[PATCH v5 13/18] ip: Prepare ip.[ch] for sharing with pesto tool

[David Gibson <david@gibson.dropbear.id.au>]

Most things in ip.[ch] related purely to IP addresses and headers with
no dependency on other passt/pasta internals.  A number of these will be
useful to re-use in pesto.  The exception is ipv6_l4hdr() which uses
iov_tail.

The only caller of this is in tap.c, so move the function there.  Along
with moving the constant byteswapping functions to common.h, that lets
ip.[ch] to be linked into pesto as well as passt/pasta.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 common.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 inany.h  |  2 ++
 ip.c     | 56 +++-----------------------------------------------------
 ip.h     |  4 +---
 tap.c    | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 util.h   | 48 ------------------------------------------------
 6 files changed, 106 insertions(+), 104 deletions(-)

diff --git a/common.h b/common.h
index 45f66ea6..4a167ae0 100644
--- a/common.h
+++ b/common.h
@@ -55,4 +55,52 @@ static inline const char *strerror_(int errnum)
 
 #define ARRAY_SIZE(a)		((int)(sizeof(a) / sizeof((a)[0])))
 
+#ifndef __bswap_constant_16
+#define __bswap_constant_16(x)						\
+	((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
+#endif
+
+#ifndef __bswap_constant_32
+#define __bswap_constant_32(x)						\
+	((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |	\
+	 (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
+#endif
+
+#ifndef __bswap_constant_32
+#define __bswap_constant_32(x)						\
+	((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |	\
+	 (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
+#endif
+
+#ifndef __bswap_constant_64
+#define __bswap_constant_64(x) \
+	((((x) & 0xff00000000000000ULL) >> 56) |			\
+	 (((x) & 0x00ff000000000000ULL) >> 40) |			\
+	 (((x) & 0x0000ff0000000000ULL) >> 24) |			\
+	 (((x) & 0x000000ff00000000ULL) >> 8)  |			\
+	 (((x) & 0x00000000ff000000ULL) << 8)  |			\
+	 (((x) & 0x0000000000ff0000ULL) << 24) |			\
+	 (((x) & 0x000000000000ff00ULL) << 40) |			\
+	 (((x) & 0x00000000000000ffULL) << 56))
+#endif
+
+#if __BYTE_ORDER == __BIG_ENDIAN
+#define	htons_constant(x)	(x)
+#define	htonl_constant(x)	(x)
+#define htonll_constant(x)	(x)
+#define	ntohs_constant(x)	(x)
+#define	ntohl_constant(x)	(x)
+#define ntohll_constant(x)	(x)
+#else
+#define	htons_constant(x)	(__bswap_constant_16(x))
+#define	htonl_constant(x)	(__bswap_constant_32(x))
+#define	htonll_constant(x)	(__bswap_constant_64(x))
+#define	ntohs_constant(x)	(__bswap_constant_16(x))
+#define	ntohl_constant(x)	(__bswap_constant_32(x))
+#define	ntohll_constant(x)	(__bswap_constant_64(x))
+#endif
+
+#define ntohll(x)		(be64toh((x)))
+#define htonll(x)		(htobe64((x)))
+
 #endif /* _COMMON_H */
diff --git a/inany.h b/inany.h
index 30e24164..1f7741d1 100644
--- a/inany.h
+++ b/inany.h
@@ -10,8 +10,10 @@
 #define INANY_H
 
 #include <assert.h>
+#include <stdbool.h>
 #include <string.h>
 
+#include "util.h"
 #include "ip.h"
 #include "siphash.h"
 
diff --git a/ip.c b/ip.c
index 25fa4073..f2506bb1 100644
--- a/ip.c
+++ b/ip.c
@@ -6,6 +6,9 @@
  * PASTA - Pack A Subtle Tap Abstraction
  *  for network namespace/tap device mode
  *
+ * PESTO - Programmable Extensible Socket Translation Orchestrator
+ *  front-end for passt(1) and pasta(1) forwarding configuration
+ *
  * ip.c - IP related functions
  *
  * Copyright (c) 2020-2021 Red Hat GmbH
@@ -16,61 +19,8 @@
 #include <stddef.h>
 #include <netinet/in.h>
 
