I've been searching for a while without any success, how am I supposed to get a DNS TXT record for a domain in Objective-C?
My goal is to get the same output as: dig -t txt google.com +short
PS: No NSTask/pipping please! (I'm currently doing that but it's bad). The code can be written in C, I'll just write a wrapper later. I don't care about AppStore rules.
Thank you!
Use DNSServiceQueryRecord in dns_sd.h:
#import <dns_sd.h>
// ...
DNSServiceRef serviceRef;
DNSServiceQueryRecord(&serviceRef, 0, 0, "hmspl.de", kDNSServiceType_TXT,
kDNSServiceClass_IN, queryCallback, NULL);
DNSServiceProcessResult(serviceRef);
DNSServiceRefDeallocate(serviceRef);
// ...
static void queryCallback(DNSServiceRef sdRef, DNSServiceFlags flags, uint32_t interfaceIndex,
DNSServiceErrorType errorCode, const char *fullname, uint16_t rrtype,
uint16_t rrclass, uint16_t rdlen, const void *rdata, uint32_t ttl, void *context) {
if (errorCode == kDNSServiceErr_NoError && rdlen > 1) {
NSMutableData *txtData = [NSMutableData dataWithCapacity:rdlen];
for (uint16_t i = 1; i < rdlen; i += 256) {
[txtData appendBytes:rdata + i length:MIN(rdlen - i, 255)];
}
NSString *theTXT = [[NSString alloc] initWithBytes:txtData.bytes length:txtData.length encoding:NSASCIIStringEncoding];
NSLog(#"%#", theTXT);
}
}
See https://developer.apple.com/library/mac/#documentation/Networking/Reference/DNSServiceDiscovery_CRef/Reference/reference.html#//apple_ref/doc/c_ref/DNSServiceQueryRecord
can use like this code remove \x02 \x03, I removed \0x12 \0x17
use $man ascii check
char result[256]={0};
dn_expand(rdata, rdata + rdlen, rdata, result, 256);
NSMutableData *txtData = [NSMutableData dataWithCapacity:rdlen];
char *p=(char*)rdata;
for (uint16_t i = 0; i < rdlen; i++) {
DLog(#"%c\n",*p);
if (*p > 0x20) {
[txtData appendBytes:p length:1];
}
p++;
}
Related
For some code challenge used in the oauth2 login process I need to do the following:
code_challenge = BASE64URL-ENCODE(SHA256(ASCII(code_verifier)))
How can I do this from my random string contained in code_verifier?
UPDATE: Can you check if this is correct? Or is some stuff unneccesary/deprecated? I actually have not really an idea what I am doing here, I just copied code from everywhere to solve it...
- (NSString *)createCodeChallengeWithVerifier:(NSString *)codeVerifier {
//Create ASCII
const char *asciiString = [codeVerifier cStringUsingEncoding:NSASCIIStringEncoding];
//Sha256
unsigned char buf[CC_SHA256_DIGEST_LENGTH];
CC_SHA256(asciiString, strlen(asciiString), buf);
NSMutableString * shaString = [NSMutableString stringWithCapacity:(CC_SHA256_DIGEST_LENGTH * 2)];
for (int i = 0; i < CC_SHA256_DIGEST_LENGTH; ++i) {
[shaString appendFormat:#"%02x", buf[i]];
}
//Base 64 encode
NSData *dataFromShaString = [shaString dataUsingEncoding:NSUTF8StringEncoding];
return([dataFromShaString base64EncodedStringWithOptions:0]);
}
I get strange code errors when I rename the following command line program from main.m to main.mm. Works just fine as main.m. Anyone know why?
