Add a very simple low cost database

Makefile.am

@@ -13,7 +13,9 @@ glorytun_SOURCES = \
     src/option.c \
     src/option.h \
     src/tun.c \
-    src/tun.h
+    src/tun.h \
+    src/db.c \
+    src/db.h
 
 EXTRA_DIST = \
 	LICENSE \

src/common-static.h

@@ -50,16 +50,18 @@ static inline int str_empty (const char *restrict str)
 }
 
 _pure_
-static inline int str_cmp (const char *restrict sa, const char *restrict sb)
+static inline size_t str_cmp (const char *restrict sa, const char *restrict sb)
 {
     if (!sa || !sb)
         return 1;
 
-     while (*sa==*sb++)
-         if (!*sa++)
-             return 0;
+    size_t i = 0;
 
-    return 1;
+    while (sa[i]==sb[i])
+        if (!sa[i++])
+            return 0;
+
+    return i+1;
 }
 
 _pure_

src/common.h

@@ -17,12 +17,14 @@
 #define _1_(x)         (__builtin_expect((x), 1))
 #define _0_(x)         (__builtin_expect((x), 0))
 
-#define _printf_(A,B)  __attribute__((format(printf,A,B)))
-#define _noreturn_     __attribute__((noreturn))
-#define _unused_       __attribute__((unused))
-#define _pure_         __attribute__((pure))
-#define _const_        __attribute__((const))
-#define _align_(...)   __attribute__((aligned(__VA_ARGS__)))
+#define CLZ(x)         (__builtin_clz(x))
+
+#define _printf_(A,B)  __attribute__ ((format(printf,A,B)))
+#define _noreturn_     __attribute__ ((noreturn))
+#define _unused_       __attribute__ ((unused))
+#define _pure_         __attribute__ ((pure))
+#define _const_        __attribute__ ((const))
+#define _align_(...)   __attribute__ ((aligned(__VA_ARGS__)))
 
 typedef struct buffer buffer_t;
 

src/db.c

@@ -0,0 +1,152 @@
+#include "db.h"
+#include "common-static.h"
+
+#define CBIT(X)      (1&(intptr_t)(X))
+#define CBIT_PTR(X)  (uint8_t *)(1|(intptr_t)(X))
+#define CBIT_NODE(X) (struct node *)(1^(intptr_t)(X))
+
+struct node {
+    uint8_t *child[2];
+    uint8_t size;
+    uint8_t mask;
+};
+
+static inline size_t db_size (const uint8_t *a)
+{
+    return (a[0]?:str_len((char *)a+1))+1;
+}
+
+static inline size_t db_cmp (const uint8_t *a, const uint8_t *b)
+{
+    const size_t size = a[0];
+
+    if (size!=b[0])
+        return 1;
+
+    if (!size) {
+        size_t i = str_cmp((char *)a+1, (char *)b+1);
+        return i?i+1:0;
+    }
+
+    for (size_t i=1; i<=size; i++) {
+        if (a[i]!=b[i])
+            return i+1;
+    }
+
+    return 0;
+}
+
+static inline int db_dir (struct node *node, const uint8_t *data, const size_t size)
+{
+    if (node->size>=size)
+        return 0;
+
+    return (node->mask|data[node->size])==255;
+}
+
+uint8_t *db_search (uint8_t **p, uint8_t *data)
+{
+    if (!*p)
+        return NULL;
+
+    uint8_t *r = *p;
+    const size_t size = db_size(data);
+
+    while (CBIT(r)) {
+        struct node *node = CBIT_NODE(r);
+        r = node->child[db_dir(node, data, size)];
+    }
+
+    if (!db_cmp(r, data))
+        return r;
+
+    return NULL;
+}
+
+int db_insert (uint8_t **p, uint8_t *data)
+{
+    if (CBIT(data))
+        return 0;
+
+    if (!*p) {
+        *p = data;
+        return 1;
+    }
+
+    uint8_t *r = *p;
+    size_t data_size = db_size(data);
+
+    while (CBIT(r)) {
+        struct node *node = CBIT_NODE(r);
+        r = node->child[db_dir(node, data, data_size)];
+    }
+
+    const size_t diff = db_cmp(r, data);
+
+    if (!diff)
+        return 2;
+
+    const uint8_t size = diff-1;
+    const uint8_t mask = ~((1u<<31)>>CLZ(r[size]^data[size]));
+
+    while (CBIT(*p)) {
+        struct node *node = CBIT_NODE(*p);
+
+        if ((node->size>size) ||
+            (node->size==size && node->mask>mask)) {
+            break;
+        }
+
+        p = node->child+db_dir(node, data, data_size);
+    }
+
+    struct node *node = malloc(sizeof(struct node));
+
+    if (!node)
+        return 0;
+
+    const int dir = (mask|r[size])==255;
+
+    node->child[dir] = *p;
+    node->child[1-dir] = data;
+    node->size = size;
+    node->mask = mask;
+
+    *p = CBIT_PTR(node);
+
+    return 1;
+}
+
+int db_delete (uint8_t **p, uint8_t *data)
+{
+    if (!*p)
+        return 0;
+
+    uint8_t **p_old = NULL;
+    struct node *node = NULL;
+    int dir = 0;
+
+    const size_t size = db_size(data);
+
+    while (CBIT(*p)) {
+        p_old = p;
+        node = CBIT_NODE(*p);
+        dir = db_dir(node, data, size);
+        p = node->child+dir;
+    }
+
+    if (db_cmp(data, *p))
+        return 0;
+
+    free(*p);
+
+    if (!p_old) {
+        *p = NULL;
+        return 1;
+    }
+
+    *p_old = node->child[1-dir];
+    free(node);
+
+    return 1;
+}

src/db.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stdint.h>
+
+uint8_t *db_search (uint8_t **, uint8_t *);
+int      db_insert (uint8_t **, uint8_t *);
+int      db_remove (uint8_t **, uint8_t *);