<!--
The default pull request template is for types feat, fix, or refactor.
For other templates, add one of the following parameters to the url:
- template=docs.md
- template=other.md
-->
## Description
Closes: #10443
For creating an intermediary/auxiliary tx (e.g. by the tipper in tipped transactions), using the existing `client.TxBuilder` is awkward. We propose a new client-side builder for this purpose.
API Usage (e.g. how the tipper would programmtically use this):
```go
// Note: there's no need to use clientCtx.TxConfig anymore!
bldr := clienttx.NewAuxTxBuilder()
err := bldr.SetMsgs(msgs...)
bldr.SetAddress("cosmos1...")
bldr.SetMemo(...)
bldr.SetTip(...)
bldr.SetPubKey(...)
err := bldr.SetSignMode(...) // DIRECT_AUX or AMINO, or else error
// ... other setters are available
// Get the bytes to sign.
signBz, err := bldr.GetSignBytes()
// Sign the bz using your favorite method.
sig, err := privKey.sign(signBz)
// Set the signature
bldr.SetSig(sig)
// Get the final auxSignerData to be sent to the fee payer
auxSignerData, err:= bldr.GetAuxSignerData()
```
auxSignerData is a protobuf message, whose JSON reprensentation looks like:
```json
{
"address": "cosmos1...",
"mode": "SIGN_MODE_{DIRECT_AUX,LEGACY_AMINO_JSON}",
"sign_doc": {
"body_bytes": "{base64 bytes}",
"public_key": {
"@type": "cosmos.sepc256k1.PubKey",
"key": "{base64 bytes}"
},
"chain_id": "...",
"account_number": 24,
"sequence": 42,
"tip": {
"amount": [{ "denom": "uregen", "amount": 1000 }],
"tipper": "cosmos1..."
}
},
"sig": "{base64 bytes}"
}
```
Then the fee payer would use the TxBuilder to construct the final TX, with a new helper method: `AddAuxSignerData`:
```go
// get auxSignerData from AuxTxBuilder
auxSignerData := ...
txBuilder := txConfig.NewTxBuilder()
err := txBuilder.AddAuxSignerData(auxSignerData)
// Set fee payer data
txBuilder.SetFee()
txBuilder.SetGasLimit()
txBuilder.SetFeePayer()
sigs, err := txBuilder.GetSignaturesV2()
auxSig := sigs[0] // the aux signer's signature
// Set all signer infos (1st round of calling SetSignatures)
txBuilder.SetSignatures(
auxSig, // The aux SignatureV2
signing.SignatureV2{...}, // The feePayer's SignatureV2
)
// Sign
signBz, err = encCfg.TxConfig.SignModeHandler().GetSignBytes(...)
feepayerSig, err := feepayerPriv.Sign(signBz)
// Set all signatures (2nd round of calling SetSignatures)
txBuilder.SetSignatures(
auxSig, // The aux SignatureV2
signing.SignatureV2{feepayerSig, ...}, // The feePayer's SignatureV2
)
```
---
### Author Checklist
*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*
I have...
- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed
### Reviewers Checklist
*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*
I have...
- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)
