I have subject name of CA certificate in CN=CA1, O=DEVANG.
I want to convert into X509_NAME format.
Is there any APIs to help me convert it ?
How can I compare ?
There do not seem to be any helper functions available in OpenSSL to do this. It looks like the only way to achieve what you want is by parsing the string and building up the X509_NAME_ENTRY elements one by one. You could use strsep for that, resulting in something like this code (which does not do any error checking and is error prone with regard to variations in the name format):
#define TEST_NAME "CN=CA1, O=DEVANG"
X509_NAME *x509name = X509_NAME_new();
char *x509nameString = strdup(TEST_NAME);
char *toFree = x509nameString;
char *x509nameEntryString = strsep(&x509nameString, ",");
char *x509nameEntryTypeString;
char *x509nameEntryValueString;
while (NULL != x509nameEntryString) {
x509nameEntryValueString = x509nameEntryString;
x509nameEntryTypeString = strsep(&x509nameEntryValueString, "=");
X509_NAME_add_entry_by_txt(x509name, x509nameEntryTypeString,
MBSTRING_ASC, x509nameEntryValueString, -1, -1, 0);
/* Need to skip spaces */
while ((NULL != x509nameString) &&
(' ' == *x509nameString)) {
x509nameString = &x509nameString[1];
}
x509nameEntryString = strsep(&x509nameString, ",");
}
/* See the result, just FYI */
X509_NAME_print_ex_fp(stdout, x509name, 0, XN_FLAG_ONELINE);
free(toFree);
For comparing two X509_NAME instances, the function X509_NAME_cmp() is available.
I do hope somebody has a better answer...
Related
I'm writing a hand-written lexer for a small language but have one weird requirement that I'm not sure how to handle.
I need to be able to support the notion of delimited strings where the delimiter could be any char. eg. strings are most likely to be delimited using double quotes (eg. "hello") but it could just as easily be /hello/ or ,hello,
eg. some sample input lines might be:
x = /abc/
y = "abc" + ,def,
z = zabcz
The last case is a bit pathological, but technically possible.
I'm trying work out if there's any way I can do this in the tokenization phase in the general case? Any thoughts or suggestions would be grand.
Here are solutions in c++ and js.
c++
#include "vector"
#include "string"
#include "iostream"
using namespace std;
// Lexically Analyze method
auto lex_argument(string code){
// Define variables
size_t equal_location;
int counter = 0;
auto variable;
string variable_name;
auto variable_info[2]
string code_for_inspection;
/* In the case of a variable , these two characters will hold the beginning and end of the string */
char string_variable_characters[2];
equal_location = code.find("=",0,code.length());
variable_value = code.substr(equal_location + 2,code.length());
variable_name = code.substr(code.begin(),equal_location - 2);
variable_info[0] = variable_name;
string_variable_characters[0] = (char) variable_value.substr(0,1);
string_variable_characters[1] = (char)
variable_value.substr(variable_value.length() - 1,variable_value.length());
if(string_variable_charecters[0] = string_variable_charecters[1]){
variable_name.erase(0,1);
variable_value.erase(variable_value.length() - 1,variable_value.length());
variable_info[1] = variable_value;
}
return variable_info;
}
and in js:
function lex_argument(code){
var equalLocation = code.search("=");
var variableInfo = [null,null];
variableInfo[1] = code.substr(1,equalLocation - 2);
variableInfo[0] = code.substr(equalLocation,code.length);
string_delimeters = [variableInfo[0].substr(1,2),variableInfo[0].substr(variableInfo[0].length - 1,variableInfo[0].length];
return variableInfo;
}
I fear I'm trying to reinvent the wheel here. I'm putting Objects into my SQFL database:
https://pub.dev/packages/sqflite
some of the object fields are Lists of ints others are Lists of Strings. I'm encoding these as plain Strings to place in a TEXT field in my SQFL database.
At some point I'm going to have to turn them back, I couldn't find anything on Google, which is surprising because this must be a very common occurrence with SQFL
I've started coding the 'decoding', but it's rookie dart. Is there anything performant around I ought to use?
