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* Improve types and names for port forwarding configurationDavid Gibson2022-09-241-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | enum conf_port_type is local to conf.c and is used to track the port forwarding mode during configuration. We don't keep it around in the context structure, however the 'init_detect_ports' and 'ns_detect_ports' fields in the context are based solely on this. Rather than changing encoding, just include the forwarding mode into the context structure. Move the type definition to a new port_fwd.h, which is kind of trivial at the moment but will have more stuff later. While we're there, "conf_port_type" doesn't really convey that this enum is describing how port forwarding is configured. Rename it to port_fwd_mode. The variables (now fields) of this type also have mildly confusing names since it's not immediately obvious whether 'ns' and 'init' refer to the source or destination of the packets. Use "in" (host to guest / init to ns) and "out" (guest to host / ns to init) instead. This has the added bonus that we no longer have locals 'udp_init' and 'tcp_init' which shadow global functions. In addition, add a typedef 'port_fwd_map' for a bitmap of each port number, which is used in several places. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Make substructures for IPv4 and IPv6 specific context informationDavid Gibson2022-07-301-17/+17
| | | | | | | | | | | | The context structure contains a batch of fields specific to IPv4 and to IPv6 connectivity. Split those out into a sub-structure. This allows the conf_ip4() and conf_ip6() functions, which take the entire context but touch very little of it, to be given more specific parameters, making it clearer what it affects without stepping through the code. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* Separate IPv4 and IPv6 configurationDavid Gibson2022-07-301-10/+10
| | | | | | | | | | | | | | | | | | | After recent changes, conf_ip() now has essentially entirely disjoint paths for IPv4 and IPv6 configuration. So, it's cleaner to split them out into different functions conf_ip4() and conf_ip6(). Splitting these out also lets us make the interface a bit nicer, having them return success or failure directly, rather than manipulating c->v4 and c->v6 to indicate success/failure of the two versions. Since these functions may also initialize the interface index for each protocol, it turns out we can then drop c->v4 and c->v6 entirely, replacing tests on those with tests on whether c->ifi4 or c->ifi6 is non-zero (since a 0 interface index is never valid). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> [sbrivio: Whitespace fixes] Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Allow different external interfaces for IPv4 and IPv6 connectivityDavid Gibson2022-07-301-1/+1
| | | | | | | | | | | | | | | | It's quite plausible for a host to have both IPv4 and IPv6 connectivity, but only via different interfaces. For example, this will happen in the case that IPv6 connectivity is via a tunnel (e.g. 6in4 or 6rd). It would also happen in the case that IPv4 access is via a tunnel on an otherwise IPv6 only local network, which is a setup that might become more common in the post IPv4 address exhaustion world. In turns out there's no real need for passt/pasta to get its IPv4 and IPv6 connectivity via the same interface, so we can handle this situation fairly easily. Change the core to allow eparate external interfaces for IPv4 and IPv6. We don't actually set these separately for now. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Silence warning from gcc 11.3 with -OfastStefano Brivio2022-06-081-2/+8
| | | | | | | If the first packet_get() call doesn't assign len, the second one will also return NULL, but gcc doesn't see this. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Work around gcc 12 bogus warning in tcp_rtt_dst_check()Stefano Brivio2022-05-201-0/+6
| | | | | | | | | | | | | | | | | | | gcc 12.1.x (e.g. current OpenSUSE Tumbleweed, x86_64 only, gcc-12-1.4.x86_64) reports: tcp.c: In function ‘tcp_send_flag’: tcp.c:1014:9: warning: writing 16 bytes into a region of size 0 [-Wstringop-overflow=] 1014 | memcpy(low_rtt_dst + hole++, &conn->a.a6, sizeof(conn->a.a6)); | ^ tcp.c:559:24: note: at offset -16 into destination object ‘low_rtt_dst’ of size 128 559 | static struct in6_addr low_rtt_dst[LOW_RTT_TABLE_SIZE]; | but 'hole' can't be -1, because the low_rtt_dst table is guaranteed to have a hole: if we happened to write to the last entry, we'll go back to index 0 and clear that one. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf, tcp, udp: Allow address specification for forwarded portsStefano Brivio2022-05-011-27/+36
