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https://passt.top/passt
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5913f26415
Currently we deal with hash collisions by letting a hash bucket contain multiple entries, forming a linked list using an index in the connection structure. That's a pretty standard and simple approach, but in our case we can use an even simpler one: linear probing. Here if a hash bucket is occupied we just move onto the next one until we find a feww one. This slightly simplifies lookup and more importantly saves some precious bytes in the connection structure by removing the need for a link. It does require some additional complexity for hash removal. This approach can perform poorly with hash table load is high. However, we already size our hash table of pointers larger than the connection table, which puts an upper bound on the load. It's relatively cheap to decrease that bound if we find we need to. I adapted the linear probing operations from Knuth's The Art of Computer Programming, Volume 3, 2nd Edition. Specifically Algorithm L and Algorithm R in Section 6.4. Note that there is an error in Algorithm R as printed, see errata at [0]. [0] https://www-cs-faculty.stanford.edu/~knuth/all3-prepre.ps.gz Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
299 lines
8.1 KiB
C
299 lines
8.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright (c) 2021 Red Hat GmbH
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* Author: Stefano Brivio <sbrivio@redhat.com>
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*/
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#ifndef UTIL_H
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#define UTIL_H
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#include <stdlib.h>
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#include <stdarg.h>
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#include <stdbool.h>
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#include <string.h>
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#include <signal.h>
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#include "log.h"
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#define VERSION_BLOB \
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VERSION "\n" \
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"Copyright Red Hat\n" \
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"GNU General Public License, version 2 or later\n" \
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" <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>\n" \
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"This is free software: you are free to change and redistribute it.\n" \
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"There is NO WARRANTY, to the extent permitted by law.\n\n"
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#ifndef SECCOMP_RET_KILL_PROCESS
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#define SECCOMP_RET_KILL_PROCESS SECCOMP_RET_KILL
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#endif
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#ifndef ETH_MAX_MTU
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#define ETH_MAX_MTU USHRT_MAX
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#endif
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#ifndef ETH_MIN_MTU
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#define ETH_MIN_MTU 68
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#endif
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#ifndef MIN
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#define MIN(x, y) (((x) < (y)) ? (x) : (y))
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#endif
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#ifndef MAX
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#define MAX(x, y) (((x) > (y)) ? (x) : (y))
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#endif
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#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
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#define ROUND_DOWN(x, y) ((x) & ~((y) - 1))
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#define ROUND_UP(x, y) (((x) + (y) - 1) & ~((y) - 1))
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#define MAX_FROM_BITS(n) (((1U << (n)) - 1))
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#define BIT(n) (1UL << (n))
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#define BITMAP_BIT(n) (BIT((n) % (sizeof(long) * 8)))
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#define BITMAP_WORD(n) (n / (sizeof(long) * 8))
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#define SWAP(a, b) \
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do { \
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__typeof__(a) __x = (a); (a) = (b); (b) = __x; \
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} while (0) \
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#define STRINGIFY(x) #x
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#define STR(x) STRINGIFY(x)
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#define ASSERT(expr) \
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do { \
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if (!(expr)) { \
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err("ASSERTION FAILED in %s (%s:%d): %s", \
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__func__, __FILE__, __LINE__, STRINGIFY(expr)); \
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/* This may actually SIGSYS, due to seccomp, \
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* but that will still get the job done \
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*/ \
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abort(); \
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} \
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} while (0)
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#ifdef P_tmpdir
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#define TMPDIR P_tmpdir
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#else
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#define TMPDIR "/tmp"
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#endif
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#define V4 0
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#define V6 1
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#define IP_VERSIONS 2
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#define ARRAY_SIZE(a) ((int)(sizeof(a) / sizeof((a)[0])))
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#define IN_INTERVAL(a, b, x) ((x) >= (a) && (x) <= (b))
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#define FD_PROTO(x, proto) \
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(IN_INTERVAL(c->proto.fd_min, c->proto.fd_max, (x)))
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#define PORT_EPHEMERAL_MIN ((1 << 15) + (1 << 14)) /* RFC 6335 */
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#define PORT_IS_EPHEMERAL(port) ((port) >= PORT_EPHEMERAL_MIN)
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#define MAC_ZERO ((uint8_t [ETH_ALEN]){ 0 })
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#define MAC_IS_ZERO(addr) (!memcmp((addr), MAC_ZERO, ETH_ALEN))
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#ifndef __bswap_constant_16
