCModule` +interface](https://github.com/cosmos/ibc-go/tree/main/modules/core/05-port/types/module.go). This interface contains all of the callbacks IBC expects modules to implement. They include callbacks related to channel handshake, closing and packet callbacks (`OnRecvPacket`, `OnAcknowledgementPacket` and `OnTimeoutPacket`). + +```go +// IBCModule implements the ICS26 interface for given the keeper. +// The implementation of the IBCModule interface could for example be in a file called ibc_module.go, +// but ultimately file structure is up to the developer +type IBCModule struct { + keeper keeper.Keeper +} +``` + +Additionally, in the `module.go` file, add the following line: + +```go +var ( + _ module.AppModule = AppModule{} + _ module.AppModuleBasic = AppModuleBasic{} + // Add this line + _ porttypes.IBCModule = IBCModule{} +) +``` + +## Pre-requisites Readings + +- [IBC Overview](../overview.md)) {prereq} +- [IBC default integration](../integration.md) {prereq} + +## Channel handshake callbacks + +This section will describe the callbacks that are called during channel handshake execution. Among other things, it will claim channel capabilities passed on from core IBC. For a refresher on capabilities, check [the Overview section](../overview.md#capabilities). + +Here are the channel handshake callbacks that modules are expected to implement: + +> Note that some of the code below is _pseudo code_, indicating what actions need to happen but leaving it up to the developer to implement a custom implementation. E.g. the `checkArguments` and `negotiateAppVersion` functions. + +```go +// Called by IBC Handler on MsgOpenInit +func (im IBCModule) OnChanOpenInit(ctx sdk.Context, + order channeltypes.Order, + connectionHops []string, + portID string, + channelID string, + channelCap *capabilitytypes.Capability, + counterparty channeltypes.Counterparty, + version string, +) (string, error) { + // ... do custom initialization logic + + // Use above arguments to determine if we want to abort handshake + // Examples: + // - Abort if order == UNORDERED, + // - Abort if version is unsupported + if err := checkArguments(args); err != nil { + return "", err + } + + // OpenInit must claim the channelCapability that IBC passes into the callback + if err := im.keeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil { + return "", err + } + + return version, nil +} + +// Called by IBC Handler on MsgOpenTry +func (im IBCModule) OnChanOpenTry( + ctx sdk.Context, + order channeltypes.Order, + connectionHops []string, + portID, + channelID string, + channelCap *capabilitytypes.Capability, + counterparty channeltypes.Counterparty, + counterpartyVersion string, +) (string, error) { + // ... do custom initialization logic + + // Use above arguments to determine if we want to abort handshake + if err := checkArguments(args); err != nil { + return "", err + } + + // OpenTry must claim the channelCapability that IBC passes into the callback + if err := im.keeper.scopedKeeper.ClaimCapability(ctx, chanCap, host.ChannelCapabilityPath(portID, channelID)); err != nil { + return err + } + + // Construct application version + // IBC applications must return the appropriate application version + // This can be a simple string or it can be a complex version constructed + // from the counterpartyVersion and other arguments. + // The version returned will be the channel version used for both channel ends. + appVersion := negotiateAppVersion(counterpartyVersion, args) + + return appVersion, nil +} + +// Called by IBC Handler on MsgOpenAck +func (im IBCModule) OnChanOpenAck( + ctx sdk.Context, + portID, + channelID string, + counterpartyVersion string, +) error { + if counterpartyVersion != types.Version { + return sdkerrors.Wrapf(types.ErrInvalidVersion, "invalid counterparty version: %s, expected %s", counterpartyVersion, types.Version) + } + + // do custom logic + + return nil +} + +// Called by IBC Handler on MsgOpenConfirm +func (im IBCModule) OnChanOpenConfirm( + ctx sdk.Context, + portID, + channelID string, +) error { + // do custom logic + + return nil +} +``` + +The channel closing handshake will also invoke module callbacks that can return errors to abort the closing handshake. Closing a channel is a 2-step handshake, the initiating chain calls `ChanCloseInit` and the finalizing chain calls `ChanCloseConfirm`. + +```go +// Called by IBC Handler on MsgCloseInit +func (im IBCModule) OnChanCloseInit( + ctx sdk.Context, + portID, + channelID string, +) error { + // ... do custom finalization logic + + // Use above arguments to determine if we want to abort handshake + err := checkArguments(args) + return err +} + +// Called by IBC Handler on MsgCloseConfirm +func (im IBCModule) OnChanCloseConfirm( + ctx