| | | | | | | | | | | | | This feature is available in slirp4netns but was missing in passt and pasta. Given that we don't do dynamic memory allocation, we need to bind sockets while parsing port configuration. This means we need to process all other options first, as they might affect addressing and IP version support. It also implies a minor rework of how TCP and UDP implementations bind sockets. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: False "Out-of-bounds read" positive, CWE-125Stefano Brivio2022-04-071-1/+5
| | | | | | | Reported by Coverity: it doesn't see that tcp{4,6}_l2_buf_used are set to zero by tcp_l2_data_buf_flush(), repeat that explicitly here. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, tcp_splice: False "Negative array index read" positives, CWE-129Stefano Brivio2022-04-071-4/+8
| | | | | | A flag or event bit is always set by callers. Reported by Coverity. Signed-by-off: Stefano Brivio <sbrivio@redhat.com>
* tcp: Dereference null return value, CWE-476Stefano Brivio2022-04-071-1/+1
| | | | | | Not an issue with a sane kernel behaviour. Reported by Coverity. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Unchecked return value from library, CWE-252Stefano Brivio2022-04-071-7/+12
| | | | | | | All instances were harmless, but it might be useful to have some debug messages here and there. Reported by Coverity. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: False "Untrusted loop bound" positive, CWE-606Stefano Brivio2022-04-051-0/+2
| | | | | | | | Field doff in struct tcp_hdr is 4 bits wide, so optlen in tcp_tap_handler() is already bound, but make that explicit. Reported by Coverity. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Invalid type in argument to printf format specifier, CWE-686Stefano Brivio2022-04-051-19/+19
| | | | | | Harmless except for two bad debugging prints. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tap, tcp, udp, icmp: Cut down on some oversized buffersStefano Brivio2022-03-291-10/+41
| | | | | | | | | The existing sizes provide no measurable differences in throughput and packet rates at this point. They were probably needed as batched implementations were not complete, but they can be decreased quite a bit now. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Fix warning by gcc 5.4 on ppc64le about comparison in CONN_OR_NULL()Stefano Brivio2022-03-291-13/+13
| | | | | | | ...we don't really need two extra bits, but it's easier to organise things differently than to silence this. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Mark constant references as constStefano Brivio2022-03-291-44/+51
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Packet abstraction with mandatory boundary checksStefano Brivio2022-03-291-195/+247
| | | | | | | | | | | | | | | | | | | | 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>
* tcp, tcp_splice: Use less awkward syntax to swap in/out sockets from poolsStefano Brivio2022-03-291-5/+4
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Fit struct tcp_conn into a single 64-byte cachelineStefano Brivio2022-03-291-135/+163
| | | | | | | | | | | | | | | | | | | | | | ...by: - storing the chained-hash next connection pointer as numeric reference rather than as pointer - storing the MSS as 14-bit value, and rounding it - using only the effective amount of bits needed to store the hash bucket number - explicitly limiting window scaling factors to 4-bit values (maximum factor is 14, from RFC 7323) - scaling SO_SNDBUF values, and using a 8-bit representation for the duplicate ACK sequence - keeping window values unscaled, as received and sent Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp_splice: Close sockets right away on high number of open filesStefano Brivio2022-03-291-0/+1
| | | | | | | | | | | | | We can't take for granted that the hard limit for open files is big enough as to allow to delay closing sockets to a timer. Store the value of RTLIMIT_NOFILE we set at start, and use it to understand if we're approaching the limit with pending, spliced TCP connections. If that's the case, close sockets right away as soon as they're not needed, instead of deferring this task to a timer. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Rework timers to use timerfd instead of periodic bitmap scanStefano Brivio2022-03-291-231/+272
| | | | | | | | | | | | | | | | | | With a lot of concurrent connections, the bitmap scan approach is not really sustainable. Switch to per-connection timerfd timers, set based on events and on two new flags, ACK_FROM_TAP_DUE and ACK_TO_TAP_DUE. Timers are added to the common epoll list, and implement the existing timeouts. While at it, drop the CONN_ prefix from flag names, otherwise they get quite long, and fix the logic to decide if a connection has a local, possibly unreachable endpoint: we shouldn't go through the rest of tcp_conn_from_tap() if we reset the connection due to a successful bind(2), and we'll get EACCES if the port number is low. Suggested by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, udp, util: Enforce 24-bit limit on socket numbersStefano Brivio2022-03-291-0/+17
