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Cygwin: resolver: A few fixes for cygwin_query() 

- Make sure the answer buffer is properly cleared so there is no trailing
garbage when the response does not fit entirely in;
- Make sure an internal decomp failure gets reported correctly (w/return code -1);
- Make sure that the buffer is not overrun when filling out the header.
This commit is contained in:
Anton Lavrentiev via Cygwin-patches 2022-01-18 16:34:34 -05:00 committed by Corinna Vinschen
parent fa279a583d
commit 12bf36f72b
1 changed files with 13 additions and 8 deletions
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11
winsup/cygwin/libc/minires-os-if.c
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@ -193,6 +193,8 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
dnptrs[0] = AnsPtr; dnptrs[0] = AnsPtr;
dnptrs[1] = NULL; dnptrs[1] = NULL;
memset(AnsPtr, 0, AnsLength);
if (Class != ns_c_in) { if (Class != ns_c_in) {
errno = ENOSYS; errno = ENOSYS;
statp->res_h_errno = NETDB_INTERNAL; statp->res_h_errno = NETDB_INTERNAL;
@ -214,7 +216,7 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
switch (res) { switch (res) {
case ERROR_INVALID_NAME: case ERROR_INVALID_NAME:
errno = EINVAL; errno = EINVAL;
statp->res_h_errno = NETDB_INTERNAL;; statp->res_h_errno = NETDB_INTERNAL;
break; break;
case ERROR_TIMEOUT: case ERROR_TIMEOUT:
statp->res_h_errno = TRY_AGAIN; statp->res_h_errno = TRY_AGAIN;
@ -259,8 +261,9 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
/* No question. Adopt the first name as the name in the question */ /* No question. Adopt the first name as the name in the question */
if ((len = dn_comp(rr->pName, ptr, AnsLength - 4, if ((len = dn_comp(rr->pName, ptr, AnsLength - 4,
dnptrs, &dnptrs[DIM(dnptrs) - 1])) < 0) { dnptrs, &dnptrs[DIM(dnptrs) - 1])) < 0) {
ptr = NULL; statp->res_h_errno = NETDB_INTERNAL; /* dn_comp sets errno */
break; len = -1;
goto done;
} }
ptr += len; ptr += len;
PUTSHORT(Type, ptr); PUTSHORT(Type, ptr);
@ -289,12 +292,14 @@ static int cygwin_query(res_state statp, const char * DomName, int Class, int Ty
len = ptr - AnsPtr; len = ptr - AnsPtr;
done: done:
if (HFIXEDSZ <= AnsLength) {
ptr = AnsPtr; ptr = AnsPtr;
PUTSHORT(0, ptr); /* Id */ PUTSHORT(0, ptr); /* Id */
PUTSHORT((QR << 8) + RA + RD, ptr); PUTSHORT((QR << 8) + RA + RD, ptr);
for (section = 0; section < DIM(counts); section++) { for (section = 0; section < DIM(counts); section++) {
PUTSHORT(counts[section], ptr); PUTSHORT(counts[section], ptr);
} }
}
return len; return len;
} }