Code included to prove I'm not totally lazy, no need to look, edge cases make it fail.
List<int> listOfInts = new List<int>();
String testStringOfInts = "[1,2,4]";
List<String> intermediateStep2 = testStringOfInts.split(',');
int numListElements = intermediateStep2.length;
print("intermediateStep2: $intermediateStep2, numListElements: $numListElements");
for (int i = 0; i < numListElements; i++) {
if (i == 0) {
listOfInts.add(int.parse(intermediateStep2[i].substring(1)));
continue;
}
else if ((i) == (numListElements - 1)) {
print('final element: ${intermediateStep2[i]}');
listOfInts.add(int.parse(intermediateStep2[i].substring(0, intermediateStep2[i].length - 1)));
continue;
}
else listOfInts.add(int.parse(intermediateStep2[i]));
}
print('Output: $listOfInts');
/* DECODING LISTS OF STRINGS */
String testString = "['element1','element2','element23']";
List<String> intermediateStep = testString.split("'");
List<String> output = new List<String>();
for (int i = 0; i < intermediateStep.length; i++) {
if (i % 2 == 0) {
continue;
} else {
print('adding a value to output: ${intermediateStep[i]}');
//print('value is a: ${(intermediateStep[i]).runtimeType}');
output.add(intermediateStep[i]);
}
}
print('Output: $output');
}
For the integers your could make the parsing like:
void main() {
print(parseStringAsIntList("[1,2,4]")); // [1, 2, 4]
}
List<int> parseStringAsIntList(String stringOfInts) => stringOfInts
.substring(1, stringOfInts.length - 1)
.split(',')
.map(int.parse)
.toList();
I need more information about how the Strings are saved in some corner cases like if they contain , and/or ' since this will change how the parsing should be done. But if both characters are valid in the string (especially ,) I will recommend you to change the storage format into JSON instead which makes it a lot easier to encode/decode and without the risk of using characters which can give you issues).
But a rather naive solution can be made like this if we know each String does not contain ,:
void main() {
print(parseStringAsStringList("['element1','element2','element23']"));
// [element1, element2, element23]
}
List<String> parseStringAsStringList(String stringOfStrings) => stringOfStrings
.substring(1, stringOfStrings.length - 1)
.split(',')
.map((string) => string.substring(1, string.length - 1))
.toList();
I'd like a step by step explanation on how to parse the arguments of a variadic function
so that when calling va_arg(ap, TYPE); I pass the correct data TYPE of the argument being passed.
Currently I'm trying to code printf.
I am only looking for an explanation preferably with simple examples but not the solution to printf since I want to solve it myself.
Here are three examples which look like what I am looking for:
https://stackoverflow.com/a/1689228/3206885
https://stackoverflow.com/a/5551632/3206885
https://stackoverflow.com/a/1722238/3206885
I know the basics of what typedef, struct, enum and union do but can't figure out some practical application cases like the examples in the links.
What do they really mean? I can't wrap my brain around how they work.
How can I pass the data type from a union to va_arg like in the links examples? How does it match?
with a modifier like %d, %i ... or the data type of a parameter?
Here's what I've got so far:
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include "my.h"
typedef struct s_flist
{
char c;
(*f)();
} t_flist;
int my_printf(char *format, ...)
