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https://passt.top/passt
synced 2025-06-08 00:35:33 +02:00
passt: Introduce packet batching mechanism
Receive packets in batches from AF_UNIX, check if they can be sent with a single syscall, and batch them up with sendmmsg() in case. A bit rudimentary, currently only implemented for UDP, but it seems to work. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio
parent
5b0c88d4ef
commit
1f7cf04d34
8 changed files with 337 additions and 122 deletions
290
passt.c
290
passt.c
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@ -19,6 +19,7 @@
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <sys/resource.h>
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#include <sys/uio.h>
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#include <sys/un.h>
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#include <ifaddrs.h>
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#include <linux/if_ether.h>
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@ -56,7 +57,9 @@
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#define EPOLL_EVENTS 10
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#define TIMER_INTERVAL 20 /* ms, for protocol periodic handlers */
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#define TAP_NMSG 32 /* maximum messages to buffer from tap */
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#define TIMER_INTERVAL 100 /* ms, for protocol periodic handlers */
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/**
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* sock_unix() - Create and bind AF_UNIX socket, add to epoll list
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@ -303,87 +306,182 @@ static void get_dns(struct ctx *c)
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/**
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* tap4_handler() - IPv4 and ARP packet handler for tap file descriptor
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* @c: Execution context
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* @len: Total L2 packet length
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* @in: Packet buffer, L2 headers
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* @msg: Array of messages with the same L3 protocol
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* @count: Count of messages with the same L3 protocol
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*
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* Return: count of packets consumed by handlers
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*/
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static void tap4_handler(struct ctx *c, char *in, size_t len)
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static int tap4_handler(struct ctx *c, struct tap_msg *msg, size_t count)
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{
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char buf_s[INET_ADDRSTRLEN] __attribute((__unused__));
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char buf_d[INET_ADDRSTRLEN] __attribute((__unused__));
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struct ethhdr *eh = (struct ethhdr *)in;
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struct iphdr *iph = (struct iphdr *)(eh + 1);
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struct ethhdr *eh = (struct ethhdr *)msg[0].start;
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struct iphdr *iph, *prev_iph = NULL;
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struct udphdr *uh, *prev_uh = NULL;
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size_t len = msg[0].len;
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unsigned int i;
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char *l4h;
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if (!c->v4)
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return;
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if (arp(c, eh, len) || dhcp(c, eh, len))
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return;
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return count;
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if (len < sizeof(*eh) + sizeof(*iph))
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return;
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return 1;
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l4h = (char *)iph + iph->ihl * 4;
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len -= (intptr_t)l4h - (intptr_t)eh;
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if (arp(c, eh, len) || dhcp(c, eh, len))
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return 1;
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if (iph->protocol == IPPROTO_ICMP) {
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for (i = 0; i < count; i++) {
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len = msg[i].len;
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if (len < sizeof(*eh) + sizeof(*iph))
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return 1;
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eh = (struct ethhdr *)msg[i].start;
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iph = (struct iphdr *)(eh + 1);
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l4h = (char *)iph + iph->ihl * 4;
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msg[i].l4h = l4h;
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msg[i].l4_len = len - ((intptr_t)l4h - (intptr_t)eh);
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if (iph->protocol != IPPROTO_TCP &&
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iph->protocol != IPPROTO_UDP)
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break;
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if (len < sizeof(*uh))
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break;
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uh = (struct udphdr *)l4h;
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if (!i) {
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prev_iph = iph;
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prev_uh = uh;
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continue;
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}
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if (iph->tos != prev_iph->tos ||
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iph->frag_off != prev_iph->frag_off ||
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iph->protocol != prev_iph->protocol ||
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iph->saddr != prev_iph->saddr ||
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iph->daddr != prev_iph->daddr ||
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uh->source != prev_uh->source ||
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uh->dest != prev_uh->dest)
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break;
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prev_iph = iph;
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prev_uh = uh;
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}
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eh = (struct ethhdr *)msg[0].start;
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iph = (struct iphdr *)(eh + 1);
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if (iph->protocol == IPPROTO_TCP || iph->protocol == IPPROTO_UDP ||
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iph->protocol == IPPROTO_SCTP) {
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uh = (struct udphdr *)msg[0].l4h;
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if (msg[0].len < sizeof(*uh))
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return 1;
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debug("%s from tap: %s:%i -> %s:%i (%i packet%s)",
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getprotobynumber(iph->protocol)->p_name,
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inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
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ntohs(uh->source),
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inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)),
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ntohs(uh->dest),
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i, i > 1 ? "s" : "");
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} else if (iph->protocol == IPPROTO_ICMP) {
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debug("icmp from tap: %s -> %s",
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inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
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inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)));
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} else if (iph->protocol == IPPROTO_TCP ||
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iph->protocol == IPPROTO_UDP ||
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iph->protocol == IPPROTO_SCTP) {
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struct tcphdr *th = (struct tcphdr *)l4h;
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if (len < sizeof(*th) && len < sizeof(struct udphdr))
