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-rw-r--r--src/shared/dns-domain.c1375
1 files changed, 1375 insertions, 0 deletions
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
new file mode 100644
index 0000000..4b31cb3
--- /dev/null
+++ b/src/shared/dns-domain.c
@@ -0,0 +1,1375 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#if HAVE_LIBIDN2
+# include <idn2.h>
+#elif HAVE_LIBIDN
+# include <idna.h>
+# include <stringprep.h>
+#endif
+
+#include <endian.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+
+#include "alloc-util.h"
+#include "dns-domain.h"
+#include "hashmap.h"
+#include "hexdecoct.h"
+#include "hostname-util.h"
+#include "in-addr-util.h"
+#include "macro.h"
+#include "parse-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "utf8.h"
+
+int dns_label_unescape(const char **name, char *dest, size_t sz, DNSLabelFlags flags) {
+ const char *n;
+ char *d, last_char = 0;
+ int r = 0;
+
+ assert(name);
+ assert(*name);
+
+ n = *name;
+ d = dest;
+
+ for (;;) {
+ if (*n == 0 || *n == '.') {
+ if (FLAGS_SET(flags, DNS_LABEL_LDH) && last_char == '-')
+ /* Trailing dash */
+ return -EINVAL;
+
+ if (*n == '.')
+ n++;
+ break;
+ }
+
+ if (r >= DNS_LABEL_MAX)
+ return -EINVAL;
+
+ if (sz <= 0)
+ return -ENOBUFS;
+
+ if (*n == '\\') {
+ /* Escaped character */
+ if (FLAGS_SET(flags, DNS_LABEL_NO_ESCAPES))
+ return -EINVAL;
+
+ n++;
+
+ if (*n == 0)
+ /* Ending NUL */
+ return -EINVAL;
+
+ else if (IN_SET(*n, '\\', '.')) {
+ /* Escaped backslash or dot */
+
+ if (FLAGS_SET(flags, DNS_LABEL_LDH))
+ return -EINVAL;
+
+ last_char = *n;
+ if (d)
+ *(d++) = *n;
+ sz--;
+ r++;
+ n++;
+
+ } else if (n[0] >= '0' && n[0] <= '9') {
+ unsigned k;
+
+ /* Escaped literal ASCII character */
+
+ if (!(n[1] >= '0' && n[1] <= '9') ||
+ !(n[2] >= '0' && n[2] <= '9'))
+ return -EINVAL;
+
+ k = ((unsigned) (n[0] - '0') * 100) +
+ ((unsigned) (n[1] - '0') * 10) +
+ ((unsigned) (n[2] - '0'));
+
+ /* Don't allow anything that doesn't
+ * fit in 8bit. Note that we do allow
+ * control characters, as some servers
+ * (e.g. cloudflare) are happy to
+ * generate labels with them
+ * inside. */
+ if (k > 255)
+ return -EINVAL;
+
+ if (FLAGS_SET(flags, DNS_LABEL_LDH) &&
+ !valid_ldh_char((char) k))
+ return -EINVAL;
+
+ last_char = (char) k;
+ if (d)
+ *(d++) = (char) k;
+ sz--;
+ r++;
+
+ n += 3;
+ } else
+ return -EINVAL;
+
+ } else if ((uint8_t) *n >= (uint8_t) ' ' && *n != 127) {
+
+ /* Normal character */
+
+ if (FLAGS_SET(flags, DNS_LABEL_LDH)) {
+ if (!valid_ldh_char(*n))
+ return -EINVAL;
+ if (r == 0 && *n == '-')
+ /* Leading dash */
+ return -EINVAL;
+ }
+
+ last_char = *n;
+ if (d)
+ *(d++) = *n;
+ sz--;
+ r++;
+ n++;
+ } else
+ return -EINVAL;
+ }
+
+ /* Empty label that is not at the end? */
+ if (r == 0 && *n)
+ return -EINVAL;
+
+ /* More than one trailing dot? */
+ if (*n == '.')
+ return -EINVAL;
+
+ if (sz >= 1 && d)
+ *d = 0;
+
+ *name = n;
+ return r;
+}
+
+/* @label_terminal: terminal character of a label, updated to point to the terminal character of
+ * the previous label (always skipping one dot) or to NULL if there are no more
+ * labels. */
+int dns_label_unescape_suffix(const char *name, const char **label_terminal, char *dest, size_t sz) {
+ const char *terminal;
+ int r;
+
+ assert(name);
+ assert(label_terminal);
+ assert(dest);
+
+ /* no more labels */
+ if (!*label_terminal) {
+ if (sz >= 1)
+ *dest = 0;
+
+ return 0;
+ }
+
+ terminal = *label_terminal;
+ assert(IN_SET(*terminal, 0, '.'));
+
+ /* Skip current terminal character (and accept domain names ending it ".") */
+ if (*terminal == 0)
+ terminal--;
+ if (terminal >= name && *terminal == '.')
