X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fodhcpd.git;a=blobdiff_plain;f=src%2Fdhcpv4.c;h=04ef182472d1945e92c0b87388096947010aff64;hp=eed634f8fe4fe2e3fc7729f028778670021e0c54;hb=bc14cf3779925eadefbced51b70bc6f90b90a79e;hpb=82f3096351911d8c4f3b38e7a5bbeaf75938b6b8;ds=sidebyside diff --git a/src/dhcpv4.c b/src/dhcpv4.c index eed634f..04ef182 100644 --- a/src/dhcpv4.c +++ b/src/dhcpv4.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -33,7 +34,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, - struct interface *iface); + struct interface *iface, void *dest_addr); static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr, const char *hostname); @@ -44,6 +45,29 @@ int init_dhcpv4(void) return 0; } +char *dhcpv4_msg_to_string(uint8_t reqmsg) +{ + switch (reqmsg) { + case (DHCPV4_MSG_DISCOVER): + return "DHCPV4_MSG_DISCOVER"; + case (DHCPV4_MSG_OFFER): + return "DHCPV4_MSG_OFFER"; + case (DHCPV4_MSG_REQUEST): + return "DHCPV4_MSG_REQUEST"; + case (DHCPV4_MSG_DECLINE): + return "DHCPV4_MSG_DECLINE"; + case (DHCPV4_MSG_ACK): + return "DHCPV4_MSG_ACK"; + case (DHCPV4_MSG_NAK): + return "DHCPV4_MSG_NAK"; + case (DHCPV4_MSG_RELEASE): + return "DHCPV4_MSG_RELEASE"; + case (DHCPV4_MSG_INFORM): + return "DHCPV4_MSG_INFORM"; + default: + return "UNKNOWN"; + } +} int setup_dhcpv4_interface(struct interface *iface, bool enable) { @@ -113,8 +137,8 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable) if (start && end && start < end && start > ntohl(addr.s_addr & ~mask.s_addr) && - (start & ntohl(mask.s_addr)) == start && - (end & ntohl(mask.s_addr)) == end) { + (start & ntohl(~mask.s_addr)) == start && + (end & ntohl(~mask.s_addr)) == end) { iface->dhcpv4_start.s_addr = htonl(start) | (addr.s_addr & mask.s_addr); iface->dhcpv4_end.s_addr = htonl(end) | @@ -224,7 +248,7 @@ static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie, // Simple DHCPv6-server for information requests static void handle_dhcpv4(void *addr, void *data, size_t len, - struct interface *iface) + struct interface *iface, _unused void *dest_addr) { if (!iface->dhcpv4) return; @@ -330,8 +354,26 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, return; } else if (reqmsg == DHCPV4_MSG_DISCOVER) { msg = DHCPV4_MSG_OFFER; + } else if (reqmsg == DHCPV4_MSG_REQUEST && reqaddr.s_addr && + reqaddr.s_addr != htonl(lease->addr)) { + msg = DHCPV4_MSG_NAK; + /* + * DHCP client requested an IP which we can't offer to him. Probably the + * client changed the network. The reply type is set to DHCPV4_MSG_NAK, + * because the client should not use that IP. + * + * For modern devices we build an answer that includes a valid IP, like + * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to + * perform additional DHCP round trips. + * + */ } + syslog(LOG_WARNING, "received %s from %x:%x:%x:%x:%x:%x", + dhcpv4_msg_to_string(reqmsg), + req->chaddr[0],req->chaddr[1],req->chaddr[2], + req->chaddr[3],req->chaddr[4],req->chaddr[5]); + if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE) return; @@ -379,8 +421,11 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, len, search_buf); } - dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr); - + if (iface->dhcpv4_router_cnt == 0) + dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr); + else + dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, + 4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router); if (iface->dhcpv4_dns_cnt == 0) @@ -394,16 +439,36 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, struct sockaddr_in dest = *((struct sockaddr_in*)addr); if (req->giaddr.s_addr) { + /* + * relay agent is configured, send reply to the agent + */ dest.sin_addr = req->giaddr; dest.sin_port = htons(DHCPV4_SERVER_PORT); } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) { + /* + * client has existing configuration (ciaddr is set) AND this address is + * not the address it used for the dhcp message + */ dest.sin_addr = req->ciaddr; dest.sin_port = htons(DHCPV4_CLIENT_PORT); } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) || - req->hlen != reply.hlen) { + req->hlen != reply.hlen || !reply.yiaddr.s_addr) { + /* + * client requests a broadcast reply OR we can't offer an IP + */ + dest.sin_addr.s_addr = INADDR_BROADCAST; + dest.sin_port = htons(DHCPV4_CLIENT_PORT); + } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) { + /* + * client has no previous configuration -> no IP, so we need to reply + * with a broadcast packet + */ dest.sin_addr.s_addr = INADDR_BROADCAST; dest.sin_port = htons(DHCPV4_CLIENT_PORT); } else { + /* + * send reply to the newly (in this proccess) allocated IP + */ dest.sin_addr = reply.yiaddr; dest.sin_port = htons(DHCPV4_CLIENT_PORT); @@ -414,54 +479,97 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, ioctl(sock, SIOCSARP, &arp); } + if (dest.sin_addr.s_addr == INADDR_BROADCAST) { + /* + * reply goes to IP broadcast -> MAC broadcast + */ + syslog(LOG_WARNING, "sending %s to ff:ff:ff:ff:ff:ff - %s", + dhcpv4_msg_to_string(msg), + inet_ntoa(dest.sin_addr)); + } else { + /* + * reply is send directly to IP, + * MAC is assumed to be the same as the request + */ + syslog(LOG_WARNING, "sending %s to %x:%x:%x:%x:%x:%x - %s", + dhcpv4_msg_to_string(msg), + req->chaddr[0],req->chaddr[1],req->chaddr[2], + req->chaddr[3],req->chaddr[4],req->chaddr[5], + inet_ntoa(dest.sin_addr)); + } + sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest)); } +static bool dhcpv4_test(struct interface *iface, uint32_t try) +{ + struct dhcpv4_assignment *c; + list_for_each_entry(c, &iface->dhcpv4_assignments, head) { + if (c->addr == try) { + return false; + } + } + return true; +} static bool dhcpv4_assign(struct interface *iface, struct dhcpv4_assignment *assign, uint32_t raddr) { - const unsigned tries = 10; uint32_t start = ntohl(iface->dhcpv4_start.s_addr); uint32_t end = ntohl(iface->dhcpv4_end.s_addr); uint32_t count = end - start + 1; - // Seed RNG with checksum of DUID + // try to assign the IP the client asked for + if (start <= raddr && raddr <= end && dhcpv4_test(iface, raddr)) { + assign->addr = raddr; + list_add(&assign->head, &iface->dhcpv4_assignments); + syslog(LOG_DEBUG, "assigning the IP the client asked for: %u.%u.%u.%u", + (assign->addr & 0xff000000) >> 24, + (assign->addr & 0x00ff0000) >> 16, + (assign->addr & 0x0000ff00) >> 8, + (assign->addr & 0x000000ff)); + return true; + } + + // Seed RNG with checksum of hwaddress uint32_t seed = 0; - for (size_t i = 0; i < sizeof(assign->hwaddr); ++i) - seed += assign->hwaddr[i]; + for (size_t i = 0; i < sizeof(assign->hwaddr); ++i) { + // Knuth's multiplicative method + uint8_t o = assign->hwaddr[i]; + seed += (o*2654435761) % UINT32_MAX; + } srand(seed); - // Try to assign up to 100x - for (unsigned i = 0; i < tries; ++i) { - uint32_t try = (((uint32_t)rand()) % count) + start; - if (i == 0 && raddr >= start && raddr <= end) - try = raddr; - else if (i == tries - 1) - try = start; + uint32_t try = (((uint32_t)rand()) % count) + start; + + if (list_empty(&iface->dhcpv4_assignments)) { + assign->addr = try; + list_add(&assign->head, &iface->dhcpv4_assignments); + syslog(LOG_DEBUG, "assigning mapped IP (empty list): %u.%u.%u.%u", + (assign->addr & 0xff000000) >> 24, + (assign->addr & 0x00ff0000) >> 16, + (assign->addr & 0x0000ff00) >> 8, + (assign->addr & 0x000000ff)); + return true; + } - if (list_empty(&iface->dhcpv4_assignments)) { + for (uint32_t i = 0; i < count; ++i) { + if (dhcpv4_test(iface, try)) { + /* test was successful: IP address is not assigned, assign it */ assign->addr = try; list_add(&assign->head, &iface->dhcpv4_assignments); + syslog(LOG_DEBUG, "assigning mapped IP: %u.%u.%u.%u (try %u of %u)", + (assign->addr & 0xff000000) >> 24, + (assign->addr & 0x00ff0000) >> 16, + (assign->addr & 0x0000ff00) >> 8, + (assign->addr & 0x000000ff), i, count); return true; } - - struct dhcpv4_assignment *c; - list_for_each_entry(c, &iface->dhcpv4_assignments, head) { - if (c->addr > try) { - assign->addr = try; - list_add_tail(&assign->head, &c->head); - return true; - } else if (c->addr == try) { - if (i < tries - 1) - break; - else - ++try; - } - } + try = (((try - start) + 1) % count) + start; } + syslog(LOG_DEBUG, "can't assign any IP address -> address space is full"); return false; } @@ -486,7 +594,6 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, } } - bool update_state = false; if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) { bool assigned = !!a; size_t hostlen = strlen(hostname) + 1; @@ -525,24 +632,17 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, a = NULL; } - if (a) - update_state = true; - if (assigned && a) lease = a; } else if (msg == DHCPV4_MSG_RELEASE) { - if (a) { + if (a && a->valid_until != LONG_MAX) a->valid_until = 0; - update_state = true; - } - } else if (msg == DHCPV4_MSG_DECLINE) { + } else if (msg == DHCPV4_MSG_DECLINE && a->valid_until != LONG_MAX) { memset(a->hwaddr, 0, sizeof(a->hwaddr)); a->valid_until = now + 3600; // Block address for 1h - update_state = true; } - if (update_state) - dhcpv6_write_statefile(); + dhcpv6_write_statefile(); return lease; }