From 1f7cf04d343f185f9e044fdca70a1d0252492aed Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Thu, 22 Apr 2021 13:39:36 +0200 Subject: 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 --- passt.c | 284 ++++++++++++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 215 insertions(+), 69 deletions(-) (limited to 'passt.c') diff --git a/passt.c b/passt.c index c580298..df7bbde 100644 --- a/passt.c +++ b/passt.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -56,7 +57,9 @@ #define EPOLL_EVENTS 10 -#define TIMER_INTERVAL 20 /* ms, for protocol periodic handlers */ +#define TAP_NMSG 32 /* maximum messages to buffer from tap */ + +#define TIMER_INTERVAL 100 /* ms, for protocol periodic handlers */ /** * sock_unix() - Create and bind AF_UNIX socket, add to epoll list @@ -303,87 +306,182 @@ static void get_dns(struct ctx *c) /** * tap4_handler() - IPv4 and ARP packet handler for tap file descriptor * @c: Execution context - * @len: Total L2 packet length - * @in: Packet buffer, L2 headers + * @msg: Array of messages with the same L3 protocol + * @count: Count of messages with the same L3 protocol + * + * Return: count of packets consumed by handlers */ -static void tap4_handler(struct ctx *c, char *in, size_t len) +static int tap4_handler(struct ctx *c, struct tap_msg *msg, size_t count) { char buf_s[INET_ADDRSTRLEN] __attribute((__unused__)); char buf_d[INET_ADDRSTRLEN] __attribute((__unused__)); - struct ethhdr *eh = (struct ethhdr *)in; - struct iphdr *iph = (struct iphdr *)(eh + 1); + struct ethhdr *eh = (struct ethhdr *)msg[0].start; + struct iphdr *iph, *prev_iph = NULL; + struct udphdr *uh, *prev_uh = NULL; + size_t len = msg[0].len; + unsigned int i; char *l4h; if (!c->v4) - return; + return count; + + if (len < sizeof(*eh) + sizeof(*iph)) + return 1; if (arp(c, eh, len) || dhcp(c, eh, len)) - return; + return 1; - if (len < sizeof(*eh) + sizeof(*iph)) - return; + for (i = 0; i < count; i++) { + len = msg[i].len; + if (len < sizeof(*eh) + sizeof(*iph)) + return 1; - l4h = (char *)iph + iph->ihl * 4; - len -= (intptr_t)l4h - (intptr_t)eh; + eh = (struct ethhdr *)msg[i].start; + iph = (struct iphdr *)(eh + 1); + l4h = (char *)iph + iph->ihl * 4; - if (iph->protocol == IPPROTO_ICMP) { - debug("icmp from tap: %s -> %s", - inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)), - inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d))); - } else if (iph->protocol == IPPROTO_TCP || - iph->protocol == IPPROTO_UDP || - iph->protocol == IPPROTO_SCTP) { - struct tcphdr *th = (struct tcphdr *)l4h; + msg[i].l4h = l4h; + msg[i].l4_len = len - ((intptr_t)l4h - (intptr_t)eh); + + if (iph->protocol != IPPROTO_TCP && + iph->protocol != IPPROTO_UDP) + break; + + if (len < sizeof(*uh)) + break; + + uh = (struct udphdr *)l4h; + + if (!i) { + prev_iph = iph; + prev_uh = uh; + continue; + } - if (len < sizeof(*th) && len < sizeof(struct udphdr)) - return; + if (iph->tos != prev_iph->tos || + iph->frag_off != prev_iph->frag_off || + iph->protocol != prev_iph->protocol || + iph->saddr != prev_iph->saddr || + iph->daddr != prev_iph->daddr || + uh->source != prev_uh->source || + uh->dest != prev_uh->dest) + break; + + prev_iph = iph; + prev_uh = uh; + } - debug("%s from tap: %s:%i -> %s:%i", + eh = (struct ethhdr *)msg[0].start; + iph = (struct iphdr *)(eh + 1); + + if (iph->protocol == IPPROTO_TCP || iph->protocol == IPPROTO_UDP || + iph->protocol == IPPROTO_SCTP) { + uh = (struct udphdr *)msg[0].l4h; + + if (msg[0].len < sizeof(*uh)) + return 1; + + debug("%s from tap: %s:%i -> %s:%i (%i