+ terminal--;
+
+ /* Point name to the last label, and terminal to the preceding terminal symbol (or make it a NULL pointer) */
+ for (;;) {
+ if (terminal < name) {
+ /* Reached the first label, so indicate that there are no more */
+ terminal = NULL;
+ break;
+ }
+
+ /* Find the start of the last label */
+ if (*terminal == '.') {
+ const char *y;
+ unsigned slashes = 0;
+
+ for (y = terminal - 1; y >= name && *y == '\\'; y--)
+ slashes++;
+
+ if (slashes % 2 == 0) {
+ /* The '.' was not escaped */
+ name = terminal + 1;
+ break;
+ } else {
+ terminal = y;
+ continue;
+ }
+ }
+
+ terminal--;
+ }
+
+ r = dns_label_unescape(&name, dest, sz, 0);
+ if (r < 0)
+ return r;
+
+ *label_terminal = terminal;
+
+ return r;
+}
+
+int dns_label_escape(const char *p, size_t l, char *dest, size_t sz) {
+ char *q;
+
+ /* DNS labels must be between 1 and 63 characters long. A
+ * zero-length label does not exist. See RFC 2182, Section
+ * 11. */
+
+ if (l <= 0 || l > DNS_LABEL_MAX)
+ return -EINVAL;
+ if (sz < 1)
+ return -ENOBUFS;
+
+ assert(p);
+ assert(dest);
+
+ q = dest;
+ while (l > 0) {
+
+ if (IN_SET(*p, '.', '\\')) {
+
+ /* Dot or backslash */
+
+ if (sz < 3)
+ return -ENOBUFS;
+
+ *(q++) = '\\';
+ *(q++) = *p;
+
+ sz -= 2;
+
+ } else if (IN_SET(*p, '_', '-') ||
+ (*p >= '0' && *p <= '9') ||
+ (*p >= 'a' && *p <= 'z') ||
+ (*p >= 'A' && *p <= 'Z')) {
+
+ /* Proper character */
+
+ if (sz < 2)
+ return -ENOBUFS;
+
+ *(q++) = *p;
+ sz -= 1;
+
+ } else {
+
+ /* Everything else */
+
+ if (sz < 5)
+ return -ENOBUFS;
+
+ *(q++) = '\\';
+ *(q++) = '0' + (char) ((uint8_t) *p / 100);
+ *(q++) = '0' + (char) (((uint8_t) *p / 10) % 10);
+ *(q++) = '0' + (char) ((uint8_t) *p % 10);
+
+ sz -= 4;
+ }
+
+ p++;
+ l--;
+ }
+
+ *q = 0;
+ return (int) (q - dest);
+}
+
+int dns_label_escape_new(const char *p, size_t l, char **ret) {
+ _cleanup_free_ char *s = NULL;
+ int r;
+
+ assert(p);
+ assert(ret);
+
+ if (l <= 0 || l > DNS_LABEL_MAX)
+ return -EINVAL;
+
+ s = new(char, DNS_LABEL_ESCAPED_MAX);
+ if (!s)
+ return -ENOMEM;
+
+ r = dns_label_escape(p, l, s, DNS_LABEL_ESCAPED_MAX);
+ if (r < 0)
+ return r;
+
+ *ret = TAKE_PTR(s);
+
+ return r;
+}
+
+#if HAVE_LIBIDN
+int dns_label_apply_idna(const char *encoded, size_t encoded_size, char *decoded, size_t decoded_max) {
+ _cleanup_free_ uint32_t *input = NULL;
+ size_t input_size, l;
+ const char *p;
+ bool contains_8bit = false;
+ char buffer[DNS_LABEL_MAX+1];
+
+ assert(encoded);
+ assert(decoded);
+
+ /* Converts an U-label into an A-label */
+
+ if (encoded_size <= 0)
+ return -EINVAL;
+
+ for (p = encoded; p < encoded + encoded_size; p++)
+ if ((uint8_t) *p > 127)
+ contains_8bit = true;
+
+ if (!contains_8bit) {
+ if (encoded_size > DNS_LABEL_MAX)
+ return -EINVAL;
+
+ return 0;
+ }
+
+ input = stringprep_utf8_to_ucs4(encoded, encoded_size, &input_size);
+ if (!input)
+ return -ENOMEM;
+
+ if (idna_to_ascii_4i(input, input_size, buffer, 0) != 0)
+ return -EINVAL;
+
+ l = strlen(buffer);
+
+ /* Verify that the result is not longer than one DNS label. */
+ if (l <= 0 || l > DNS_LABEL_MAX)
+ return -EINVAL;
+ if (l > decoded_max)
+ return -ENOBUFS;
+
+ memcpy(decoded, buffer, l);
+
+ /* If there's room, append a trailing NUL byte, but only then */
+ if (decoded_max > l)
+ decoded[l] = 0;
+
