Merge pull request robertdavidgraham#748 from robertdavidgraham/integ…

…ration extract
orcooo · Dec 3, 2023 · dfd2001 · dfd2001
2 parents 082c8ed + 3ac323a
commit dfd2001
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diff --git a/src/util-extract.c b/src/util-extract.c
@@ -0,0 +1,73 @@
+#include "util-extract.h"
+
+
+unsigned char
+e_next_byte(struct ebuf_t *ebuf) {
+    if (ebuf->offset + 1 > ebuf->max)
+        return -1;
+
+    return ebuf->buf[ebuf->offset++];
+}
+
+unsigned short
+e_next_short16(struct ebuf_t *ebuf, int endian) {
+    const unsigned char *buf = ebuf->buf;
+    size_t offset = ebuf->offset;
+    unsigned short result;
+
+    if (ebuf->offset + 2 > ebuf->max)
+        return -1;
+
+    if (endian == EBUF_BE) {
+        result = buf[offset+0]<<8 | buf[offset+1];
+    } else {
+        result = buf[offset+1]<<8 | buf[offset+0];
+    }
+    ebuf->offset += 2;
+    return result;
+}
+unsigned e_next_int32(struct ebuf_t *ebuf, int endian) {
+    const unsigned char *buf = ebuf->buf;
+    size_t offset = ebuf->offset;
+    unsigned result;
+
+    if (ebuf->offset + 4 > ebuf->max)
+        return -1;
+
+    if (endian == EBUF_BE) {
+        result = buf[offset+0]<<24 | buf[offset+1] << 16
+                    | buf[offset+2]<<8 | buf[offset+3] << 0;
+    } else {
+        result = buf[offset+3]<<24 | buf[offset+2] << 16
+                    | buf[offset+1]<<8 | buf[offset+0] << 0;
+    }
+    ebuf->offset += 4;
+    return result;
+}
+unsigned long long
+e_next_long64(struct ebuf_t *ebuf, int endian) {
+    const unsigned char *buf = ebuf->buf;
+    size_t offset = ebuf->offset;
+    unsigned long long hi;
+    unsigned long long lo;
+
+    if (ebuf->offset + 8 > ebuf->max)
+        return -1ll;
+
+    if (endian == EBUF_BE) {
+        hi = buf[offset+0]<<24 | buf[offset+1] << 16
+                    | buf[offset+2]<<8 | buf[offset+3] << 0;
+        lo = buf[offset+4]<<24 | buf[offset+5] << 16
+                    | buf[offset+6]<<8 | buf[offset+7] << 0;
+    } else {
+        lo = buf[offset+3]<<24 | buf[offset+2] << 16
+                    | buf[offset+1]<<8 | buf[offset+0] << 0;
+        hi = buf[offset+7]<<24 | buf[offset+6] << 16
+                    | buf[offset+5]<<8 | buf[offset+4] << 0;
+    }
+    ebuf->offset += 8;
+    return hi<<32ull | lo;
+
+}
+
+
diff --git a/src/util-extract.h b/src/util-extract.h
@@ -0,0 +1,22 @@
+#ifndef UTIL_EXTRACT_H
+#define UTIL_EXTRACT_H
+#include <stdio.h>
+
+struct ebuf_t {
+    const unsigned char *buf;
+    size_t offset;
+    size_t max;
+};
+
+enum {
+    EBUF_BE,
+    EBUG_LE,
+};
+
+unsigned char e_next_byte(struct ebuf_t *ebuf);
+unsigned short e_next_short16(struct ebuf_t *ebuf, int endian);
+unsigned e_next_int32(struct ebuf_t *ebuf, int endian);
+unsigned long long e_next_long64(struct ebuf_t *ebuf, int endian);
+
+
+#endif