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/etag.hpp>
10   
#include <boost/http/server/etag.hpp>
11   
#include <cstdio>
11   
#include <cstdio>
12  
12  
13   
namespace boost {
13   
namespace boost {
14   
namespace http {
14   
namespace http {
15  
15  
16   
namespace {
16   
namespace {
17  
17  
18   
// Simple FNV-1a hash for content
18   
// Simple FNV-1a hash for content
19   
std::uint64_t
19   
std::uint64_t
20   
fnv1a_hash( core::string_view data ) noexcept
20   
fnv1a_hash( core::string_view data ) noexcept
21   
{
21   
{
22   
    constexpr std::uint64_t basis = 14695981039346656037ULL;
22   
    constexpr std::uint64_t basis = 14695981039346656037ULL;
23   
    constexpr std::uint64_t prime = 1099511628211ULL;
23   
    constexpr std::uint64_t prime = 1099511628211ULL;
24  
24  
25   
    std::uint64_t hash = basis;
25   
    std::uint64_t hash = basis;
26   
    for( unsigned char c : data )
26   
    for( unsigned char c : data )
27   
    {
27   
    {
28   
        hash ^= c;
28   
        hash ^= c;
29   
        hash *= prime;
29   
        hash *= prime;
30   
    }
30   
    }
31   
    return hash;
31   
    return hash;
32   
}
32   
}
33  
33  
34   
// Convert to null-terminated hex string
34   
// Convert to null-terminated hex string
35   
void
35   
void
36   
to_hex( std::uint64_t value, char* out ) noexcept
36   
to_hex( std::uint64_t value, char* out ) noexcept
37   
{
37   
{
38   
    constexpr char hex[] = "0123456789abcdef";
38   
    constexpr char hex[] = "0123456789abcdef";
39   
    for( int i = 15; i >= 0; --i )
39   
    for( int i = 15; i >= 0; --i )
40   
    {
40   
    {
41   
        out[i] = hex[value & 0xF];
41   
        out[i] = hex[value & 0xF];
42   
        value >>= 4;
42   
        value >>= 4;
43   
    }
43   
    }
44   
    out[16] = '\0';
44   
    out[16] = '\0';
45   
}
45   
}
46  
46  
47   
} // (anon)
47   
} // (anon)
48  
48  
49   
std::string
49   
std::string
50   
etag( core::string_view body, etag_options opts )
50   
etag( core::string_view body, etag_options opts )
51   
{
51   
{
52   
    auto const hash = fnv1a_hash( body );
52   
    auto const hash = fnv1a_hash( body );
53  
53  
54   
    char hex[17];
54   
    char hex[17];
55   
    to_hex( hash, hex );
55   
    to_hex( hash, hex );
56  
56  
57   
    char buf[64];
57   
    char buf[64];
58   
    int n;
58   
    int n;
59   
    if( opts.weak )
59   
    if( opts.weak )
60   
        n = std::snprintf( buf, sizeof(buf),
60   
        n = std::snprintf( buf, sizeof(buf),
61   
            "W/\"%zx-%s\"", body.size(), hex );
61   
            "W/\"%zx-%s\"", body.size(), hex );
62   
    else
62   
    else
63   
        n = std::snprintf( buf, sizeof(buf),
63   
        n = std::snprintf( buf, sizeof(buf),
64   
            "\"%zx-%s\"", body.size(), hex );
64   
            "\"%zx-%s\"", body.size(), hex );
65  
65  
66   
    return std::string( buf, static_cast<std::size_t>(n) );
66   
    return std::string( buf, static_cast<std::size_t>(n) );
67   
}
67   
}
68  
68  
69   
std::string
69   
std::string
70   
etag(
70   
etag(
71   
    std::uint64_t size,
71   
    std::uint64_t size,
72   
    std::uint64_t mtime,
72   
    std::uint64_t mtime,
73   
    etag_options opts )
73   
    etag_options opts )
74   
{
74   
{
75   
    char buf[64];
75   
    char buf[64];
76   
    int n;
76   
    int n;
77   
    if( opts.weak )
77   
    if( opts.weak )
78   
        n = std::snprintf( buf, sizeof(buf),
78   
        n = std::snprintf( buf, sizeof(buf),
79   
            "W/\"%llx-%llx\"",
79   
            "W/\"%llx-%llx\"",
80   
            static_cast<unsigned long long>( size ),
80   
            static_cast<unsigned long long>( size ),
81   
            static_cast<unsigned long long>( mtime ) );
81   
            static_cast<unsigned long long>( mtime ) );
82   
    else
82   
    else
83   
        n = std::snprintf( buf, sizeof(buf),
83   
        n = std::snprintf( buf, sizeof(buf),
84   
            "\"%llx-%llx\"",
84   
            "\"%llx-%llx\"",
85   
            static_cast<unsigned long long>( size ),
85   
            static_cast<unsigned long long>( size ),
86   
            static_cast<unsigned long long>( mtime ) );
86   
            static_cast<unsigned long long>( mtime ) );
87  
87  
88   
    return std::string( buf, static_cast<std::size_t>(n) );
88   
    return std::string( buf, static_cast<std::size_t>(n) );
89   
}
89   
}
90  
90  
91   
} // http
91   
} // http
92   
} // boost
92   
} // boost