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libc/resolv: Refactor the option parser
Start the loop by finding the end of the option name, the name-value separator (if any), and the end of the option. Use those pointers to simplify matching the option name and parsing the option value, and validate option names and values more strictly. This means that: * We no longer accept trailing garbage in an option name or value. For instance, we would previously interpret “edns0123” as “edns0” and “timeout:3xyz” as “timeout:3”. This was actually quite lucky because we also failed to recognize the newline at the end of the option line as a whitespace character. * For options that take a numerical argument, we would previously accept negative values and treat non-numerical arguments as 0, while large numerical arguments would be capped to the option's maximum permitted value. Now, any failure to parse the argument, including overflow, results in the option being left unchanged. MFC after: 1 week Relnotes: yes Reviewed by: markj Differential Revision: https://reviews.freebsd.org/D57923
This commit is contained in:
Dag-Erling Smørgrav committed
1 parent
aba9fffebf
commit
9bfdfecd27
1 file changed
+106
-90
+106
-90
@@ -3,6 +3,7 @@
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*
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* Copyright (c) 1985, 1989, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (c) 2026 Dag-Erling Smørgrav
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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@@ -80,6 +81,7 @@
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#include <arpa/nameser.h>
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#include <ctype.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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@@ -103,9 +105,11 @@ static const char sort_mask[] = "/&";
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static u_int32_t net_mask(struct in_addr);
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#endif
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#if !defined(isascii) /*%< XXX - could be a function */
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# define isascii(c) (!(c & 0200))
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#endif
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#define res_space(ch) \
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isspace((unsigned char)(ch))
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#define res_match(str, end, word) \
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(strncmp((str), (word), (end) - (str)) == 0 && \
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(word)[(end) - (str)] == '\0')
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/*
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* Resolver state default settings.
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@@ -520,129 +524,141 @@ __res_vinit(res_state statp, int preinit) {
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static void
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res_setoptions(res_state statp, const char *options, const char *source)
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{
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const char *cp = options;
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int i;
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const char *cp = options, *sp, *ep;
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char *numend;
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long num;
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struct __res_state_ext *ext = statp->_u._ext.ext;
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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if (statp->options & RES_DEBUG) {
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printf(";; res_setoptions(\"%s\", \"%s\")...\n",
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options, source);
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}
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#endif
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while (*cp) {
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for (;;) {
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/* skip leading and inner runs of spaces */
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while (*cp == ' ' || *cp == '\t')
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while (res_space(*cp))
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cp++;
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/* find the separator if there is one */
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sp = cp;
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while (*sp != '\0' && !res_space(*sp) && *sp != ':')
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sp++;
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/* find the end of the option */
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ep = sp;
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while (*ep != '\0' && !res_space(*ep))
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ep++;
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/* end of option line */
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if (ep == cp)
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break;
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/* search for and process individual options */
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if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
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i = atoi(cp + sizeof("ndots:") - 1);
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if (i <= RES_MAXNDOTS)
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statp->ndots = i;
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else
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statp->ndots = RES_MAXNDOTS;
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/* note: sp < ep if implies *sp == ':' */
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if (res_match(cp, sp, "ndots") && sp < ep) {
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num = strtol(sp + 1, &numend, 10);
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if (numend == ep && num >= 0 && num <= RES_MAXNDOTS) {
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statp->ndots = num;
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";;\tndots=%d\n", statp->ndots);
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if (statp->options & RES_DEBUG)
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printf(";;\tndots=%d\n", statp->ndots);
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#endif
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} else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
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i = atoi(cp + sizeof("timeout:") - 1);
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if (i <= RES_MAXRETRANS)
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statp->retrans = i;
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else
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statp->retrans = RES_MAXRETRANS;
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}
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} else if (res_match(cp, sp, "timeout") && sp < ep) {
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num = strtol(sp + 1, &numend, 10);
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if (numend == ep && num > 0 && num <= RES_MAXRETRANS) {
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statp->retrans = num;
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";;\ttimeout=%d\n", statp->retrans);
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if (statp->options & RES_DEBUG)
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printf(";;\ttimeout=%d\n",
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statp->retrans);
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#endif
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} else if (!strncmp(cp, "attempts:", sizeof("attempts:") - 1)){
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i = atoi(cp + sizeof("attempts:") - 1);
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if (i <= RES_MAXRETRY)
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statp->retry = i;
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else
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statp->retry = RES_MAXRETRY;
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}
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} else if (res_match(cp, sp, "attempts") && sp < ep) {
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num = strtol(sp + 1, &numend, 10);
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if (numend == ep && num > 0 && num <= RES_MAXRETRY) {
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statp->retry = num;
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";;\tattempts=%d\n", statp->retry);
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if (statp->options & RES_DEBUG)
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printf(";;\tattempts=%d\n",
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statp->retry);
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#endif
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} else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
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}
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} else if (res_match(cp, ep, "debug")) {
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#ifdef DEBUG
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if (!(statp->options & RES_DEBUG)) {
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printf(";; res_setoptions(\"%s\", \"%s\")..\n",
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options, source);
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statp->options |= RES_DEBUG;
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}
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#endif
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statp->options |= RES_DEBUG;
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#ifdef DEBUG
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printf(";;\tdebug\n");
