117 lines
3.2 KiB
Go
117 lines
3.2 KiB
Go
package client
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import (
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"github.com/pkg/errors"
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"github.com/tendermint/go-wire/data"
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"github.com/tendermint/iavl"
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"github.com/tendermint/light-client/certifiers"
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certerr "github.com/tendermint/light-client/certifiers/errors"
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"github.com/tendermint/tendermint/rpc/client"
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)
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// GetWithProof will query the key on the given node, and verify it has
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// a valid proof, as defined by the certifier.
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//
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// If there is any error in checking, returns an error.
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// If val is non-empty, proof should be KeyExistsProof
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// If val is empty, proof should be KeyMissingProof
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func GetWithProof(key []byte, reqHeight int, node client.Client,
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cert certifiers.Certifier) (
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val data.Bytes, height uint64, proof iavl.KeyProof, err error) {
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if reqHeight < 0 {
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err = errors.Errorf("Height cannot be negative")
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return
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}
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resp, err := node.ABCIQueryWithOptions("/key", key,
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client.ABCIQueryOptions{Height: uint64(reqHeight)})
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if err != nil {
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return
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}
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// make sure the proof is the proper height
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if !resp.Code.IsOK() {
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err = errors.Errorf("Query error %d: %s", resp.Code, resp.Code.String())
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return
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}
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if len(resp.Key) == 0 || len(resp.Proof) == 0 {
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err = ErrNoData()
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return
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}
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if resp.Height == 0 {
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err = errors.New("Height returned is zero")
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return
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}
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// AppHash for height H is in header H+1
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var commit *certifiers.Commit
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commit, err = GetCertifiedCommit(int(resp.Height+1), node, cert)
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if err != nil {
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return
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}
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if len(resp.Value) > 0 {
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// The key was found, construct a proof of existence.
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var eproof *iavl.KeyExistsProof
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eproof, err = iavl.ReadKeyExistsProof(resp.Proof)
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if err != nil {
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err = errors.Wrap(err, "Error reading proof")
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return
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}
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// Validate the proof against the certified header to ensure data integrity.
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err = eproof.Verify(resp.Key, resp.Value, commit.Header.AppHash)
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if err != nil {
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err = errors.Wrap(err, "Couldn't verify proof")
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return
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}
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val = data.Bytes(resp.Value)
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proof = eproof
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} else {
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// The key wasn't found, construct a proof of non-existence.
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var aproof *iavl.KeyAbsentProof
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aproof, err = iavl.ReadKeyAbsentProof(resp.Proof)
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if err != nil {
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err = errors.Wrap(err, "Error reading proof")
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return
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}
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// Validate the proof against the certified header to ensure data integrity.
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err = aproof.Verify(resp.Key, nil, commit.Header.AppHash)
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if err != nil {
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err = errors.Wrap(err, "Couldn't verify proof")
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return
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}
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err = ErrNoData()
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proof = aproof
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}
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height = resp.Height
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return
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}
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// GetCertifiedCommit gets the signed header for a given height
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// and certifies it. Returns error if unable to get a proven header.
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func GetCertifiedCommit(h int, node client.Client,
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cert certifiers.Certifier) (empty *certifiers.Commit, err error) {
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// FIXME: cannot use cert.GetByHeight for now, as it also requires
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// Validators and will fail on querying tendermint for non-current height.
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// When this is supported, we should use it instead...
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client.WaitForHeight(node, h, nil)
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cresp, err := node.Commit(&h)
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if err != nil {
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return
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}
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commit := certifiers.CommitFromResult(cresp)
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// validate downloaded checkpoint with our request and trust store.
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if commit.Height() != h {
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return empty, certerr.ErrHeightMismatch(h, commit.Height())
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}
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err = cert.Certify(commit)
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return commit, nil
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}
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