84 lines
2.6 KiB
Diff
84 lines
2.6 KiB
Diff
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From 362f91d807d293791008cdb7616d40f7784ece83 Mon Sep 17 00:00:00 2001
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From: bradh352 <brad@brad-house.com>
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Date: Fri, 11 Jun 2021 11:27:45 -0400
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Subject: [PATCH] ares_expand_name() should escape more characters
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RFC1035 5.1 specifies some reserved characters and escaping sequences
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that are allowed to be specified. Expand the list of reserved characters
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and also escape non-printable characters using the \DDD format as
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specified in the RFC.
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Bug Reported By: philipp.jeitner@sit.fraunhofer.de
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Fix By: Brad House (@bradh352)
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---
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src/lib/ares_expand_name.c | 41 +++++++++++++++++++++++++++++++++++---
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1 file changed, 38 insertions(+), 3 deletions(-)
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diff --git a/src/lib/ares_expand_name.c b/src/lib/ares_expand_name.c
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index 407200ef..f1c874a9 100644
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--- a/src/lib/ares_expand_name.c
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+++ b/src/lib/ares_expand_name.c
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@@ -32,6 +32,26 @@
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static int name_length(const unsigned char *encoded, const unsigned char *abuf,
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int alen);
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+/* Reserved characters for names that need to be escaped */
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+static int is_reservedch(int ch)
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+{
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+ switch (ch) {
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+ case '"':
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+ case '.':
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+ case ';':
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+ case '\\':
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+ case '(':
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+ case ')':
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+ case '@':
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+ case '$':
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+ return 1;
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+ default:
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+ break;
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+ }
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+
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+ return 0;
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+}
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+
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/* Expand an RFC1035-encoded domain name given by encoded. The
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* containing message is given by abuf and alen. The result given by
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* *s, which is set to a NUL-terminated allocated buffer. *enclen is
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@@ -111,9 +131,18 @@ int ares_expand_name(const unsigned char *encoded, const unsigned char *abuf,
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p++;
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while (len--)
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{
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- if (*p == '.' || *p == '\\')
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+ if (!isprint(*p)) {
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+ /* Output as \DDD for consistency with RFC1035 5.1 */
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+ *q++ = '\\';
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+ *q++ = '0' + *p / 100;
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+ *q++ = '0' + (*p % 100) / 10;
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+ *q++ = '0' + (*p % 10);
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+ } else if (is_reservedch(*p)) {
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*q++ = '\\';
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- *q++ = *p;
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+ *q++ = *p;
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+ } else {
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+ *q++ = *p;
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+ }
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p++;
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}
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*q++ = '.';
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@@ -171,7 +200,13 @@ static int name_length(const unsigned char *encoded, const unsigned char *abuf,
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encoded++;
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while (offset--)
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{
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- n += (*encoded == '.' || *encoded == '\\') ? 2 : 1;
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+ if (!isprint(*encoded)) {
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+ n += 4;
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+ } else if (is_reservedch(*encoded)) {
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+ n += 2;
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+ } else {
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+ n += 1;
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+ }
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encoded++;
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}
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n++;
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