ccipocr3: add getocrconfigs method and test (#1102)

## Motivation

We need to be able to fetch OCR configs from the home chain reader in
the capability launcher.

## Solution

Add a method to fetch OCR configs for a (don ID, plugin type) pair in
the home chain reader.

core/services/ocr3/plugins/ccip/internal/reader/home_chain.go

@@ -23,6 +23,8 @@ type HomeChain interface {
 	GetKnownCCIPChains() (mapset.Set[cciptypes.ChainSelector], error)
 	// GetFChain Gets the FChain value for each chain
 	GetFChain() (map[cciptypes.ChainSelector]int, error)
+	// GetOCRConfigs Gets the OCR3Configs for a given donID and pluginType
+	GetOCRConfigs(ctx context.Context, donID uint32, pluginType uint8) ([]OCR3ConfigWithMeta, error)
 	services.Service
 }
 
@@ -179,6 +181,19 @@ func (r *homeChainPoller) GetFChain() (map[cciptypes.ChainSelector]int, error) {
 	return r.state.fChain, nil
 }
 
+func (r *homeChainPoller) GetOCRConfigs(ctx context.Context, donID uint32, pluginType uint8) ([]OCR3ConfigWithMeta, error) {
+	var ocrConfigs []OCR3ConfigWithMeta
+	err := r.homeChainReader.GetLatestValue(ctx, "CCIPCapabilityConfiguration", "getOCRConfig", map[string]any{
+		"donId":      donID,
+		"pluginType": pluginType,
+	}, &ocrConfigs)
+	if err != nil {
+		return nil, fmt.Errorf("error fetching OCR configs: %w", err)
+	}
+
+	return ocrConfigs, nil
+}
+
 func (r *homeChainPoller) Close() error {
 	return r.sync.StopOnce(r.Name(), func() error {
 		close(r.stopCh)
@@ -273,4 +288,25 @@ type ChainConfig struct {
 	Config []byte `json:"config"`
 }
 
+// OCR3Config mirrors CCIPCapabilityConfiguration.sol's OCR3Config struct
+type OCR3Config struct {
+	PluginType            uint8                   `json:"pluginType"`
+	ChainSelector         cciptypes.ChainSelector `json:"chainSelector"`
+	F                     uint8                   `json:"F"`
+	OffchainConfigVersion uint64                  `json:"offchainConfigVersion"`
+	OfframpAddress        []byte                  `json:"offrampAddress"`
+	BootstrapP2PIds       [][32]byte              `json:"bootstrapP2PIds"`
+	P2PIds                [][32]byte              `json:"p2pIds"`
+	Signers               [][]byte                `json:"signers"`
+	Transmitters          [][]byte                `json:"transmitters"`
+	OffchainConfig        []byte                  `json:"offchainConfig"`
+}
+
+// OCR3ConfigWithmeta mirrors CCIPCapabilityConfiguration.sol's OCR3ConfigWithMeta struct
+type OCR3ConfigWithMeta struct {
+	Config       OCR3Config `json:"config"`
+	ConfigCount  uint64     `json:"configCount"`
+	ConfigDigest [32]byte   `json:"configDigest"`
+}
+
 var _ HomeChain = (*homeChainPoller)(nil)

core/services/ocr3/plugins/ccip/internal/reader/home_chain_test.go

@@ -17,6 +17,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
 )
 
 var (
@@ -154,3 +155,46 @@ func Test_PollingWorking(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, homeChainConfig, configs)
 }
+
+func Test_HomeChainPoller_GetOCRConfig(t *testing.T) {
+	donID := uint32(1)
+	pluginType := uint8(1) // execution
+	homeChainReader := mocks.NewContractReaderMock()
+	homeChainReader.On(
+		"GetLatestValue",
+		mock.Anything,
+		"CCIPCapabilityConfiguration",
+		"getOCRConfig",
+		map[string]any{
+			"donId":      donID,
+			"pluginType": pluginType,
+		},
+		mock.AnythingOfType("*[]reader.OCR3ConfigWithMeta"),
+	).Return(nil).Run(func(args mock.Arguments) {
+		arg := args.Get(4).(*[]OCR3ConfigWithMeta)
+		*arg = append(*arg, OCR3ConfigWithMeta{
+			ConfigCount: 1,
+			Config: OCR3Config{
+				PluginType:     pluginType,
+				ChainSelector:  1,
+				F:              1,
+				OfframpAddress: []byte("offramp"),
+			},
+		})
+	})
+	defer homeChainReader.AssertExpectations(t)
+
+	configPoller := NewHomeChainConfigPoller(
+		homeChainReader,
+		logger.Test(t),
+		10*time.Millisecond,
+	)
+
+	configs, err := configPoller.GetOCRConfigs(context.Background(), donID, pluginType)
+	require.NoError(t, err)
+	require.Len(t, configs, 1)
+	require.Equal(t, uint8(1), configs[0].Config.PluginType)
+	require.Equal(t, cciptypes.ChainSelector(1), configs[0].Config.ChainSelector)
+	require.Equal(t, uint8(1), configs[0].Config.F)
+	require.Equal(t, []byte("offramp"), configs[0].Config.OfframpAddress)
+}