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return;
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debug("%s from tap: %s:%i -> %s:%i",
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getprotobynumber(iph->protocol)->p_name,
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inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)),
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ntohs(th->source),
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inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)),
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ntohs(th->dest));
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}
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if (iph->protocol == IPPROTO_TCP)
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tcp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
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else if (iph->protocol == IPPROTO_UDP)
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udp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
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else if (iph->protocol == IPPROTO_ICMP)
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icmp_tap_handler(c, AF_INET, &iph->daddr, l4h, len);
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return tcp_tap_handler(c, AF_INET, &iph->daddr, msg, i);
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if (iph->protocol == IPPROTO_UDP)
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return udp_tap_handler(c, AF_INET, &iph->daddr, msg, i);
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if (iph->protocol == IPPROTO_ICMP)
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icmp_tap_handler(c, AF_INET, &iph->daddr, msg, 1);
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return 1;
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}
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/**
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* tap6_handler() - IPv6 packet handler for tap file descriptor
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* @c: Execution context
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* @len: Total L2 packet length
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* @in: Packet buffer, L2 headers
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* @msg: Array of messages with the same L3 protocol
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* @count: Count of messages with the same L3 protocol
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*/
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static void tap6_handler(struct ctx *c, char *in, size_t len)
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static int tap6_handler(struct ctx *c, struct tap_msg *msg, size_t count)
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{
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char buf_s[INET6_ADDRSTRLEN] __attribute((__unused__));
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char buf_d[INET6_ADDRSTRLEN] __attribute((__unused__));
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struct ethhdr *eh = (struct ethhdr *)in;
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struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
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uint8_t proto;
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struct ethhdr *eh = (struct ethhdr *)msg[0].start;
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struct udphdr *uh, *prev_uh = NULL;
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uint8_t proto = 0, prev_proto = 0;
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size_t len = msg[0].len;
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struct ipv6hdr *ip6h;
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unsigned int i;
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char *l4h;
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if (!c->v6)
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return;
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return count;
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if (len < sizeof(*eh) + sizeof(*ip6h))
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return;
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return 1;
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if (ndp(c, eh, len) || dhcpv6(c, eh, len))
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return;
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return 1;
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l4h = ipv6_l4hdr(ip6h, &proto);
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for (i = 0; i < count; i++) {
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struct ipv6hdr *p_ip6h;
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c->addr6_guest = ip6h->saddr;
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ip6h->saddr = c->addr6;
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len = msg[i].len;
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if (len < sizeof(*eh) + sizeof(*ip6h))
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return 1;
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len -= (intptr_t)l4h - (intptr_t)eh;
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eh = (struct ethhdr *)msg[i].start;
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ip6h = (struct ipv6hdr *)(eh + 1);
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l4h = ipv6_l4hdr(ip6h, &proto);
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msg[i].l4h = l4h;
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msg[i].l4_len = len - ((intptr_t)l4h - (intptr_t)eh);
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c->addr6_guest = ip6h->saddr;
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ip6h->saddr = c->addr6;
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if (proto != IPPROTO_TCP && proto != IPPROTO_UDP)
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break;
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if (len < sizeof(*uh))
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break;
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uh = (struct udphdr *)l4h;
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if (!i) {
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p_ip6h = ip6h;
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prev_proto = proto;
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prev_uh = uh;
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continue;
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}
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if (proto != prev_proto ||
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memcmp(&ip6h->saddr, &p_ip6h->saddr, sizeof(ip6h->saddr)) ||
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memcmp(&ip6h->daddr, &p_ip6h->daddr, sizeof(ip6h->daddr)) ||
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uh->source != prev_uh->source ||
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uh->dest != prev_uh->dest)
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break;
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p_ip6h = ip6h;
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prev_proto = proto;
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prev_uh = uh;
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}
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if (prev_proto)
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proto = prev_proto;
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eh = (struct ethhdr *)msg[0].start;
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ip6h = (struct ipv6hdr *)(eh + 1);
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if (proto == IPPROTO_ICMPV6) {
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debug("icmpv6 from tap: %s ->\n\t%s",
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@ -391,27 +489,34 @@ static void tap6_handler(struct ctx *c, char *in, size_t len)
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inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d)));
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} else if (proto == IPPROTO_TCP || proto == IPPROTO_UDP ||
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proto == IPPROTO_SCTP) {
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struct tcphdr *th = (struct tcphdr *)l4h;
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uh = (struct udphdr *)msg[0].l4h;
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if (len < sizeof(*th) && len < sizeof(struct udphdr))
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return;
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if (msg[0].len < sizeof(*uh))
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return 1;
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debug("%s from tap: [%s]:%i\n\t-> [%s]:%i",
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debug("%s from tap: [%s]:%i\n\t-> [%s]:%i (%i packet%s)",
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getprotobynumber(proto)->p_name,
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inet_ntop(AF_INET6, &ip6h->saddr, buf_s, sizeof(buf_s)),
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ntohs(th->source),
