--- /dev/null
+/* Copyright (c) 2024 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "array.h"
+#include "str.h"
+#include "unichar.h"
+#include "punycode.h"
+
+/* Bootstring parameters for Punycode */
+
+static const unsigned int base = 36; /* maximum basic code point */
+static const unsigned int tmin = 1;
+static const unsigned int tmax = 26;
+static const unsigned int skew = 38;
+static const unsigned int damp = 700;
+static const unsigned int initialBias = 72;
+static const unsigned int initialN = 0x80;
+static const unsigned int delimiter = u'-';
+
+/*
+ code points digit-values
+ ------------ ----------------------
+ 41..5A (A-Z) = 0 to 25, respectively
+ 61..7A (a-z) = 0 to 25, respectively
+ 30..39 (0-9) = 26 to 35, respectively
+*/
+static inline unsigned int decode_digit(unsigned char cp)
+{
+ if (cp >= '0' && cp <= '9')
+ return cp - u'0' + 26;
+ else if (cp >= 'A' && cp <= 'Z')
+ return cp - u'A';
+ else if (cp >= 'a' && cp <= 'z')
+ return cp - u'a';
+ else
+ return base;
+}
+
+/* Bias adaptation function */
+
+static unsigned int adapt(unsigned int delta, unsigned int numpoints, bool firsttime)
+{
+ unsigned int 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);
+}
+
+/* Decodes a punycoded string into output, or returns -1 on error. */
+int punycode_decode(const char *input, size_t len, string_t *output)
+{
+ ARRAY(unichar_t) label;
+ size_t i = 0;
+ size_t out = 0;
+ unsigned int n = initialN, bias = initialBias;
+ const char *delim = NULL;
+ const char *end = CONST_PTR_OFFSET(input, len);
+ const char *ptr = input;
+ t_array_init(&label, len);
+
+ /* find the rightmost delimiter, if present in string */
+ delim = strrchr(ptr, delimiter);
+ i_assert(delim == NULL || delim < end);
+
+ /* no delimiter found, reset to start of string */
+ if (delim == NULL)
+ delim = input;
+ i_assert(delim <= end);
+
+ for (ptr = input; ptr < delim; ptr++) {
+ if ((unsigned char)*ptr >= 0x80)
+ /* Has non-ascii input, this cannot be punycoded. */
+ return -1;
+ i_assert(out < sizeof(label));
+ /* Add basic code points to label */
+ unichar_t ch = (unsigned char)*ptr;
+ array_push_back(&label, &ch);
+ }
+
+ out = array_count(&label);
+
+ /* Main decoding loop: start from after delimiter */
+ if (delim != input)
+ ptr = delim + 1;
+ else
+ ptr = input;
+
+ i_assert(ptr < end);
+ while (ptr < end) {
+ unsigned int oldi, w, k, digit, t;
+ /* 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. */
+
+ oldi = i;
+ w = 1;
+ k = base;
+
+ while (ptr <= end) {
+ /* ptr points to next digit to decode */
+ digit = decode_digit(*ptr++);
+ if (digit >= base)
+ return -1;
+ if (digit > (UINT_MAX - i) / w)
+ return -1;
+ i += digit * w;
+ t = k <= bias ? tmin :
+ k >= bias + tmax ? tmax : k - bias;
+ if (digit < t)
+ break;
+ if (w > UINT_MAX / (base - t))
+ return -1;
+ w *= (base - t);
+ k += base;
+ }
+
+ 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) > UINT_MAX - n)
+ return -1;
+
+ n += i / (out + 1);
+ i %= (out + 1);
+
+ if (n < initialN)
+ return -1;
+
+ /* Insert n at position i of the output: */
+ if (i <= out) {
+ out++;
+ array_insert(&label, i, &n, 1);
+ } else
+ return -1;
+
+ i++;
+ }
+
+ uni_ucs4_to_utf8(array_front(&label), out, output);
+ return 0;
+}
--- /dev/null
+/* Copyright (c) 2024 Dovecot authors, see the included COPYING file */
+
+#include "test-lib.h"
+#include "punycode.h"
+#include "str.h"
+
+static void test_punycode_decode(void)
+{
+ const struct test_case {
+ const char *in;
+ const char *out;
+ int ret;
+ } cases[] = {
+ /* has ASCII, appends */
+ { .in = "gr-zia", .out = "\x67\x72\xc3\xa5", .ret = 0 },
+ /* has ASCII, inserts */
+ { .in = "bl-yia", .out = "\x62\xc3\xa5\x6c", .ret = 0 },
+ /* has ASCII, inserts AND appends */
+ { .in = "stlbl-nrad",
+ .out = "\x73\x74\xc3\xa5\x6c\x62\x6c\xc3\xa5", .ret = 0 },
+ /* has no ASCII, appends */
+ { .in = "--7sbabjsrp6aymef",
+ .out = "\xd0\xb0\xd0\xba\xd1\x82\xd1\x80\xd0\xb8\xd1\x81\xd0"
+ "\xb0\x2d\xd0\xb2\xd0\xb5\xd1\x81\xd0\xbd\xd0\xb0",
+ .ret = 0 },
+ /* broken */
+ { .in = "zz-zzzz", .out = "", .ret = -1 },
+ };
+
+ unsigned int i;
+ string_t *r = t_str_new(42);
+
+ test_begin("punycode decoding");
+ for (i = 0; i < N_ELEMENTS(cases); i ++) {
+ str_truncate(r, 0);
+ int ret = punycode_decode(cases[i].in, strlen(cases[i].in), r);
+ test_assert_idx(ret == cases[i].ret, i);
+ test_assert_strcmp_idx(str_c(r), cases[i].out, i);
+ }
+ test_end();
+}
+
+void test_punycode(void)
+{
+ test_punycode_decode();
+}
projects / thirdparty / dovecot / core.git / commitdiff
