diff options
Diffstat (limited to 'showlease.c')
| -rw-r--r-- | showlease.c | 349 |
1 files changed, 349 insertions, 0 deletions
diff --git a/showlease.c b/showlease.c new file mode 100644 index 0000000..9bee4ab --- /dev/null +++ b/showlease.c @@ -0,0 +1,349 @@ +#include <stdio.h> +#include <stdlib.h> +#include <errno.h> +#include <fcntl.h> + +#include "dhcp.h" +#include "config.h" + +#define REQUEST (1 << 0) +#define UINT8 (1 << 1) +#define UINT16 (1 << 2) +#define SINT16 (1 << 3) +#define UINT32 (1 << 4) +#define SINT32 (1 << 5) +#define IPV4 (1 << 6) +#define STRING (1 << 7) +#define PAIR (1 << 8) +#define ARRAY (1 << 9) +#define RFC3361 (1 << 10) +#define RFC3397 (1 << 11) +#define RFC3442 (1 << 12) + +struct dhcp_opt { + uint8_t option; + int type; + const char *var; +}; + +static const struct dhcp_opt const dhcp_opts[] = { + { 1, IPV4 | REQUEST, "subnet_mask" }, + { 2, UINT32, "time_offset" }, + { 3, IPV4 | ARRAY | REQUEST, "routers" }, + { 4, IPV4 | ARRAY, "time_servers" }, + { 5, IPV4 | ARRAY, "ien116_name_servers" }, + { 6, IPV4 | ARRAY, "domain_name_servers" }, + { 7, IPV4 | ARRAY, "log_servers" }, + { 8, IPV4 | ARRAY, "cookie_servers" }, + { 9, IPV4 | ARRAY, "lpr_servers" }, + { 10, IPV4 | ARRAY, "impress_servers" }, + { 11, IPV4 | ARRAY, "resource_location_servers" }, + { 12, STRING, "host_name" }, + { 13, UINT16, "boot_size" }, + { 14, STRING, "merit_dump" }, + { 15, STRING, "domain_name" }, + { 16, IPV4, "swap_server" }, + { 17, STRING, "root_path" }, + { 18, STRING, "extensions_path" }, + { 19, UINT8, "ip_forwarding" }, + { 20, UINT8, "non_local_source_routing" }, + { 21, IPV4 | ARRAY, "policy_filter" }, + { 22, SINT16, "max_dgram_reassembly" }, + { 23, UINT16, "default_ip_ttl" }, + { 24, UINT32, "path_mtu_aging_timeout" }, + { 25, UINT16 | ARRAY, "path_mtu_plateau_table" }, + { 26, UINT16, "interface_mtu" }, + { 27, UINT8, "all_subnets_local" }, + { 28, IPV4 | REQUEST, "broadcast_address" }, + { 29, UINT8, "perform_mask_discovery" }, + { 30, UINT8, "mask_supplier" }, + { 31, UINT8, "router_discovery" }, + { 32, IPV4, "router_solicitation_address" }, + { 33, IPV4 | ARRAY | REQUEST, "static_routes" }, + { 34, UINT8, "trailer_encapsulation" }, + { 35, UINT32, "arp_cache_timeout" }, + { 36, UINT16, "ieee802_3_encapsulation" }, + { 37, UINT8, "default_tcp_ttl" }, + { 38, UINT32, "tcp_keepalive_interval" }, + { 39, UINT8, "tcp_keepalive_garbage" }, + { 40, STRING, "nis_domain" }, + { 41, IPV4 | ARRAY, "nis_servers" }, + { 42, IPV4 | ARRAY, "ntp_servers" }, + { 43, STRING, "vendor_encapsulated_options" }, + { 44, IPV4 | ARRAY, "netbios_name_servers" }, + { 45, IPV4, "netbios_dd_server" }, + { 46, UINT8, "netbios_node_type" }, + { 47, STRING, "netbios_scope" }, + { 48, IPV4 | ARRAY, "font_servers" }, + { 49, IPV4 | ARRAY, "x_display_manager" }, + { 50, IPV4, "dhcp_requested_address" }, + { 51, UINT32 | REQUEST, "dhcp_lease_time" }, + { 52, UINT8, "dhcp_option_overload" }, + { 53, UINT8, "dhcp_message_type" }, + { 54, IPV4, "dhcp_server_identifier" }, + { 55, UINT8 | ARRAY, "dhcp_parameter_request_list" }, + { 56, STRING, "dhcp_message" }, + { 