| | | | | | | This should never happen, but there are no formal guarantees: ensure socket numbers are below SOCKET_MAX. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* dhcpv6, tap, tcp: Use IN6_ARE_ADDR_EQUAL instead of open-coded memcmp()Stefano Brivio2022-03-281-6/+6
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Refactor to use events instead of states, split out spliced implementationStefano Brivio2022-03-281-1495/+851
| | | | | | | | | | | | | | | | | | | | | Using events and flags instead of states makes the implementation much more straightforward: actions are mostly centered on events that occurred on the connection rather than states. An example is given by the ESTABLISHED_SOCK_FIN_SENT and FIN_WAIT_1_SOCK_FIN abominations: we don't actually care about which side started closing the connection to handle closing of connection halves. Split out the spliced implementation, as it has very little in common with the "regular" TCP path. Refactor things here and there to improve clarity. Add helpers to trace where resets and flag settings come from. No functional changes intended. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* seccomp, tcp: Add fcntl64 to pasta syscalls for armv6l, armv7lStefano Brivio2022-02-281-1/+1
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, udp: Receive batching doesn't pay off when writing single frames to tapStefano Brivio2022-02-211-16/+20
| | | | | | | | | | | | | | | | In pasta mode, when we get data from sockets and write it as single frames to the tap device, we batch receive operations considerably, and then (conceptually) split the data in many smaller writes. It looked like an obvious choice, but performance is actually better if we receive data in many small frame-sized recvmsg()/recvmmsg(). The syscall overhead with the previous behaviour, observed by perf, comes predominantly from write operations, but receiving data in shorter chunks probably improves cache locality by a considerable amount. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt, pasta: Namespace-based sandboxing, defer seccomp policy applicationStefano Brivio2022-02-211-8/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To reach (at least) a conceptually equivalent security level as implemented by --enable-sandbox in slirp4netns, we need to create a new mount namespace and pivot_root() into a new (empty) mountpoint, so that passt and pasta can't access any filesystem resource after initialisation. While at it, also detach IPC, PID (only for passt, to prevent vulnerabilities based on the knowledge of a target PID), and UTS namespaces. With this approach, if we apply the seccomp filters right after the configuration step, the number of allowed syscalls grows further. To prevent this, defer the application of seccomp policies after the initialisation phase, before the main loop, that's where we expect bad things to happen, potentially. This way, we get back to 22 allowed syscalls for passt and 34 for pasta, on x86_64. While at it, move #syscalls notes to specific code paths wherever it conceptually makes sense. We have to open all the file handles we'll ever need before sandboxing: - the packet capture file can only be opened once, drop instance numbers from the default path and use the (pre-sandbox) PID instead - /proc/net/tcp{,v6} and /proc/net/udp{,v6}, for automatic detection of bound ports in pasta mode, are now opened only once, before sandboxing, and their handles are stored in the execution context - the UNIX domain socket for passt is also bound only once, before sandboxing: to reject clients after the first one, instead of closing the listening socket, keep it open, accept and immediately discard new connection if we already have a valid one Clarify the (unchanged) behaviour for --netns-only in the man page. To actually make passt and pasta processes run in a separate PID namespace, we need to unshare(CLONE_NEWPID) before forking to background (if configured to do so). Introduce a small daemon() implementation, __daemon(), that additionally saves the PID file before forking. While running in foreground, the process itself can't move to a new PID namespace (a process can't change the notion of its own PID): mention that in the man page. For some reason, fork() in a detached PID namespace causes SIGTERM and SIGQUIT to be ignored, even if the handler is still reported as SIG_DFL: add a signal handler that just exits. We can now drop most of the pasta_child_handler() implementation, that took care of terminating all processes running in the same namespace, if pasta started a shell: the shell itself is now the init process in that namespace, and all children will terminate once the init process exits. Issuing 'echo $$' in a detached PID namespace won't return the actual namespace PID as seen from the init namespace: adapt demo and test setup scripts to reflect that. