Import Punycode reference implementation.

2 files changed, 447 insertions, 0 deletions

diff --git a/utils/punycode.c b/utils/punycode.c
new file mode 100644
index 000000000..8b2197d66
--- /dev/null
+++ b/utils/punycode.c
@@ -0,0 +1,280 @@
+/*
+punycode-sample.c 2.0.0 (2004-Mar-21-Sun)
+http://www.nicemice.net/idn/
+Adam M. Costello
+http://www.nicemice.net/amc/
+
+This is ANSI C code (C89) implementing Punycode 1.0.x.
+*/
+
+/**********************************************************/
+/* Implementation (would normally go in its own .c file): */
+
+#include <string.h>
+
+#include "punycode.h"
+
+/*** Bootstring parameters for Punycode ***/
+
+enum { base = 36, tmin = 1, tmax = 26, skew = 38, damp = 700,
+       initial_bias = 72, initial_n = 0x80, delimiter = 0x2D };
+
+/* basic(cp) tests whether cp is a basic code point: */
+#define basic(cp) ((punycode_uint)(cp) < 0x80)
+
+/* delim(cp) tests whether cp is a delimiter: */
+#define delim(cp) ((cp) == delimiter)
+
+/* decode_digit(cp) returns the numeric value of a basic code */
+/* point (for use in representing integers) in the range 0 to */
+/* base-1, or base if cp does not represent a value.          */
+
+static punycode_uint decode_digit(punycode_uint cp)
+{
+  return  cp - 48 < 10 ? cp - 22 :  cp - 65 < 26 ? cp - 65 :
+          cp - 97 < 26 ? cp - 97 :  base;
+}
+
+/* encode_digit(d,flag) returns the basic code point whose value      */
+/* (when used for representing integers) is d, which needs to be in   */
+/* the range 0 to base-1.  The lowercase form is used unless flag is  */
+/* nonzero, in which case the uppercase form is used.  The behavior   */
+/* is undefined if flag is nonzero and digit d has no uppercase form. */
+
+static char encode_digit(punycode_uint d, int flag)
+{
+  return d + 22 + 75 * (d < 26) - ((flag != 0) << 5);
+  /*  0..25 map to ASCII a..z or A..Z */
+  /* 26..35 map to ASCII 0..9         */
+}
+
+/* flagged(bcp) tests whether a basic code point is flagged */
+/* (uppercase).  The behavior is undefined if bcp is not a  */
+/* basic code point.                                        */
+
+#define flagged(bcp) ((punycode_uint)(bcp) - 65 < 26)
+
+/* encode_basic(bcp,flag) forces a basic code point to lowercase */
+/* if flag is zero, uppercase if flag is nonzero, and returns    */
+/* the resulting code point.  The code point is unchanged if it  */
+/* is caseless.  The behavior is undefined if bcp is not a basic */
+/* code point.                                                   */
+
+static char encode_basic(punycode_uint bcp, int flag)
+{
+  bcp -= (bcp - 97 < 26) << 5;
+  return bcp + ((!flag && (bcp - 65 < 26)) << 5);
+}
+
+/*** Platform-specific constants ***/
+
+/* maxint is the maximum value of a punycode_uint variable: */
+static const punycode_uint maxint = -1;
+/* Because maxint is unsigned, -1 becomes the maximum value. */
+
+/*** Bias adaptation function ***/
+
+static punycode_uint adapt(
+  punycode_uint delta, punycode_uint numpoints, int firsttime )
+{
+  punycode_uint k;
+
+  delta = firsttime ? delta / damp : delta >> 1;
+  /* delta >> 1 is a faster way of doing delta / 2 */
+  delta += delta / numpoints;
+
+  for (k = 0;  delta > ((base - tmin) * tmax) / 2;  k += base) {
+    delta /= base - tmin;
+  }
+
+  return k + (base - tmin + 1) * delta / (delta + skew);
+}
+
+/*** Main encode function ***/
+
+enum punycode_status punycode_encode(
+  size_t input_length_orig,
+  const punycode_uint input[],
+  const unsigned char case_flags[],
+  size_t *output_length,
+  char output[] )
+{
+  punycode_uint input_length, n, delta, h, b, bias, j, m, q, k, t;
+  size_t out, max_out;
+
+  /* The Punycode spec assumes that the input length is the same type */
+  /* of integer as a code point, so we need to convert the size_t to  */
+  /* a punycode_uint, which could overflow.                           */
+
+  if (input_length_orig > maxint) return punycode_overflow;
+  input_length = (punycode_uint) input_length_orig;
+
+  /* Initialize the state: */
+
+  n = initial_n;
+  delta = 0;
+  out = 0;
+  max_out = *output_length;
+  bias = initial_bias;
+
+  /* Handle the basic code points: */
+
+  for (j = 0;  j < input_length;  ++j) {
+    if (basic(input[j])) {
+      if (max_out - out < 2) return punycode_big_output;
+      output[out++] = case_flags ?