-#include "util.h"
 #include "ip.h"
 
-#define IPV6_NH_OPT(nh)							\
-	((nh) == 0   || (nh) == 43  || (nh) == 44  || (nh) == 50  ||	\
-	 (nh) == 51  || (nh) == 60  || (nh) == 135 || (nh) == 139 ||	\
-	 (nh) == 140 || (nh) == 253 || (nh) == 254)
-
-/**
- * ipv6_l4hdr() - Find pointer to L4 header in IPv6 packet and extract protocol
- * @data:	IPv6 packet
- * @proto:	Filled with L4 protocol number
- * @dlen:	Data length (payload excluding header extensions), set on return
- *
- * Return: true if the L4 header is found and @data, @proto, @dlen are set,
- * 	   false on error. Outputs are indeterminate on failure.
- */
-bool ipv6_l4hdr(struct iov_tail *data, uint8_t *proto, size_t *dlen)
-{
-	struct ipv6_opt_hdr o_storage;
-	const struct ipv6_opt_hdr *o;
-	struct ipv6hdr ip6h_storage;
-	const struct ipv6hdr *ip6h;
-	int hdrlen;
-	uint8_t nh;
-
-	ip6h = IOV_REMOVE_HEADER(data, ip6h_storage);
-	if (!ip6h)
-		return false;
-
-	nh = ip6h->nexthdr;
-	if (!IPV6_NH_OPT(nh))
-		goto found;
-
-	while ((o = IOV_PEEK_HEADER(data, o_storage))) {
-		nh = o->nexthdr;
-		hdrlen = (o->hdrlen + 1) * 8;
-
-		if (IPV6_NH_OPT(nh))
-			iov_drop_header(data, hdrlen);
-		else
-			goto found;
-	}
-
-	return false;
-
-found:
-	if (nh == IPPROTO_NONE)
-		return false;
-
-	*dlen = iov_tail_size(data);
-	*proto = nh;
-	return true;
-}
-
 /**
  * ipproto_name() - Get IP protocol name from number
  * @proto:	IP protocol number
diff --git a/ip.h b/ip.h
index fb4119a7..aab9b86a 100644
--- a/ip.h
+++ b/ip.h
@@ -9,7 +9,7 @@
 #include <netinet/ip.h>
 #include <netinet/ip6.h>
 
-#include "util.h"
+#include "common.h"
 
 #define IN4_IS_ADDR_UNSPECIFIED(a) \
 	(((struct in_addr *)(a))->s_addr == htonl_constant(INADDR_ANY))
@@ -117,8 +117,6 @@ static inline uint32_t ip6_get_flow_lbl(const struct ipv6hdr *ip6h)
 		ip6h->flow_lbl[2];
 }
 
-bool ipv6_l4hdr(struct iov_tail *data, uint8_t *proto, size_t *dlen);
-
 #define IPPROTO_STRLEN		(sizeof("<unknown protocol>"))
 const char *ipproto_name(uint8_t proto);
 
diff --git a/tap.c b/tap.c
index 87acd531..d94b06d2 100644
--- a/tap.c
+++ b/tap.c
@@ -874,6 +874,58 @@ append:
 	return in->count;
 }
 
