let the ykpiv_connect() function select as well

lib/error.c

@@ -45,6 +45,7 @@ static const err_t errors[] = {
   ERR (YKPIV_MEMORY_ERROR, "Error allocating memory"),
   ERR (YKPIV_PCSC_ERROR, "Error in PCSC call"),
   ERR (YKPIV_SIZE_ERROR, "Wrong buffer size"),
+  ERR (YKPIV_APPLET_ERROR, "No PIV applet found"),
 };
 
 /**

lib/ykpiv.c

@@ -145,6 +145,28 @@ ykpiv_rc ykpiv_connect(ykpiv_state *state, const char *wanted) {
     return YKPIV_PCSC_ERROR;
   }
 
+  {
+    APDU apdu;
+    unsigned char data[0xff];
+    unsigned long recv_len = sizeof(data);
+    int sw;
+    ykpiv_rc res;
+
+    memset(apdu.raw, 0, sizeof(apdu));
+    apdu.st.ins = 0xa4;
+    apdu.st.p1 = 0x04;
+    apdu.st.lc = sizeof(aid);
+    memcpy(apdu.st.data, aid, sizeof(aid));
+
+    if((res = ykpiv_send_data(state, apdu.raw, data, &recv_len, &sw) != YKPIV_OK)) {
+      return res;
+    } else if(sw == 0x9000) {
+      return YKPIV_OK;
+    }
+
+    return YKPIV_APPLET_ERROR;
+  }
+
   return YKPIV_OK;
 }
 

lib/ykpiv.h

@@ -44,6 +44,7 @@ extern "C"
 		YKPIV_MEMORY_ERROR = -1,
 		YKPIV_PCSC_ERROR = -2,
 		YKPIV_SIZE_ERROR = -3,
+		YKPIV_APPLET_ERROR = -4,
 	} ykpiv_rc;
 
 	const char *ykpiv_strerror(ykpiv_rc err);