packet%s)", getprotobynumber(iph->protocol)->p_name, inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)), - ntohs(th->source), + ntohs(uh->source), inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d)), - ntohs(th->dest)); + ntohs(uh->dest), + i, i > 1 ? "s" : ""); + } else if (iph->protocol == IPPROTO_ICMP) { + debug("icmp from tap: %s -> %s", + inet_ntop(AF_INET, &iph->saddr, buf_s, sizeof(buf_s)), + inet_ntop(AF_INET, &iph->daddr, buf_d, sizeof(buf_d))); } if (iph->protocol == IPPROTO_TCP) - tcp_tap_handler(c, AF_INET, &iph->daddr, l4h, len); - else if (iph->protocol == IPPROTO_UDP) - udp_tap_handler(c, AF_INET, &iph->daddr, l4h, len); - else if (iph->protocol == IPPROTO_ICMP) - icmp_tap_handler(c, AF_INET, &iph->daddr, l4h, len); + return tcp_tap_handler(c, AF_INET, &iph->daddr, msg, i); + + if (iph->protocol == IPPROTO_UDP) + return udp_tap_handler(c, AF_INET, &iph->daddr, msg, i); + + if (iph->protocol == IPPROTO_ICMP) + icmp_tap_handler(c, AF_INET, &iph->daddr, msg, 1); + + return 1; } /** * tap6_handler() - IPv6 packet handler for tap file descriptor * @c: Execution context - * @len: Total L2 packet length - * @in: Packet buffer, L2 headers + * @msg: Array of messages with the same L3 protocol + * @count: Count of messages with the same L3 protocol */ -static void tap6_handler(struct ctx *c, char *in, size_t len) +static int tap6_handler(struct ctx *c, struct tap_msg *msg, size_t count) { char buf_s[INET6_ADDRSTRLEN] __attribute((__unused__)); char buf_d[INET6_ADDRSTRLEN] __attribute((__unused__)); - struct ethhdr *eh = (struct ethhdr *)in; - struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1); - uint8_t proto; + struct ethhdr *eh = (struct ethhdr *)msg[0].start; + struct udphdr *uh, *prev_uh = NULL; + uint8_t proto = 0, prev_proto = 0; + size_t len = msg[0].len; + struct ipv6hdr *ip6h; + unsigned int i; char *l4h; if (!c->v6) - return; + return count; if (len < sizeof(*eh) + sizeof(*ip6h)) - return; + return 1; if (ndp(c, eh, len) || dhcpv6(c, eh, len)) - return; + return 1; - l4h = ipv6_l4hdr(ip6h, &proto); + for (i = 0; i < count; i++) { + struct ipv6hdr *p_ip6h; - c->addr6_guest = ip6h->saddr; - ip6h->saddr = c->addr6; + len = msg[i].len; + if (len < sizeof(*eh) + sizeof(*ip6h)) + return 1; - len -= (intptr_t)l4h - (intptr_t)eh; + eh = (struct ethhdr *)msg[i].start; + ip6h = (struct ipv6hdr *)(eh + 1); + l4h = ipv6_l4hdr(ip6h, &proto); + + msg[i].l4h = l4h; + msg[i].l4_len = len - ((intptr_t)l4h - (intptr_t)eh); + + c->addr6_guest = ip6h->saddr; + ip6h->saddr = c->addr6; + + if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) + break; + + if (len < sizeof(*uh)) + break; + + uh = (struct udphdr *)l4h; + + if (!i) { + p_ip6h = ip6h; + prev_proto = proto; + prev_uh = uh; + continue; + } + + if (proto != prev_proto || + memcmp(&ip6h->saddr, &p_ip6h->saddr, sizeof(ip6h->saddr)) || + memcmp(&ip6h->daddr, &p_ip6h->daddr, sizeof(ip6h->daddr)) || + uh->source != prev_uh->source || + uh->dest != prev_uh->dest) + break; + + p_ip6h = ip6h; + prev_proto = proto; + prev_uh = uh; + } + + if (prev_proto) + proto = prev_proto; + + eh = (struct ethhdr *)msg[0].start; + ip6h = (struct ipv6hdr *)(eh + 1); if (proto == IPPROTO_ICMPV6) { debug("icmpv6 from tap: %s ->\n\t%s", @@ -391,27 +489,34 @@ static void tap6_handler(struct ctx *c, char *in, size_t len) inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d))); } else if (proto == IPPROTO_TCP || proto == IPPROTO_UDP || proto == IPPROTO_SCTP) { - struct tcphdr *th = (struct tcphdr *)l4h; + uh = (struct udphdr *)msg[0].l4h; - if (len < sizeof(*th) && len < sizeof(struct udphdr)) - return; + if (msg[0].len < sizeof(*uh)) + return 1; - debug("%s from tap: [%s]:%i\n\t-> [%s]:%i", + debug("%s from tap: [%s]:%i\n\t-> [%s]:%i (%i packet%s)", getprotobynumber(proto)->p_name, inet_ntop(AF_INET6, &ip6h->saddr, buf_s, sizeof(buf_s)), - ntohs(th->source), + ntohs(uh->source), inet_ntop(AF_INET6, &ip6h->daddr, buf_d, sizeof(buf_d)), - ntohs(th->dest)); + ntohs(uh->dest), + i, i > 1 ? "s" : ""); } if (proto == IPPROTO_TCP) - tcp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len); - else if (proto == IPPROTO_UDP) - udp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len); - else if (proto == IPPROTO_ICMPV6) - icmp_tap_handler(c, AF_INET6, &ip6h->daddr, l4h, len); + return tcp_tap_handler(c, AF_INET6, &ip6h->daddr, msg, i); + + if (proto == IPPROTO_UDP) + return udp_tap_handler(c, AF_INET6, &ip6h->daddr, msg, i); + + if (proto == IPPROTO_ICMPV6) + icmp_tap_handler(c, AF_INET6, &ip6h->daddr, msg, 1); + + return 1; } +static char tap_buf[ETH_MAX_MTU * TAP_NMSG]; + /** * tap_handler() - Packet handler for tap file descriptor * @c: Execution context @@ -420,33 +525,74 @@ static void tap6_handler(struct ctx *c, char *in, size_t len) */ static int tap_handler(struct ctx *c) { - char buf[ETH_MAX_MTU]; + int msg_count = 0, same, rcv = 0, i = 0; + struct tap_msg msg[UIO_MAXIOV]; + ssize_t n, rem, fill; struct ethhdr *eh; - uint32_t vnet_len; - ssize_t n; + char *p = tap_buf; - eh = (struct ethhdr *)buf; + fill = ETH_MAX_MTU * (TAP_NMSG - 1); - while ((n = recv(c->fd_unix, &vnet_len, 4, MSG_DONTWAIT)) == 4) { - n = recv(c->fd_unix, buf, ntohl(vnet_len), MSG_DONTWAIT); + while ((n = recv(c->fd_unix, p, fill, MSG_DONTWAIT)) > 0) { + fill -= n; + while (n > 0) { + ssize_t len = ntohl(*(uint32_t *)p); - if (n < (ssize_t)sizeof(*eh)) - break; + p += sizeof(uint32_t); + n -= sizeof(uint32_t); - switch (ntohs(eh->h_proto)) { - case ETH_P_IP: + if (len < (ssize_t)sizeof(*eh)) + break; + + /* At most one packet might not fit in a single read */ + if (len > n) { + rem = recv(c->fd_unix, p + n, fill, + MSG_DONTWAIT); + rcv = errno; + if (rem <= 0 || rem + n != len) + break; + } + + msg[msg_count].start = p; + msg[msg_count++].len = len; + + n -= len; + p += len; + } + } + + rcv = errno; + + while (i < msg_count) { + eh = (struct ethhdr *)msg[i].start; + switch (ntohs(eh->h_proto)) { case ETH_P_ARP: - tap4_handler(c, buf, n); + tap4_handler(c, msg + i, 1); + i++; + break; + case ETH_P_IP: + for (same = 1; i + same < msg_count; same++) { + eh = (struct ethhdr *)msg[i + same].start; + if (ntohs(eh->h_proto) != ETH_P_IP) + break; + } + i += tap4_handler(c, msg + i, same); break; case ETH_P_IPV6: - tap6_handler(c, buf, n); + for (same = 1; i + same < msg_count; same++) { + eh = (struct ethhdr *)msg[i + same].start; + if (ntohs(eh->h_proto) != ETH_P_IPV6) + break; + } + i += tap6_handler(c, msg + i, same); break; default: + i++; break; } } - if (n >= 0 || errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) + if (n >= 0 || rcv == EINTR || rcv == EAGAIN || rcv == EWOULDBLOCK) return 0; epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_unix, NULL); @@ -552,7 +698,7 @@ int main(int argc, char **argv) exit(EXIT_FAILURE); } -#if DEBUG +#if DEBUG || 1 openlog("passt", LOG_PERROR, LOG_DAEMON); #else openlog("passt", 0, LOG_DAEMON); @@ -610,7 +756,7 @@ listen: UNIX_SOCK_PATH " -net nic,model=virtio"); c.fd_unix = accept(fd_unix, NULL, NULL); - ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP | EPOLLERR | EPOLLHUP; + ev.events = EPOLLIN | EPOLLRDHUP | EPOLLERR | EPOLLHUP; ev.data.fd = c.fd_unix; epoll_ctl(c.epollfd, EPOLL_CTL_ADD, c.fd_unix, &ev); -- cgit v1.2.3