1   
//
1   
//
2   
// Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
2   
// Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3   
//
3   
//
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   
//
6   
//
7   
// Official repository: https://github.com/cppalliance/http
7   
// Official repository: https://github.com/cppalliance/http
8   
//
8   
//
9  
9  
10   
#include <boost/http/server/fresh.hpp>
10   
#include <boost/http/server/fresh.hpp>
11   
#include <boost/http/field.hpp>
11   
#include <boost/http/field.hpp>
12  
12  
13   
namespace boost {
13   
namespace boost {
14   
namespace http {
14   
namespace http {
15  
15  
16   
namespace {
16   
namespace {
17  
17  
18   
// Check if ETag matches If-None-Match
18   
// Check if ETag matches If-None-Match
19   
// Returns true if they match (response is fresh)
19   
// Returns true if they match (response is fresh)
20   
bool
20   
bool
21   
etag_matches(
21   
etag_matches(
22   
    core::string_view if_none_match,
22   
    core::string_view if_none_match,
23   
    core::string_view etag ) noexcept
23   
    core::string_view etag ) noexcept
24   
{
24   
{
25   
    if( if_none_match.empty() || etag.empty() )
25   
    if( if_none_match.empty() || etag.empty() )
26   
        return false;
26   
        return false;
27  
27  
28   
    // "*" matches any ETag
28   
    // "*" matches any ETag
29   
    if( if_none_match == "*" )
29   
    if( if_none_match == "*" )
30   
        return true;
30   
        return true;
31  
31  
32   
    // Simple comparison - check if ETag appears in the list
32   
    // Simple comparison - check if ETag appears in the list
33   
    // In full implementation, would need to handle weak vs strong
33   
    // In full implementation, would need to handle weak vs strong
34   
    // and parse comma-separated list properly
34   
    // and parse comma-separated list properly
35  
35  
36   
    // Remove W/ prefix for comparison if present
36   
    // Remove W/ prefix for comparison if present
37   
    auto strip_weak = []( core::string_view s ) -> core::string_view
37   
    auto strip_weak = []( core::string_view s ) -> core::string_view
38   
    {
38   
    {
39   
        if( s.size() >= 2 &&
39   
        if( s.size() >= 2 &&
40   
            ( s[0] == 'W' || s[0] == 'w' ) &&
40   
            ( s[0] == 'W' || s[0] == 'w' ) &&
41   
            s[1] == '/' )
41   
            s[1] == '/' )
42   
            return s.substr( 2 );
42   
            return s.substr( 2 );
43   
        return s;
43   
        return s;
44   
    };
44   
    };
45  
45  
46   
    auto const etag_val = strip_weak( etag );
46   
    auto const etag_val = strip_weak( etag );
47  
47  
48   
    // Simple contains check for the ETag value
48   
    // Simple contains check for the ETag value
49   
    auto pos = if_none_match.find( etag_val );
49   
    auto pos = if_none_match.find( etag_val );
50   
    if( pos != core::string_view::npos )
50   
    if( pos != core::string_view::npos )
51   
        return true;
51   
        return true;
52  
52  
53   
    // Also check without weak prefix in if_none_match
53   
    // Also check without weak prefix in if_none_match
54   
    auto const inm_stripped = strip_weak( if_none_match );
54   
    auto const inm_stripped = strip_weak( if_none_match );
55   
    if( inm_stripped == etag_val )
55   
    if( inm_stripped == etag_val )
56   
        return true;
56   
        return true;
57  
57  
58   
    return false;
58   
    return false;
59   
}
59   
}
60  
60  
61   
// Parse HTTP date and compare
61   
// Parse HTTP date and compare
62   
// Returns true if response's Last-Modified <= request's If-Modified-Since
62   
// Returns true if response's Last-Modified <= request's If-Modified-Since
63   
// For simplicity, doing string comparison (works for RFC 7231 dates)
63   
// For simplicity, doing string comparison (works for RFC 7231 dates)
64   
bool
64   
bool
65   
not_modified_since(
65   
not_modified_since(
66   
    core::string_view if_modified_since,
66   
    core::string_view if_modified_since,
67   
    core::string_view last_modified ) noexcept
67   
    core::string_view last_modified ) noexcept
68   
{
68   
{
69   
    if( if_modified_since.empty() || last_modified.empty() )
69   
    if( if_modified_since.empty() || last_modified.empty() )
70   
        return false;
70   
        return false;
71  
71  
72   
    // HTTP dates in RFC 7231 format are lexicographically comparable
72   
    // HTTP dates in RFC 7231 format are lexicographically comparable
73   
    // when in the same format (preferred format)
73   
    // when in the same format (preferred format)
74   
    // For a robust implementation, would parse dates properly
74   
    // For a robust implementation, would parse dates properly
75   
    return last_modified <= if_modified_since;
75   
    return last_modified <= if_modified_since;
76   
}
76   
}
77  
77  
78   
} // (anon)
78   
} // (anon)
79  
79  
80   
bool
80   
bool
81   
is_fresh(
81   
is_fresh(
82   
    request const& req,
82   
    request const& req,
83   
    response const& res ) noexcept
83   
    response const& res ) noexcept
84   
{
84   
{
85   
    // Get conditional request headers
85   
    // Get conditional request headers
86   
    auto const if_none_match = req.value_or(
86   
    auto const if_none_match = req.value_or(
87   
        field::if_none_match, "" );
87   
        field::if_none_match, "" );
88   
    auto const if_modified_since = req.value_or(
88   
    auto const if_modified_since = req.value_or(
89   
        field::if_modified_since, "" );
89   
        field::if_modified_since, "" );
90  
90  
91   
    // If no conditional headers, not fresh
91   
    // If no conditional headers, not fresh
92   
    if( if_none_match.empty() && if_modified_since.empty() )
92   
    if( if_none_match.empty() && if_modified_since.empty() )
93   
        return false;
93   
        return false;
94  
94  
95   
    // Get response caching headers
95   
    // Get response caching headers
96   
    auto const etag = res.value_or( field::etag, "" );
96   
    auto const etag = res.value_or( field::etag, "" );
97   
    auto const last_modified = res.value_or(
97   
    auto const last_modified = res.value_or(
98   
        field::last_modified, "" );
98   
        field::last_modified, "" );
99  
99  
100   
    // Check ETag first (stronger validator)
100   
    // Check ETag first (stronger validator)
101   
    if( ! if_none_match.empty() )
101   
    if( ! if_none_match.empty() )
102   
    {
102   
    {
103   
        if( ! etag.empty() && etag_matches( if_none_match, etag ) )
103   
        if( ! etag.empty() && etag_matches( if_none_match, etag ) )
104   
            return true;
104   
            return true;
105   
        // If If-None-Match present but doesn't match, not fresh
105   
        // If If-None-Match present but doesn't match, not fresh
106   
        return false;
106   
        return false;
107   
    }
107   
    }
108  
108  
109   
    // Fall back to If-Modified-Since
109   
    // Fall back to If-Modified-Since
110   
    if( ! if_modified_since.empty() && ! last_modified.empty() )
110   
    if( ! if_modified_since.empty() && ! last_modified.empty() )
111   
    {
111   
    {
112   
        return not_modified_since( if_modified_since, last_modified );
112   
        return not_modified_since( if_modified_since, last_modified );
113   
    }
113   
    }
114  
114  
115   
    return false;
115   
    return false;
116   
}
116   
}
117  
117  
118   
} // http
118   
} // http
119   
} // boost
119   
} // boost