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#define __bswap_constant_16(x) \
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((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
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#endif
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#ifndef __bswap_constant_32
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#define __bswap_constant_32(x) \
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((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
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(((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
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#endif
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#if __BYTE_ORDER == __BIG_ENDIAN
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#define htons_constant(x) (x)
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#define htonl_constant(x) (x)
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#else
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#define htons_constant(x) (__bswap_constant_16(x))
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#define htonl_constant(x) (__bswap_constant_32(x))
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#endif
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#define IN4_IS_ADDR_UNSPECIFIED(a) \
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((a)->s_addr == htonl(INADDR_ANY))
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#define IN4_IS_ADDR_BROADCAST(a) \
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((a)->s_addr == htonl(INADDR_BROADCAST))
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#define IN4_IS_ADDR_LOOPBACK(a) \
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(ntohl((a)->s_addr) >> IN_CLASSA_NSHIFT == IN_LOOPBACKNET)
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#define IN4_IS_ADDR_MULTICAST(a) \
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(IN_MULTICAST(ntohl((a)->s_addr)))
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#define IN4_ARE_ADDR_EQUAL(a, b) \
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(((struct in_addr *)(a))->s_addr == ((struct in_addr *)b)->s_addr)
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#define IN4ADDR_LOOPBACK_INIT \
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{ .s_addr = htonl_constant(INADDR_LOOPBACK) }
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#define NS_FN_STACK_SIZE (RLIMIT_STACK_VAL * 1024 / 8)
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int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
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void *arg);
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#define NS_CALL(fn, arg) \
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do { \
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char ns_fn_stack[NS_FN_STACK_SIZE]; \
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\
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do_clone((fn), ns_fn_stack, sizeof(ns_fn_stack), \
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CLONE_VM | CLONE_VFORK | CLONE_FILES | SIGCHLD,\
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(void *)(arg)); \
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} while (0)
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#define L2_BUF_IP4_INIT(proto) \
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{ \
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.version = 4, \
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.ihl = 5, \
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.tos = 0, \
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.tot_len = 0, \
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.id = 0, \
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.frag_off = 0, \
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.ttl = 0xff, \
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.protocol = (proto), \
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.saddr = 0, \
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.daddr = 0, \
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}
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#define L2_BUF_IP4_PSUM(proto) ((uint32_t)htons_constant(0x4500) + \
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(uint32_t)htons_constant(0xff00 | (proto)))
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#define L2_BUF_IP6_INIT(proto) \
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{ \
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.priority = 0, \
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.version = 6, \
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.flow_lbl = { 0 }, \
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.payload_len = 0, \
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.nexthdr = (proto), \
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.hop_limit = 255, \
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.saddr = IN6ADDR_ANY_INIT, \
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.daddr = IN6ADDR_ANY_INIT, \
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}
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#define RCVBUF_BIG (2UL * 1024 * 1024)
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#define SNDBUF_BIG (4UL * 1024 * 1024)
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#define SNDBUF_SMALL (128UL * 1024)
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#include <net/if.h>
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#include <limits.h>
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#include <stdint.h>
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#include <netinet/ip6.h>
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#include "packet.h"
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struct ctx;
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struct ipv6hdr {
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wpedantic"
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#if __BYTE_ORDER == __BIG_ENDIAN
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uint8_t version:4,
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priority:4;
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#else
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uint8_t priority:4,
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version:4;
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#endif
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#pragma GCC diagnostic pop
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uint8_t flow_lbl[3];
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uint16_t payload_len;
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uint8_t nexthdr;
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uint8_t hop_limit;
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struct in6_addr saddr;
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struct in6_addr daddr;
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};
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struct ipv6_opt_hdr {
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uint8_t nexthdr;
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uint8_t hdrlen;
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/*
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* TLV encoded option data follows.
