DNS Write: fix name compression

src/lib/ares__buf.c

@@ -832,3 +832,75 @@ ares_status_t ares__buf_parse_dns_str(ares__buf_t *buf, size_t remaining_len,
   return ares__buf_parse_dns_binstr(buf, remaining_len, (unsigned char **)str,
                                     &len, allow_multiple);
 }
+
+static ares_status_t ares__buf_append_num_hex(ares__buf_t *buf, size_t num,
+                                              size_t len)
+{
+  size_t i;
+  static const unsigned char hexbytes[] = "0123456789ABCDEF";
+  for (i=len; i>0; i--) {
+    ares_status_t status;
+    status = ares__buf_append_byte(buf, hexbytes[(num >> ((i-1) * 4)) & 0xF]);
+    if (status != ARES_SUCCESS)
+      return status;
+  }
+  return ARES_SUCCESS;
+}
+
+static ares_status_t ares__buf_append_str(ares__buf_t *buf, const char *str)
+{
+  return ares__buf_append(buf, (const unsigned char *)str, ares_strlen(str));
+}
+
+ares_status_t ares__buf_hexdump(ares__buf_t *buf, const unsigned char *data,
+                                size_t len)
+{
+  size_t        i;
+  ares_status_t status;
+  /* Each line is 16 bytes */
+  for (i=0; i<len; i += 16) {
+    size_t j;
+
+    /* Address */
+    status = ares__buf_append_num_hex(buf, i, 6);
+    if (status != ARES_SUCCESS)
+      return status;
+
+    /* | */
+    status = ares__buf_append_str(buf, " | ");
+    if (status != ARES_SUCCESS)
+      return status;
+
+    for (j=i; j<i+16; j++) {
+      if (j >= len) {
+        status = ares__buf_append_str(buf, "  ");
+      } else {
+        status = ares__buf_append_num_hex(buf, data[j], 2);
+      }
+      if (status != ARES_SUCCESS)
+        return status;
+
+      status = ares__buf_append_byte(buf, ' ');
+      if (status != ARES_SUCCESS)
+        return status;
+    }
+
+    /* | */
+    status = ares__buf_append_str(buf, " | ");
+    if (status != ARES_SUCCESS)
+      return status;
+
+    for (j=i; j<i+16; j++) {
+      if (j >= len) {
+        break;
+      }
+      status = ares__buf_append_byte(buf, ares__isprint(data[j])?data[j]:'.');
+      if (status != ARES_SUCCESS)
+        return status;
+    }
+
+    ares__buf_append_byte(buf, '\n');
+  }
+
+  return status;
+}

src/lib/ares__buf.h

@@ -145,6 +145,16 @@ unsigned char *ares__buf_append_start(ares__buf_t *buf, size_t *len);
  */
 void           ares__buf_append_finish(ares__buf_t *buf, size_t len);
 
+/*! Write the data provided to the buffer in a hexdump format.
+ *
+ *  \param[in] buf      Initialized buffer object.
+ *  \param[in] data     Data to hex dump
+ *  \param[in] data_len Length of data to hexdump
+ *  \return ARES_SUCCESS on success.
+ */
+ares_status_t ares__buf_hexdump(ares__buf_t *buf, const unsigned char *data,
+                                size_t len);
+
 /*! Clean up ares__buf_t and return allocated pointer to unprocessed data.  It
  *  is the responsibility of the  caller to ares_free() the returned buffer.
  *  The passed in buf parameter is invalidated by this call.

src/lib/ares_dns_name.c

@@ -76,7 +76,7 @@ static ares_status_t ares__nameoffset_create(ares__llist_t **list,
     goto fail;
   }
 
-  status = ARES_SUCCESS;
+  return ARES_SUCCESS;
 
 fail:
   ares__nameoffset_free(off);
@@ -361,7 +361,7 @@ ares_status_t ares__dns_name_write(ares__buf_t *buf, ares__llist_t **list,
 {
   const ares_nameoffset_t *off = NULL;
   size_t                   name_len;
-  size_t                   pos = ares__buf_get_position(buf);
+  size_t                   pos = ares__buf_len(buf);
   ares_dns_labels_t        labels;
   char                     name_copy[512];
   ares_status_t            status;
@@ -381,8 +381,8 @@ ares_status_t ares__dns_name_write(ares__buf_t *buf, ares__llist_t **list,
     off = ares__nameoffset_find(*list, name_copy);
     if (off != NULL && off->name_len != name_len) {
       /* truncate */
-      name_len                -= (off->name_len + 1);
-      name_copy[name_len - 1]  = 0;
+      name_len            -= (off->name_len + 1);
+      name_copy[name_len]  = 0;
     }
   }
 
@@ -431,7 +431,7 @@ ares_status_t ares__dns_name_write(ares__buf_t *buf, ares__llist_t **list,
 
   /* Store pointer for future jumps as long as its not an exact match for
    * a prior entry */
-  if (list != NULL && off != NULL && off->name_len != name_len &&
+  if (list != NULL && (off == NULL || off->name_len != name_len) &&
       name_len > 0) {
     status = ares__nameoffset_create(list, name /* not truncated copy! */, pos);
     if (status != ARES_SUCCESS) {

test/ares-test-internal.cc

@@ -470,7 +470,6 @@ TEST_F(LibraryTest, DNSRecord) {
   struct ares_in6_addr addr6;
   unsigned char       *msg    = NULL;
   size_t               msglen = 0;
-
   size_t               qdcount = 0;
   size_t               ancount = 0;
   size_t               nscount = 0;
@@ -651,6 +650,11 @@ TEST_F(LibraryTest, DNSRecord) {
 
   /* Write */
   EXPECT_EQ(ARES_SUCCESS, ares_dns_write(dnsrec, &msg, &msglen));
+
+  ares__buf_t *hexdump = ares__buf_create();
+  EXPECT_EQ(ARES_SUCCESS, ares__buf_hexdump(hexdump, msg, msglen));
+  char *hexdata = ares__buf_finish_str(hexdump, NULL);
+  //printf("HEXDUMP\n%s", hexdata);
   ares_dns_record_destroy(dnsrec); dnsrec = NULL;
 
   /* Parse */