1 files changed, 44 insertions, 0 deletions
diff --git a/src/cmd/netstack/util.h b/src/cmd/netstack/util.h
new file mode 100644
index 0000000..0b29560
--- /dev/null
+++ b/src/cmd/netstack/util.h
@@ -0,0 +1,44 @@
+#pragma once
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define eprintf(fmt, ...) fprintf(stderr, "netstack: "fmt"\n" __VA_OPT__(,) __VA_ARGS__)
+
+uint32_t crc32(const uint8_t *buf, size_t len);
+uint16_t ip_checksum(const uint8_t *buf, size_t len);
+uint16_t ip_checksumphdr(
+	const uint8_t *buf, size_t len,
+	uint32_t ip1, uint32_t ip2,
+	uint16_t proto);
+/* 0 on success, negative failure */
+int ip_parse(const char *s, uint32_t *ip);
+
+static inline void nput16(void *vbuf, uint16_t n) {
+	uint8_t *b = vbuf;
+	b[0] = n >> 8;
+	b[1] = n >> 0;
+}
+
+static inline void nput32(void *vbuf, uint32_t n) {
+	uint8_t *b = vbuf;
+	b[0] = n >> 24;
+	b[1] = n >> 16;
+	b[2] = n >>  8;
+	b[3] = n >>  0;
+}
+
+static inline uint16_t nget16(const void *vbuf) {
+	const uint8_t *b = vbuf;
+	return (b[0] << 8)
+	     | (b[1] << 0);
+}
+
+static inline uint32_t nget32(const void *vbuf) {
+	const uint8_t *b = vbuf;
+	return (b[0] << 24)
+	     | (b[1] << 16)
+	     | (b[2] <<  8)
+	     | (b[3] <<  0);
+}