https://stackoverflow.com/a/36469891/105539
SOURCE
#import <Foundation/Foundation.h>
void detectNewFile (
ConstFSEventStreamRef streamRef,
void *clientCallBackInfo,
size_t numEvents,
void *eventPaths,
const FSEventStreamEventFlags eventFlags[],
const FSEventStreamEventId eventIds[])
{
int i;
char **paths = eventPaths;
printf("GOT AN EVENT!!!!\n");
for (i=0; i<numEvents; i++) {
printf("Change %llu in %s, flags %u\n", eventIds[i], paths[i], (unsigned int)eventFlags[i]);
}
}
int main(int argc, const char * argv[]) {
#autoreleasepool {
short nPathCount = 2;
CFStringRef mypath[nPathCount];
mypath[0] = CFSTR("/Users/mike/Documents");
mypath[1] = CFSTR("/Users/mike/Downloads");
CFArrayRef pathsToWatch = CFArrayCreate(NULL, (const void **)&mypath, nPathCount, NULL);
void *callbackInfo = NULL;
CFAbsoluteTime latency = 1.0; // seconds
FSEventStreamRef hStream = FSEventStreamCreate(NULL,
&detectNewFile,
callbackInfo,
pathsToWatch,
kFSEventStreamEventIdSinceNow,
latency,
kFSEventStreamCreateFlagFileEvents
);
FSEventStreamScheduleWithRunLoop(hStream, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
FSEventStreamStart(hStream);
printf("Waiting on new file creations...\n");
CFRunLoopRun(); // runs in an endless loop, only letting the callback function run
} // end autorelease pool
return 0;
}
ERRORS
FOR:
char **paths = eventPaths;
Cannot initialize a variable of type 'char **' with an lvalue of type 'void *'
FOR:
FSEventStreamRef hStream = FSEventStreamCreate(NULL,
&detectNewFile,
callbackInfo,
pathsToWatch,
kFSEventStreamEventIdSinceNow,
latency,
kFSEventStreamCreateFlagFileEvents
);
No matching function for call to 'FSEventStreamCreate'
Thanks to #johnelemans, I found the problems. In C, it's legal to have automatic casting from void * to char **, but not in C++, which is what the .mm file would switch this into. The fix is to use casting:
char **paths = (char **)eventPaths;
Then, on the FSEventStreamCreate, it didn't like the void * instead of this:
FSEventStreamContext *callbackInfo = NULL;
...and didn't like the CFAbsoluteTime instead of:
CFTimeInterval latency = 1.0; // seconds
Then, you need to add CoreServices.framework library to the build steps.
I made those changes and it compiles now.
i have this function that reads a line from a file character by character and inserts it into a NSString.
RANDOMNLY the system crashes with this error:
malloc: *** error for object 0x1e1f6a00: incorrect checksum for freed
object - object was probably modified after being freed.
*** set a breakpoint in malloc_error_break to debug
function:
NSDictionary *readLineAsNSString(FILE *f,int pospass,
BOOL testata, int dimensioneriga)
{
char *strRet = (char *)malloc(BUFSIZ);
int size = BUFSIZ;
BOOL finito=NO;
int pos = 0;
int c;
fseek(f,pospass,SEEK_SET);
do{ // read one line
c = fgetc(f);
//Array expansion
if (pos >= size-1) {
size=size+BUFSIZ;
strRet = (char *)realloc(strRet, size);
}
if(c != EOF) {
strRet[pos] = c;
pos=pos+1;
}
if(c == EOF) {
finito=YES;
}
} while(c != EOF && c != '\n');
if (pos!=0) {
for (int i = pos; i<=strlen(strRet)-1; i++) //size al posto di pos
{
strRet[i] = ' ';
}
}
NSString *stringa;
if (pos!=0) {
stringa=[NSString stringWithCString:strRet encoding:NSASCIIStringEncoding];
} else {
stringa=#"";
}
long long sizerecord;
if (pos!=0) {
sizerecord= (long long) [[NSString stringWithFormat:#"%ld",sizeof(char)*(pos)] longLongValue];
} else {
sizerecord=0;
}
pos = pospass + pos;
NSDictionary *risultatoc = #{st_risultatofunzione: stringa,
st_criterio: [NSString stringWithFormat:#"%d",pos],
st_finito: [NSNumber numberWithBool:finito],
st_size: [NSNumber numberWithLongLong: sizerecord]
};
//free
free(strRet);
return risultatoc;
}
where "finito" is a flag, "pos" is the position in the file line,"pospass" is the position in the entire file, "c" is the character, "strRet" is the line and BUFSIZ is 1024.
Each file has n line with the same lenght (for file).
Thanks!!!
This part:
if (pos!=0) {
for (int i = pos; i<=strlen(strRet)-1; i++) //size al posto di pos
{
strRet[i] = ' ';
}
}
is broken. strlen just reads until it finds a \0 ... since you didn't put one in, it can just keep reading off the end of your buffer.