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*/
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} __attribute__((packed)); /* required for some archs */
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/* cppcheck-suppress funcArgNamesDifferent */
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__attribute__ ((weak)) int ffsl(long int i) { return __builtin_ffsl(i); }
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char *ipv6_l4hdr(const struct pool *p, int idx, size_t offset, uint8_t *proto,
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size_t *dlen);
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int sock_l4(const struct ctx *c, int af, uint8_t proto,
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const void *bind_addr, const char *ifname, uint16_t port,
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uint32_t data);
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void sock_probe_mem(struct ctx *c);
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int timespec_diff_ms(const struct timespec *a, const struct timespec *b);
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void bitmap_set(uint8_t *map, int bit);
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void bitmap_clear(uint8_t *map, int bit);
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int bitmap_isset(const uint8_t *map, int bit);
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void bitmap_or(uint8_t *dst, size_t size, const uint8_t *a, const uint8_t *b);
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char *line_read(char *buf, size_t len, int fd);
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void ns_enter(const struct ctx *c);
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bool ns_is_init(void);
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int open_in_ns(const struct ctx *c, const char *path, int flags);
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void write_pidfile(int fd, pid_t pid);
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int __daemon(int pidfile_fd, int devnull_fd);
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int fls(unsigned long x);
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int write_file(const char *path, const char *buf);
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/**
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* mod_sub() - Modular arithmetic subtraction
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* @a: Minued, unsigned value < @m
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* @b: Subtrahend, unsigned value < @m
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* @m: Modulus, must be less than (UINT_MAX / 2)
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*
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* Returns (@a - @b) mod @m, correctly handling unsigned underflows.
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*/
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static inline unsigned mod_sub(unsigned a, unsigned b, unsigned m)
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{
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if (a < b)
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a += m;
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return a - b;
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}
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/**
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* mod_between() - Determine if a value is in a cyclic range
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* @x, @i, @j: Unsigned values < @m
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* @m: Modulus
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*
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* Returns true iff @x is in the cyclic range of values from @i..@j (mod @m),
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* inclusive of @i, exclusive of @j.
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*/
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static inline bool mod_between(unsigned x, unsigned i, unsigned j, unsigned m)
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{
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return mod_sub(x, i, m) < mod_sub(j, i, m);
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}
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/*
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* Workarounds for https://github.com/llvm/llvm-project/issues/58992
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*
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* For a number (maybe all) system calls that _write_ a socket address,
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* clang-tidy doesn't register that the memory of the socket address will be
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* initialised after the call. This can't easily be worked around with
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* clang-tidy suppressions, because the warning doesn't show on the syscall
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* itself but later when we access the supposedly uninitialised field.
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*/
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static inline void sa_init(struct sockaddr *sa, const socklen_t *sl)
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{
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#ifdef CLANG_TIDY_58992
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if (sa)
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memset(sa, 0, *sl);
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#else
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(void)sa;
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(void)sl;
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#endif /* CLANG_TIDY_58992 */
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}
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static inline ssize_t wrap_recvfrom(int sockfd, void *buf, size_t len,
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int flags,
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struct sockaddr *src_addr,
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socklen_t *addrlen)
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{
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sa_init(src_addr, addrlen);
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return recvfrom(sockfd, buf, len, flags, src_addr, addrlen);
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}
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#define recvfrom(s, buf, len, flags, src, addrlen) \
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wrap_recvfrom((s), (buf), (len), (flags), (src), (addrlen))
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static inline int wrap_accept4(int sockfd, struct sockaddr *addr,
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socklen_t *addrlen, int flags)
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{
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sa_init(addr, addrlen);
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return accept4(sockfd, addr, addrlen, flags);
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}
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#define accept4(s, addr, addrlen, flags) \
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wrap_accept4((s), (addr), (addrlen), (flags))
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#endif /* UTIL_H */
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