{
va_list ap;
int i;
int j;
int result;
int arg_count;
char *cur_arg = format;
char *types;
t_flist flist[] =
{
{ 's', &my_putstr },
{ 'i', &my_put_nbr },
{ 'd', &my_put_nbr }
};
i = 0;
result = 0;
types = (char*)malloc( sizeof(*format) * (my_strlen(format) / 2 + 1) );
fparser(types, format);
arg_count = my_strlen(types);
while (format[i])
{
if (format[i] == '%' && format[i + 1])
{
i++;
if (format[i] == '%')
result += my_putchar(format[i]);
else
{
j = 0;
va_start(ap, format);
while (flist[j].c)
{
if (format[i] == flist[j].c)
result += flist[i].f(va_arg(ap, flist[i].DATA_TYPE??));
j++;
}
}
}
result += my_putchar(format[i]);
i++;
}
va_end(ap);
return (result);
}
char *fparser(char *types, char *str)
{
int i;
int j;
i = 0;
j = 0;
while (str[i])
{
if (str[i] == '%' && str[i + 1] &&
str[i + 1] != '%' && str[i + 1] != ' ')
{
i++;
types[j] = str[i];
j++;
}
i++;
}
types[j] = '\0';
return (types);
}
You can't get actual type information from va_list. You can get what you're looking for from format. What it seems you're not expecting is: none of the arguments know what the actual types are, but format represents the caller's idea of what the types should be. (Perhaps a further hint: what would the actual printf do if a caller gave it format specifiers that didn't match the varargs passed in? Would it notice?)
Your code would have to parse the format string for "%" format specifiers, and use those specifiers to branch into reading the va_list with specific hardcoded types. For example, (pseudocode) if (fspec was "%s") { char* str = va_arg(ap, char*); print out str; }. Not giving more detail because you explicitly said you didn't want a complete solution.
You will never have a type as a piece of runtime data that you can pass to va_arg as a value. The second argument to va_arg must be a literal, hardcoded specification referring to a known type at compile time. (Note that va_arg is a macro that gets expanded at compile time, not a function that gets executed at runtime - you couldn't have a function taking a type as an argument.)
A couple of your links suggest keeping track of types via an enum, but this is only for the benefit of your own code being able to branch based on that information; it is still not something that can be passed to va_arg. You have to have separate pieces of code saying literally va_arg(ap, int) and va_arg(ap, char*) so there's no way to avoid a switch or a chain of ifs.
The solution you want to make, using the unions and structs, would start from something like this:
typedef union {
int i;
char *s;
} PRINTABLE_THING;
int print_integer(PRINTABLE_THING pt) {
// format and print pt.i
}
int print_string(PRINTABLE_THING pt) {
// format and print pt.s
}
The two specialized functions would work fine on their own by taking explicit int or char* params; the reason we make the union is to enable the functions to formally take the same type of parameter, so that they have the same signature, so that we can define a single type that means pointer to that kind of function:
typedef int (*print_printable_thing)(PRINTABLE_THING);
Now your code can have an array of function pointers of type print_printable_thing, or an array of structs that have print_printable_thing as one of the structs' fields:
typedef struct {
char format_char;
print_printable_thing printing_function;
} FORMAT_CHAR_AND_PRINTING_FUNCTION_PAIRING;
FORMAT_CHAR_AND_PRINTING_FUNCTION_PAIRING formatters[] = {
{ 'd', print_integer },
{ 's', print_string }
};
int formatter_count = sizeof(formatters) / sizeof(FORMAT_CHAR_AND_PRINTING_FUNCTION_PAIRING);
(Yes, the names are all intentionally super verbose. You'd probably want shorter ones in the real program, or even anonymous types where appropriate.)
Now you can use that array to select the correct formatter at runtime:
for (int i = 0; i < formatter_count; i++)
if (current_format_char == formatters[i].format_char)
result += formatters[i].printing_function(current_printable_thing);
But the process of getting the correct thing into current_printable_thing is still going to involve branching to get to a va_arg(ap, ...) with the correct hardcoded type. Once you've written it, you may find yourself deciding that you didn't actually need the union nor the array of structs.
I want to keep white space when I call text attribute of token, is there any way to do it?
Here is the situation:
We have the following code
IF L > 40 THEN;
ELSE
IF A = 20 THEN
PUT "HELLO";
In this case, I want to transform it into:
if (!(L>40){
if (A=20)
put "hello";
}
The rule in Antlr is that:
stmt_if_block: IF expr
THEN x=stmt
(ELSE y=stmt)?
