X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fodhcpd.git;a=blobdiff_plain;f=src%2Fdhcpv4.c;h=509b09230c5431d8582d1debc3415c082ccddd13;hp=7b200cded2b5e70725a8427c0c51b71abd98fa5a;hb=4c89614ccf5d72ee0c0824e5050a8814748a32c3;hpb=f2cda6c15b55c80be8739f492a8ee7b4dbd1cf52 diff --git a/src/dhcpv4.c b/src/dhcpv4.c index 7b200cd..509b092 100644 --- a/src/dhcpv4.c +++ b/src/dhcpv4.c @@ -37,7 +37,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, 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); + uint32_t *leasetime, const char *hostname); // Create socket and register events int init_dhcpv4(void) @@ -45,6 +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) { @@ -114,8 +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) | @@ -153,10 +176,15 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable) iface->ifname); return -1; } + if (lease->dhcpv4_leasetime >= 60) + a->leasetime = lease->dhcpv4_leasetime; a->addr = ntohl(lease->ipaddr.s_addr); memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr)); memcpy(a->hostname, lease->hostname, hostlen); - a->valid_until = LONG_MAX; + /* Static assignment */ + a->flags |= OAF_STATIC; + /* Infinite valid */ + a->valid_until = 0; // Assign to all interfaces struct dhcpv4_assignment *c; @@ -199,7 +227,6 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable) struct dhcpv4_assignment *a = list_first_entry(&iface->dhcpv4_assignments, struct dhcpv4_assignment, head); list_del(&a->head); - free(a->hostname); free(a); } @@ -222,8 +249,7 @@ static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie, *cookie = c + len; } - -// Simple DHCPv6-server for information requests +// Handler for DHCPv4 messages static void handle_dhcpv4(void *addr, void *data, size_t len, struct interface *iface, _unused void *dest_addr) { @@ -288,6 +314,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, uint8_t msg = DHCPV4_MSG_ACK; struct in_addr reqaddr = {INADDR_ANY}; + uint32_t leasetime = 0; char hostname[256]; hostname[0] = 0; @@ -312,7 +339,8 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, if (*c == elen && !memcmp(&c[1], iface->filter_class, elen)) return; // Ignore from homenet } - } + } else if (opt->type == DHCPV4_OPT_LEASETIME && opt->len == 4) + memcpy(&leasetime, opt->data, 4); } if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST && @@ -322,7 +350,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, struct dhcpv4_assignment *lease = NULL; if (reqmsg != DHCPV4_MSG_INFORM) - lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, hostname); + lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, &leasetime, hostname); if (!lease) { if (reqmsg == DHCPV4_MSG_REQUEST) @@ -334,9 +362,23 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, } else if (reqmsg == DHCPV4_MSG_REQUEST && reqaddr.s_addr && reqaddr.s_addr != htonl(lease->addr)) { msg = DHCPV4_MSG_NAK; - lease = NULL; + /* + * 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; @@ -344,16 +386,20 @@ static void handle_dhcpv4(void *addr, void *data, size_t len, dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &ifaddr.sin_addr); if (lease) { + uint32_t val; + reply.yiaddr.s_addr = htonl(lease->addr); - uint32_t val = htonl(iface->dhcpv4_leasetime); + val = htonl(leasetime); dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val); - val = htonl(500 * iface->dhcpv4_leasetime / 1000); - dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val); + if (leasetime != UINT32_MAX) { + val = htonl(500 * leasetime / 1000); + dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val); - val = htonl(875 * iface->dhcpv4_leasetime / 1000); - dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val); + val = htonl(875 * leasetime / 1000); + dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val); + } dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4, &ifnetmask.sin_addr); @@ -402,16 +448,36 @@ 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 || !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); @@ -422,61 +488,104 @@ 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; } static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr, - const char *hostname) + uint32_t *leasetime, const char *hostname) { struct dhcpv4_assignment *lease = NULL; uint32_t raddr = ntohl(reqaddr.s_addr); @@ -488,7 +597,7 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, a = c; if (c->addr == raddr) break; - } else if (c->valid_until < now) { + } else if (!INFINITE_VALID(c->valid_until) && c->valid_until < now) { list_del(&c->head); free(c); } @@ -497,6 +606,7 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) { bool assigned = !!a; size_t hostlen = strlen(hostname) + 1; + uint32_t my_leasetime; if (!a && !iface->no_dynamic_dhcp) { // Create new binding a = calloc(1, sizeof(*a) + hostlen); @@ -506,6 +616,8 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, } memcpy(a->hwaddr, mac, sizeof(a->hwaddr)); memcpy(a->hostname, hostname, hostlen); + // Don't consider new assignment as infinite + a->valid_until = now; assigned = dhcpv4_assign(iface, a, raddr); } @@ -523,10 +635,27 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, a->head.prev->next = &a->head; } - // Was only a solicitation: mark binding for removal - if (assigned && a->valid_until < now) { - a->valid_until = (msg == DHCPV4_MSG_DISCOVER) ? 0 : - (now + iface->dhcpv4_leasetime); + if (a->leasetime >= 60) { + my_leasetime = a->leasetime; + } else { + my_leasetime = iface->dhcpv4_leasetime; + } + + if ((*leasetime == 0) || (my_leasetime < *leasetime)) + *leasetime = my_leasetime; + + if (assigned) { + if (msg == DHCPV4_MSG_DISCOVER) { + a->flags &= ~OAF_BOUND; + + if (!(a->flags & OAF_STATIC)) + a->valid_until = now; + } else { + a->flags |= OAF_BOUND; + + if (!(a->flags & OAF_STATIC)) + a->valid_until = ((*leasetime == UINT32_MAX) ? 0 : (time_t)(now + *leasetime)); + } } else if (!assigned && a) { // Cleanup failed assignment free(a); a = NULL; @@ -534,13 +663,19 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface, if (assigned && a) lease = a; - } else if (msg == DHCPV4_MSG_RELEASE) { - if (a) { - a->valid_until = 0; + } else if (msg == DHCPV4_MSG_RELEASE && a) { + a->flags &= ~OAF_BOUND; + + if (!(a->flags & OAF_STATIC)) + a->valid_until = now - 1; + + } else if (msg == DHCPV4_MSG_DECLINE && a) { + a->flags &= ~OAF_BOUND; + + if (!(a->flags & OAF_STATIC)) { + memset(a->hwaddr, 0, sizeof(a->hwaddr)); + a->valid_until = now + 3600; // Block address for 1h } - } else if (msg == DHCPV4_MSG_DECLINE) { - memset(a->hwaddr, 0, sizeof(a->hwaddr)); - a->valid_until = now + 3600; // Block address for 1h } dhcpv6_write_statefile();