+        encode_basic(input[j], case_flags[j]) : (char) input[j];
+    }
+    /* else if (input[j] < n) return punycode_bad_input; */
+    /* (not needed for Punycode with unsigned code points) */
+  }
+
+  h = b = (punycode_uint) out;
+  /* cannot overflow because out <= input_length <= maxint */
+
+  /* h is the number of code points that have been handled, b is the  */
+  /* number of basic code points, and out is the number of ASCII code */
+  /* points that have been output.                                    */
+
+  if (b > 0) output[out++] = delimiter;
+
+  /* Main encoding loop: */
+
+  while (h < input_length) {
+    /* All non-basic code points < n have been     */
+    /* handled already.  Find the next larger one: */
+
+    for (m = maxint, j = 0;  j < input_length;  ++j) {
+      /* if (basic(input[j])) continue; */
+      /* (not needed for Punycode) */
+      if (input[j] >= n && input[j] < m) m = input[j];
+    }
+
+    /* Increase delta enough to advance the decoder's    */
+    /* <n,i> state to <m,0>, but guard against overflow: */
+
+    if (m - n > (maxint - delta) / (h + 1)) return punycode_overflow;
+    delta += (m - n) * (h + 1);
+    n = m;
+
+    for (j = 0;  j < input_length;  ++j) {
+      /* Punycode does not need to check whether input[j] is basic: */
+      if (input[j] < n /* || basic(input[j]) */ ) {
+        if (++delta == 0) return punycode_overflow;
+      }
+
+      if (input[j] == n) {
+        /* Represent delta as a generalized variable-length integer: */
+
+        for (q = delta, k = base;  ;  k += base) {
+          if (out >= max_out) return punycode_big_output;
+          t = k <= bias /* + tmin */ ? tmin :     /* +tmin not needed */
+              k >= bias + tmax ? tmax : k - bias;
+          if (q < t) break;
+          output[out++] = encode_digit(t + (q - t) % (base - t), 0);
+          q = (q - t) / (base - t);
+        }
+
+        output[out++] = encode_digit(q, case_flags && case_flags[j]);
+        bias = adapt(delta, h + 1, h == b);
+        delta = 0;
+        ++h;
+      }
+    }
+
+    ++delta, ++n;
+  }
+
+  *output_length = out;
+  return punycode_success;
+}
+
+/*** Main decode function ***/
+
+enum punycode_status punycode_decode(
+  size_t input_length,
+  const char input[],
+  size_t *output_length,
+  punycode_uint output[],
+  unsigned char case_flags[] )
+{
+  punycode_uint n, out, i, max_out, bias, oldi, w, k, digit, t;
+  size_t b, j, in;
+
+  /* Initialize the state: */
+
+  n = initial_n;
+  out = i = 0;
+  max_out = *output_length > maxint ? maxint
+            : (punycode_uint) *output_length;
+  bias = initial_bias;
+
+  /* Handle the basic code points:  Let b be the number of input code */
+  /* points before the last delimiter, or 0 if there is none, then    */
+  /* copy the first b code points to the output.                      */
+
+  for (b = j = 0;  j < input_length;  ++j)  if (delim(input[j])) b = j;
+  if (b > max_out) return punycode_big_output;
+
+  for (j = 0;  j < b;  ++j) {
+    if (case_flags) case_flags[out] = flagged(input[j]);
+    if (!basic(input[j])) return punycode_bad_input;
+    output[out++] = input[j];
+  }
+
+  /* Main decoding loop:  Start just after the last delimiter if any  */
+  /* basic code points were copied; start at the beginning otherwise. */
+
+  for (in = b > 0 ? b + 1 : 0;  in < input_length;  ++out) {
+
+    /* in is the index of the next ASCII code point to be consumed, */
+    /* and out is the number of code points in the output array.    */
+
+    /* Decode a generalized variable-length integer into delta,  */
