199 lines
5.7 KiB
Diff
199 lines
5.7 KiB
Diff
From 4bde615c5fa2a6a6f61ca533e46a062691d83f45 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 1/2] 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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ares_expand_name.c | 41 ++++++++++++++++++++++++++++++++++++++---
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1 file changed, 38 insertions(+), 3 deletions(-)
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diff --git a/ares_expand_name.c b/ares_expand_name.c
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index 3a38e67..8604543 100644
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--- a/ares_expand_name.c
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+++ b/ares_expand_name.c
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@@ -38,6 +38,26 @@
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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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@@ -117,9 +137,18 @@ 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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@@ -177,7 +206,13 @@ 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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--
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2.26.3
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From 86cc9241f89c1155111b992ccc03bf76d8ae634a 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 12:39:24 -0400
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Subject: [PATCH 2/2] ares_expand_name(): fix formatting and handling of root
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name response
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Fixes issue introduced in prior commit with formatting and handling
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of parsing a root name response which should not be escaped.
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Fix By: Brad House
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---
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ares_expand_name.c | 62 ++++++++++++++++++++++++++++++----------------
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1 file changed, 40 insertions(+), 22 deletions(-)
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diff --git a/ares_expand_name.c b/ares_expand_name.c
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index 8604543..f89ee3f 100644
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--- a/ares_expand_name.c
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+++ b/ares_expand_name.c
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@@ -133,27 +133,37 @@ int ares_expand_name(const unsigned char *encoded, const unsigned char *abuf,
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}
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else
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{
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- len = *p;
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+ int name_len = *p;
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+ len = name_len;
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p++;
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+
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while (len--)
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{
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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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- } else {
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- *q++ = *p;
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- }
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+ /* Output as \DDD for consistency with RFC1035 5.1, except
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+ * for the special case of a root name response */
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+ if (!isprint(*p) && !(name_len == 1 && *p == 0))
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+ {
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+
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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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+ }
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+ else if (is_reservedch(*p))
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+ {
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+ *q++ = '\\';
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+ *q++ = *p;
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+ }
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+ else
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+ {
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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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}
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- }
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+ }
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+
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if (!indir)
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*enclen = aresx_uztosl(p + 1U - encoded);
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@@ -200,21 +210,29 @@ static int name_length(const unsigned char *encoded, const unsigned char *abuf,
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}
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else if (top == 0x00)
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{
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- offset = *encoded;
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+ int name_len = *encoded;
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+ offset = name_len;
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if (encoded + offset + 1 >= abuf + alen)
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return -1;
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encoded++;
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+
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while (offset--)
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{
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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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+ if (!isprint(*encoded) && !(name_len == 1 && *encoded == 0))
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+ {
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+ n += 4;
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+ }
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+ else if (is_reservedch(*encoded))
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+ {
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+ n += 2;
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+ }
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+ else
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+ {
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+ n += 1;
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+ }
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encoded++;
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}
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+
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n++;
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}
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else
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--
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2.26.3
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