{
if ($x.text.equalsIgnoreCase(";"))
{
WriteLn("if(!(" + $expr.text +")){");
WriteLn($stmt.text);
Writeln("}");
}
}
But the result looks like:
if(!(L>40))
{
ifA=20put"hello";
}
The reason is that the white space in $stmt was removed. I was wondering if there is anyway to keep these white space
Thank you so much
Update: If I add
SPACE: [ ] -> channel(HIDDEN);
The space will be preserved, and the result would look like below, many spaces between tokens:
IF SUBSTR(WNAME3,M-1,1) = ')' THEN M = L; ELSE M = L - 1;
This is the C# extension method I use for exactly this purpose:
public static string GetFullText(this ParserRuleContext context)
{
if (context.Start == null || context.Stop == null || context.Start.StartIndex < 0 || context.Stop.StopIndex < 0)
return context.GetText(); // Fallback
return context.Start.InputStream.GetText(Interval.Of(context.Start.StartIndex, context.Stop.StopIndex));
}
Since you're using java, you'll have to translate it, but it should be straightforward - the API is the same.
Explanation: Get the first token, get the last token, and get the text from the input stream between the first char of the first token and the last char of the last token.
#Lucas solution, but in java in case you have troubles in translating:
private String getFullText(ParserRuleContext context) {
if (context.start == null || context.stop == null || context.start.getStartIndex() < 0 || context.stop.getStopIndex() < 0)
return context.getText();
return context.start.getInputStream().getText(Interval.of(context.start.getStartIndex(), context.stop.getStopIndex()));
}
Looks like InputStream is not always updated after removeLastChild/addChild operations. This solution helped me for one grammar, but it doesn't work for another.
Works for this grammar.
Doesn't work for modern groovy grammar (for some reason inputStream.getText contains old text).
I am trying to implement function name replacement like this:
enterPostfixExpression(ctx: PostfixExpressionContext) {
// Get identifierContext from ctx
...
const token = CommonTokenFactory.DEFAULT.createSimple(GroovyParser.Identifier, 'someNewFnName');
const node = new TerminalNode(token);
identifierContext.removeLastChild();
identifierContext.addChild(node);
UPD: I used visitor pattern for the first implementation
I am using libclang to parse a objective c source code file. The following code finds all Objective-C instance method declarations, but it also finds declarations in the includes:
enum CXCursorKind curKind = clang_getCursorKind(cursor);
CXString curKindName = clang_getCursorKindSpelling(curKind);
const char *funcDecl="ObjCInstanceMethodDecl";
if(strcmp(clang_getCString(curKindName),funcDecl)==0{
}
How can I skip everything, which comes from header includes? I am only interested in my own Objective-C instance method declarations in the source file, not in any of the includes.
e.g. the following should not be included
...
Location: /System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:15:9:315
Type:
TypeKind: Invalid
CursorKind: ObjCInstanceMethodDecl
...
Answering this question because I couldn't believe that hard-coding paths comparisons was the only solution, and indeed, there is a clang_Location_isFromMainFile function that does exactly what you want, so that you can filter unwanted results in the visitor, like this :
if (clang_Location_isFromMainFile (clang_getCursorLocation (cursor)) == 0) {
return CXChildVisit_Continue;
}
The only way I know would be to skip unwanted paths during the AST visit. You can for example put something like the following in your visitor function. Returning CXChildVisit_Continue avoids visiting the entire file.
CXFile file;
unsigned int line, column, offset;
CXString fileName;
char * canonicalPath = NULL;
clang_getExpansionLocation (clang_getCursorLocation (cursor),
&file, &line, &column, &offset);
fileName = clang_getFileName (file);
if (clang_getCString (fileName)) {
canonicalPath = realpath (clang_getCString (fileName), NULL);
}
clang_disposeString (fileName);
if (strcmp(canonicalPath, "/canonical/path/to/your/source/file") != 0) {
return CXChildVisit_Continue;
}
Also, why compare CursorKindSpelling instead of the CursorKind directly?