sdk.Context, + portID, + channelID string, +) error { + // ... do custom finalization logic + + // Use above arguments to determine if we want to abort handshake + err := checkArguments(args) + return err +} +``` + +### Channel handshake version negotiation + +Application modules are expected to verify versioning used during the channel handshake procedure. + +- `OnChanOpenInit` will verify that the relayer-chosen parameters + are valid and perform any custom `INIT` logic. + It may return an error if the chosen parameters are invalid + in which case the handshake is aborted. + If the provided version string is non-empty, `OnChanOpenInit` should return + the version string if valid or an error if the provided version is invalid. + **If the version string is empty, `OnChanOpenInit` is expected to + return a default version string representing the version(s) + it supports.** + If there is no default version string for the application, + it should return an error if the provided version is an empty string. +- `OnChanOpenTry` will verify the relayer-chosen parameters along with the + counterparty-chosen version string and perform custom `TRY` logic. + If the relayer-chosen parameters + are invalid, the callback must return an error to abort the handshake. + If the counterparty-chosen version is not compatible with this module's + supported versions, the callback must return an error to abort the handshake. + If the versions are compatible, the try callback must select the final version + string and return it to core IBC. + `OnChanOpenTry` may also perform custom initialization logic. +- `OnChanOpenAck` will error if the counterparty selected version string + is invalid and abort the handshake. It may also perform custom ACK logic. + +Versions must be strings but can implement any versioning structure. If your application plans to +have linear releases then semantic versioning is recommended. If your application plans to release +various features in between major releases then it is advised to use the same versioning scheme +as IBC. This versioning scheme specifies a version identifier and compatible feature set with +that identifier. Valid version selection includes selecting a compatible version identifier with +a subset of features supported by your application for that version. The struct used for this +scheme can be found in [03-connection/types](https://github.com/cosmos/ibc-go/blob/main/modules/core/03-connection/types/version.go#L16). + +Since the version type is a string, applications have the ability to do simple version verification +via string matching or they can use the already impelemented versioning system and pass the proto +encoded version into each handhshake call as necessary. + +ICS20 currently implements basic string matching with a single supported version. + +## Packet callbacks + +Just as IBC expects modules to implement callbacks for channel handshakes, it also expects modules to implement callbacks for handling the packet flow through a channel, as defined in the `IBCModule` interface. + +Once a module A and module B are connected to each other, relayers can start relaying packets and acknowledgements back and forth on the channel. + +![IBC packet flow diagram](https://ibcprotocol.org/_nuxt/img/packet_flow.1d89ee0.png) + +Briefly, a successful packet flow works as follows: + +1. module A sends a packet through the IBC module +2. the packet is received by module B +3. if module B writes an acknowledgement of the packet then module A will process the + acknowledgement +4. if the packet is not successfully received before the timeout, then module A processes the + packet's timeout. + +### Sending packets + +Modules **do not send packets through callbacks**, since the modules initiate the action of sending packets to the IBC module, as opposed to other parts of the packet flow where messages sent to the IBC +module must trigger execution on the port-bound module through the use of callbacks. Thus, to send a packet a module simply needs to call `SendPacket` on the `IBCChannelKeeper`. + +> Note that some of the code below is _pseudo code_, indicating what actions need to happen but leaving it up to the developer to implement a custom implementation. E.g. the `EncodePacketData(customPacketData)` function. + +```go +// retrieve the dynamic capability for this channel +channelCap := scopedKeeper.GetCapability(ctx, channelCapName) +// Sending custom application packet data +data := EncodePacketData(customPacketData) +packet.Data = data +// Send packet to IBC, authenticating with channelCap +IBCChannelKeeper.SendPacket(ctx, channelCap, packet) +``` + +::: warning +In order to prevent modules from sending packets on channels they do not own, IBC