You already have size, so just use that, or better still just terminate strRet instead of right-filling with spaces:
strRet[pos] = '\0';
Below code runs just fine on GCC 4.2 but fails with EXC_BAD_ACCESS in LLVM GCC 4.2
- (double_t)readDouble {
double_t *dt = (double_t *)(buffer+offset);
double_t ret = *dt; // Program received signal: EXC_BAD_ACCESS
offset += 8;
return ret;
}
That's how I allocate
int dataLength = [data length];
buffer = malloc(dataLength + 1);
buffer[dataLength] = 0; // null terminate to log
[data getBytes:(void *)buffer length:[data length]];
//NSLog(#"%s", buffer);
Offset and buffer is like
#interface PRDataSet : NSObject {
NSMutableArray *tables;
NSMutableDictionary *tablesByName;
NSMutableDictionary *tablesById;
#private
NSURLConnection *conn;
int offset;
char *buffer;
}
Yes offset is within range.
I do not free the buffer before I use it.
Any ideas?
This could be an aligment problem. The ARM processors (and many other processors) have restrictions regarding the data alignment, e.g. they can only read and write floating-point numbers from addresses that are a multiple of 4 or 8.
From the way the buffer is allocated in your code, it might not be allocated properly, or your double_t data elements aren't aligned within the buffer.
In order to avoid the problem, you should try to first copy the data into an aligned buffer and read it from there.
LLVM just doesn't read float directly.
Here's the solution:
- (uint32_t)readUInt32 {
uint32_t ret = *(uint32_t *)(buffer+offset);
offset += 4;
return ret;
}
- (uint16_t)readUInt16 {
uint16_t ret = *(uint16_t *)(buffer+offset);
offset += 2;
return ret;
}
- (uint64_t)readUInt64 {
uint64_t ret = *(uint64_t *)(buffer+offset);
offset += 8;
return ret;
}
- (float_t)readSingle {
uint32_t t = [self readUInt32];
float_t ret = *((float_t *)(&t));
return ret;
}
- (double_t)readDouble {
uint64_t t = [self readUInt64];
double_t ret = *((double_t *)(&t));
return ret;
}
How to validate an IP address in Objective-C?
Here's a category using the modern inet_pton which will return YES for a valid IPv4 or IPv6 string.
#include <arpa/inet.h>
#implementation NSString (IPValidation)
- (BOOL)isValidIPAddress
{
const char *utf8 = [self UTF8String];
int success;
struct in_addr dst;
success = inet_pton(AF_INET, utf8, &dst);
if (success != 1) {
struct in6_addr dst6;
success = inet_pton(AF_INET6, utf8, &dst6);
}
return success == 1;
}
#end
Here's an alternative approach that might also help. Let's assume you have an NSString* that contains your IP address, called ipAddressStr, of the format a.b.c.d:
int ipQuads[4];
const char *ipAddress = [ipAddressStr cStringUsingEncoding:NSUTF8StringEncoding];
sscanf(ipAddress, "%d.%d.%d.%d", &ipQuads[0], &ipQuads[1], &ipQuads[2], &ipQuads[3]);
#try {
for (int quad = 0; quad < 4; quad++) {
if ((ipQuads[quad] < 0) || (ipQuads[quad] > 255)) {
NSException *ipException = [NSException
exceptionWithName:#"IPNotFormattedCorrectly"
reason:#"IP range is invalid"
userInfo:nil];
#throw ipException;
}
}
}
#catch (NSException *exc) {
NSLog(#"ERROR: %#", [exc reason]);
}
You could modify the if conditional block to follow RFC 1918 guidelines, if you need that level of validation.
Swift edition:
func isIPAddressValid(ip: String) -> Bool {
guard let utf8Str = (ip as NSString).utf8String else {
return false
}
let utf8:UnsafePointer<Int8> = UnsafePointer(utf8Str)
var success: Int32
var dst: in_addr = in_addr()
success = inet_pton(AF_INET, utf8, &dst)
if (success != 1) {
var dst6: in6_addr? = in6_addr()
success = inet_pton(AF_INET6, utf8, &dst6);
}
return success == 1
}
A trick you can do is test the return of the inet_aton BSD call like this:
#include <arpa/inet.h>
- (BOOL)isIp:(NSString*)string{
struct in_addr pin;
int success = inet_aton([string UTF8String],&pin);
if (success == 1) return TRUE;
return FALSE;
}
Be aware however that this validates the string if it contains a ip address in any format, it is not restricted to the dotted format.