+ return (int) l;
+}
+
+int dns_label_undo_idna(const char *encoded, size_t encoded_size, char *decoded, size_t decoded_max) {
+ size_t input_size, output_size;
+ _cleanup_free_ uint32_t *input = NULL;
+ _cleanup_free_ char *result = NULL;
+ uint32_t *output = NULL;
+ size_t w;
+
+ /* To be invoked after unescaping. Converts an A-label into an U-label. */
+
+ assert(encoded);
+ assert(decoded);
+
+ if (encoded_size <= 0 || encoded_size > DNS_LABEL_MAX)
+ return -EINVAL;
+
+ if (!memory_startswith(encoded, encoded_size, IDNA_ACE_PREFIX))
+ return 0;
+
+ input = stringprep_utf8_to_ucs4(encoded, encoded_size, &input_size);
+ if (!input)
+ return -ENOMEM;
+
+ output_size = input_size;
+ output = newa(uint32_t, output_size);
+
+ idna_to_unicode_44i(input, input_size, output, &output_size, 0);
+
+ result = stringprep_ucs4_to_utf8(output, output_size, NULL, &w);
+ if (!result)
+ return -ENOMEM;
+ if (w <= 0)
+ return -EINVAL;
+ if (w > decoded_max)
+ return -ENOBUFS;
+
+ memcpy(decoded, result, w);
+
+ /* Append trailing NUL byte if there's space, but only then. */
+ if (decoded_max > w)
+ decoded[w] = 0;
+
+ return w;
+}
+#endif
+
+int dns_name_concat(const char *a, const char *b, DNSLabelFlags flags, char **_ret) {
+ _cleanup_free_ char *ret = NULL;
+ size_t n = 0, allocated = 0;
+ const char *p;
+ bool first = true;
+ int r;
+
+ if (a)
+ p = a;
+ else if (b)
+ p = TAKE_PTR(b);
+ else
+ goto finish;
+
+ for (;;) {
+ char label[DNS_LABEL_MAX];
+
+ r = dns_label_unescape(&p, label, sizeof label, flags);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ if (*p != 0)
+ return -EINVAL;
+
+ if (b) {
+ /* Now continue with the second string, if there is one */
+ p = TAKE_PTR(b);
+ continue;
+ }
+
+ break;
+ }
+
+ if (_ret) {
+ if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX))
+ return -ENOMEM;
+
+ r = dns_label_escape(label, r, ret + n + !first, DNS_LABEL_ESCAPED_MAX);
+ if (r < 0)
+ return r;
+
+ if (!first)
+ ret[n] = '.';
+ } else {
+ char escaped[DNS_LABEL_ESCAPED_MAX];
+
+ r = dns_label_escape(label, r, escaped, sizeof(escaped));
+ if (r < 0)
+ return r;
+ }
+
+ if (!first)
+ n++;
+ else
+ first = false;
+
+ n += r;
+ }
+
+finish:
+ if (n > DNS_HOSTNAME_MAX)
+ return -EINVAL;
+
+ if (_ret) {
+ if (n == 0) {
+ /* Nothing appended? If so, generate at least a single dot, to indicate the DNS root domain */
+ if (!GREEDY_REALLOC(ret, allocated, 2))
+ return -ENOMEM;
+
+ ret[n++] = '.';
+ } else {
+ if (!GREEDY_REALLOC(ret, allocated, n + 1))
+ return -ENOMEM;
+ }
+
+ ret[n] = 0;
+ *_ret = TAKE_PTR(ret);
+ }
+
+ return 0;
+}
+
+void dns_name_hash_func(const char *p, struct siphash *state) {
+ int r;
+
+ assert(p);
+
+ for (;;) {
+ char label[DNS_LABEL_MAX+1];
+
+ r = dns_label_unescape(&p, label, sizeof label, 0);
+ if (r < 0)
+ break;
+ if (r == 0)
+ break;
+
+ ascii_strlower_n(label, r);
+ siphash24_compress(label, r, state);
+ siphash24_compress_byte(0, state); /* make sure foobar and foo.bar result in different hashes */
+ }
+
+ /* enforce that all names are terminated by the empty label */
+ string_hash_func("", state);
+}
+
+int dns_name_compare_func(const char *a, const char *b) {
+ const char *x, *y;
+ int r, q;
+
+ assert(a);
+ assert(b);
+
+ x = a + strlen(a);
+ y = b + strlen(b);
+
+ for (;;) {
+ char la[DNS_LABEL_MAX], lb[DNS_LABEL_MAX];