expects +modules to pass in the correct channel capability for the packet's source channel. +::: + +### Receiving packets + +To handle receiving packets, the module must implement the `OnRecvPacket` callback. This gets +invoked by the IBC module after the packet has been proved valid and correctly processed by the IBC +keepers. Thus, the `OnRecvPacket` callback only needs to worry about making the appropriate state +changes given the packet data without worrying about whether the packet is valid or not. + +Modules may return to the IBC handler an acknowledgement which implements the `Acknowledgement` interface. +The IBC handler will then commit this acknowledgement of the packet so that a relayer may relay the +acknowledgement back to the sender module. + +The state changes that occurred during this callback will only be written if: + +- the acknowledgement was successful as indicated by the `Success()` function of the acknowledgement +- if the acknowledgement returned is nil indicating that an asynchronous process is occurring + +NOTE: Applications which process asynchronous acknowledgements must handle reverting state changes +when appropriate. Any state changes that occurred during the `OnRecvPacket` callback will be written +for asynchronous acknowledgements. + +> Note that some of the code below is _pseudo code_, indicating what actions need to happen but leaving it up to the developer to implement a custom implementation. E.g. the `DecodePacketData(packet.Data)` function. + +```go +func (im IBCModule) OnRecvPacket( + ctx sdk.Context, + packet channeltypes.Packet, +) ibcexported.Acknowledgement { + // Decode the packet data + packetData := DecodePacketData(packet.Data) + + // do application state changes based on packet data and return the acknowledgement + // NOTE: The acknowledgement will indicate to the IBC handler if the application + // state changes should be written via the `Success()` function. Application state + // changes are only written if the acknowledgement is successful or the acknowledgement + // returned is nil indicating that an asynchronous acknowledgement will occur. + ack := processPacket(ctx, packet, packetData) + + return ack +} +``` + +Reminder, the `Acknowledgement` interface: + +```go +// Acknowledgement defines the interface used to return +// acknowledgements in the OnRecvPacket callback. +type Acknowledgement interface { + Success() bool + Acknowledgement() []byte +} +``` + +### Acknowledging packets + +After a module writes an acknowledgement, a relayer can relay back the acknowledgement to the sender module. The sender module can +then process the acknowledgement using the `OnAcknowledgementPacket` callback. The contents of the +acknowledgement is entirely up to the modules on the channel (just like the packet data); however, it +may often contain information on whether the packet was successfully processed along +with some additional data that could be useful for remediation if the packet processing failed. + +Since the modules are responsible for agreeing on an encoding/decoding standard for packet data and +acknowledgements, IBC will pass in the acknowledgements as `[]byte` to this callback. The callback +is responsible for decoding the acknowledgement and processing it. + +> Note that some of the code below is _pseudo code_, indicating what actions need to happen but leaving it up to the developer to implement a custom implementation. E.g. the `DecodeAcknowledgement(acknowledgments)` and `processAck(ack)` functions. + +```go +func (im IBCModule) OnAcknowledgementPacket( + ctx sdk.Context, + packet channeltypes.Packet, + acknowledgement []byte, +) (*sdk.Result, error) { + // Decode acknowledgement + ack := DecodeAcknowledgement(acknowledgement) + + // process ack + res, err := processAck(ack) + return res, err +} +``` + +### Timeout packets + +If the timeout for a packet is reached before the packet is successfully received or the +counterparty channel end is closed before the packet is successfully received, then the receiving +chain can no longer process it. Thus, the sending chain must process the timeout using +`OnTimeoutPacket` to handle this situation. Again the IBC module will verify that the timeout is +indeed valid, so our module only needs to implement the state machine logic for what to do once a +timeout is reached and the packet can no longer be received. + +```go +func (im IBCModule) OnTimeoutPacket( + ctx sdk.Context, + packet channeltypes.Packet, +) (*sdk.Result, error) { + // do custom timeout logic +} +``` diff --git a/docs/ibc/apps/keeper.md b/docs/ibc/apps/keeper.md new file mode 100644 index 00000000000..6cbba0fbb8f --- /dev/null +++ b/docs/ibc/apps/keeper.md @@ -0,0 +1,88 @@ + + +# Keeper + +Learn how to