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ntohs(uh->source),
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inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d)),
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ntohs(th->dest));
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ntohs(uh->dest),
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i, i > 1 ? "s" : "");
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}
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if (proto == IPPROTO_TCP)
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tcp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len);
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else if (proto == IPPROTO_UDP)
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udp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len);
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else if (proto == IPPROTO_ICMPV6)
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icmp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len);
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return tcp_tap_handler(c, AF_INET6, &ip6h->daddr, msg, i);
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if (proto == IPPROTO_UDP)
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return udp_tap_handler(c, AF_INET6, &ip6h->daddr, msg, i);
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if (proto == IPPROTO_ICMPV6)
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icmp_tap_handler(c, AF_INET6, &ip6h->daddr, msg, 1);
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return 1;
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}
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static char tap_buf[ETH_MAX_MTU * TAP_NMSG];
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/**
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* tap_handler() - Packet handler for tap file descriptor
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* @c: Execution context
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@ -420,33 +525,74 @@ static void tap6_handler(struct ctx *c, char *in, size_t len)
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*/
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static int tap_handler(struct ctx *c)
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{
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char buf[ETH_MAX_MTU];
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int msg_count = 0, same, rcv = 0, i = 0;
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struct tap_msg msg[UIO_MAXIOV];
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ssize_t n, rem, fill;
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struct ethhdr *eh;
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uint32_t vnet_len;
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ssize_t n;
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char *p = tap_buf;
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eh = (struct ethhdr *)buf;
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fill = ETH_MAX_MTU * (TAP_NMSG - 1);
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while ((n = recv(c->fd_unix, &vnet_len, 4, MSG_DONTWAIT)) == 4) {
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n = recv(c->fd_unix, buf, ntohl(vnet_len), MSG_DONTWAIT);
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while ((n = recv(c->fd_unix, p, fill, MSG_DONTWAIT)) > 0) {
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fill -= n;
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while (n > 0) {
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ssize_t len = ntohl(*(uint32_t *)p);
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if (n < (ssize_t)sizeof(*eh))
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break;
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p += sizeof(uint32_t);
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n -= sizeof(uint32_t);
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switch (ntohs(eh->h_proto)) {
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case ETH_P_IP:
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if (len < (ssize_t)sizeof(*eh))
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break;
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/* At most one packet might not fit in a single read */
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if (len > n) {
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rem = recv(c->fd_unix, p + n, fill,
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MSG_DONTWAIT);
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rcv = errno;
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if (rem <= 0 || rem + n != len)
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break;
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}
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msg[msg_count].start = p;
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msg[msg_count++].len = len;
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n -= len;
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p += len;
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}
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}
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rcv = errno;
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while (i < msg_count) {
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eh = (struct ethhdr *)msg[i].start;
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switch (ntohs(eh->h_proto)) {
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case ETH_P_ARP:
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tap4_handler(c, buf, n);
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tap4_handler(c, msg + i, 1);
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i++;
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break;
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case ETH_P_IP:
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for (same = 1; i + same < msg_count; same++) {
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eh = (struct ethhdr *)msg[i + same].start;
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if (ntohs(eh->h_proto) != ETH_P_IP)
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break;
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}
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i += tap4_handler(c, msg + i, same);
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break;
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case ETH_P_IPV6:
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tap6_handler(c, buf, n);
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for (same = 1; i + same < msg_count; same++) {
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eh = (struct ethhdr *)msg[i + same].start;
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if (ntohs(eh->h_proto) != ETH_P_IPV6)
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break;
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}
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i += tap6_handler(c, msg + i, same);
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break;
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default:
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i++;
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break;
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}
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}
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if (n >= 0 || errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
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if (n >= 0 || rcv == EINTR || rcv == EAGAIN || rcv == EWOULDBLOCK)
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return 0;
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epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_unix, NULL);
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@ -552,7 +698,7 @@ int main(int argc, char **argv)
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exit(EXIT_FAILURE);
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}
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#if DEBUG
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#if DEBUG || 1
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openlog("passt", LOG_PERROR, LOG_DAEMON);
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#else
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openlog("passt", 0, LOG_DAEMON);
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@ -610,7 +756,7 @@ listen:
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UNIX_SOCK_PATH " -net nic,model=virtio");
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c.fd_unix = accept(fd_unix, NULL, NULL);
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ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP | EPOLLERR | EPOLLHUP;
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ev.events = EPOLLIN | EPOLLRDHUP | EPOLLERR | EPOLLHUP;
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ev.data.fd = c.fd_unix;
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epoll_ctl(c.epollfd, EPOLL_CTL_ADD, c.fd_unix, &ev);
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