go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/cipkg/base/actions/url.go (about)

     1  // Copyright 2023 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //	http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package actions
    16  
    17  import (
    18  	"context"
    19  	"crypto"
    20  	"errors"
    21  	"fmt"
    22  	"hash"
    23  	"io"
    24  	"net/http"
    25  	"os"
    26  	"path/filepath"
    27  
    28  	"go.chromium.org/luci/cipkg/core"
    29  )
    30  
    31  // ActionURLFetchTransformer is the default transformer for
    32  // core.ActionURLFetch.
    33  func ActionURLFetchTransformer(a *core.ActionURLFetch, deps []Package) (*core.Derivation, error) {
    34  	return ReexecDerivation(a, false)
    35  }
    36  
    37  // ActionURLFetchExecutor is the default executor for core.ActionURLFetch.
    38  func ActionURLFetchExecutor(ctx context.Context, a *core.ActionURLFetch, out string) (err error) {
    39  	req, err := http.NewRequestWithContext(ctx, http.MethodGet, a.Url, nil)
    40  	if err != nil {
    41  		return
    42  	}
    43  
    44  	joinErr := func(f func() error) { err = errors.Join(err, f()) }
    45  
    46  	resp, err := http.DefaultClient.Do(req)
    47  	if err != nil {
    48  		return
    49  	}
    50  	defer joinErr(resp.Body.Close)
    51  
    52  	f, err := os.Create(filepath.Join(out, "file"))
    53  	if err != nil {
    54  		return
    55  	}
    56  	defer joinErr(f.Close)
    57  
    58  	h, err := hashFromEnum(a.HashAlgorithm)
    59  	if err != nil {
    60  		return
    61  	}
    62  
    63  	if _, err = io.Copy(f, io.TeeReader(resp.Body, h)); err != nil {
    64  		return
    65  	}
    66  
    67  	if actual := fmt.Sprintf("%x", h.Sum(nil)); actual != a.HashValue {
    68  		return fmt.Errorf("hash mismatch: expected: %s, actual: %s", a.HashValue, actual)
    69  	}
    70  	return
    71  }
    72  
    73  func hashFromEnum(h core.HashAlgorithm) (hash.Hash, error) {
    74  	if h == core.HashAlgorithm_HASH_UNSPECIFIED {
    75  		return &emptyHash{}, nil
    76  	}
    77  
    78  	switch h {
    79  	case core.HashAlgorithm_HASH_MD5:
    80  		return crypto.MD5.New(), nil
    81  	case core.HashAlgorithm_HASH_SHA256:
    82  		return crypto.SHA256.New(), nil
    83  	}
    84  
    85  	return nil, fmt.Errorf("unknown hash algorithm: %s", h)
    86  }
    87  
    88  // If no hash algorithm is provided, we will use an empty hash to skip the
    89  // check and assume the artifact from the url is always same. This is only
    90  // used for legacy content.
    91  type emptyHash struct{}
    92  
    93  func (h *emptyHash) Write(p []byte) (int, error) { return len(p), nil }
    94  func (h *emptyHash) Sum(b []byte) []byte         { return []byte{} }
    95  func (h *emptyHash) Reset()                      {}
    96  func (h *emptyHash) Size() int                   { return 0 }
    97  func (h *emptyHash) BlockSize() int              { return 0 }