+    /* which gets added to i.  The overflow checking is easier   */
+    /* if we increase i as we go, then subtract off its starting */
+    /* value at the end to obtain delta.                         */
+
+    for (oldi = i, w = 1, k = base;  ;  k += base) {
+      if (in >= input_length) return punycode_bad_input;
+      digit = decode_digit(input[in++]);
+      if (digit >= base) return punycode_bad_input;
+      if (digit > (maxint - i) / w) return punycode_overflow;
+      i += digit * w;
+      t = k <= bias /* + tmin */ ? tmin :     /* +tmin not needed */
+          k >= bias + tmax ? tmax : k - bias;
+      if (digit < t) break;
+      if (w > maxint / (base - t)) return punycode_overflow;
+      w *= (base - t);
+    }
+
+    bias = adapt(i - oldi, out + 1, oldi == 0);
+
+    /* i was supposed to wrap around from out+1 to 0,   */
+    /* incrementing n each time, so we'll fix that now: */
+
+    if (i / (out + 1) > maxint - n) return punycode_overflow;
+    n += i / (out + 1);
+    i %= (out + 1);
+
+    /* Insert n at position i of the output: */
+
+    /* not needed for Punycode: */
+    /* if (basic(n)) return punycode_bad_input; */
+    if (out >= max_out) return punycode_big_output;
+
+    if (case_flags) {
+      memmove(case_flags + i + 1, case_flags + i, out - i);
+      /* Case of last ASCII code point determines case flag: */
+      case_flags[i] = flagged(input[in - 1]);
+    }
+
+    memmove(output + i + 1, output + i, (out - i) * sizeof *output);
+    output[i++] = n;
+  }
+
+  *output_length = (size_t) out;
+  /* cannot overflow because out <= old value of *output_length */
+  return punycode_success;
+}
+
diff --git a/utils/punycode.h b/utils/punycode.h
new file mode 100644
index 000000000..15269cc69
--- /dev/null
+++ b/utils/punycode.h
@@ -0,0 +1,167 @@
+/*
+punycode-sample.c 2.0.0 (2004-Mar-21-Sun)
+http://www.nicemice.net/idn/
+Adam M. Costello
+http://www.nicemice.net/amc/
+
+This is ANSI C code (C89) implementing Punycode 1.0.x.
+
+This single file contains three sections (an interface, an
+implementation, and a wrapper for testing) that would normally belong
+in three separate files (punycode.h, punycode.c, punycode-test.c), but
+here they are bundled into one file (punycode-sample.c) for convenient
+testing.  Anyone wishing to reuse this code will probably want to split
+it apart.
+
+*/
+
+/************************************************************/
+/* Public interface (would normally go in its own .h file): */
+
+#include <limits.h>
+#include <stddef.h>
+
+enum punycode_status {
+  punycode_success    = 0,
+  punycode_bad_input  = 1, /* Input is invalid.                       */
+  punycode_big_output = 2, /* Output would exceed the space provided. */
+  punycode_overflow   = 3  /* Wider integers needed to process input. */
+};
+
+/* punycode_uint needs to be unsigned and needs to be */
+/* at least 26 bits wide.  The particular type can be */
+/* specified by defining PUNYCODE_UINT, otherwise a   */
+/* suitable type will be chosen automatically.        */
+
+#ifdef PUNYCODE_UINT
+  typedef PUNYCODE_UINT punycode_uint;
+#elif UINT_MAX >= (1 << 26) - 1
+  typedef unsigned int punycode_uint;
+#else
+  typedef unsigned long punycode_uint;
+#endif
+
+enum punycode_status punycode_encode(
+  size_t,                 /* input_length  */
+  const punycode_uint [], /* input         */
+  const unsigned char [], /* case_flags    */
+  size_t *,               /* output_length */
+  char []                 /* output        */
+);
+
+/*
+    punycode_encode() converts a sequence of code points (presumed to be
+    Unicode code points) to Punycode.