+
+ if (x == NULL && y == NULL)
+ return 0;
+
+ r = dns_label_unescape_suffix(a, &x, la, sizeof(la));
+ q = dns_label_unescape_suffix(b, &y, lb, sizeof(lb));
+ if (r < 0 || q < 0)
+ return CMP(r, q);
+
+ r = ascii_strcasecmp_nn(la, r, lb, q);
+ if (r != 0)
+ return r;
+ }
+}
+
+DEFINE_HASH_OPS(dns_name_hash_ops, char, dns_name_hash_func, dns_name_compare_func);
+
+int dns_name_equal(const char *x, const char *y) {
+ int r, q;
+
+ assert(x);
+ assert(y);
+
+ for (;;) {
+ char la[DNS_LABEL_MAX], lb[DNS_LABEL_MAX];
+
+ r = dns_label_unescape(&x, la, sizeof la, 0);
+ if (r < 0)
+ return r;
+
+ q = dns_label_unescape(&y, lb, sizeof lb, 0);
+ if (q < 0)
+ return q;
+
+ if (r != q)
+ return false;
+ if (r == 0)
+ return true;
+
+ if (ascii_strcasecmp_n(la, lb, r) != 0)
+ return false;
+ }
+}
+
+int dns_name_endswith(const char *name, const char *suffix) {
+ const char *n, *s, *saved_n = NULL;
+ int r, q;
+
+ assert(name);
+ assert(suffix);
+
+ n = name;
+ s = suffix;
+
+ for (;;) {
+ char ln[DNS_LABEL_MAX], ls[DNS_LABEL_MAX];
+
+ r = dns_label_unescape(&n, ln, sizeof ln, 0);
+ if (r < 0)
+ return r;
+
+ if (!saved_n)
+ saved_n = n;
+
+ q = dns_label_unescape(&s, ls, sizeof ls, 0);
+ if (q < 0)
+ return q;
+
+ if (r == 0 && q == 0)
+ return true;
+ if (r == 0 && saved_n == n)
+ return false;
+
+ if (r != q || ascii_strcasecmp_n(ln, ls, r) != 0) {
+
+ /* Not the same, let's jump back, and try with the next label again */
+ s = suffix;
+ n = TAKE_PTR(saved_n);
+ }
+ }
+}
+
+int dns_name_startswith(const char *name, const char *prefix) {
+ const char *n, *p;
+ int r, q;
+
+ assert(name);
+ assert(prefix);
+
+ n = name;
+ p = prefix;
+
+ for (;;) {
+ char ln[DNS_LABEL_MAX], lp[DNS_LABEL_MAX];
+
+ r = dns_label_unescape(&p, lp, sizeof lp, 0);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return true;
+
+ q = dns_label_unescape(&n, ln, sizeof ln, 0);
+ if (q < 0)
+ return q;
+
+ if (r != q)
+ return false;
+ if (ascii_strcasecmp_n(ln, lp, r) != 0)
+ return false;
+ }
+}
+
+int dns_name_change_suffix(const char *name, const char *old_suffix, const char *new_suffix, char **ret) {
+ const char *n, *s, *saved_before = NULL, *saved_after = NULL, *prefix;
+ int r, q;
+
+ assert(name);
+ assert(old_suffix);
+ assert(new_suffix);
+ assert(ret);
+
+ n = name;
+ s = old_suffix;
+
+ for (;;) {
+ char ln[DNS_LABEL_MAX], ls[DNS_LABEL_MAX];
+
+ if (!saved_before)
+ saved_before = n;
+
+ r = dns_label_unescape(&n, ln, sizeof ln, 0);
+ if (r < 0)
+ return r;
+
+ if (!saved_after)
+ saved_after = n;
+
+ q = dns_label_unescape(&s, ls, sizeof ls, 0);
+ if (q < 0)
+ return q;
+
+ if (r == 0 && q == 0)
+ break;
+ if (r == 0 && saved_after == n) {
+ *ret = NULL; /* doesn't match */
+ return 0;
+ }
+
+ if (r != q || ascii_strcasecmp_n(ln, ls, r) != 0) {
+
+ /* Not the same, let's jump back, and try with the next label again */
+ s = old_suffix;
+ n = TAKE_PTR(saved_after);
+ saved_before = NULL;
+ }
+ }
+
+ /* Found it! Now generate the new name */
+ prefix = strndupa(name, saved_before - name);
+
+ r = dns_name_concat(prefix, new_suffix, 0, ret);
+ if (r < 0)
+ return r;
+
+ return 1;
+}
+
+int dns_name_between(const char *a, const char *b, const char *c) {
+ /* Determine if b is strictly greater than a and strictly smaller than c.
