Fix alignment calculations

Author: kosmas-valianos

src/proxy_protocol.c

@@ -656,14 +656,21 @@ uint8_t *pp2_create_hdr(const pp_info_t *pp_info, uint16_t *pp2_hdr_len, int32_t
         len += sizeof_pp2_tlv_t + sizeof(uint32_t);
     }
     *pp2_hdr_len = sizeof(proxy_hdr_v2_t) + len;
-    if (pp_info->pp2_info.align_padding > 1)
+    if (pp_info->pp2_info.alignment_power > 1)
     {
-        uint16_t pow = 1 << pp_info->pp2_info.align_padding;
-        if (*pp2_hdr_len % pow)
+        uint16_t alignment = 1 << pp_info->pp2_info.alignment_power;
+        if (*pp2_hdr_len % alignment)
         {
-            padding_bytes = (*pp2_hdr_len - sizeof_pp2_tlv_t) % pow;
-            len += sizeof_pp2_tlv_t + padding_bytes;
-            *pp2_hdr_len = sizeof(proxy_hdr_v2_t) + len;
+            uint16_t pp2_hdr_len_padded = (*pp2_hdr_len / alignment + 1) * alignment;
+            /* The NOOP TLV needs to be at least 3 bytes because a TLV can not be smaller than that */
+            if (pp2_hdr_len_padded - *pp2_hdr_len < 3)
+            {
+                pp2_hdr_len_padded += alignment;
+            }
+            padding_bytes = pp2_hdr_len_padded - sizeof(proxy_hdr_v2_t) - len - sizeof_pp2_tlv_t;
+
+            *pp2_hdr_len = pp2_hdr_len_padded;
+            len = pp2_hdr_len_padded - sizeof(proxy_hdr_v2_t);
         }
     }
     proxy_hdr_v2.len = htons(len);
@@ -688,7 +695,7 @@ uint8_t *pp2_create_hdr(const pp_info_t *pp_info, uint16_t *pp2_hdr_len, int32_t
         memcpy(pp2_hdr + index, tlv_array->tlvs[i], tlv_len);
         index += tlv_len;
     }
-    if (pp_info->pp2_info.align_padding > 1)
+    if (pp_info->pp2_info.alignment_power > 1)
     {
         pp2_tlv_t tlv = {
             .type = PP2_TYPE_NOOP,

src/proxy_protocol.h

@@ -89,7 +89,7 @@ typedef struct
      * In parsing:
      *      Ignored
      */
-    uint8_t        align_padding;
+    uint8_t        alignment_power;
     pp2_ssl_info_t pp2_ssl_info;
     tlv_array_t    tlv_array;
     /*

tests/test.c

@@ -435,7 +435,7 @@ int main()
                 .src_port = 42332,
                 .dst_port = 8080,
                 .pp2_info = {
-                    .align_padding = 2,
+                    .alignment_power = 2,
                     .pp2_ssl_info = {
                         .ssl = 1,
                         .cert_in_connection = 1,
@@ -474,13 +474,13 @@ int main()
                 {
                     .type = PP2_TYPE_AWS,
                     .subtype = PP2_SUBTYPE_AWS_VPCE_ID,
-                    .value_len = 23,
-                    .value = (uint8_t*) "vpce-24d8ezjk38bchilm4"
+                    .value_len = 24,
+                    .value = (uint8_t*) "vpce-24d8ezjk38bchilm4m"
                 },
                 {
                     .type = PP2_TYPE_CRC32C,
                     .value_len = 4,
-                    .value = (uint8_t*) "\x75\x40\xf1\x2f"
+                    .value = (uint8_t*) "\x43\x84\x86\x4e"
                 },
             },
             .pp_info_out_expected = tests[9].pp_info_in,
@@ -560,7 +560,7 @@ int main()
         else
         {
             uint16_t pp_hdr_len;
-            uint16_t pow = 1 << tests[i].pp_info_in.pp2_info.align_padding;
+            uint16_t alignment = 1 << tests[i].pp_info_in.pp2_info.alignment_power;
             int32_t error;
 
             if (tests[i].add_tlvs[0].type)
@@ -578,7 +578,7 @@ int main()
             pp_info_clear(&tests[i].pp_info_in);
             if (!pp_hdr
                 || error != ERR_NULL
-                || (pow > 1 && pp_hdr_len % pow))
+                || (alignment > 1 && pp_hdr_len % alignment))
             {
                 printf("FAILED\n");
                 pp_info_clear(&pp_info_out);