implement the IBC Module keeper. {synopsis} + +## Pre-requisites Readings + +- [IBC Overview](../overview.md)) {prereq} +- [IBC default integration](../integration.md) {prereq} + +In the previous sections, on channel handshake callbacks and port binding in `InitGenesis`, a reference was made to keeper methods that need to be implemented when creating a custom IBC module. Below is an overview of how to define an IBC module's keeper. + +> Note that some code has been left out for clarity, to get a full code overview, please refer to [the transfer module's keeper in the ibc-go repo](https://github.com/cosmos/ibc-go/blob/main/modules/apps/transfer/keeper/keeper.go). + +```go +// Keeper defines the IBC app module keeper +type Keeper struct { + storeKey sdk.StoreKey + cdc codec.BinaryCodec + paramSpace paramtypes.Subspace + + channelKeeper types.ChannelKeeper + portKeeper types.PortKeeper + scopedKeeper capabilitykeeper.ScopedKeeper + + // ... additional according to custom logic +} + +// NewKeeper creates a new IBC app module Keeper instance +func NewKeeper( + // args +) Keeper { + // ... + + return Keeper{ + cdc: cdc, + storeKey: key, + paramSpace: paramSpace, + + channelKeeper: channelKeeper, + portKeeper: portKeeper, + scopedKeeper: scopedKeeper, + + // ... additional according to custom logic + } +} + +// IsBound checks if the IBC app module is already bound to the desired port +func (k Keeper) IsBound(ctx sdk.Context, portID string) bool { + _, ok := k.scopedKeeper.GetCapability(ctx, host.PortPath(portID)) + return ok +} + +// BindPort defines a wrapper function for the port Keeper's function in +// order to expose it to module's InitGenesis function +func (k Keeper) BindPort(ctx sdk.Context, portID string) error { + cap := k.portKeeper.BindPort(ctx, portID) + return k.ClaimCapability(ctx, cap, host.PortPath(portID)) +} + +// GetPort returns the portID for the IBC app module. Used in ExportGenesis +func (k Keeper) GetPort(ctx sdk.Context) string { + store := ctx.KVStore(k.storeKey) + return string(store.Get(types.PortKey)) +} + +// SetPort sets the portID for the IBC app module. Used in InitGenesis +func (k Keeper) SetPort(ctx sdk.Context, portID string) { + store := ctx.KVStore(k.storeKey) + store.Set(types.PortKey, []byte(portID)) +} + +// AuthenticateCapability wraps the scopedKeeper's AuthenticateCapability function +func (k Keeper) AuthenticateCapability(ctx sdk.Context, cap *capabilitytypes.Capability, name string) bool { + return k.scopedKeeper.AuthenticateCapability(ctx, cap, name) +} + +// ClaimCapability allows the IBC app module to claim a capability that core IBC +// passes to it +func (k Keeper) ClaimCapability(ctx sdk.Context, cap *capabilitytypes.Capability, name string) error { + return k.scopedKeeper.ClaimCapability(ctx, cap, name) +} + +// ... additional according to custom logic +``` diff --git a/docs/ibc/apps/packets_acks.md b/docs/ibc/apps/packets_acks.md new file mode 100644 index 00000000000..1871eca8915 --- /dev/null +++ b/docs/ibc/apps/packets_acks.md @@ -0,0 +1,99 @@ + + +# Define packets and acks + +Learn how to define custom packet and acknowledgement structs and how to encode and decode them. {synopsis} + +## Pre-requisites Readings + +- [IBC Overview](../overview.md)) {prereq} +- [IBC default integration](../integration.md) {prereq} + +## Custom packets + +Modules connected by a channel must agree on what application data they are sending over the +channel, as well as how they will encode/decode it. This process is not specified by IBC as it is up +to each application module to determine how to implement this agreement. However, for most +applications this will happen as a version negotiation during the channel handshake. While more +complex version negotiation is possible to implement inside the channel opening handshake, a very +simple version negotation is implemented in the [ibc-transfer module](https://github.com/cosmos/ibc-go/tree/main/modules/apps/transfer/module.go). + +Thus, a module must define its custom packet data structure, along with a well-defined way to +encode and decode it to and from `[]byte`. + +```go +// Custom packet data defined in application module +type CustomPacketData struct { + // Custom fields ... +} + +EncodePacketData(packetData CustomPacketData) []byte { + // encode packetData to bytes +} + +DecodePacketData(encoded []byte) (CustomPacketData) { + // decode from bytes to packet data +} +``` + +> Note that the `CustomPacketData` struct is defined in the proto definition and then compiled by the protobuf compiler. + +Then a module must encode its packet data before sending it through IBC. + +```go +// Sending custom application packet data +data := EncodePacketData(customPacketData) +packet.Data = data +IBCChannelKeeper.SendPacket(ctx, packet) +``` + +A module receiving a packet must decode the `PacketData` into a structure it expects so that it can +act on it. + +```go +// Receiving custom application packet data (in OnRecvPacket) +packetData := DecodePacketData(packet.Data) +// handle received custom packet data +``` + +## Acknowledgements + +Modules may commit an acknowledgement upon receiving and processing a packet in the case of synchronous packet processing. +In the case where a packet is processed at some later point after the packet has been received (asynchronous execution), the acknowledgement +will be written once the packet has been processed by the application which may be well after the packet receipt. + +NOTE: Most blockchain modules will want to use the synchronous execution model in which the module processes and writes the acknowledgement +for a packet as soon as it has been received from the IBC module. + +This acknowledgement can then be relayed back to the original sender chain, which can take action +depending on the contents of the acknowledgement. + +Just as packet data was opaque to IBC, acknowledgements are similarly opaque. Modules must pass and +receive acknowledegments with the IBC modules as byte strings. + +Thus, modules must agree on how to encode/decode acknowledgements. The process of creating an +acknowledgement struct along with encoding and decoding it, is very similar to the packet data +example above. [ICS 04](https://github.com/cosmos/ibc/blob/master/spec/core/ics-004-channel-and-packet-semantics#acknowledgement-envelope) +specifies a recommended format for acknowledgements. This acknowledgement type can be imported from +[channel types](https://github.com/cosmos/ibc-go/tree/main/modules/core/04-channel/types). + +While modules may choose arbitrary acknowledgement structs, a default acknowledgement types is provided by IBC [here](https://github.com/cosmos/ibc-go/blob/main/proto/ibc/core/channel/v1/channel.proto): + +```protobuf +// Acknowledgement is the recommended acknowledgement format to be used by +// app-specific protocols. +// NOTE: The field numbers 21 and 22 were explicitly chosen to avoid accidental +// conflicts with other protobuf message formats used for acknowledgements. +// The first byte of any message with this format will be the non-ASCII values +// `0xaa` (result) or `0xb2` (error). Implemented as defined by ICS: +// https://github.com/cosmos/ibc/tree/master/spec/core/ics-004-channel-and-packet-semantics#acknowledgement-envelope +message Acknowledgement { + // response contains either a result or an error and must be non-empty + oneof response { + bytes result = 21; + string error = 22; + } +} +``` diff --git a/docs/ibc/apps/routing.md b/docs/ibc/apps/routing.md new file mode 100644 index 00000000000..1095462dcba --- /dev/null +++ b/docs/ibc/apps/routing.md @@ -0,0 +1,36 @@ + + +# Routing + +## Pre-requisites Readings + +- [IBC Overview](../overview.md)) {prereq} +- [IBC default integration](../integration.md) {prereq} + +Learn how to hook a route to the IBC router for the custom IBC module. {synopsis} + +As mentioned above, modules must implement the `IBCModule` interface (which contains both channel +handshake callbacks and packet handling callbacks). The concrete implementation of this interface +must be registered with the module name as a route on the IBC `Router`. + +```go +// app.go +func NewApp(...args) *App { +// ... + +// Create static IBC router, add module routes, then set and seal it +ibcRouter := port.NewRouter() + +ibcRouter.AddRoute(ibctransfertypes.ModuleName, transferModule) +// Note: moduleCallbacks must implement IBCModule interface +ibcRouter.AddRoute(moduleName, moduleCallbacks) + +// Setting Router will finalize all routes by sealing router +// No more routes can be added +app.IBCKeeper.SetRouter(ibcRouter) + +// ... +} +``` diff --git a/docs/ibc/integration.md b/docs/ibc/integration.md index 09c1d2d2de9..d2d9f057ea3 100644 --- a/docs/ibc/integration.md +++ b/docs/ibc/integration.md @@ -24,7 +24,7 @@ Integrating the IBC module to your SDK-based application is straighforward. The ### Module `BasicManager` and `ModuleAccount` permissions -The first step is to add the following modules to the `BasicManager`: `x/capability`, `x/ibc`, +The first step is to add the following modules to the `BasicManager`: `x/capability`, `x/ibc`, and `x/ibc-transfer`. After that, we need to grant `Minter` and `Burner` permissions to the `ibc-transfer` `ModuleAccount` to mint and burn relayed tokens. @@ -72,7 +72,7 @@ type App struct { ### Configure the `Keepers` -During initialization, besides initializing the IBC `Keepers` (for the `x/ibc`, and +During initialization, besides initializing the IBC `Keepers` (for