From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server-vie001.gnuweeb.org X-Spam-Level: X-Spam-Status: No, score=-1.2 required=5.0 tests=ALL_TRUSTED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,URIBL_DBL_BLOCKED_OPENDNS, URIBL_ZEN_BLOCKED_OPENDNS autolearn=ham autolearn_force=no version=3.4.6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=new2025; t=1756391868; bh=yxuYPysIwojLpmngogaNGvV6xo2/SgPgJdaWFWlRrJA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Transfer-Encoding:Message-ID:Date:From: Reply-To:Subject:To:Cc:In-Reply-To:References:Resent-Date: Resent-From:Resent-To:Resent-Cc:User-Agent:Content-Type: Content-Transfer-Encoding; b=By5ad86o13E5ZxQKyJ/9wSWd5dRTktU0Y611y/A6pkQQFlfFXMxP40Q9BZ3J+AKEi UCelwdj/0y012Y1jIhy9zaFOGE2iT2vEwIoj+J9VV8vkCPlZIulLBqW2WEr8Tg0Xud KgmCr9Rw17PdCyhRJ/aPSoWsDxdlogtW8vP3NOTU4Lmh2XnGIcsh6vIy3iQT+fIEzK X2d+L7H48FaCIGmhAuRgm43+zFleLyW2PMSP++zJoWzpUqQ4lC/xaqpnh5oOSGU3AC rHTPRaBd362NmQNohDLbqQhAkAWnjhxBdLCeN4euc49bGwGCKvKRxgWoE16JcZa7aV 4YOJ7dGaEl+7A== Received: from zero (unknown [182.253.228.107]) by server-vie001.gnuweeb.org (Postfix) with ESMTPSA id 0AFA83127F26; Thu, 28 Aug 2025 14:37:45 +0000 (UTC) From: Ahmad Gani To: Ammar Faizi Cc: Ahmad Gani , Alviro Iskandar Setiawan , GNU/Weeb Mailing List Subject: [PATCH gwproxy v6 11/11] dns: Add fallback mechanism for raw DNS Date: Thu, 28 Aug 2025 21:34:33 +0700 Message-ID: <20250828143444.540247-12-reyuki@gnuweeb.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250828143444.540247-1-reyuki@gnuweeb.org> References: <20250828143444.540247-1-reyuki@gnuweeb.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: If *_PREFER_* is used in the restyp, the raw DNS backend will attempt to retry DNS query with different address family. Signed-off-by: Ahmad Gani --- src/gwproxy/dns.c | 75 ++++++++++++++++++++++++++++++++---------- src/gwproxy/ev/epoll.c | 40 ++++++++++++++-------- 2 files changed, 84 insertions(+), 31 deletions(-) diff --git a/src/gwproxy/dns.c b/src/gwproxy/dns.c index 1eb0d9a67229..9f563e083fd2 100644 --- a/src/gwproxy/dns.c +++ b/src/gwproxy/dns.c @@ -264,11 +264,36 @@ int gwp_dns_process(struct gwp_dns_ctx *ctx, struct gwp_dns_entry *e) return (int)r; r = gwdns_parse_query(e->txid, e->service, buff, r, &ai); - if (r) + if (r) { + if (r == -ENODATA) { + uint16_t txid; + int af; + + /* Fallback to other family if this one yield no results */ + switch (ctx->cfg.restyp) { + case GWP_DNS_RESTYP_PREFER_IPV4: + af = AF_INET6; + break; + case GWP_DNS_RESTYP_PREFER_IPV6: + af = AF_INET; + break; + default: + goto exit_free_ai; + break; + } + + txid = (uint16_t)rand(); + r = gwdns_build_query(txid, e->name, af, e->payload, sizeof(e->payload)); + if (r > 0) { + e->txid = txid; + e->payloadlen = (int)r; + r = -EAGAIN; + } + } goto exit_free_ai; + } e->addr = ai->ai_addr; - // gwp_dns_find_preferred_addr(ctx, ai, e->name, &e->addr, ctx->cfg.restyp); exit_free_ai: gwdns_free_parsed_query(ai); @@ -909,6 +934,7 @@ struct gwp_dns_entry *gwp_dns_queue(struct gwp_dns_ctx *ctx, #ifdef CONFIG_RAW_DNS uint16_t txid; ssize_t r; + int af; #endif e = malloc(sizeof(*e)); @@ -917,25 +943,38 @@ struct gwp_dns_entry *gwp_dns_queue(struct gwp_dns_ctx *ctx, if (ctx->cfg.use_raw_dns) { #ifdef CONFIG_RAW_DNS - if (ctx->nr_entries == ctx->entry_cap && realloc_entries(ctx)) - return NULL; + if (ctx->nr_entries == ctx->entry_cap && realloc_entries(ctx)) + return NULL; + + r = __sys_socket(ctx->ns_addr.sa.sa_family, SOCK_DGRAM | SOCK_NONBLOCK, 0); + if (r < 0) + goto out_free_e; + e->udp_fd = (int)r; + + switch (ctx->cfg.restyp) { + case GWP_DNS_RESTYP_PREFER_IPV4: + case GWP_DNS_RESTYP_IPV4_ONLY: + af = AF_INET; + break; + case GWP_DNS_RESTYP_PREFER_IPV6: + case GWP_DNS_RESTYP_IPV6_ONLY: + af = AF_INET6; + break; + default: + assert(0); + break; + } - r = __sys_socket(ctx->ns_addr.sa.sa_family, SOCK_DGRAM | SOCK_NONBLOCK, 0); - if (r < 0) - goto out_free_e; - e->udp_fd = (int)r; - - txid = (uint16_t)rand(); - // TODO(reyuki): avoid hard-coded AF_INET and use restyp instead - r = gwdns_build_query(txid, name, AF_INET, e->payload, sizeof(e->payload)); - if (r < 0) - goto out_free_e; - e->payloadlen = (int)r; + txid = (uint16_t)rand(); + r = gwdns_build_query(txid, name, af, e->payload, sizeof(e->payload)); + if (r < 0) + goto out_free_e; + e->payloadlen = (int)r; #endif } else { - e->ev_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); - if (e->ev_fd < 0) - goto out_free_e; + e->ev_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); + if (e->ev_fd < 0) + goto out_free_e; } /* diff --git a/src/gwproxy/ev/epoll.c b/src/gwproxy/ev/epoll.c index cd8fd8752473..935f7717f926 100644 --- a/src/gwproxy/ev/epoll.c +++ b/src/gwproxy/ev/epoll.c @@ -778,6 +778,27 @@ static int handle_connect(struct gwp_wrk *w, struct gwp_conn_pair *gcp) return 0; } +#ifdef CONFIG_RAW_DNS +static int arm_poll_for_raw_dns_query(struct gwp_wrk *w, + struct gwp_conn_pair *gcp) +{ + struct gwp_dns_entry *gde = gcp->gde; + struct gwp_dns_ctx *dctx; + struct gwp_sockaddr addr; + uint8_t addrlen; + ssize_t r; + + dctx = w->ctx->dns; + cp_nsaddr(dctx, &addr, &addrlen); + r = __sys_sendto( + gde->udp_fd, gde->payload, gde->payloadlen, MSG_NOSIGNAL, + &addr.sa, addrlen + ); + + return (int)r; +} +#endif + static int arm_poll_for_dns_query(struct gwp_wrk *w, struct gwp_conn_pair *gcp) { @@ -794,18 +815,7 @@ static int arm_poll_for_dns_query(struct gwp_wrk *w, if (w->ctx->cfg.use_raw_dns) { #ifdef CONFIG_RAW_DNS - struct gwp_dns_ctx *dctx; - struct gwp_sockaddr addr; - uint8_t addrlen; - - dctx = w->ctx->dns; - cp_nsaddr(dctx, &addr, &addrlen); - r = __sys_sendto( - gde->udp_fd, gde->payload, gde->payloadlen, MSG_NOSIGNAL, - &addr.sa, addrlen - ); - if (unlikely(r < 0)) - return (int)r; + arm_poll_for_raw_dns_query(w, gcp); r = __sys_epoll_ctl(w->ep_fd, EPOLL_CTL_ADD, gde->udp_fd, &ev); if (unlikely(r)) @@ -853,7 +863,11 @@ static int handle_ev_dns_query(struct gwp_wrk *w, struct gwp_conn_pair *gcp) if (w->ctx->cfg.use_raw_dns) { #ifdef CONFIG_RAW_DNS r = gwp_dns_process(w->ctx->dns, gde); - if (r) + if (r == -EAGAIN) { + pr_dbg(&w->ctx->lh, "DNS Fallback\n"); + arm_poll_for_raw_dns_query(w, gcp); + return 0; + } else if (r) gde->res = r; #endif } else { -- Ahmad Gani