convert base64url to base64

Signed-off-by: Hyunsoo Kim <[email protected]>

Author: movence

plugins/filter_kubernetes/kubernetes_aws.c

@@ -296,6 +296,7 @@ int determine_platform(struct flb_kube *ctx)
     char *first_dot; 
     char *second_dot;
     size_t payload_b64_len;
+    size_t padded_len;
     char *payload_b64;
     size_t issuer_len;
     char *issuer_value;
@@ -321,14 +322,28 @@ int determine_platform(struct flb_kube *ctx)
 
     /* Extract and decode the payload (middle part) */
     payload_b64_len = second_dot - (first_dot + 1);
-    payload_b64 = flb_malloc(payload_b64_len + 1);
+    
+    /* Calculate padded length */
+    padded_len = payload_b64_len;
+    while (padded_len % 4 != 0) padded_len++;
+    
+    payload_b64 = flb_malloc(padded_len + 1);
     if (!payload_b64) {
         flb_free(token_buf);
         return -1;
     }
 
     memcpy(payload_b64, first_dot + 1, payload_b64_len);
-    payload_b64[payload_b64_len] = '\0';
+    
+    /* Convert base64url to base64 and add padding */
+    for (size_t i = 0; i < payload_b64_len; i++) {
+        if (payload_b64[i] == '-') payload_b64[i] = '+';
+        else if (payload_b64[i] == '_') payload_b64[i] = '/';
+    }
+    while (payload_b64_len < padded_len) {
+        payload_b64[payload_b64_len++] = '=';
+    }
+    payload_b64[padded_len] = '\0';
 
     /* Base64 decode the payload */
     payload = flb_malloc(payload_b64_len * 3 / 4 + 4); /* Conservative size estimate */
@@ -338,8 +353,8 @@ int determine_platform(struct flb_kube *ctx)
         return -1;
     }
 
-    ret = flb_base64_decode((unsigned char *)payload, payload_b64_len * 3 / 4 + 4, 
-                           &payload_len, (unsigned char *)payload_b64, payload_b64_len);
+    ret = flb_base64_decode((unsigned char *)payload, padded_len * 3 / 4 + 4, 
+                           &payload_len, (unsigned char *)payload_b64, padded_len);
 
     flb_free(token_buf);
     flb_free(payload_b64);