the `x/ibc`, and `x/ibc-transfer` modules), we need to grant specific capabilities through the capability module `ScopedKeepers` so that we can authenticate the object-capability permissions for each of the IBC channels. @@ -221,4 +221,4 @@ different chains. If you want to have a broader view of the changes take a look ## Next {hide} -Learn about how to create [custom IBC modules](./apps.md) for your application {hide} +Learn about how to create [custom IBC modules](./apps/apps.md) for your application {hide} diff --git a/docs/ibc/middleware/develop.md b/docs/ibc/middleware/develop.md index 9adc5a8cfa7..157115b55e5 100644 --- a/docs/ibc/middleware/develop.md +++ b/docs/ibc/middleware/develop.md @@ -16,7 +16,7 @@ Middleware allows developers to define the extensions as separate modules that c - [IBC Overview](../overview.md) {prereq} - [IBC Integration](../integration.md) {prereq} -- [IBC Application Developer Guide](../apps.md) {prereq} +- [IBC Application Developer Guide](../apps/apps.md) {prereq} ## Definitions @@ -26,7 +26,7 @@ Middleware allows developers to define the extensions as separate modules that c `Base Application`: A base application is an IBC application that does not contain any middleware. It may be nested by 0 or multiple middleware to form an application stack. -`Application Stack (or stack)`: A stack is the complete set of application logic (middleware(s) + base application) that gets connected to core IBC. A stack may be just a base application, or it may be a series of middlewares that nest a base application. +`Application Stack (or stack)`: A stack is the complete set of application logic (middleware(s) + base application) that gets connected to core IBC. A stack may be just a base application, or it may be a series of middlewares that nest a base application. ## Create a custom IBC middleware @@ -64,7 +64,10 @@ In the case where the IBC middleware expects to speak to a compatible IBC middle Middleware accomplishes this by formatting the version in a JSON-encoded string containing the middleware version and the application version. The application version may as well be a JSON-encoded string, possibly including further middleware and app versions, if the application stack consists of multiple milddlewares wrapping a base application. The format of the version is specified in ICS-30 as the following: ```json -{"":"","app_version":""} +{ + "": "", + "app_version": "" +} ``` The `` key in the JSON struct should be replaced by the actual name of the key for the corresponding middleware (e.g. `fee_version`). @@ -90,12 +93,12 @@ func (im IBCModule) OnChanOpenInit( counterparty channeltypes.Counterparty, version string, ) (string, error) { - // try to unmarshal JSON-encoded version string and pass + // try to unmarshal JSON-encoded version string and pass // the app-specific version to app callback. // otherwise, pass version directly to app callback. metadata, err := Unmarshal(version) if err != nil { - // Since it is valid for fee version to not be specified, + // Since it is valid for fee version to not be specified, // the above middleware version may be for another middleware. // Pass the entire version string onto the underlying application. return im.app.OnChanOpenInit( @@ -151,7 +154,7 @@ func OnChanOpenTry( ) (string, error) { doCustomLogic() - // try to unmarshal JSON-encoded version string and pass + // try to unmarshal JSON-encoded version string and pass // the app-specific version to app callback. // otherwise, pass version directly to app callback. cpMetadata, err := Unmarshal(counterpartyVersion) @@ -183,7 +186,7 @@ func OnChanOpenTry( if err != nil { return "", err } - + // negotiate final middleware version middlewareVersion := negotiateMiddlewareVersion(cpMetadata.MiddlewareVersion) version := constructVersion(middlewareVersion, appVersion) @@ -204,7 +207,7 @@ func OnChanOpenAck( counterpartyChannelID string, counterpartyVersion string, ) error { - // try to unmarshal JSON-encoded version string and pass + // try to unmarshal JSON-encoded version string and pass // the app-specific version to app callback. // otherwise, pass version directly to app callback. cpMetadata, err = UnmarshalJSON(counterpartyVersion) @@ -216,7 +219,7 @@ func OnChanOpenAck( return error } doCustomLogic() - + // call the underlying application's OnChanOpenTry callback return app.OnChanOpenAck(ctx, portID, channelID, counterpartyChannelID, cpMetadata.AppVersion) } @@ -373,7 +376,7 @@ See [here](https://github.com/cosmos/ibc-go/blob/48a6ae512b4ea42c29fdf6c6f5363f5 #### `GetAppVersion` ```go -// middleware must return the underlying application version +// middleware must return the underlying application version func GetAppVersion( ctx sdk.Context, portID,