diff options
Diffstat (limited to 'vrrpd/vrrp_arp.c')
| -rw-r--r-- | vrrpd/vrrp_arp.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/vrrpd/vrrp_arp.c b/vrrpd/vrrp_arp.c new file mode 100644 index 0000000..0072053 --- /dev/null +++ b/vrrpd/vrrp_arp.c @@ -0,0 +1,206 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * VRRP ARP handling. + * Copyright (C) 2001-2017 Alexandre Cassen + * Portions: + * Copyright (C) 2018-2019 Cumulus Networks, Inc. + * Quentin Young + */ +#include <zebra.h> + +#include <linux/if_packet.h> +#include <net/if_arp.h> +#include <netinet/if_ether.h> + +#include "lib/if.h" +#include "lib/linklist.h" +#include "lib/log.h" +#include "lib/memory.h" +#include "lib/prefix.h" + +#include "vrrp.h" +#include "vrrp_arp.h" +#include "vrrp_debug.h" + +#define VRRP_LOGPFX "[ARP] " + +/* + * The size of the garp packet buffer should be the large enough to hold the + * largest arp packet to be sent + the size of the link layer header for the + * corresponding protocol. In this case we hardcode for Ethernet. + */ +#define GARP_BUFFER_SIZE \ + sizeof(struct ether_header) + sizeof(struct arphdr) + 2 * ETH_ALEN \ + + 2 * sizeof(struct in_addr) + +/* static vars */ +static int garp_fd = -1; + +/* Send the gratuitous ARP message */ +static ssize_t vrrp_send_garp(struct interface *ifp, uint8_t *buf, + ssize_t pack_len) +{ + struct sockaddr_ll sll; + ssize_t len; + + /* Build the dst device */ + memset(&sll, 0, sizeof(sll)); + sll.sll_family = AF_PACKET; + sll.sll_protocol = ETH_P_ARP; + sll.sll_ifindex = (int)ifp->ifindex; + sll.sll_halen = ifp->hw_addr_len; + memset(sll.sll_addr, 0xFF, ETH_ALEN); + + /* Send packet */ + len = sendto(garp_fd, buf, pack_len, 0, (struct sockaddr *)&sll, + sizeof(sll)); + + return len; +} + +/* Build a gratuitous ARP message over a specific interface */ +static ssize_t vrrp_build_garp(uint8_t *buf, struct interface *ifp, + struct in_addr *v4) +{ + uint8_t *arp_ptr; + + if (ifp->hw_addr_len == 0) + return -1; + + /* Build Ethernet header */ + struct ether_header *eth = (struct ether_header *)buf; + + memset(eth->ether_dhost, 0xFF, ETH_ALEN); + memcpy(eth->ether_shost, ifp->hw_addr, ETH_ALEN); + eth->ether_type = htons(ETHERTYPE_ARP); + + /* Build ARP payload */ + struct arphdr *arph = (struct arphdr *)(buf + ETHER_HDR_LEN); + + arph->ar_hrd = htons(HWTYPE_ETHER); + arph->ar_pro = htons(ETHERTYPE_IP); + arph->ar_hln = ifp->hw_addr_len; + arph->ar_pln = sizeof(struct in_addr); + arph->ar_op = htons(ARPOP_REQUEST); + arp_ptr = (uint8_t *)(arph + 1); + /* Source MAC: us */ + memcpy(arp_ptr, ifp->hw_addr, ifp->hw_addr_len); + arp_ptr += ifp->hw_addr_len; + /* Source IP: us */ + memcpy(arp_ptr, v4, sizeof(struct in_addr)); + arp_ptr += sizeof(struct in_addr); + /* Dest MAC: broadcast */ + memset(arp_ptr, 0xFF, ETH_ALEN); + arp_ptr += ifp->hw_addr_len; + /* Dest IP: us */ + memcpy(arp_ptr, v4, sizeof(struct in_addr)); + arp_ptr += sizeof(struct in_addr); + + return arp_ptr - buf; +} + +void vrrp_garp_send(struct vrrp_router *r, struct in_addr *v4) +{ + struct interface *ifp = r->mvl_ifp; + uint8_t garpbuf[GARP_BUFFER_SIZE]; + ssize_t garpbuf_len; + ssize_t sent_len; + char astr[INET_ADDRSTRLEN]; + + /* If the interface doesn't support ARP, don't try sending */ + if (ifp->flags & IFF_NOARP) { + zlog_warn( + VRRP_LOGPFX VRRP_LOGPFX_VRID VRRP_LOGPFX_FAM + "Unable to send gratuitous ARP on %s; has IFF_NOARP", + r->vr->vrid, family2str(r->family), ifp->name); + return; + } + + /* Build garp */ + garpbuf_len = vrrp_build_garp(garpbuf, ifp, v4); + + if (garpbuf_len < 0) { + zlog_warn( + VRRP_LOGPFX VRRP_LOGPFX_VRID VRRP_LOGPFX_FAM + "Unable to send gratuitous ARP on %s; MAC address unknown", + r->vr->vrid, family2str(r->family), ifp->name); + return; + }; + + /* Send garp */ + inet_ntop(AF_INET, v4, astr, sizeof(astr)); + + DEBUGD(&vrrp_dbg_arp, + VRRP_LOGPFX VRRP_LOGPFX_VRID VRRP_LOGPFX_FAM + "Sending gratuitous ARP on %s for %s", + r->vr->vrid, family2str(r->family), ifp->name, astr); + if (DEBUG_MODE_CHECK(&vrrp_dbg_arp, DEBUG_MODE_ALL)) + zlog_hexdump(garpbuf, garpbuf_len); + + sent_len = vrrp_send_garp(ifp, garpbuf, garpbuf_len); + + if (sent_len < 0) + zlog_warn(VRRP_LOGPFX VRRP_LOGPFX_VRID VRRP_LOGPFX_FAM + "Error sending gratuitous ARP on %s for %s", + r->vr->vrid, family2str(r->family), ifp->name, astr); + else + ++r->stats.garp_tx_cnt; +} + +void vrrp_garp_send_all(struct vrrp_router *r) +{ + assert(r->family == AF_INET); + + struct interface *ifp = r->mvl_ifp; + + /* If the interface doesn't support ARP, don't try sending */ + if (ifp->flags & IFF_NOARP) { + zlog_warn( + VRRP_LOGPFX VRRP_LOGPFX_VRID VRRP_LOGPFX_FAM + "Unable to send gratuitous ARP on %s; has IFF_NOARP", + r->vr->vrid, family2str(r->family), ifp->name); + return; + } + + struct listnode *ln; + struct ipaddr *ip; + + for (ALL_LIST_ELEMENTS_RO(r->addrs, ln, ip)) + vrrp_garp_send(r, &ip->ipaddr_v4); +} + + +void vrrp_garp_init(void) +{ + /* Create the socket descriptor */ + /* FIXME: why ETH_P_RARP? */ + errno = 0; + frr_with_privs(&vrrp_privs) { + garp_fd = socket(PF_PACKET, SOCK_RAW | SOCK_CLOEXEC, + htons(ETH_P_RARP)); + } + + if (garp_fd > 0) { + DEBUGD(&vrrp_dbg_sock, + VRRP_LOGPFX "Initialized gratuitous ARP socket"); + DEBUGD(&vrrp_dbg_arp, + VRRP_LOGPFX "Initialized gratuitous ARP subsystem"); + } else { + zlog_err(VRRP_LOGPFX + "Error initializing gratuitous ARP subsystem"); + } +} + +void vrrp_garp_fini(void) +{ + close(garp_fd); + garp_fd = -1; + + DEBUGD(&vrrp_dbg_arp, + VRRP_LOGPFX "Deinitialized gratuitous ARP subsystem"); +} + +bool vrrp_garp_is_init(void) +{ + return garp_fd > 0; +} |