Refactor the send and listen socket creation functions to share common code.
Fix a regression where cooked packets would be truncated because of a typo in the buffer length calculation that was introduced in an earlier commit.
This commit is contained in:
Nicholas J. Kain
parent
52fbeb46ad
commit
4c1c1715fe
338
ndhc/packet.c
338
ndhc/packet.c
@ -48,55 +48,46 @@
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#include "strl.h"
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#include "random.h"
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// Returns fd of new listen socket bound to @ip:@port on interface @inf
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// on success, or -1 on failure.
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static int create_udp_listen_socket(unsigned int ip, int port, char *inf)
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// Returns fd of new udp socket bound on success, or -1 on failure.
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static int create_udp_socket(uint32_t ip, uint16_t port, char *iface)
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{
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log_line("Opening listen socket on 0x%08x:%d %s", ip, port, inf);
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int fd;
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if ((fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
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log_error("create_udp_listen_socket: socket failed: %s",
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strerror(errno));
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log_error("create_udp_socket: socket failed: %s", strerror(errno));
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goto out;
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}
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int opt = 1;
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if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof opt) == -1) {
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log_error("create_udp_listen_socket: set reuse addr failed: %s",
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strerror(errno));
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goto out_fd;
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}
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if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &opt, sizeof opt) == -1) {
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log_error("create_udp_listen_socket: set broadcast failed: %s",
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log_error("create_udp_socket: set reuse addr failed: %s",
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strerror(errno));
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goto out_fd;
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}
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if (setsockopt(fd, SOL_SOCKET, SO_DONTROUTE, &opt, sizeof opt) == -1) {
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log_error("create_udp_listen_socket: set don't route failed: %s",
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log_error("create_udp_socket: set don't route failed: %s",
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strerror(errno));
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goto out_fd;
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}
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struct ifreq ifr;
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memset(&ifr, 0, sizeof (struct ifreq));
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strlcpy(ifr.ifr_name, inf, IFNAMSIZ);
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strlcpy(ifr.ifr_name, iface, IFNAMSIZ);
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if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof ifr) < 0) {
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log_error("create_udp_listen_socket: set bind to device failed: %s",
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log_error("create_udp_socket: set bind to device failed: %s",
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strerror(errno));
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goto out_fd;
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}
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if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK) == -1) {
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log_error("create_udp_listen_socket: set non-blocking failed: %s",
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log_error("create_udp_socket: set non-blocking failed: %s",
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strerror(errno));
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goto out_fd;
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}
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struct sockaddr_in addr = {
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struct sockaddr_in sa = {
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.sin_family = AF_INET,
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.sin_port = htons(port),
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.sin_addr.s_addr = ip,
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};
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if (bind(fd, (struct sockaddr *)&addr, sizeof(struct sockaddr)) == -1)
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if (bind(fd, (struct sockaddr *)&sa, sizeof sa) == -1)
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goto out_fd;
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return fd;
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@ -106,101 +97,76 @@ static int create_udp_listen_socket(unsigned int ip, int port, char *inf)
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return -1;
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}
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static int create_raw_listen_socket(int ifindex)
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// Returns fd of new listen socket bound to @ip:@port on interface @inf
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// on success, or -1 on failure.
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static int create_udp_listen_socket(unsigned int ip, int port, char *inf)
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{
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/*
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* Comment:
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* I've selected not to see LL header, so BPF doesn't see it, too.
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* The filter may also pass non-IP and non-ARP packets, but we do
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* a more complete check when receiving the message in userspace.
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* and filter shamelessly stolen from:
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* http://www.flamewarmaster.de/software/dhcpclient/
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*
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* Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
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* License: GPL v2.
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*/
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#define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68)
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static const struct sock_filter filter_instr[] = {
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/* check for udp */
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BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */
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/* ugly check for arp on ethernet-like and IPv4 */
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BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */
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/* skip IP header */
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BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */
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/* check udp source and destination ports */
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BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1),/* L3, L4 */
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/* returns */
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BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */
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BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */
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};
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static const struct sock_fprog filter_prog = {
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.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
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/* casting const away: */
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.filter = (struct sock_filter *) filter_instr,
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};
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log_line("Opening listen socket on 0x%08x:%d %s", ip, port, inf);
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log_line("Opening raw socket on ifindex %d", ifindex);
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int fd;
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if ((fd = socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) {
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log_error("create_raw_listen_socket: socket failed: %s",
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strerror(errno));
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goto out;
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}
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// Ignoring error since kernel may lack support for BPF.