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#endif
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} else if (!strncmp(cp, "no_tld_query",
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sizeof("no_tld_query") - 1) ||
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!strncmp(cp, "no-tld-query",
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sizeof("no-tld-query") - 1)) {
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} else if (res_match(cp, ep, "no-tld-query") ||
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res_match(cp, ep, "no_tld_query")) {
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statp->options |= RES_NOTLDQUERY;
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} else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
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} else if (res_match(cp, ep, "inet6")) {
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statp->options |= RES_USE_INET6;
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} else if (!strncmp(cp, "insecure1", sizeof("insecure1") - 1)) {
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statp->options |= RES_INSECURE1;
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} else if (!strncmp(cp, "insecure2", sizeof("insecure2") - 1)) {
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statp->options |= RES_INSECURE2;
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} else if (!strncmp(cp, "rotate", sizeof("rotate") - 1)) {
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} else if (res_match(cp, ep, "insecure1")) {
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statp->options |= RES_INSECURE1;
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} else if (res_match(cp, ep, "insecure2")) {
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statp->options |= RES_INSECURE2;
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} else if (res_match(cp, ep, "blast")) {
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statp->options |= RES_BLAST;
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} else if (res_match(cp, ep, "rotate")) {
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statp->options |= RES_ROTATE;
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} else if (!strncmp(cp, "usevc", sizeof("usevc") - 1)) {
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} else if (res_match(cp, ep, "usevc")) {
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statp->options |= RES_USEVC;
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} else if (!strncmp(cp, "no-check-names",
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sizeof("no-check-names") - 1)) {
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} else if (res_match(cp, ep, "no-check-names")) {
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statp->options |= RES_NOCHECKNAME;
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} else if (!strncmp(cp, "reload-period:",
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sizeof("reload-period:") - 1)) {
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if (ext != NULL) {
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ext->reload_period = (u_short)
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atoi(cp + sizeof("reload-period:") - 1);
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} else if (res_match(cp, sp, "reload-period") && sp < ep) {
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num = strtol(sp + 1, &numend, 10);
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if (numend == ep && num > 0 && num <= USHRT_MAX) {
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if (ext != NULL)
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ext->reload_period = (u_short)num;
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";;\treload-period %hu\n",
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(u_short)num);
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#endif
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}
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}
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#ifdef RES_USE_EDNS0
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else if (!strncmp(cp, "edns0", sizeof("edns0") - 1)) {
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} else if (res_match(cp, ep, "edns0")) {
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statp->options |= RES_USE_EDNS0;
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}
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#endif
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#ifndef _LIBC
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else if (!strncmp(cp, "dname", sizeof("dname") - 1)) {
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} else if (res_match(cp, ep, "dname")) {
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statp->options |= RES_USE_DNAME;
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}
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else if (!strncmp(cp, "nibble:", sizeof("nibble:") - 1)) {
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if (ext == NULL)
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goto skip;
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cp += sizeof("nibble:") - 1;
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i = MIN(strcspn(cp, " \t"), sizeof(ext->nsuffix) - 1);
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strncpy(ext->nsuffix, cp, i);
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ext->nsuffix[i] = '\0';
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}
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else if (!strncmp(cp, "nibble2:", sizeof("nibble2:") - 1)) {
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if (ext == NULL)
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goto skip;
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cp += sizeof("nibble2:") - 1;
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i = MIN(strcspn(cp, " \t"), sizeof(ext->nsuffix2) - 1);
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strncpy(ext->nsuffix2, cp, i);
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ext->nsuffix2[i] = '\0';
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}
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else if (!strncmp(cp, "v6revmode:", sizeof("v6revmode:") - 1)) {
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cp += sizeof("v6revmode:") - 1;
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/* "nibble" and "bitstring" used to be valid */
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if (!strncmp(cp, "single", sizeof("single") - 1)) {
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statp->options |= RES_NO_NIBBLE2;
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} else if (!strncmp(cp, "both", sizeof("both") - 1)) {
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statp->options &=
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~RES_NO_NIBBLE2;
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} else if (res_match(cp, sp, "nibble") && sp < ep) {
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sp++;
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if (ext != NULL && ep - sp < sizeof(ext->nsuffix)) {
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memcpy(ext->nsuffix, sp, ep - sp);
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ext->nsuffix[ep - sp] = '\0';
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}
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}
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} else if (res_match(cp, sp, "nibble2") && sp < ep) {
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sp++;
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if (ext != NULL && ep - sp < sizeof(ext->nsuffix2)) {
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memcpy(ext->nsuffix2, sp, ep - sp);
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ext->nsuffix2[ep - sp] = '\0';
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}
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} else if (res_match(cp, sp, "v6revmode") && sp < ep) {
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/* "nibble" and "bitstring" used to be valid */
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if (res_match(sp + 1, ep, "single"))
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statp->options |= RES_NO_NIBBLE2;
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else if (res_match(sp + 1, ep, "both"))
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statp->options &= ~RES_NO_NIBBLE2;
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#ifdef DEBUG
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else
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printf(";;\t%.*s: unrecognized value: %.*s\n",
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(int)(sp - cp), cp,
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(int)(ep - sp - 1), sp + 1);
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#endif
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else {
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/* XXX - print a warning here? */
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}
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#ifndef _LIBC
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skip:
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#endif /* !_LIBC */
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} else {
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#ifdef DEBUG
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printf(";;\tunrecognized option: %.*s\n",
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(int)(ep - cp), cp);
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#endif
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/* skip to next run of spaces */
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while (*cp && *cp != ' ' && *cp != '\t')
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cp++;
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}
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cp = ep;
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}
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}
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