/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2014 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see . ***/ #ifdef HAVE_LIBIDN #include #include #endif #include "alloc-util.h" #include "dns-domain.h" #include "hexdecoct.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) { const char *n; char *d; int r = 0; assert(name); assert(*name); assert(dest); n = *name; d = dest; for (;;) { if (*n == '.') { n++; break; } if (*n == 0) break; if (sz <= 0) return -ENOSPC; if (r >= DNS_LABEL_MAX) return -EINVAL; if (*n == '\\') { /* Escaped character */ n++; if (*n == 0) /* Ending NUL */ return -EINVAL; else if (*n == '\\' || *n == '.') { /* Escaped backslash or dot */ *(d++) = *(n++); sz--; r++; } 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 CC characters or anything that doesn't fit in 8bit */ if (k < ' ' || k > 255 || k == 127) return -EINVAL; *(d++) = (char) k; sz--; r++; n += 3; } else return -EINVAL; } else if ((uint8_t) *n >= (uint8_t) ' ' && *n != 127) { /* Normal character */ *(d++) = *(n++); sz--; r++; } else return -EINVAL; } /* Empty label that is not at the end? */ if (r == 0 && *n) return -EINVAL; if (sz >= 1) *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; } assert(**label_terminal == '.' || **label_terminal == 0); /* skip current terminal character */ terminal = *label_terminal - 1; /* 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); 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 -ENOSPC; assert(p); assert(dest); q = dest; while (l > 0) { if (*p == '.' || *p == '\\') { /* Dot or backslash */ if (sz < 3) return -ENOSPC; *(q++) = '\\'; *(q++) = *p; sz -= 2; } else if (*p == '_' || *p == '-' || (*p >= '0' && *p <= '9') || (*p >= 'a' && *p <= 'z') || (*p >= 'A' && *p <= 'Z')) { /* Proper character */ if (sz < 2) return -ENOSPC; *(q++) = *p; sz -= 1; } else if ((uint8_t) *p >= (uint8_t) ' ' && *p != 127) { /* Everything else */ if (sz < 5) return -ENOSPC; *(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; } else return -EINVAL; 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 = s; s = NULL; return r; } int dns_label_apply_idna(const char *encoded, size_t encoded_size, char *decoded, size_t decoded_max) { #ifdef HAVE_LIBIDN _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 the result is not longer than one DNS label. */ if (l <= 0 || l > DNS_LABEL_MAX) return -EINVAL; if (l > decoded_max) return -ENOSPC; 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; #else return 0; #endif } int dns_label_undo_idna(const char *encoded, size_t encoded_size, char *decoded, size_t decoded_max) { #ifdef HAVE_LIBIDN 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 (encoded_size < sizeof(IDNA_ACE_PREFIX)-1) return 0; if (memcmp(encoded, IDNA_ACE_PREFIX, sizeof(IDNA_ACE_PREFIX) -1) != 0) 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 -ENOSPC; memcpy(decoded, result, w); /* Append trailing NUL byte if there's space, but only then. */ if (decoded_max > w) decoded[w] = 0; return w; #else return 0; #endif } int dns_name_concat(const char *a, const char *b, char **_ret) { _cleanup_free_ char *ret = NULL; size_t n = 0, allocated = 0; const char *p = a; bool first = true; int r; assert(a); for (;;) { char label[DNS_LABEL_MAX]; int k; r = dns_label_unescape(&p, label, sizeof(label)); 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 = b; b = NULL; continue; } break; } k = dns_label_undo_idna(label, r, label, sizeof(label)); if (k < 0) return k; if (k > 0) r = k; 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; } if (n > DNS_HOSTNAME_MAX) return -EINVAL; if (_ret) { if (!GREEDY_REALLOC(ret, allocated, n + 1)) return -ENOMEM; ret[n] = 0; *_ret = ret; ret = NULL; } return 0; } void dns_name_hash_func(const void *s, struct siphash *state) { const char *p = s; int r; assert(p); while (*p) { char label[DNS_LABEL_MAX+1]; int k; r = dns_label_unescape(&p, label, sizeof(label)); if (r < 0) break; k = dns_label_undo_idna(label, r, label, sizeof(label)); if (k < 0) break; if (k > 0) r = k; if (r == 0) break; label[r] = 0; ascii_strlower(label); string_hash_func(label, state); } /* enforce that all names are terminated by the empty label */ string_hash_func("", state); } int dns_name_compare_func(const void *a, const void *b) { const char *x, *y; int r, q, k, w; assert(a); assert(b); x = (const char *) a + strlen(a); y = (const char *) b + strlen(b); for (;;) { char la[DNS_LABEL_MAX+1], lb[DNS_LABEL_MAX+1]; 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 r - q; k = dns_label_undo_idna(la, r, la, sizeof(la)); w = dns_label_undo_idna(lb, q, lb, sizeof(lb)); if (k < 0 || w < 0) return k - w; if (k > 0) r = k; if (w > 0) r = w; la[r] = lb[q] = 0; r = strcasecmp(la, lb); if (r != 0) return r; } } const struct hash_ops dns_name_hash_ops = { .hash = dns_name_hash_func, .compare = dns_name_compare_func }; int dns_name_equal(const char *x, const char *y) { int r, q, k, w; assert(x); assert(y); for (;;) { char la[DNS_LABEL_MAX+1], lb[DNS_LABEL_MAX+1]; if (*x == 0 && *y == 0) return true; r = dns_label_unescape(&x, la, sizeof(la)); if (r < 0) return r; if (r > 0) { k = dns_label_undo_idna(la, r, la, sizeof(la)); if (k < 0) return k; if (k > 0) r = k; } q = dns_label_unescape(&y, lb, sizeof(lb)); if (q < 0) return q; if (q > 0) { w = dns_label_undo_idna(lb, q, lb, sizeof(lb)); if (w < 0) return w; if (w > 0) q = w; } /* If one name had fewer labels than the other, this * will show up as empty label here, which the * strcasecmp() below will properly consider different * from a non-empty label. */ la[r] = lb[q] = 0; if (strcasecmp(la, lb) != 0) return false; } } int dns_name_endswith(const char *name, const char *suffix) { const char *n, *s, *saved_n = NULL; int r, q, k, w; assert(name); assert(suffix); n = name; s = suffix; for (;;) { char ln[DNS_LABEL_MAX+1], ls[DNS_LABEL_MAX+1]; r = dns_label_unescape(&n, ln, sizeof(ln)); if (r < 0) return r; if (r > 0) { k = dns_label_undo_idna(ln, r, ln, sizeof(ln)); if (k < 0) return k; if (k > 0) r = k; } if (!saved_n) saved_n = n; q = dns_label_unescape(&s, ls, sizeof(ls)); if (q < 0) return q; if (q > 0) { w = dns_label_undo_idna(ls, q, ls, sizeof(ls)); if (w < 0) return w; if (w > 0) q = w; } if (r == 0 && q == 0) return true; if (r == 0 && saved_n == n) return false; ln[r] = ls[q] = 0; if (r != q || strcasecmp(ln, ls)) { /* Not the same, let's jump back, and try with the next label again */ s = suffix; n = saved_n; saved_n = NULL; } } } 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, k, w; assert(name); assert(old_suffix); assert(new_suffix); assert(ret); n = name; s = old_suffix; for (;;) { char ln[DNS_LABEL_MAX+1], ls[DNS_LABEL_MAX+1]; if (!saved_before) saved_before = n; r = dns_label_unescape(&n, ln, sizeof(ln)); if (r < 0) return r; if (r > 0) { k = dns_label_undo_idna(ln, r, ln, sizeof(ln)); if (k < 0) return k; if (k > 0) r = k; } if (!saved_after) saved_after = n; q = dns_label_unescape(&s, ls, sizeof(ls)); if (q < 0) return q; if (q > 0) { w = dns_label_undo_idna(ls, q, ls, sizeof(ls)); if (w < 0) return w; if (w > 0) q = w; } if (r == 0 && q == 0) break; if (r == 0 && saved_after == n) { *ret = NULL; /* doesn't match */ return 0; } ln[r] = ls[q] = 0; if (r != q || strcasecmp(ln, ls)) { /* Not the same, let's jump back, and try with the next label again */ s = old_suffix; n = saved_after; 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, ret); if (r < 0) return r; return 1; } int dns_name_between(const char *a, const char *b, const char *c) { int n; /* 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. */ n = dns_name_compare_func(a, c); if (n == 0) return -EINVAL; else if (n < 0) /* a<---b--->c */ return dns_name_compare_func(a, b) < 0 && dns_name_compare_func(b, c) < 0; else /* <--b--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)); 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)); 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)); 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) { char label[DNS_LABEL_MAX+1]; int r; assert(name); r = dns_label_unescape(&name, label, sizeof(label)); if (r <= 0) return false; return dns_name_is_root(name); } /* Encode a domain name according to RFC 1035 Section 3.1 */ int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len) { 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 */ r = dns_label_unescape(&domain, (char *) out, len); if (r < 0) return r; /* fill label length, move forward */ *label_length = r; out += r; len -= r; } while (r != 0); 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)); 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 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, 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, &n); if (r < 0) return r; return dns_name_concat(escaped, n, 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)); 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)); 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)); 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 = strndup(a, an); if (!name) return -ENOMEM; type = new(char, bn+1+cn+1); if (!type) return -ENOMEM; strcpy(stpcpy(stpcpy(type, b), "."), c); d = p; goto finish; } } else if (srv_type_label_is_valid(a, an)) { /* OK, got . . */ name = NULL; type = new(char, an+1+bn+1); if (!type) return -ENOMEM; strcpy(stpcpy(stpcpy(type, a), "."), b); d = q; goto finish; } } name = NULL; type = NULL; d = joined; finish: r = dns_name_normalize(d, &domain); if (r < 0) return r; if (_domain) { *_domain = domain; domain = NULL; } if (_type) { *_type = type; type = NULL; } if (_name) { *_name = name; name = NULL; } return 0; }