From 96cf8dffe4f7b0b910f790066ae622dc429eb522 Mon Sep 17 00:00:00 2001
From: Jannis Hoffmann <jannis@fehcom.de>
Date: Tue, 9 Jul 2024 13:02:45 +0200
Subject: initial commit of version 23

---
 cdbread.c | 169 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 169 insertions(+)
 create mode 100644 cdbread.c

(limited to 'cdbread.c')

diff --git a/cdbread.c b/cdbread.c
new file mode 100644
index 0000000..c8ffa42
--- /dev/null
+++ b/cdbread.c
@@ -0,0 +1,169 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include "error.h"
+#include "seek.h"
+#include "byte.h"
+#include "cdbread.h"
+
+/**
+	@file cdbread.c
+	@author djb
+	@source ucspi-tcp, fastforward
+	@brief read entries from a cdb 
+*/
+
+uint32 cdb_unpack(unsigned char *buf)
+{
+  uint32 num;
+  num = buf[3]; num <<= 8;
+  num += buf[2]; num <<= 8;
+  num += buf[1]; num <<= 8;
+  num += buf[0];
+  return num;
+}
+
+void cdb_free(struct cdb *c)
+{
+  if (c->map) {
+    munmap(c->map,c->size);
+    c->map = 0;
+  }
+}
+
+void cdb_findstart(struct cdb *c)
+{
+  c->loop = 0;
+}
+
+void cdb_init(struct cdb *c,int fd)
+{
+  struct stat st;
+  char *x;
+
+  cdb_free(c);
+  cdb_findstart(c);
+  c->fd = fd;
+
+  if (fstat(fd,&st) == 0)
+    if (st.st_size <= 0xffffffff) {
+      x = mmap(0,st.st_size,PROT_READ,MAP_SHARED,fd,0);
+      if (x + 1) {
+        c->size = st.st_size;
+        c->map = x;
+      }
+    }
+}
+
+int cdb_read(struct cdb *c,char *buf,unsigned int len,uint32 pos)
+{
+  if (c->map) {
+    if ((pos > c->size) || (c->size - pos < len)) goto FORMAT;
+    byte_copy(buf,len,c->map + pos);
+  }
+  else {
+    if (seek_set(c->fd,pos) == -1) return -1;
+    while (len > 0) {
+      int r;
+      do
+        r = read(c->fd,buf,len);
+      while ((r == -1) && (errno == EINTR));
+      if (r == -1) return -1;
+      if (r == 0) goto FORMAT;
+      buf += r;
+      len -= r;
+    }
+  }
+  return 0;
+
+  FORMAT:
+  errno = EPROTO;
+  return -1;
+}
+
+static int match(struct cdb *c,char *key,unsigned int len,uint32 pos)
+{
+  char buf[32];
+  int n;
+
+  while (len > 0) {
+    n = sizeof(buf);
+    if (n > len) n = len;
+    if (cdb_read(c,buf,n,pos) == -1) return -1;
+    if (byte_diff(buf,n,key)) return 0;
+    pos += n;
+    key += n;
+    len -= n;
+  }
+  return 1;
+}
+
+int cdb_findnext(struct cdb *c,char *key,unsigned int len)
+{
+  char buf[8];
+  uint32 pos;
+  uint32 u;
+
+  if (!c->loop) {
+    u = cdb_hash(key,len);
+    if (cdb_read(c,buf,8,(u << 3) & 2047) == -1) return -1;
+    uint32_unpack(buf + 4,&c->hslots);
+    if (!c->hslots) return 0;
+    uint32_unpack(buf,&c->hpos);
+    c->khash = u;
+    u >>= 8;
+    u %= c->hslots;
+    u <<= 3;
+    c->kpos = c->hpos + u;
+  }
+
+  while (c->loop < c->hslots) {
+    if (cdb_read(c,buf,8,c->kpos) == -1) return -1;
+    uint32_unpack(buf + 4,&pos);
+    if (!pos) return 0;
+    c->loop += 1;
+    c->kpos += 8;
+    if (c->kpos == c->hpos + (c->hslots << 3)) c->kpos = c->hpos;
+    uint32_unpack(buf,&u);
+    if (u == c->khash) {
+      if (cdb_read(c,buf,8,pos) == -1) return -1;
+      uint32_unpack(buf,&u);
+      if (u == len)
+      switch(match(c,key,len,pos + 8)) {
+        case -1:
+          return -1;
+        case 1:
+          uint32_unpack(buf + 4,&c->dlen);
+          c->dpos = pos + 8 + len;
+          return 1;
+      }
+    }
+  }
+
+  return 0;
+}
+
+int cdb_find(struct cdb *c,char *key,unsigned int len)
+{
+  cdb_findstart(c);
+  return cdb_findnext(c,key,len);
+}
+
+uint32 cdb_hashadd(uint32 h,unsigned char c)
+{
+  h += (h << 5);
+  return h ^ c;
+}
+
+uint32 cdb_hash(char *buf,unsigned int len)
+{
+  uint32 h;
+
+  h = CDB_HASHSTART;
+  while (len) {
+    h = cdb_hashadd(h,*buf++);
+    --len;
+  }
+  return h;
+}
-- 
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