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[dhcp-relay]: add option -si to support using src intf ip in relay (#…
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src/isc-dhcp/patch/0013-add-option-si-to-support-using-src-intf-ip-in-relay.patch
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,192 @@ | ||
| From a89c0ef099852163aaee7c0704c814293063d6f3 Mon Sep 17 00:00:00 2001 | ||
| From: Tianrong Zhang <trzhang@microsoft.com> | ||
| Date: Sun, 14 Mar 2021 17:47:07 -0700 | ||
| Subject: [PATCH] add option -si to support using src intf ip in relay | ||
|
|
||
| --- | ||
| common/socket.c | 119 ++++++++++++++++++++++++++++++++++++----------- | ||
| includes/dhcpd.h | 1 + | ||
| relay/dhcrelay.c | 8 ++++ | ||
| 3 files changed, 100 insertions(+), 28 deletions(-) | ||
|
|
||
| diff --git a/common/socket.c b/common/socket.c | ||
| index e8851b4..ddd1f2e 100644 | ||
| --- a/common/socket.c | ||
| +++ b/common/socket.c | ||
| @@ -78,6 +78,29 @@ static unsigned int global_v4_socket_references = 0; | ||
| static int global_v4_socket = -1; | ||
| #endif | ||
|
|
||
| +/* | ||
| + * If set, uses "from" interface IP for packet Tx. | ||
| + * If not set, kernel chooses appropriate src ip for tx pkts | ||
| + */ | ||
| +int use_src_intf_ip_for_tx; | ||
| + | ||
| +/* | ||
| + * For both send_packet6() and receive_packet6() we need to allocate | ||
| + * space for the cmsg header information. We do this once and reuse | ||
| + * the buffer. We also need the control buf for send_packet() and | ||
| + * receive_packet() when we use a single socket and IP_PKTINFO to | ||
| + * send the packet out the correct interface. | ||
| + */ | ||
| +static void *v4_control_buf = NULL; | ||
| +static size_t v4_control_buf_len = 0; | ||
| + | ||
| +static void | ||
| +v4_allocate_cmsg_cbuf(void) { | ||
| + v4_control_buf_len = CMSG_SPACE(sizeof(struct in_pktinfo)); | ||
| + v4_control_buf = dmalloc(v4_control_buf_len, MDL); | ||
| + return; | ||
| +} | ||
| + | ||
| /* | ||
| * If we can't bind() to a specific interface, then we can only have | ||
| * a single socket. This variable insures that we don't try to listen | ||
| @@ -629,37 +652,77 @@ ssize_t send_packet (interface, packet, raw, len, from, to, hto) | ||
| struct hardware *hto; | ||
| { | ||
| int result; | ||
| -#ifdef IGNORE_HOSTUNREACH | ||
| - int retry = 0; | ||
| - do { | ||
| -#endif | ||
| -#if defined(IP_PKTINFO) && defined(IP_RECVPKTINFO) && defined(USE_V4_PKTINFO) | ||
| - struct in_pktinfo pktinfo; | ||
| - | ||
| - if (interface->ifp != NULL) { | ||
| - memset(&pktinfo, 0, sizeof (pktinfo)); | ||
| - pktinfo.ipi_ifindex = interface->ifp->ifr_index; | ||
| - if (setsockopt(interface->wfdesc, IPPROTO_IP, | ||
| - IP_PKTINFO, (char *)&pktinfo, | ||
| - sizeof(pktinfo)) < 0) | ||
| - log_fatal("setsockopt: IP_PKTINFO: %m"); | ||
| + struct msghdr m; | ||
| + struct iovec v; | ||
| + struct sockaddr_in dst; | ||
| + struct in_pktinfo *pktinfo; | ||
| + struct cmsghdr *cmsg; | ||
| + unsigned int ifindex; | ||
| + | ||
| + /* | ||
| + * If necessary allocate space for the control message header. | ||
| + * The space is common between send and receive. | ||
| + */ | ||
| + | ||
| + if (v4_control_buf == NULL) { | ||
| + v4_allocate_cmsg_cbuf(); | ||
| + if (v4_control_buf == NULL) { | ||
| + log_error("send_packet: unable to allocate cmsg header"); | ||
| + return(ENOMEM); | ||
| } | ||
| -#endif | ||
| - result = sendto (interface -> wfdesc, (char *)raw, len, 0, | ||
| - (struct sockaddr *)to, sizeof *to); | ||
| -#ifdef IGNORE_HOSTUNREACH | ||
| - } while (to -> sin_addr.s_addr == htonl (INADDR_BROADCAST) && | ||
| - result < 0 && | ||
| - (errno == EHOSTUNREACH || | ||