+ We consider the order of names to be circular, so that if a is
+ strictly greater than c, we consider b to be between them if it is
+ either greater than a or smaller than c. This is how the canonical
+ DNS name order used in NSEC records work. */
+
+ if (dns_name_compare_func(a, c) < 0)
+ /*
+ a and c are properly ordered:
+ a<---b--->c
+ */
+ return dns_name_compare_func(a, b) < 0 &&
+ dns_name_compare_func(b, c) < 0;
+ else
+ /*
+ a and c are equal or 'reversed':
+ <--b--c a----->
+ or:
+ <-----c a--b-->
+ */
+ return dns_name_compare_func(b, c) < 0 ||
+ dns_name_compare_func(a, b) < 0;
+}
+
+int dns_name_reverse(int family, const union in_addr_union *a, char **ret) {
+ const uint8_t *p;
+ int r;
+
+ assert(a);
+ assert(ret);
+
+ p = (const uint8_t*) a;
+
+ if (family == AF_INET)
+ r = asprintf(ret, "%u.%u.%u.%u.in-addr.arpa", p[3], p[2], p[1], p[0]);
+ else if (family == AF_INET6)
+ r = asprintf(ret, "%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.%c.ip6.arpa",
+ hexchar(p[15] & 0xF), hexchar(p[15] >> 4), hexchar(p[14] & 0xF), hexchar(p[14] >> 4),
+ hexchar(p[13] & 0xF), hexchar(p[13] >> 4), hexchar(p[12] & 0xF), hexchar(p[12] >> 4),
+ hexchar(p[11] & 0xF), hexchar(p[11] >> 4), hexchar(p[10] & 0xF), hexchar(p[10] >> 4),
+ hexchar(p[ 9] & 0xF), hexchar(p[ 9] >> 4), hexchar(p[ 8] & 0xF), hexchar(p[ 8] >> 4),
+ hexchar(p[ 7] & 0xF), hexchar(p[ 7] >> 4), hexchar(p[ 6] & 0xF), hexchar(p[ 6] >> 4),
+ hexchar(p[ 5] & 0xF), hexchar(p[ 5] >> 4), hexchar(p[ 4] & 0xF), hexchar(p[ 4] >> 4),
+ hexchar(p[ 3] & 0xF), hexchar(p[ 3] >> 4), hexchar(p[ 2] & 0xF), hexchar(p[ 2] >> 4),
+ hexchar(p[ 1] & 0xF), hexchar(p[ 1] >> 4), hexchar(p[ 0] & 0xF), hexchar(p[ 0] >> 4));
+ else
+ return -EAFNOSUPPORT;
+ if (r < 0)
+ return -ENOMEM;
+
+ return 0;
+}
+
+int dns_name_address(const char *p, int *family, union in_addr_union *address) {
+ int r;
+
+ assert(p);
+ assert(family);
+ assert(address);
+
+ r = dns_name_endswith(p, "in-addr.arpa");
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ uint8_t a[4];
+ unsigned i;
+
+ for (i = 0; i < ELEMENTSOF(a); i++) {
+ char label[DNS_LABEL_MAX+1];
+
+ r = dns_label_unescape(&p, label, sizeof label, 0);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -EINVAL;
+ if (r > 3)
+ return -EINVAL;
+
+ r = safe_atou8(label, &a[i]);
+ if (r < 0)
+ return r;
+ }
+
+ r = dns_name_equal(p, "in-addr.arpa");
+ if (r <= 0)
+ return r;
+
+ *family = AF_INET;
+ address->in.s_addr = htobe32(((uint32_t) a[3] << 24) |
+ ((uint32_t) a[2] << 16) |
+ ((uint32_t) a[1] << 8) |
+ (uint32_t) a[0]);
+
+ return 1;
+ }
+
+ r = dns_name_endswith(p, "ip6.arpa");
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ struct in6_addr a;
+ unsigned i;
+
+ for (i = 0; i < ELEMENTSOF(a.s6_addr); i++) {
+ char label[DNS_LABEL_MAX+1];
+ int x, y;
+
+ r = dns_label_unescape(&p, label, sizeof label, 0);
+ if (r <= 0)
+ return r;
+ if (r != 1)
+ return -EINVAL;
+ x = unhexchar(label[0]);
+ if (x < 0)
+ return -EINVAL;
+
+ r = dns_label_unescape(&p, label, sizeof label, 0);
+ if (r <= 0)
+ return r;
+ if (r != 1)
+ return -EINVAL;
+ y = unhexchar(label[0]);
+ if (y < 0)
+ return -EINVAL;
+
+ a.s6_addr[ELEMENTSOF(a.s6_addr) - i - 1] = (uint8_t) y << 4 | (uint8_t) x;
+ }
+
+ r = dns_name_equal(p, "ip6.arpa");
+ if (r <= 0)
+ return r;
+
+ *family = AF_INET6;
+ address->in6 = a;
+ return 1;
+ }
+
+ return 0;
+}
+
+bool dns_name_is_root(const char *name) {
+
+ assert(name);
+
+ /* There are exactly two ways to encode the root domain name:
+ * as empty string, or with a single dot. */
