certvalidator.c

/**
    Example certifcate code
    gcc -o certexample certexample.c -lssl -lcrypto
*/
#include <openssl/x509.h>
#include <openssl/asn1.h>
#include <openssl/crypto.h>
#include <openssl/asn1t.h>
#include <openssl/x509v3.h>
#include <openssl/bio.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <time.h>
#include <openssl/asn1_mac.h>
#define DEBUG 0
#define LINE_BUFFER 100

const ASN1_TIME *X509_get0_notBefore(const X509 *x);
char** str_split(const char* a_str, const char a_delim);
char* concat(char *s1, char *s2);
char* get_basic_constraints(X509 *cert);
char* get_key_usage(X509 *cert);
char* compare_not_before(X509 *cert);
char* compare_not_after(X509 *cert);
char* get_SAN(X509 *cert);
char *get_domain_name(X509 *cert);
int matches_subject_alternative_name(const char *hostname, X509 *server_cert);
int get_public_key_length(X509 *cert);
int validate_basic_constraints(char* basic_constraints);
int validate_key_usage(char* key_usage);
int validate_key_length(int length);
int validate_CN(const char* hostname, char*cn);
int validate_wildcard_string(const char *hostname, char*hostname_with_wildcard);
int validate_CN_and_SAN(const char *url, X509 *cert);
int validate_not_before(X509 *cert);
int validate_not_after(X509 *cert);
int validate_certificate(const char *url, X509 *cert);
int find_first_instanceof(const char *str, char delim);
char *str_slice_to_end(const char *str, int begin);

int main(int argc, char **argv){

    char line[LINE_BUFFER];
    //open the file, create the file to write to
    FILE *csv_input = fopen(argv[1], "r");
    FILE *csv_output = fopen("output_test.csv" ,"w");
    //for each line in the csv file, process each certificate
    OpenSSL_add_all_algorithms();
    ERR_load_BIO_strings();
    ERR_load_crypto_strings();

    int n = 0;
    while (fgets(line, LINE_BUFFER, csv_input) != NULL){

        if(DEBUG){
            printf("CSV LINE # %d\n", n);
        }

        //init all the things we use to describe a certificate
        BIO *certificate_bio = NULL;
        X509 *cert = NULL;
        X509_NAME *cert_issuer = NULL;
        X509_CINF *cert_inf = NULL;
        STACK_OF(X509_EXTENSION) * ext_list;
        certificate_bio = BIO_new(BIO_s_file());
        //here we are able to access each line