Initial libdcache implementation

1 files changed, 81 insertions, 0 deletions

diff --git a/src/caches/dcache_load.c b/src/caches/dcache_load.c
new file mode 100644
index 0000000..8f9383f
--- /dev/null
+++ b/src/caches/dcache_load.c
@@ -0,0 +1,81 @@
+/* ISC license. */
+
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+#include <skalibs/posixishard.h>
+#include <skalibs/uint16.h>
+#include <skalibs/uint64.h>
+#include <skalibs/buffer.h>
+#include <skalibs/tai.h>
+#include <skalibs/djbunix.h>
+
+#include <s6-dns/dcache.h>
+
+static inline int dcache_load_node (dcache_t *z, uint64_t max, buffer *b)
+{
+  tain_t entry = { .nano = 0 } ;
+  tain_t expire = { .nano = 0 } ;
+  uint16_t keylen ;
+  uint16_t datalen ;
+  char pack[TAI_PACK * 2 + 4] ;
+  ssize_t r = buffer_get(b, pack, TAI_PACK * 2 + 4) ;
+  if (!r) return 0 ;
+  if (r < TAI_PACK * 2 + 4) return -1 ;
+  tai_unpack(pack, tain_secp(&entry)) ;
+  tai_unpack(pack + TAI_PACK, tain_secp(&expire)) ;
+  uint16_unpack_big(pack + TAI_PACK * 2, &keylen) ;
+  uint16_unpack_big(pack + TAI_PACK * 2 + 2, &datalen) ;
+  {
+    uint32_t len = (uint32_t)keylen + (uint32_t)datalen ;
+    char blob[len+1] ;  /* 128 kB max, it's ok */ 
+    r = buffer_get(b, blob, len+1) ;
+    if (!r) return (errno = EPIPE, -1) ;
+    if (r < len) return -1 ;
+    if (blob[len]) return (errno = EPROTO, -1) ;
+    if (!dcache_add(z, max, blob, keylen, blob + keylen, datalen, &expire, &entry)) return -1 ;
+  }
+  return 1 ;
+}
+
+static inline int dcache_load_from_buffer (dcache_t *z, uint64_t max, buffer *b)
+{
+  {
+    char banner[sizeof(DCACHE_MAGIC) - 1] ;
+    char pack[8] ;
+    if (buffer_get(b, banner, sizeof(DCACHE_MAGIC) - 1) < sizeof(DCACHE_MAGIC) - 1)
+      return 0 ;
+    if (memcmp(banner, DCACHE_MAGIC, sizeof(DCACHE_MAGIC) - 1)) return 0 ;
+    if (buffer_get(b, pack, 8) < 8) return 0 ;
+    uint64_unpack_big(pack, &z->size) ;
+    if (buffer_get(b, pack, 8) < 8) return 0 ;
+    uint64_unpack_big(pack, &z->motion) ;
+  }
+  for (;;)
+  {
+    int r = dcache_load_node(z, max, b) ;
+    if (r < 0) return 0 ;
+    if (!r) break ;
+  }
+  return 1 ;
+}
+
+#define N 8192
+
+int dcache_load (dcache_t *z, uint64_t max, char const *file)
+{
+  char buf[N] ;
+  buffer b ;
+  int fd = open_readb(file) ;
+  if (fd == -1) return 0 ;
+  buffer_init(&b, &buffer_read, fd, buf, N) ;
+  if (!dcache_load_from_buffer(z, max, &b)) goto err ;
+  fd_close(fd) ;
+  return 1 ;
+
+ err:
+  dcache_free(z) ;
+  fd_close(fd) ;
+  return 0 ;
+}