+
+ return STR_IN_SET(name, "", ".");
+}
+
+bool dns_name_is_single_label(const char *name) {
+ int r;
+
+ assert(name);
+
+ r = dns_name_parent(&name);
+ if (r <= 0)
+ return false;
+
+ return dns_name_is_root(name);
+}
+
+/* Encode a domain name according to RFC 1035 Section 3.1, without compression */
+int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len, bool canonical) {
+ uint8_t *label_length, *out;
+ int r;
+
+ assert(domain);
+ assert(buffer);
+
+ out = buffer;
+
+ do {
+ /* Reserve a byte for label length */
+ if (len <= 0)
+ return -ENOBUFS;
+ len--;
+ label_length = out;
+ out++;
+
+ /* Convert and copy a single label. Note that
+ * dns_label_unescape() returns 0 when it hits the end
+ * of the domain name, which we rely on here to encode
+ * the trailing NUL byte. */
+ r = dns_label_unescape(&domain, (char *) out, len, 0);
+ if (r < 0)
+ return r;
+
+ /* Optionally, output the name in DNSSEC canonical
+ * format, as described in RFC 4034, section 6.2. Or
+ * in other words: in lower-case. */
+ if (canonical)
+ ascii_strlower_n((char*) out, (size_t) r);
+
+ /* Fill label length, move forward */
+ *label_length = r;
+ out += r;
+ len -= r;
+
+ } while (r != 0);
+
+ /* Verify the maximum size of the encoded name. The trailing
+ * dot + NUL byte account are included this time, hence
+ * compare against DNS_HOSTNAME_MAX + 2 (which is 255) this
+ * time. */
+ if (out - buffer > DNS_HOSTNAME_MAX + 2)
+ return -EINVAL;
+
+ return out - buffer;
+}
+
+static bool srv_type_label_is_valid(const char *label, size_t n) {
+ size_t k;
+
+ assert(label);
+
+ if (n < 2) /* Label needs to be at least 2 chars long */
+ return false;
+
+ if (label[0] != '_') /* First label char needs to be underscore */
+ return false;
+
+ /* Second char must be a letter */
+ if (!(label[1] >= 'A' && label[1] <= 'Z') &&
+ !(label[1] >= 'a' && label[1] <= 'z'))
+ return false;
+
+ /* Third and further chars must be alphanumeric or a hyphen */
+ for (k = 2; k < n; k++) {
+ if (!(label[k] >= 'A' && label[k] <= 'Z') &&
+ !(label[k] >= 'a' && label[k] <= 'z') &&
+ !(label[k] >= '0' && label[k] <= '9') &&
+ label[k] != '-')
+ return false;
+ }
+
+ return true;
+}
+
+bool dns_srv_type_is_valid(const char *name) {
+ unsigned c = 0;
+ int r;
+
+ if (!name)
+ return false;
+
+ for (;;) {
+ char label[DNS_LABEL_MAX];
+
+ /* This more or less implements RFC 6335, Section 5.1 */
+
+ r = dns_label_unescape(&name, label, sizeof label, 0);
+ if (r < 0)
+ return false;
+ if (r == 0)
+ break;
+
+ if (c >= 2)
+ return false;
+
+ if (!srv_type_label_is_valid(label, r))
+ return false;
+
+ c++;
+ }
+
+ return c == 2; /* exactly two labels */
+}
+
+bool dnssd_srv_type_is_valid(const char *name) {
+ return dns_srv_type_is_valid(name) &&
+ ((dns_name_endswith(name, "_tcp") > 0) ||
+ (dns_name_endswith(name, "_udp") > 0)); /* Specific to DNS-SD. RFC 6763, Section 7 */
+}
+
+bool dns_service_name_is_valid(const char *name) {
+ size_t l;
+
+ /* This more or less implements RFC 6763, Section 4.1.1 */
+
+ if (!name)
+ return false;
+
+ if (!utf8_is_valid(name))
+ return false;
+
+ if (string_has_cc(name, NULL))
+ return false;
+
+ l = strlen(name);
+ if (l <= 0)
+ return false;
+ if (l > 63)
+ return false;
+
+ return true;
+}
+
+int dns_service_join(const char *name, const char *type, const char *domain, char **ret) {
+ char escaped[DNS_LABEL_ESCAPED_MAX];
+ _cleanup_free_ char *n = NULL;
+ int r;
+
+ assert(type);
+ assert(domain);
+ assert(ret);
+
+ if (!dns_srv_type_is_valid(type))
+ return -EINVAL;
+
