From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202410 header.b=j6I2jWWI; dkim-atps=neutral Received: from mail.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id 0BAB25A004E for ; Wed, 23 Oct 2024 02:43:03 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202410; t=1729644174; bh=bU7h/TgPesgHQrGAhUkSmgaPk8w8PWeBB0EfB41lUbs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j6I2jWWIYaom2X2wfxQzLJAkrNYonfLtLaah22GmSOHq7+mR39hlLMFMp7HjNDW2e ARgIo6bcHi4TBLt3+02ktmNqAAYfM0h+gcYAPdiiM888N0QpY80u0vaWfYMQh9N1b5 Jbn6KQ033pRshGzxnb9nj/sL8fRuZazB7n+3POXuoLdpjsm3j7uHX6NWI1S/PSAlj/ aZQuUk2160EJOePCUW1CgPoSAvn+mXrixMMPtkM8zesKnzpBWUkOgGIXpfC2mM/sBo KEPbnBWJlzZEawQZ50uxHhuRakT9w+YGO6KOPoPNInEbdeHv6n30T89OaaAR3+MNEI ftEgrJ9d9yqmw== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4XY9Hy1CH6z4wb1; Wed, 23 Oct 2024 11:42:54 +1100 (AEDT) From: David Gibson To: Stefano Brivio , passt-dev@passt.top Subject: [PATCH 1/2] tcp: Generalise probing for tcpi_snd_wnd field Date: Wed, 23 Oct 2024 11:42:52 +1100 Message-ID: <20241023004253.1729124-2-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241023004253.1729124-1-david@gibson.dropbear.id.au> References: <20241023004253.1729124-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: W4XJWASNOEXKHAVQ4NAQ45Q3JTTIJVYQ X-Message-ID-Hash: W4XJWASNOEXKHAVQ4NAQ45Q3JTTIJVYQ X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: In order to use the tcpi_snd_wnd field from the TCPI_INFO getsockopt() we need both for the field to be present in the headers (HAS_SND_WND) and for the runtime kernel to actually report it (snd_wnd_cap). In fact we really need to check the same things for every tcp_info field we want to use. Prepare to do that, by generalising the probing for the tcpi_snd_wnd field which set a single bool to instead record the size of the returned tcp_info structure. We can then use that recorded value to check for the presence of any field we need. Signed-off-by: David Gibson --- tcp.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/tcp.c b/tcp.c index 0d22e07..3cca5c6 100644 --- a/tcp.c +++ b/tcp.c @@ -365,11 +365,18 @@ char tcp_buf_discard [MAX_WINDOW]; /* Does the kernel support TCP_PEEK_OFF? */ bool peek_offset_cap; +/* Size of data returned by TCP_INFO getsockopt() */ +socklen_t tcp_info_size; + +#define tcp_info_cap(f_) \ + ((offsetof(struct tcp_info, tcpi_##f_) + \ + sizeof(((struct tcp_info *)NULL)->tcpi_##f_)) <= tcp_info_size) + #ifdef HAS_SND_WND /* Does the kernel report sending window in TCP_INFO (kernel commit * 8f7baad7f035) */ -bool snd_wnd_cap; +#define snd_wnd_cap tcp_info_cap(snd_wnd) #else #define snd_wnd_cap (false) #endif @@ -2578,13 +2585,12 @@ static bool tcp_probe_peek_offset_cap(sa_family_t af) return ret; } -#ifdef HAS_SND_WND /** - * tcp_probe_snd_wnd_cap() - Check if TCP_INFO reports tcpi_snd_wnd + * tcp_probe_tcp_info() - Check what data TCP_INFO reports * - * Return: true if supported, false otherwise + * Return: Number of bytes returned by TCP_INFO getsockopt() */ -static bool tcp_probe_snd_wnd_cap(void) +static socklen_t tcp_probe_tcp_info(void) { struct tcp_info tinfo; socklen_t sl = sizeof(tinfo); @@ -2604,13 +2610,8 @@ static bool tcp_probe_snd_wnd_cap(void) close(s); - if (sl < (offsetof(struct tcp_info, tcpi_snd_wnd) + - sizeof(tinfo.tcpi_snd_wnd))) - return false; - - return true; + return sl; } -#endif /* HAS_SND_WND */ /** * tcp_init() - Get initial sequence, hash secret, initialise per-socket data @@ -2645,11 +2646,14 @@ int tcp_init(struct ctx *c) (!c->ifi6 || tcp_probe_peek_offset_cap(AF_INET6)); debug("SO_PEEK_OFF%ssupported", peek_offset_cap ? " " : " not "); + tcp_info_size = tcp_probe_tcp_info(); + +#define dbg_tcpi(f_) debug("TCP_INFO tcpi_%s field%s supported", \ + STRINGIFY(f_), tcp_info_cap(f_) ? " " : " not ") #ifdef HAS_SND_WND - snd_wnd_cap = tcp_probe_snd_wnd_cap(); + dbg_tcpi(snd_wnd); #endif - debug("TCP_INFO tcpi_snd_wnd field%ssupported", - snd_wnd_cap ? " " : " not "); +#undef dbg_tcpi return 0; } -- 2.47.0