github.com/mendersoftware/go-lib-micro@v0.0.0-20240304135804-e8e39c59b148/context/httpheader/header.go (about)

     1  // Copyright 2023 Northern.tech AS
     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  package httpheader
    15  
    16  import (
    17  	"context"
    18  	"net/http"
    19  	"net/textproto"
    20  )
    21  
    22  type headerKeyType string
    23  
    24  func makeKeyName(hdr string) headerKeyType {
    25  	key := textproto.CanonicalMIMEHeaderKey(hdr)
    26  	return headerKeyType(key)
    27  }
    28  
    29  // WithContext stores HTTP headers from `hdrs` which listed in `which` in a
    30  // context and returns the new context (ctx becomes the parent of newly created
    31  // context). Headers care provided as http.Header. Headers that are unset in
    32  // `hdrs` are skipped. Empty header names are skipped as well. Headers are
    33  // stored using httpheader package specific key namespace.
    34  func WithContext(ctx context.Context, hdrs http.Header, which ...string) context.Context {
    35  	if hdrs == nil || len(hdrs) == 0 {
    36  		return ctx
    37  	}
    38  	if len(which) == 0 {
    39  		return ctx
    40  	}
    41  
    42  	for _, h := range which {
    43  		if h == "" {
    44  			continue
    45  		}
    46  		hv := hdrs.Get(h)
    47  		if hv == "" {
    48  			continue
    49  		}
    50  		ctx = context.WithValue(ctx, makeKeyName(h), hdrs.Get(h))
    51  	}
    52  	return ctx
    53  }
    54  
    55  // FromContext extracts httpheader header and returns a string. If header was
    56  // not set in the context, an empty string is returned.
    57  func FromContext(ctx context.Context, hdr string) string {
    58  	v, ok := ctx.Value(makeKeyName(hdr)).(string)
    59  	if !ok {
    60  		return ""
    61  	}
    62  	return v
    63  }