+ if (!name)
+ return dns_name_concat(type, domain, 0, ret);
+
+ if (!dns_service_name_is_valid(name))
+ return -EINVAL;
+
+ r = dns_label_escape(name, strlen(name), escaped, sizeof(escaped));
+ if (r < 0)
+ return r;
+
+ r = dns_name_concat(type, domain, 0, &n);
+ if (r < 0)
+ return r;
+
+ return dns_name_concat(escaped, n, 0, ret);
+}
+
+static bool dns_service_name_label_is_valid(const char *label, size_t n) {
+ char *s;
+
+ assert(label);
+
+ if (memchr(label, 0, n))
+ return false;
+
+ s = strndupa(label, n);
+ return dns_service_name_is_valid(s);
+}
+
+int dns_service_split(const char *joined, char **_name, char **_type, char **_domain) {
+ _cleanup_free_ char *name = NULL, *type = NULL, *domain = NULL;
+ const char *p = joined, *q = NULL, *d = NULL;
+ char a[DNS_LABEL_MAX], b[DNS_LABEL_MAX], c[DNS_LABEL_MAX];
+ int an, bn, cn, r;
+ unsigned x = 0;
+
+ assert(joined);
+
+ /* Get first label from the full name */
+ an = dns_label_unescape(&p, a, sizeof(a), 0);
+ if (an < 0)
+ return an;
+
+ if (an > 0) {
+ x++;
+
+ /* If there was a first label, try to get the second one */
+ bn = dns_label_unescape(&p, b, sizeof(b), 0);
+ if (bn < 0)
+ return bn;
+
+ if (bn > 0) {
+ x++;
+
+ /* If there was a second label, try to get the third one */
+ q = p;
+ cn = dns_label_unescape(&p, c, sizeof(c), 0);
+ if (cn < 0)
+ return cn;
+
+ if (cn > 0)
+ x++;
+ } else
+ cn = 0;
+ } else
+ an = 0;
+
+ if (x >= 2 && srv_type_label_is_valid(b, bn)) {
+
+ if (x >= 3 && srv_type_label_is_valid(c, cn)) {
+
+ if (dns_service_name_label_is_valid(a, an)) {
+ /* OK, got <name> . <type> . <type2> . <domain> */
+
+ name = strndup(a, an);
+ if (!name)
+ return -ENOMEM;
+
+ type = strjoin(b, ".", c);
+ if (!type)
+ return -ENOMEM;
+
+ d = p;
+ goto finish;
+ }
+
+ } else if (srv_type_label_is_valid(a, an)) {
+
+ /* OK, got <type> . <type2> . <domain> */
+
+ name = NULL;
+
+ type = strjoin(a, ".", b);
+ if (!type)
+ return -ENOMEM;
+
+ d = q;
+ goto finish;
+ }
+ }
+
+ name = NULL;
+ type = NULL;
+ d = joined;
+
+finish:
+ r = dns_name_normalize(d, 0, &domain);
+ if (r < 0)
+ return r;
+
+ if (_domain)
+ *_domain = TAKE_PTR(domain);
+
+ if (_type)
+ *_type = TAKE_PTR(type);
+
+ if (_name)
+ *_name = TAKE_PTR(name);
+
+ return 0;
+}
+
+static int dns_name_build_suffix_table(const char *name, const char *table[]) {
+ const char *p;
+ unsigned n = 0;
+ int r;
+
+ assert(name);
+ assert(table);
+
+ p = name;
+ for (;;) {
+ if (n > DNS_N_LABELS_MAX)
+ return -EINVAL;
+
+ table[n] = p;
+ r = dns_name_parent(&p);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+
+ n++;
+ }
+
+ return (int) n;
+}
+
+int dns_name_suffix(const char *name, unsigned n_labels, const char **ret) {
+ const char* labels[DNS_N_LABELS_MAX+1];
+ int n;
+
+ assert(name);
+ assert(ret);
+
+ n = dns_name_build_suffix_table(name, labels);
+ if (n < 0)
+ return n;
+
+ if ((unsigned) n < n_labels)
+ return -EINVAL;
+
+ *ret = labels[n - n_labels];
+ return (int) (n - n_labels);
+}
+
+int dns_name_skip(const char *a, unsigned n_labels, const char **ret) {
+ int r;
+
+ assert(a);
+ assert(ret);
+
+ for (; n_labels > 0; n_labels--) {
+ r = dns_name_parent(&a);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ *ret = "";
+ return 0;
+ }
+ }
+
+ *ret = a;
+ return 1;
+}
+
+int dns_name_count_labels(const char *name) {
+ unsigned n = 0;
+ const char *p;
+ int r;
+
+ assert(name);
+
+ p = name;
+ for (;;) {
+ r = dns_name_parent(&p);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+
+ if (n >= DNS_N_LABELS_MAX)
+ return -EINVAL;
+
+ n++;
+ }
