darwinssl: fix SSL client certificate not found on MacOS Sierra

Reviewed-by: Nick Zitzmann

Closes #1105

lib/vtls/darwinssl.c

@@ -883,14 +883,18 @@ static OSStatus CopyIdentityWithLabel(char *label,
                                       SecIdentityRef *out_cert_and_key)
 {
   OSStatus status = errSecItemNotFound;
+  CFArrayRef keys_list;
+  CFIndex keys_list_count;
+  CFIndex i;
+  CFStringRef common_name;
 
 #if CURL_BUILD_MAC_10_7 || CURL_BUILD_IOS
   /* SecItemCopyMatching() was introduced in iOS and Snow Leopard.
      kSecClassIdentity was introduced in Lion. If both exist, let's use them
      to find the certificate. */
   if(SecItemCopyMatching != NULL && kSecClassIdentity != NULL) {
-    CFTypeRef keys[4];
-    CFTypeRef values[4];
+    CFTypeRef keys[5];
+    CFTypeRef values[5];
     CFDictionaryRef query_dict;
     CFStringRef label_cf = CFStringCreateWithCString(NULL, label,
       kCFStringEncodingUTF8);
@@ -900,21 +904,53 @@ static OSStatus CopyIdentityWithLabel(char *label,
     keys[0] = kSecClass;
     values[1] = kCFBooleanTrue;    /* we want a reference */
     keys[1] = kSecReturnRef;
-    values[2] = kSecMatchLimitOne; /* one is enough, thanks */
+    values[2] = kSecMatchLimitAll; /* kSecMatchLimitOne would be better if the
+                                    * label matching below worked correctly */
     keys[2] = kSecMatchLimit;
     /* identity searches need a SecPolicyRef in order to work */
-    values[3] = SecPolicyCreateSSL(false, label_cf);
+    values[3] = SecPolicyCreateSSL(false, NULL);
     keys[3] = kSecMatchPolicy;
+    /* match the name of the certificate (doesn't work in macOS 10.12.1) */
+    values[4] = label_cf;
+    keys[4] = kSecAttrLabel;
     query_dict = CFDictionaryCreate(NULL, (const void **)keys,
-                                   (const void **)values, 4L,
-                                   &kCFCopyStringDictionaryKeyCallBacks,
-                                   &kCFTypeDictionaryValueCallBacks);
+                                    (const void **)values, 5L,
+                                    &kCFCopyStringDictionaryKeyCallBacks,
+                                    &kCFTypeDictionaryValueCallBacks);
     CFRelease(values[3]);
-    CFRelease(label_cf);
 
     /* Do we have a match? */
-    status = SecItemCopyMatching(query_dict, (CFTypeRef *)out_cert_and_key);
+    status = SecItemCopyMatching(query_dict, (CFTypeRef *) &keys_list);
+
+    /* Because kSecAttrLabel matching doesn't work with kSecClassIdentity,
+     * we need to find the correct identity ourselves */
+    if(status == noErr) {
+      keys_list_count = CFArrayGetCount(keys_list);
+      *out_cert_and_key = NULL;
+      for(i=0; i<keys_list_count; i++) {
+        OSStatus err = noErr;
+        SecCertificateRef cert = NULL;
+        *out_cert_and_key =
+          (SecIdentityRef) CFArrayGetValueAtIndex(keys_list, i);
+        err = SecIdentityCopyCertificate(*out_cert_and_key, &cert);
+        if(err == noErr) {
+          SecCertificateCopyCommonName(cert, &common_name);
+          if(CFStringCompare(common_name, label_cf, 0) == kCFCompareEqualTo) {
+            CFRelease(cert);
+            CFRelease(common_name);
+            status = noErr;
+            break;
+          }
+          CFRelease(common_name);
+        }
+        *out_cert_and_key = NULL;
+        status = 1;
+        CFRelease(cert);
+      }
+    }
+
     CFRelease(query_dict);
+    CFRelease(label_cf);
   }
   else {
 #if CURL_SUPPORT_MAC_10_6