libmicrohttpd2

HTTP server C library (MHD 2.x, alpha)
Log | Files | Refs | README | LICENSE

extract_h2_huffman.sh (3414B)

      1 #!/bin/bash
      2 # SPDX-License-Identifier: LGPL-2.1-or-later OR (GPL-2.0-or-later WITH eCos-exception-2.0)
      3 
      4 set -euo pipefail
      5 
      6 OUT="h2_huffman_insert.h"
      7 TMPDIR="$(mktemp -d)"
      8 RFC_TEXT_FILE="$TMPDIR/rfc7541.txt"
      9 trap 'rm -rf "$TMPDIR"' EXIT
     10 
     11 echo "Downloading RFC specification..."
     12 wget --show-progress -O "$RFC_TEXT_FILE" "https://www.rfc-editor.org/rfc/rfc7541.txt"
     13 
     14 echo "Extractibe data..."
     15 {
     16   gawk -f - "$RFC_TEXT_FILE" <<'END_OF_AWK_SCRIPT'
     17 BEGIN { IGNORECASE=1 }
     18 {
     19   sub(/\r$/, "", $0)  # CRLF -> LF (if any)
     20 
     21   # Strictly match table lines
     22   if (match($0,
     23     /^[ ]+('.'[ ]+)?\([ ]*([0-9]+)[ ]*\)[ ]*\|[ 01|]+[ ]+([0-9A-Fa-f]+)[ ]+\[[ ]*([0-9]{1,2})[ ]*\][ ]*$/,
     24     M))
     25   {
     26     idx  = M[2] + 0
     27     hex  = M[3]
     28     blen = M[4] + 0
     29     if (idx <= 255) {
     30       code[idx] = strtonum("0x" hex)
     31       clen[idx] = blen
     32     }
     33   }
     34 }
     35 END {
     36   # Check completeness
     37   for (i = 0; i <= 255; i++)
     38   {
     39     if (!(i in code)) {
     40       printf("/* ERROR: missing Huffman entry %d */\n", i) > "/dev/stderr"
     41       exit 2
     42     }
     43   }
     44 
     45   print "/**"
     46   print " * HTTP/2 static Huffman codes from RFC 7541"
     47   print " *"
     48   print " * Index is the character value (0..255)."
     49   print " * The table values are codes that are left-algined (MSB-aligned) to"
     50   print " * the 32 bit value."
     51   print " * See https://www.rfc-editor.org/rfc/rfc7541.html#appendix-B"
     52   print " *"
     53   print " * @note The table does not include EOS code."
     54   print " */"
     55   print "mhd_constexpr uint_least32_t mhd_h2huff_code_by_sym[256] ="
     56   print "{"
     57   lens = ""
     58   for (i = 0; i <= 255; i++)
     59   {
     60     blen = clen[i]
     61 
     62     # Check length
     63     if (blen < 1 || blen > 32)
     64     {
     65       printf("/* ERROR: bad bit length %u for index %d */\n", blen, i) > "/dev/stderr"
     66       exit 2
     67     }
     68 
     69     # Check code value fits into the declared length
     70     if (rshift(code[i], blen) != 0)
     71     {
     72       printf("/* ERROR: code 0x%X for index %d exceeds its length %u */\n",
     73              code[i], i, blen) > "/dev/stderr"
     74       exit 2
     75     }
     76 
     77     # Left-align to the MSB of a 32-bit word
     78     shift = 32 - blen
     79     msb   = lshift(code[i], shift)
     80 
     81     # Check nothing beyond 32 bits (not really needed, the length has been already checked)
     82     if (rshift(msb, 32) != 0)
     83     {
     84       printf("/* ERROR: left-aligned code for index %d does not fit in 32 bits */\n",
     85              i) > "/dev/stderr"
     86       exit 2
     87     }
     88 
     89     # A label for printable US-ASCII chars
     90     label = ""
     91     if (i >= 32 && i <= 126)
     92     {
     93       ch = sprintf("%c", i)
     94       if (i == 92) ch = "\\"   # this prints a single backslash
     95       label = sprintf("%c%s%c", 39, ch, 39)
     96     }
     97     comment = sprintf("/* %3s (%3d) */", label, i)
     98 
     99     printf("  %s 0x%08Xu%s\n", comment, msb, (i < 255 ? "," : ""))
    100     lens = (lens sprintf("  %s %2uu%s\n", comment, blen, (i < 255 ? "," : "")))
    101   }
    102   print "};"
    103   print ""
    104   print ""
    105   print "/**"
    106   print " * HTTP/2 static Huffman codes length in bits from RFC 7541"
    107   print " * See https://www.rfc-editor.org/rfc/rfc7541.html#appendix-B"
    108   print " *"
    109   print " * Index is the character value (0..255)."
    110   print " * The table values are lengths of the code in bits."
    111   print " * See https://www.rfc-editor.org/rfc/rfc7541.html#appendix-B"
    112   print " *"
    113   print " * @note The table does not include EOS code."
    114   print " */"
    115   print "mhd_constexpr uint8_t mhd_h2huff_bitlen_by_sym[256] ="
    116   printf ("{\n%s};\n", lens)
    117 }
    118 END_OF_AWK_SCRIPT
    119 } > "$OUT"
    120 
    121 echo "Success."
    122 echo "The output file is: $OUT"