treewide: Packet abstraction with mandatory boundary checks

Implement a packet abstraction providing boundary and size checks
based on packet descriptors: packets stored in a buffer can be queued
into a pool (without storage of its own), and data can be retrieved
referring to an index in the pool, specifying offset and length.

Checks ensure data is not read outside the boundaries of buffer and
descriptors, and that packets added to a pool are within the buffer
range with valid offset and indices.

This implies a wider rework: usage of the "queueing" part of the
abstraction mostly affects tap_handler_{passt,pasta}() functions and
their callees, while the "fetching" part affects all the guest or tap
facing implementations: TCP, UDP, ICMP, ARP, NDP, DHCP and DHCPv6
handlers.

Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/util.h b/util.h
index 3073f58..073a913 100644
--- a/util.h
+++ b/util.h
@@ -153,6 +153,8 @@ enum {
 #include <limits.h>
 #include <stdarg.h>
 
+#include "packet.h"
+
 enum bind_type {
 	BIND_ANY = 0,
 	BIND_LOOPBACK,
@@ -194,7 +196,8 @@ __attribute__ ((weak)) int ffsl(long int i) { return __builtin_ffsl(i); }
 void __openlog(const char *ident, int option, int facility);
 void passt_vsyslog(int pri, const char *format, va_list ap);
 void __setlogmask(int mask);
-char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto);
+char *ipv6_l4hdr(struct pool *p, int index, size_t offset, uint8_t *proto,
+		 size_t *dlen);
 int sock_l4(struct ctx *c, int af, uint8_t proto, uint16_t port,
 	    enum bind_type bind_addr, uint32_t data);
 void sock_probe_mem(struct ctx *c);