+#define IPV6_NH_OPT(nh)							\
+	((nh) == 0   || (nh) == 43  || (nh) == 44  || (nh) == 50  ||	\
+	 (nh) == 51  || (nh) == 60  || (nh) == 135 || (nh) == 139 ||	\
+	 (nh) == 140 || (nh) == 253 || (nh) == 254)
+
+/**
+ * ipv6_l4hdr() - Find pointer to L4 header in IPv6 packet and extract protocol
+ * @data:	IPv6 packet
+ * @proto:	Filled with L4 protocol number
+ * @dlen:	Data length (payload excluding header extensions), set on return
+ *
+ * Return: true if the L4 header is found and @data, @proto, @dlen are set,
+ * 	   false on error. Outputs are indeterminate on failure.
+ */
+static bool ipv6_l4hdr(struct iov_tail *data, uint8_t *proto, size_t *dlen)
+{
+	struct ipv6_opt_hdr o_storage;
+	const struct ipv6_opt_hdr *o;
+	struct ipv6hdr ip6h_storage;
+	const struct ipv6hdr *ip6h;
+	int hdrlen;
+	uint8_t nh;
+
+	ip6h = IOV_REMOVE_HEADER(data, ip6h_storage);
+	if (!ip6h)
+		return false;
+
+	nh = ip6h->nexthdr;
+	if (!IPV6_NH_OPT(nh))
+		goto found;
+
+	while ((o = IOV_PEEK_HEADER(data, o_storage))) {
+		nh = o->nexthdr;
+		hdrlen = (o->hdrlen + 1) * 8;
+
+		if (IPV6_NH_OPT(nh))
+			iov_drop_header(data, hdrlen);
+		else
+			goto found;
+	}
+
+	return false;
+
+found:
+	if (nh == IPPROTO_NONE)
+		return false;
+
+	*dlen = iov_tail_size(data);
+	*proto = nh;
+	return true;
+}
+
 /**
  * tap6_handler() - IPv6 packet handler for tap file descriptor
  * @c:		Execution context
diff --git a/util.h b/util.h
index c7883824..dc14c78c 100644
--- a/util.h
+++ b/util.h
@@ -101,54 +101,6 @@ void abort_with_msg(const char *fmt, ...)
 #define MAC_UNDEF		MAC_BROADCAST
 #define MAC_IS_UNDEF(addr)	(!memcmp((addr), MAC_UNDEF, ETH_ALEN))
 
-#ifndef __bswap_constant_16
-#define __bswap_constant_16(x)						\
-	((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
-#endif
-
-#ifndef __bswap_constant_32
-#define __bswap_constant_32(x)						\
-	((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |	\
-	 (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
-#endif
-
-#ifndef __bswap_constant_32
-#define __bswap_constant_32(x)						\
-	((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |	\
-	 (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
-#endif
-
-#ifndef __bswap_constant_64
-#define __bswap_constant_64(x) \
-	((((x) & 0xff00000000000000ULL) >> 56) |			\
-	 (((x) & 0x00ff000000000000ULL) >> 40) |			\
-	 (((x) & 0x0000ff0000000000ULL) >> 24) |			\
-	 (((x) & 0x000000ff00000000ULL) >> 8)  |			\
-	 (((x) & 0x00000000ff000000ULL) << 8)  |			\
-	 (((x) & 0x0000000000ff0000ULL) << 24) |			\
-	 (((x) & 0x000000000000ff00ULL) << 40) |			\
-	 (((x) & 0x00000000000000ffULL) << 56))
-#endif
-
-#if __BYTE_ORDER == __BIG_ENDIAN
-#define	htons_constant(x)	(x)
-#define	htonl_constant(x)	(x)
-#define htonll_constant(x)	(x)
-#define	ntohs_constant(x)	(x)
-#define	ntohl_constant(x)	(x)
-#define ntohll_constant(x)	(x)
-#else
-#define	htons_constant(x)	(__bswap_constant_16(x))
-#define	htonl_constant(x)	(__bswap_constant_32(x))
-#define	htonll_constant(x)	(__bswap_constant_64(x))
-#define	ntohs_constant(x)	(__bswap_constant_16(x))
-#define	ntohl_constant(x)	(__bswap_constant_32(x))
-#define	ntohll_constant(x)	(__bswap_constant_64(x))
-#endif
-
-#define ntohll(x)		(be64toh((x)))
-#define htonll(x)		(htobe64((x)))
-
 extern uint8_t eth_pad[ETH_ZLEN];
 
 /**
-- 
2.53.0