+
+    Input arguments (to be supplied by the caller):
+
+        input_length
+            The number of code points in the input array and the number
+            of flags in the case_flags array.
+
+        input
+            An array of code points.  They are presumed to be Unicode
+            code points, but that is not strictly necessary.  The
+            array contains code points, not code units.  UTF-16 uses
+            code units D800 through DFFF to refer to code points
+            10000..10FFFF.  The code points D800..DFFF do not occur in
+            any valid Unicode string.  The code points that can occur in
+            Unicode strings (0..D7FF and E000..10FFFF) are also called
+            Unicode scalar values.
+
+        case_flags
+            A null pointer or an array of boolean values parallel to
+            the input array.  Nonzero (true, flagged) suggests that the
+            corresponding Unicode character be forced to uppercase after
+            being decoded (if possible), and zero (false, unflagged)
+            suggests that it be forced to lowercase (if possible).
+            ASCII code points (0..7F) are encoded literally, except that
+            ASCII letters are forced to uppercase or lowercase according
+            to the corresponding case flags.  If case_flags is a null
+            pointer then ASCII letters are left as they are, and other
+            code points are treated as unflagged.
+
+    Output arguments (to be filled in by the function):
+
+        output
+            An array of ASCII code points.  It is *not* null-terminated;
+            it will contain zeros if and only if the input contains
+            zeros.  (Of course the caller can leave room for a
+            terminator and add one if needed.)
+
+    Input/output arguments (to be supplied by the caller and overwritten
+    by the function):
+
+        output_length
+            The caller passes in the maximum number of ASCII code points
+            that it can receive.  On successful return it will contain
+            the number of ASCII code points actually output.
+
+    Return value:
+
+        Can be any of the punycode_status values defined above except
+        punycode_bad_input.  If not punycode_success, then output_size
+        and output might contain garbage.
+*/
+
+enum punycode_status punycode_decode(
+  size_t,           /* input_length  */
+  const char [],    /* input         */
+  size_t *,         /* output_length */
+  punycode_uint [], /* output        */
+  unsigned char []  /* case_flags    */
+);
+
+/*
+    punycode_decode() converts Punycode to a sequence of code points
+    (presumed to be Unicode code points).
+
+    Input arguments (to be supplied by the caller):
+
+        input_length
+            The number of ASCII code points in the input array.
+
+        input
+            An array of ASCII code points (0..7F).
+
+    Output arguments (to be filled in by the function):
+
+        output
+            An array of code points like the input argument of
+            punycode_encode() (see above).
+
+        case_flags
+            A null pointer (if the flags are not needed by the caller)
+            or an array of boolean values parallel to the output array.
+            Nonzero (true, flagged) suggests that the corresponding
+            Unicode character be forced to uppercase by the caller (if
+            possible), and zero (false, unflagged) suggests that it
+            be forced to lowercase (if possible).  ASCII code points
+            (0..7F) are output already in the proper case, but their
+            flags will be set appropriately so that applying the flags
+            would be harmless.
+
+    Input/output arguments (to be supplied by the caller and overwritten
+    by the function):
+
+        output_length
+            The caller passes in the maximum number of code points
+            that it can receive into the output array (which is also
+            the maximum number of flags that it can receive into the
+            case_flags array, if case_flags is not a null pointer).  On
+            successful return it will contain the number of code points
+            actually output (which is also the number of flags actually
+            output, if case_flags is not a null pointer).  The decoder
+            will never need to output more code points than the number
+            of ASCII code points in the input, because of the way the
+            encoding is defined.  The number of code points output
+            cannot exceed the maximum possible value of a punycode_uint,
+            even if the supplied output_length is greater than that.
+
+    Return value:
+
+        Can be any of the punycode_status values defined above.  If not
+        punycode_success, then output_length, output, and case_flags
+        might contain garbage.
+*/
+