+
+ return (int) n;
+}
+
+int dns_name_equal_skip(const char *a, unsigned n_labels, const char *b) {
+ int r;
+
+ assert(a);
+ assert(b);
+
+ r = dns_name_skip(a, n_labels, &a);
+ if (r <= 0)
+ return r;
+
+ return dns_name_equal(a, b);
+}
+
+int dns_name_common_suffix(const char *a, const char *b, const char **ret) {
+ const char *a_labels[DNS_N_LABELS_MAX+1], *b_labels[DNS_N_LABELS_MAX+1];
+ int n = 0, m = 0, k = 0, r, q;
+
+ assert(a);
+ assert(b);
+ assert(ret);
+
+ /* Determines the common suffix of domain names a and b */
+
+ n = dns_name_build_suffix_table(a, a_labels);
+ if (n < 0)
+ return n;
+
+ m = dns_name_build_suffix_table(b, b_labels);
+ if (m < 0)
+ return m;
+
+ for (;;) {
+ char la[DNS_LABEL_MAX], lb[DNS_LABEL_MAX];
+ const char *x, *y;
+
+ if (k >= n || k >= m) {
+ *ret = a_labels[n - k];
+ return 0;
+ }
+
+ x = a_labels[n - 1 - k];
+ r = dns_label_unescape(&x, la, sizeof la, 0);
+ if (r < 0)
+ return r;
+
+ y = b_labels[m - 1 - k];
+ q = dns_label_unescape(&y, lb, sizeof lb, 0);
+ if (q < 0)
+ return q;
+
+ if (r != q || ascii_strcasecmp_n(la, lb, r) != 0) {
+ *ret = a_labels[n - k];
+ return 0;
+ }
+
+ k++;
+ }
+}
+
+int dns_name_apply_idna(const char *name, char **ret) {
+ /* Return negative on error, 0 if not implemented, positive on success. */
+
+#if HAVE_LIBIDN2
+ int r;
+ _cleanup_free_ char *t = NULL;
+
+ assert(name);
+ assert(ret);
+
+ r = idn2_lookup_u8((uint8_t*) name, (uint8_t**) &t,
+ IDN2_NFC_INPUT | IDN2_NONTRANSITIONAL);
+ log_debug("idn2_lookup_u8: %s → %s", name, t);
+ if (r == IDN2_OK) {
+ if (!startswith(name, "xn--")) {
+ _cleanup_free_ char *s = NULL;
+
+ r = idn2_to_unicode_8z8z(t, &s, 0);
+ if (r != IDN2_OK) {
+ log_debug("idn2_to_unicode_8z8z(\"%s\") failed: %d/%s",
+ t, r, idn2_strerror(r));
+ return 0;
+ }
+
+ if (!streq_ptr(name, s)) {
+ log_debug("idn2 roundtrip failed: \"%s\" → \"%s\" → \"%s\", ignoring.",
+ name, t, s);
+ return 0;
+ }
+ }
+
+ *ret = TAKE_PTR(t);
+
+ return 1; /* *ret has been written */
+ }
+
+ log_debug("idn2_lookup_u8(\"%s\") failed: %d/%s", name, r, idn2_strerror(r));
+ if (r == IDN2_2HYPHEN)
+ /* The name has two hyphens — forbidden by IDNA2008 in some cases */
+ return 0;
+ if (IN_SET(r, IDN2_TOO_BIG_DOMAIN, IDN2_TOO_BIG_LABEL))
+ return -ENOSPC;
+ return -EINVAL;
+#elif HAVE_LIBIDN
+ _cleanup_free_ char *buf = NULL;
+ size_t n = 0, allocated = 0;
+ bool first = true;
+ int r, q;
+
+ assert(name);
+ assert(ret);
+
+ for (;;) {
+ char label[DNS_LABEL_MAX];
+
+ r = dns_label_unescape(&name, label, sizeof label, 0);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+
+ q = dns_label_apply_idna(label, r, label, sizeof label);
+ if (q < 0)
+ return q;
+ if (q > 0)
+ r = q;
+
+ if (!GREEDY_REALLOC(buf, allocated, n + !first + DNS_LABEL_ESCAPED_MAX))
+ return -ENOMEM;
+
+ r = dns_label_escape(label, r, buf + n + !first, DNS_LABEL_ESCAPED_MAX);
+ if (r < 0)
+ return r;
+
+ if (first)
+ first = false;
+ else
+ buf[n++] = '.';
+
+ n += r;
+ }
+
+ if (n > DNS_HOSTNAME_MAX)
+ return -EINVAL;
+
+ if (!GREEDY_REALLOC(buf, allocated, n + 1))
+ return -ENOMEM;
+
+ buf[n] = 0;
+ *ret = TAKE_PTR(buf);
+
+ return 1;
+#else
+ return 0;
+#endif
+}
+
+int dns_name_is_valid_or_address(const char *name) {
+ /* Returns > 0 if the specified name is either a valid IP address formatted as string or a valid DNS name */
+
+ if (isempty(name))
+ return 0;
+
+ if (in_addr_from_string_auto(name, NULL, NULL) >= 0)
+ return 1;
+
+ return dns_name_is_valid(name);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 12:52:06 +0000