github.com/google/trillian-examples@v0.0.0-20240520080811-0d40d35cef0e/clone/internal/download/http.go (about)

     1  // Copyright 2021 Google LLC
     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  //    https://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 download provides a fetcher to get data via http(s).
    16  package download
    17  
    18  import (
    19  	"fmt"
    20  	"io"
    21  	"net/http"
    22  	"net/url"
    23  
    24  	"github.com/golang/glog"
    25  )
    26  
    27  // NewHTTPFetcher returns an HTTPFetcher that gets paths appended to the given prefix.
    28  func NewHTTPFetcher(prefix *url.URL) HTTPFetcher {
    29  	return HTTPFetcher{
    30  		baseURL: prefix,
    31  	}
    32  }
    33  
    34  // HTTPFetcher gets the data over HTTP(S).
    35  // This is thread safe.
    36  type HTTPFetcher struct {
    37  	baseURL *url.URL
    38  }
    39  
    40  // GetData gets the data at the given path.
    41  func (f HTTPFetcher) GetData(path string) ([]byte, error) {
    42  	u, err := f.baseURL.Parse(path)
    43  	if err != nil {
    44  		return nil, fmt.Errorf("url (%s) failed to parse(%s): %w", f.baseURL, path, err)
    45  	}
    46  	target := u.String()
    47  	resp, err := http.Get(target)
    48  	if err != nil {
    49  		return nil, fmt.Errorf("http.Get: %w", err)
    50  	}
    51  	defer func() {
    52  		if err := resp.Body.Close(); err != nil {
    53  			glog.Errorf("resp.Body.Close(): %v", err)
    54  		}
    55  	}()
    56  	if resp.StatusCode != 200 {
    57  		// Could be worth returning a special error when we've been explicitly told to back off.
    58  		return nil, fmt.Errorf("GET %v: %v", target, resp.Status)
    59  	}
    60  	// TODO(mhutchinson): Consider using io.LimitReader and making it configurable.
    61  	data, err := io.ReadAll(resp.Body)
    62  	if err != nil {
    63  		return nil, fmt.Errorf("io.ReadAll: %w", err)
    64  	}
    65  	return data, nil
    66  }