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Address new clang-tidy warnings from LLVM 13.0.1Stefano Brivio2022-01-301-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | clang-tidy from LLVM 13.0.1 reports some new warnings from these checkers: - altera-unroll-loops, altera-id-dependent-backward-branch: ignore for the moment being, add a TODO item - bugprone-easily-swappable-parameters: ignore, nothing to do about those - readability-function-cognitive-complexity: ignore for the moment being, add a TODO item - altera-struct-pack-align: ignore, alignment is forced in protocol headers - concurrency-mt-unsafe: ignore for the moment being, add a TODO item Fix bugprone-implicit-widening-of-multiplication-result warnings, though, that's doable and they seem to make sense. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt, tap: Daemonise once socket is ready without waiting for connectionStefano Brivio2022-01-281-1/+1
| | | | | | | | | | | | | The existing behaviour is not really practical: an automated agent in charge of starting both qemu and passt would need to fork itself to start passt, because passt won't fork to background until qemu connects, and the agent needs to unblock to start qemu. Instead of waiting for a connection to daemonise, do it right away as soon as a socket is available: that can be considered an initialised state already. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* seccomp: Add a number of alternate and per-arch syscallsStefano Brivio2022-01-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Depending on the C library, but not necessarily in all the functions we use, statx() might be used instead of stat(), getdents() instead of getdents64(), readlinkat() instead of readlink(), openat() instead of open(). On aarch64, it's clone() and not fork(), and dup3() instead of dup2() -- just allow the existing alternative instead of dealing with per-arch selections. Since glibc commit 9a7565403758 ("posix: Consolidate fork implementation"), we need to allow set_robust_list() for fork()/clone(), even in a single-threaded context. On some architectures, epoll_pwait() is provided instead of epoll_wait(), but never both. Same with newfstat() and fstat(), sigreturn() and rt_sigreturn(), getdents64() and getdents(), readlink() and readlinkat(), unlink() and unlinkat(), whereas pipe() might not be available, but pipe2() always is, exclusively or not. Seen on Fedora 34: newfstatat() is used on top of fstat(). syslog() is an actual system call on some glibc/arch combinations, instead of a connect()/send() implementation. On ppc64 and ppc64le, _llseek(), recv(), send() and getuid() are used. For ppc64 only: ugetrlimit() for the getrlimit() implementation, plus sigreturn() and fcntl64(). On s390x, additionally, we need to allow socketcall() (on top of socket()), and sigreturn() also for passt (not just for pasta). Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Don't round down MSS to >= 64KiB page size, but clamp it in any caseStefano Brivio2022-01-261-3/+3
| | | | | | | On some architectures, the page size is bigger than the maximum size of an Ethernet frame. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, udp, util: Fixes for bitmap handling on big-endian, castsStefano Brivio2022-01-261-1/+1
| | | | | | | | Bitmap manipulating functions would otherwise refer to inconsistent sets of bits on big-endian architectures. While at it, fix up a couple of casts. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, netlink, HAS{BYTES_ACKED,MIN_RTT,GETRANDOM} and NETLINK_GET_STRICT_CHKStefano Brivio2022-01-261-0/+36
| | | | | | | | | | | | | | | | tcpi_bytes_acked and tcpi_min_rtt are only available on recent kernel versions: provide fall-back paths (incurring some grade of performance penalty). Support for getrandom() was introduced in Linux 3.17 and glibc 2.25: provide an alternate mechanism for that as well, reading from /dev/random. Also check if NETLINK_GET_STRICT_CHK is defined before using it: it's not strictly needed, we'll filter out irrelevant results from netlink anyway. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Drop <linux/ipv6.h> include, carry own ipv6hdr and opt_hdr definitionsStefano Brivio2022-01-261-1/+0
| | | | | | | This is the only remaining Linux-specific include -- drop it to avoid clang-tidy warnings and to make code more portable. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tap, tcp: Fix two comparisons with different signedness reported by gcc 7Stefano Brivio2022-01-261-1/+1
| | | | | | For some reason, those are not reported by recent versions of gcc. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Cover all usages of tcpi_snd_wnd with HAS_SND_WNDStefano Brivio2022-01-261-0/+2
