mDNSMacOSX/mdns_objects/mdns_helpers.c

   1 /*
   2  * Copyright (c) 2019-2020 Apple Inc. All rights reserved.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     https://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include "mdns_helpers.h"
  18
  19 #include <CoreUtils/CoreUtils.h>
  20 #include "DNSMessage.h"
  21
  22 //======================================================================================================================
  23 // MARK: - Internals
  24
  25 MDNS_LOG_CATEGORY_DEFINE(helpers, "helpers");
  26
  27 //======================================================================================================================
  28
  29 int
  30 mdns_snprintf_add(char **ptr, const char *lim, const char *fmt, ...)
  31 {
  32         va_list args;
  33         char * const dst = ptr ? *ptr : NULL;
  34         const size_t len = (size_t)(lim - dst);
  35         va_start(args, fmt);
  36         const int n = vsnprintf(dst, len, fmt, args);
  37         va_end(args);
  38         require_quiet(n >= 0, exit);
  39
  40         if (ptr) {
  41                 if (((size_t)n) > len) {
  42                         *ptr = dst + len;
  43                 } else {
  44                         *ptr = dst + n;
  45                 }
  46         }
  47
  48 exit:
  49         return n;
  50 }
  51
  52 //======================================================================================================================
  53
  54 OSStatus
  55 mdns_replace_string(char **string_ptr, const char *replacement)
  56 {
  57         OSStatus err;
  58         char *new_string;
  59         if (replacement) {
  60                 new_string = strdup(replacement);
  61                 require_action_quiet(new_string, exit, err = kNoMemoryErr);
  62         } else {
  63                 new_string = NULL;
  64         }
  65         FreeNullSafe(*string_ptr);
  66         *string_ptr = new_string;
  67         err = kNoErr;
  68
  69 exit:
  70         return err;
  71 }
  72
  73 //======================================================================================================================
  74
  75 OSStatus
  76 mdns_make_socket_nonblocking(int sock)
  77 {
  78         int flags = fcntl(sock, F_GETFL, 0);
  79         flags |= O_NONBLOCK;
  80         OSStatus err = fcntl(sock, F_SETFL, flags);
  81         err = map_global_value_errno(err != -1, err);
  82     return err;
  83 }
  84
  85 //======================================================================================================================
  86
  87 uint64_t
  88 mdns_mach_ticks_per_second(void)
  89 {
  90         static dispatch_once_t  s_once = 0;
  91         static uint64_t                 s_ticks_per_second = 0;
  92         dispatch_once(&s_once,
  93         ^{
  94                 mach_timebase_info_data_t info;
  95                 const kern_return_t err = mach_timebase_info(&info);
  96                 if (!err && (info.numer != 0) && (info.denom != 0)) {
  97                         s_ticks_per_second = (info.denom * UINT64_C_safe(kNanosecondsPerSecond)) / info.numer;
  98                 } else {
  99                         os_log_error(_mdns_helpers_log(),
 100                                 "Unexpected results from mach_timebase_info: err %d numer %u denom %u", err, info.numer, info.denom);
 101                         s_ticks_per_second = kNanosecondsPerSecond;
 102                 }
 103         });
 104         return s_ticks_per_second;
 105 }
 106
 107 //======================================================================================================================
 108
 109 int
 110 mdns_print_obfuscated_ip_address(char * const buf_ptr, const size_t buf_len, const struct sockaddr * const sa)
 111 {
 112         int n;
 113         char strbuf[64];
 114         switch (sa->sa_family) {
 115                 case AF_INET: {
 116                         const struct sockaddr_in * const sin = (const struct sockaddr_in *)sa;
 117                         n = DNSMessagePrintObfuscatedIPv4Address(strbuf, sizeof(strbuf), ntohl(sin->sin_addr.s_addr));
 118                         require_return_value(n >= 0, n);
 119                         return snprintf(buf_ptr, buf_len, "<IPv4:%s>", strbuf);
 120                 }
 121                 case AF_INET6: {
 122                         const struct sockaddr_in6 * const sin6 = (const struct sockaddr_in6 *)sa;
 123                         n = DNSMessagePrintObfuscatedIPv6Address(strbuf, sizeof(strbuf), sin6->sin6_addr.s6_addr);
 124                         require_return_value(n >= 0, n);
 125                         return snprintf(buf_ptr, buf_len, "<IPv6:%s>", strbuf);
 126                 }
 127                 default: {
 128                         return kTypeErr;
 129                 }
 130         }
 131 }