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if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
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sizeof filter_prog) >= 0)
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log_line("Attached filter to raw socket fd %d", fd);
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int fd = create_udp_socket(ip, port, inf);
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if (fd == -1)
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return -1;
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int opt = 1;
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if (setsockopt(fd, SOL_SOCKET, SO_DONTROUTE, &opt, sizeof opt) == -1) {
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log_error("create_raw_listen_socket: failed to set don't route: %s",
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if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &opt, sizeof opt) == -1) {
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log_error("create_udp_listen_socket: set broadcast failed: %s",
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strerror(errno));
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goto out_fd;
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}
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if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK) == -1) {
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log_error("create_raw_listen_socket: set non-blocking failed: %s",
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strerror(errno));
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goto out_fd;
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}
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struct sockaddr_ll sock = {
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.sll_family = AF_PACKET,
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.sll_protocol = htons(ETH_P_IP),
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.sll_ifindex = ifindex,
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};
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if (bind(fd, (struct sockaddr *)&sock, sizeof(sock)) < 0) {
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log_error("create_raw_listen_socket: bind failed: %s",
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strerror(errno));
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goto out_fd;
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}
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return fd;
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out_fd:
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close(fd);
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out:
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return -1;
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}
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return fd;
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}
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// Broadcast a DHCP message using a UDP socket.
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static int send_dhcp_cooked(struct dhcpmsg *payload, uint32_t source_ip,
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uint32_t dest_ip)
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{
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int ret = -1;
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int fd = create_udp_socket(source_ip, DHCP_CLIENT_PORT,
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client_config.interface);
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if (fd == -1)
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goto out;
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struct sockaddr_in raddr = {
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.sin_family = AF_INET,
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.sin_port = htons(DHCP_SERVER_PORT),
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.sin_addr.s_addr = dest_ip,
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};
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if (connect(fd, (struct sockaddr *)&raddr, sizeof(struct sockaddr)) == -1) {
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log_error("send_dhcp_cooked: connect failed: %s", strerror(errno));
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goto out_fd;
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}
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ssize_t endloc = get_end_option_idx(payload);
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if (endloc < 0) {
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log_error("send_dhcp_cooked: attempt to send packet with no DHCP_END");
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goto out_fd;
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}
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size_t payload_len =
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sizeof *payload - (sizeof payload->options - 1 - endloc);
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ret = safe_write(fd, (const char *)payload, payload_len);
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if (ret == -1)
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log_error("send_dhcp_cooked: write failed: %s", strerror(errno));
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out_fd:
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close(fd);
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out:
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return ret;
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}
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// Read a packet from a cooked socket. Returns -1 on fatal error, -2 on
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// transient error.
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static int get_packet(struct dhcpmsg *packet, int fd)
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static int get_cooked_packet(struct dhcpmsg *packet, int fd)
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{
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int bytes;
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memset(packet, 0, sizeof *packet);
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bytes = safe_read(fd, (char *)packet, sizeof *packet);
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int bytes = safe_read(fd, (char *)packet, sizeof *packet);
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if (bytes == -1) {
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if (errno == EAGAIN || errno == EWOULDBLOCK)
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return -2;
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log_line("Read on listen socket failed: %s", strerror(errno));
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return -1;
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}
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log_line("Received a packet via cooked socket.");
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return bytes;
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}
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@ -325,44 +291,113 @@ static int get_raw_packet(struct dhcpmsg *payload, int fd)
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return l;
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}
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// Broadcast a DHCP message using a raw socket.
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static int send_dhcp_raw(struct dhcpmsg *payload)
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static int create_raw_socket(struct sockaddr_ll *sa,
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const struct sock_fprog *filter_prog)
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{
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int fd, r = -1;
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int fd;
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if ((fd = socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) {
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log_error("send_dhcp_raw: socket failed: %s", strerror(errno));
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log_error("create_raw_socket: socket failed: %s", strerror(errno));
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goto out;
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}
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// Ignoring error since kernel may lack support for BPF.