| | | | | | ...I forgot two of them. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Restore source address to network endianness before using it for hash tableStefano Brivio2021-10-211-2/+3
| | | | | | | | | This was actually fine "on the wire", but it's inconsistent with the way we hash other addresses/protocols and also ends up with a wrong endianness in captures in case we replace the address with our default gateway. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Add cppcheck target, test, and address resulting warningsStefano Brivio2021-10-211-53/+56
| | | | | | | ...mostly false positives, but a number of very relevant ones too, in tcp_get_sndbuf(), tcp_conn_from_tap(), and siphash PREAMBLE(). Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Fix build with gcc 7, use std=c99, enable some more Clang checkersStefano Brivio2021-10-211-82/+90
| | | | | | | | | | | | | | Unions and structs, you all have names now. Take the chance to enable bugprone-reserved-identifier, cert-dcl37-c, and cert-dcl51-cpp checkers in clang-tidy. Provide a ffsl() weak declaration using gcc built-in. Start reordering includes, but that's not enough for the llvm-include-order checker yet. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Makefile, tcp: Don't try to use tcpi_snd_wnd from tcp_info on pre-5.3 kernelsStefano Brivio2021-10-211-1/+8
| | | | | | | Detect missing tcpi_snd_wnd in struct tcp_info at build time, otherwise build fails with a pre-5.3 linux/tcp.h header. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* ndp, dhcpv6, tcp, udp: Always use link-local as source if gateway isn'tStefano Brivio2021-10-201-2/+10
| | | | | | | | | | | | This shouldn't happen on any sane configuration, but I just met an example of that: the default IPv6 gateway on the host is configured with a global unicast address, we use that as source for RA, DHCPv6 replies, and the guest ignores it. Same later on if we talk TCP or UDP and the guest has no idea where that address comes from. Use our link-local address in case the gateway address is global. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Add clang-tidy Makefile target and test, take care of warningsStefano Brivio2021-10-201-30/+32
| | | | | | | Most are just about style and form, but a few were actually serious mistakes (NDP-related). Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Address warnings from Clang's scan-buildStefano Brivio2021-10-201-16/+21
| | | | | | All false positives so far. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Address gcc 11 warningsStefano Brivio2021-10-201-11/+25
| | | | | | | | | A mix of unchecked return values, a missing permission mask for open(2) with O_CREAT, and some false positives from -Wstringop-overflow and -Wmaybe-uninitialized. Reported-by: Martin Hauke <mardnh@gmx.de> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Fix for non-blocking splice() on older kernelsStefano Brivio2021-10-191-2/+2
| | | | | | | | For some reason, on 4.19, splice() doesn't honour SOCK_NONBLOCK from accept4() while reading from a TCP socket. Pass SPLICE_F_NONBLOCK explicitly in all cases. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Fix ACK reporting on older kernels (no tcp.kernel_snd_wnd case)Stefano Brivio2021-10-191-3/+4
| | | | | | | | If the window isn't updated on !c->tcp.kernel_snd_wnd, we still have to send ACKs if the ACK sequence was updated, or if an error occurred while querying TCP_INFO. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Arm tcp_data_noack on insufficient window too, don't reset if ACK ↵Stefano Brivio2021-10-161-2/+4
| | | | | | | | | | doesn't match ...and while at it, reverse the operands in the window equality comparison to detect the need for fast re-transmit: it's easier to read this way. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: ...and so I got a socket called zeroStefano Brivio2021-10-151-35/+44
| | | | | | | | I thought I'd get away with it, but no, after some clean-ups, I finally got a socket with number 0. Fix up all the convenient, yet botched assumptions. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Bump TCP_TAP_FRAMES back to 256Stefano Brivio2021-10-151-1/+1
| | | | | | With a batched sendmsg(), this is now beneficial. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Get rid of iov with cached MSS, drop sendmmsg(), add deferred flushStefano Brivio2021-10-151-139/+130
| | | | | | | | | | | | | | | Caching iov_len for messages from socket doesn't actually decrease overhead by the tiniest bit, and added a lot of complexity. Drop that. Also drop the sendmmsg(), we don't need to send multiple messages with TCP, as long as we make sure no messages with a length descriptor are sent partially, qemu is fine with it. Just like it's done for segments without data (flags), also defer the sendmsg() for sending data segments, to improve batching. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
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