| - errno == ECONNREFUSED) && | ||
| - retry++ < 10); | ||
| -#endif | ||
| + } | ||
| + memset(v4_control_buf, 0, v4_control_buf_len); | ||
| + | ||
| + /* | ||
| + * Initialize our message header structure. | ||
| + */ | ||
| + memset(&m, 0, sizeof(m)); | ||
| + | ||
| + /* | ||
| + * Set the target address we're sending to. | ||
| + */ | ||
| + memcpy(&dst, to, sizeof(dst)); | ||
| + m.msg_name = &dst; | ||
| + m.msg_namelen = sizeof(dst); | ||
| + ifindex = if_nametoindex(interface->name); | ||
| + | ||
| + /* | ||
| + * Set the data buffer we're sending. (Using this wacky | ||
| + * "scatter-gather" stuff... we only have a single chunk | ||
| + * of data to send, so we declare a single vector entry.) | ||
| + */ | ||
| + v.iov_base = (char *)raw; | ||
| + v.iov_len = len; | ||
| + m.msg_iov = &v; | ||
| + m.msg_iovlen = 1; | ||
| + | ||
| + /* | ||
| + * Setting the interface is a bit more involved. | ||
| + * | ||
| + * We have to create a "control message", and set that to | ||
| + * define the IP packet information. We let he kernel decide | ||
| + * the source IP address unless 'use_src_intf_ip_for_tx' is | ||
| + * set, in which case we use the IP address of the ingress | ||
| + * interface we received the request on as the source IP. | ||
| + */ | ||
| + m.msg_control = v4_control_buf; | ||
| + m.msg_controllen = v4_control_buf_len; | ||
| + cmsg = CMSG_FIRSTHDR(&m); | ||
| + INSIST(cmsg != NULL); | ||
| + cmsg->cmsg_level = IPPROTO_IP; | ||
| + cmsg->cmsg_type = IP_PKTINFO; | ||
| + cmsg->cmsg_len = CMSG_LEN(sizeof(*pktinfo)); | ||
| + pktinfo = (struct in_pktinfo *)CMSG_DATA(cmsg); | ||
| + memset(pktinfo, 0, sizeof(*pktinfo)); | ||
| + pktinfo->ipi_ifindex = ifindex; | ||
| + if (use_src_intf_ip_for_tx) | ||
| + pktinfo->ipi_spec_dst = from; | ||
| + | ||
| + result = sendmsg(interface->wfdesc, &m, 0); | ||
| if (result < 0) { | ||
| - log_error ("send_packet: %m"); | ||
| - if (errno == ENETUNREACH) | ||
| - log_error ("send_packet: please consult README file%s", | ||
| - " regarding broadcast address."); | ||
| + log_error("send_packet: %m"); | ||
| } | ||
| + | ||
| return result; | ||
| } | ||
|
|
||
| diff --git a/includes/dhcpd.h b/includes/dhcpd.h | ||
| index 89bfe82..4f7a71d 100644 | ||
| --- a/includes/dhcpd.h | ||
| +++ b/includes/dhcpd.h | ||
| @@ -2611,6 +2611,7 @@ ssize_t send_fallback6(struct interface_info *, struct packet *, | ||
| #endif | ||
|
|
||
| #ifdef USE_SOCKET_SEND | ||
| +extern int use_src_intf_ip_for_tx; | ||
| void if_reinitialize_send (struct interface_info *); | ||
| void if_register_send (struct interface_info *); | ||
| void if_deregister_send (struct interface_info *); | ||
| diff --git a/relay/dhcrelay.c b/relay/dhcrelay.c | ||
| index 8aac4b3..1316591 100644 | ||
| --- a/relay/dhcrelay.c | ||
| +++ b/relay/dhcrelay.c | ||
| @@ -85,6 +85,12 @@ int max_hop_count = 10; /* Maximum hop count */ | ||
| isc_boolean_t use_if_id = ISC_FALSE; | ||
| #endif | ||
|
|
||
| +/* | ||
| + * If not set, kernel chooses what the src ip is. | ||
| + * If set, uses "from" interface IP for packet Tx. | ||
| + */ | ||
| +extern int use_src_intf_ip_for_tx = 0; | ||
| + | ||
| /* Maximum size of a packet with agent options added. */ | ||
| int dhcp_max_agent_option_packet_length = DHCP_MTU_MIN; | ||
|
|
||
| @@ -317,6 +323,8 @@ main(int argc, char **argv) { | ||
| #endif | ||
| } else if (!strcmp(argv[i], "-d")) { | ||
| no_daemon = 1; | ||
| + } else if (!strcmp(argv[i], "-si")) { | ||
| + use_src_intf_ip_for_tx = 1; | ||
| } else if (!strcmp(argv[i], "-q")) { | ||
| quiet = 1; | ||
| quiet_interface_discovery = 1; | ||
| -- | ||
| 2.17.1 | ||
|
|
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