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if (filter_prog && (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER,
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&filter_prog, sizeof filter_prog) >= 0))
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log_line("Attached filter to raw socket fd %d", fd);
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int opt = 1;
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if (setsockopt(fd, SOL_SOCKET, SO_DONTROUTE, &opt, sizeof opt) == -1) {
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log_error("send_dhcp_raw: failed to set don't route: %s",
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log_error("create_raw_socket: failed to set don't route: %s",
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strerror(errno));
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goto out_fd;
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}
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if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK) == -1) {
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log_error("send_dhcp_raw: set non-blocking failed: %s",
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log_error("create_raw_socket: set non-blocking failed: %s",
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strerror(errno));
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goto out_fd;
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}
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struct sockaddr_ll dest = {
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if (bind(fd, (struct sockaddr *)sa, sizeof *sa) < 0) {
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log_error("create_raw_socket: bind failed: %s", strerror(errno));
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goto out_fd;
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}
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return fd;
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out_fd:
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close(fd);
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out:
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return -1;
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}
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static int create_raw_listen_socket(int ifindex)
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{
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/*
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* Comment:
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* I've selected not to see LL header, so BPF doesn't see it, too.
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* The filter may also pass non-IP and non-ARP packets, but we do
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* a more complete check when receiving the message in userspace.
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* and filter shamelessly stolen from:
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* http://www.flamewarmaster.de/software/dhcpclient/
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*
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* Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
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* License: GPL v2.
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*/
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#define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68)
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static const struct sock_filter filter_instr[] = {
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/* check for udp */
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BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */
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/* ugly check for arp on ethernet-like and IPv4 */
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BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */
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/* skip IP header */
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BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */
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/* check udp source and destination ports */
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BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1),/* L3, L4 */
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/* returns */
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BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */
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BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */
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};
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static const struct sock_fprog filter_prog = {
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.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
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/* casting const away: */
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.filter = (struct sock_filter *) filter_instr,
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};
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log_line("Opening raw socket on ifindex %d", ifindex);
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struct sockaddr_ll sa = {
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.sll_family = AF_PACKET,
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.sll_protocol = htons(ETH_P_IP),
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.sll_ifindex = ifindex,
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};
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int fd = create_raw_socket(&sa, &filter_prog);
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if (fd == -1)
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return -1;
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return fd;
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}
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// Broadcast a DHCP message using a raw socket.
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static int send_dhcp_raw(struct dhcpmsg *payload)
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{
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int ret = -1;
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struct sockaddr_ll da = {
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.sll_family = AF_PACKET,
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.sll_protocol = htons(ETH_P_IP),
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.sll_ifindex = client_config.ifindex,
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.sll_halen = 6,
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};
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memcpy(dest.sll_addr, "\xff\xff\xff\xff\xff\xff", 6);
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if (bind(fd, (struct sockaddr *)&dest, sizeof(struct sockaddr_ll)) < 0) {
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log_error("send_dhcp_raw: bind failed: %s", strerror(errno));
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goto out_fd;
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}
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memcpy(da.sll_addr, "\xff\xff\xff\xff\xff\xff", 6);
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int fd = create_raw_socket(&da, NULL);
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if (fd == -1)
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return ret;
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// Send packets that are as short as possible, since some servers are buggy
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// and drop packets that are longer than 562 bytes.
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ssize_t endloc = get_end_option_idx(payload);
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if (endloc < 0) {
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log_error("send_dhcp_raw: attempt to send packet with no DHCP_END");
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goto out_fd;
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close(fd);
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return ret;
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}
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size_t padding = sizeof payload->options - 1 - endloc;
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size_t iud_len = sizeof(struct ip_udp_dhcp_packet) - padding;
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@ -396,85 +431,12 @@ static int send_dhcp_raw(struct dhcpmsg *payload)
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iudmsg.udp.check = net_checksum_add(udpcs, phcs);
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iudmsg.ip.check = net_checksum(&iudmsg.ip, sizeof iudmsg.ip);
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r = safe_sendto(fd, (const char *)&iudmsg, iud_len, 0,
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(struct sockaddr *)&dest, sizeof dest);
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if (r == -1)
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ret = safe_sendto(fd, (const char *)&iudmsg, iud_len, 0,
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(struct sockaddr *)&da, sizeof da);
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if (ret == -1)
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log_error("send_dhcp_raw: sendto failed: %s", strerror(errno));
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out_fd:
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close(fd);
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out:
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return r;
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}
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// Broadcast a DHCP message using a UDP socket.
