common: Improved the certificate information extračtion

Added a function to extract the needed information from an
OpenSSL X509 object.  Also extended parse_tlsid() to include
a pointer to the certificate digest, to have a common behaviour
between parse_tlsid() and parse_x509_cert().

Signed-off-by: David Sommerseth <dazo@users.sourceforge.net>

2 files changed, 88 insertions, 2 deletions

diff --git a/common/certinfo.c b/common/certinfo.c
index 12a03fc..36a92a7 100644
--- a/common/certinfo.c
+++ b/common/certinfo.c
@@ -32,6 +32,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <openssl/x509.h>
 
 #include <eurephia_nullsafe.h>
 #include <certinfo.h>
@@ -53,7 +54,7 @@
  *
  * @return Pointer to a certinfo structure containing the information
  */
-certinfo *parse_tlsid(const char *input) {
+certinfo *parse_tlsid(const char *input, const char *digest) {
         char tmp[130], *mainp, *origptr, *sub, *tok, *tok2;
         certinfo *ret = NULL;
 
@@ -86,6 +87,9 @@ certinfo *parse_tlsid(const char *input) {
         }
         free(origptr); mainp = NULL; origptr = NULL;
 
+        /* Copy over the digest info */
+        ret->digest = digest;
+
         /* Make sure we at least have empty NULL terminated strings */
         if( ret->org == NULL ) {
                 ret->org = strdup("\0");
@@ -100,6 +104,86 @@ certinfo *parse_tlsid(const char *input) {
         return ret;
 }
 
+/**
+ *  Parses an X.509 certificate data structure into a certinfo struct
+ *  This implementation depends on OpenSSL
+ */
+certinfo *parse_x509_cert (X509 *cert)
+{
+        int i, n, objnid;
+        const int hashlen = SHA_DIGEST_LENGTH*3+2;
+        ASN1_OBJECT *asn1 = NULL;
+        ASN1_STRING *asn1val = NULL;
+        X509_NAME *x509_name = NULL;
+        X509_NAME_ENTRY *ent = NULL;
+        const char *objbuf = NULL;
+        unsigned char *buf = NULL;
+        char *ptr = NULL;
+        certinfo *ret = NULL;
+
+        ret = (certinfo *) malloc_nullsafe(NULL, sizeof(certinfo)+2);
+
+        x509_name = X509_get_subject_name(cert);
+        n = X509_NAME_entry_count(x509_name);
+        for (i = 0; i < n; i++) {
+                ent = X509_NAME_get_entry(x509_name, i);
+                if( !ent ) {
+                        continue;
+                }
+
+                asn1 = X509_NAME_ENTRY_get_object(ent);
+                if( !asn1 ) {
+                        continue;
+                }
+
+                asn1val = X509_NAME_ENTRY_get_data(ent);
+                if( !asn1val ) {
+                        continue;
+                }
+
+                objnid = OBJ_obj2nid(asn1);
+                if( objnid == NID_undef ) {
+                        continue;
+                }
+
+                objbuf = OBJ_nid2sn(objnid);
+                if( !objbuf ) {
+                        continue;
+                }
+
+                if( ASN1_STRING_to_UTF8(&buf, asn1val) <= 0 ) {
+                        continue;
+                }
+
+                // At this point we now have the 'field name' from the certificate
+                // available in objbuf and the 'field value' in buf.
+
+                if( (ret->org == NULL) && (strcmp(objbuf, "O") == 0) ) {
+                        ret->org = strdup_nullsafe((char *) buf);
+                } else if( (ret->common_name == NULL) && (strcmp(objbuf, "CN") == 0) ) {
+                        ret->common_name = strdup_nullsafe((char *) buf);
+                } else if( (ret->email == NULL) && (strcmp(objbuf, "emailAddress") == 0) ) {
+                        ret->email = strdup_nullsafe((char *) buf);
+                }
+                OPENSSL_free(buf); buf = NULL;
+
+                if( ret->org && ret->common_name && ret->email ) {
+                        // If we got all we need, skip the rest
+                        break;
+                }
+        }
+
+        // Extract the SHA1 certificate fingerprint/digest
+        ptr = ret->digest = malloc_nullsafe(NULL, hashlen);
+        buf = cert->sha1_hash;
+        for( i = 0; i < SHA_DIGEST_LENGTH; ++i ) {
+                snprintf(ptr, 4, "%02x:", buf[i]);
+                ptr += 3;
+        }
+        *(ptr-1) = 0;
+
+        return ret;
+}
 
 /**
  * Frees up the memory used by a certinfo structure
diff --git a/common/certinfo.h b/common/certinfo.h
index 91103d8..f306e36 100644
--- a/common/certinfo.h
+++ b/common/certinfo.h
@@ -41,7 +41,9 @@ typedef struct _certinfo {
         char *email;		/**< Contains the emailAddress field from the X.509 certificate */
 } certinfo;
 
-certinfo *parse_tlsid(const char *);
+certinfo *parse_tlsid(const char *, const char *);
+certinfo *parse_x509_cert (X509 *cert);
+
 void free_certinfo(certinfo *);
 
 #endif