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static int send_dhcp_cooked(struct dhcpmsg *payload, uint32_t source_ip,
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uint32_t dest_ip)
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{
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int fd, result = -1;
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if ((fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
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log_error("send_dhcp_cooked: socket failed: %s", strerror(errno));
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goto out;
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}
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int opt = 1;
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if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof opt) == -1) {
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log_error("send_dhcp_cooked: set reuse addr failed: %s",
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strerror(errno));
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goto out_fd;
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}
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if (setsockopt(fd, SOL_SOCKET, SO_DONTROUTE, &opt, sizeof opt) == -1) {
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log_error("send_dhcp_cooked: failed to set don't route: %s",
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strerror(errno));
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goto out_fd;
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}
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struct ifreq ifr;
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memset(&ifr, 0, sizeof (struct ifreq));
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strlcpy(ifr.ifr_name, client_config.interface, IFNAMSIZ);
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if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof ifr) < 0) {
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log_error("send_dhcp_cooked: set bind to device failed: %s",
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strerror(errno));
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goto out_fd;
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}
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if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK) == -1) {
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log_error("send_dhcp_cooked: set non-blocking failed: %s",
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strerror(errno));
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goto out_fd;
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}
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struct sockaddr_in laddr = {
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.sin_family = AF_INET,
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.sin_port = htons(DHCP_CLIENT_PORT),
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.sin_addr.s_addr = source_ip,
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};
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if (bind(fd, (struct sockaddr *)&laddr, sizeof(struct sockaddr)) == -1) {
|
||||
log_error("send_dhcp_cooked: bind failed: %s", strerror(errno));
|
||||
goto out_fd;
|
||||
}
|
||||
|
||||
struct sockaddr_in raddr = {
|
||||
.sin_family = AF_INET,
|
||||
.sin_port = htons(DHCP_SERVER_PORT),
|
||||
.sin_addr.s_addr = dest_ip,
|
||||
};
|
||||
if (connect(fd, (struct sockaddr *)&raddr, sizeof(struct sockaddr)) == -1) {
|
||||
log_error("send_dhcp_cooked: connect failed: %s", strerror(errno));
|
||||
goto out_fd;
|
||||
}
|
||||
|
||||
ssize_t endloc = get_end_option_idx(payload);
|
||||
if (endloc < 0) {
|
||||
log_error("send_dhcp_cooked: attempt to send packet with no DHCP_END");
|
||||
goto out_fd;
|
||||
}
|
||||
size_t payload_len = sizeof *payload - sizeof payload->options - 1 - endloc;
|
||||
result = safe_write(fd, (const char *)payload, payload_len);
|
||||
if (result == -1)
|
||||
log_error("send_dhcp_cooked: write failed: %s", strerror(errno));
|
||||
out_fd:
|
||||
close(fd);
|
||||
out:
|
||||
return result;
|
||||
return ret;
|
||||
}
|
||||
|
||||
// Switch listen socket between raw (if-bound), kernel (ip-bound), and none
|
||||
@ -579,7 +541,7 @@ void handle_packet(struct client_state_t *cs)
|
||||
ssize_t optlen;
|
||||
|
||||
if (cs->listenMode == LM_KERNEL)
|
||||
len = get_packet(&packet, cs->listenFd);
|
||||
len = get_cooked_packet(&packet, cs->listenFd);
|
||||
else if (cs->listenMode == LM_RAW)
|
||||
len = get_raw_packet(&packet, cs->listenFd);
|
||||
else // LM_NONE
|
||||
@ -683,8 +645,8 @@ int send_selecting(uint32_t xid, uint32_t server, uint32_t requested)
|
||||
add_u32_option(&packet, DHCP_REQUESTED_IP, requested);
|
||||
add_u32_option(&packet, DHCP_SERVER_ID, server);
|
||||
add_option_request_list(&packet);
|
||||
struct in_addr addr = { .s_addr = requested };
|
||||
log_line("Sending select for %s...", inet_ntoa(addr));
|
||||
log_line("Sending select for %s...",
|
||||
inet_ntoa((struct in_addr){.s_addr = requested}));
|
||||
return send_dhcp_raw(&packet);
|
||||
}
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user