57, UINT16, "dhcp_max_message_size" }, + { 58, UINT32 | REQUEST, "dhcp_renewal_time" }, + { 59, UINT32 | REQUEST, "dhcp_rebinding_time" }, + { 64, STRING, "nisplus_domain" }, + { 65, IPV4 | ARRAY, "nisplus_servers" }, + { 66, STRING, "tftp_server_name" }, + { 67, STRING, "bootfile_name" }, + { 68, IPV4 | ARRAY, "mobile_ip_home_agent" }, + { 69, IPV4 | ARRAY, "smtp_server" }, + { 70, IPV4 | ARRAY, "pop_server" }, + { 71, IPV4 | ARRAY, "nntp_server" }, + { 72, IPV4 | ARRAY, "www_server" }, + { 73, IPV4 | ARRAY, "finger_server" }, + { 74, IPV4 | ARRAY, "irc_server" }, + { 75, IPV4 | ARRAY, "streettalk_server" }, + { 76, IPV4 | ARRAY, "streettalk_directory_assistance_server" }, + { 77, STRING, "user_class" }, + { 85, IPV4 | ARRAY, "nds_servers" }, + { 86, STRING, "nds_tree_name" }, + { 87, STRING, "nds_context" }, + { 88, STRING | RFC3397, "bcms_controller_names" }, + { 89, IPV4 | ARRAY, "bcms_controller_address" }, + { 91, UINT32, "client_last_transaction_time" }, + { 92, IPV4 | ARRAY, "associated_ip" }, + { 98, STRING, "uap_servers" }, + { 112, IPV4 | ARRAY, "netinfo_server_address" }, + { 113, STRING, "netinfo_server_tag" }, + { 114, STRING, "default_url" }, + { 118, IPV4, "subnet_selection" }, + { 119, STRING | RFC3397, "domain_search" }, + { 121, RFC3442 | REQUEST, "classless_static_routes" }, + { 249, RFC3442, "ms-classless_static_routes" }, + { 0, 0, NULL } +}; + +struct dhcp_message * +get_lease(const char *leasefile) +{ + int fd; + struct dhcp_message *dhcp; + ssize_t bytes; + + fd = open(leasefile, O_RDONLY); + if (fd == -1) + return NULL; + dhcp = malloc(sizeof(*dhcp)); + memset(dhcp, 0, sizeof(*dhcp)); + bytes = read(fd, dhcp, sizeof(*dhcp)); + close(fd); + if (bytes < 0) { + free(dhcp); + dhcp = NULL; + } + return dhcp; +} + +static uint8_t *dhcp_opt_buffer = NULL; + +static int +valid_length(uint8_t option, int dl, int *type) +{ + const struct dhcp_opt *opt; + ssize_t sz; + + if (dl == 0) + return -1; + + for (opt = dhcp_opts; opt->option; opt++) { + if (opt->option != option) + continue; + + if (type) + *type = opt->type; + + if (opt->type == 0 || opt->type & STRING || opt->type & RFC3442) + return 0; + + sz = 0; + if (opt->type & UINT32 || opt->type & IPV4) + sz = sizeof(uint32_t); + if (opt->type & UINT16) + sz = sizeof(uint16_t); + if (opt->type & UINT8) + sz = sizeof(uint8_t); + if (opt->type & IPV4 || opt->type & ARRAY) + return dl % sz; + return (dl == sz ? 0 : -1); + } + + /* unknown option, so let it pass */ + return 0; +} + +static void +free_option_buffer(void) +{ + free(dhcp_opt_buffer); +} + + +#define get_option_raw(dhcp, opt) get_option(dhcp, opt, NULL, NULL) +static const uint8_t * +get_option(const struct dhcp_message *dhcp, uint8_t opt, int *len, int *type) +{ + const uint8_t *p = dhcp->options; + const uint8_t *e = p + sizeof(dhcp->options); + uint8_t l, ol = 0; + uint8_t o = 0; + uint8_t overl = 0; + uint8_t *bp = NULL; + const uint8_t *op = NULL; + int bl = 0; + + while (p < e) { + o = *p++; + if (o == opt) { + if (op) { + if (!dhcp_opt_buffer) { + dhcp_opt_buffer = malloc(sizeof(struct dhcp_message)); + atexit(free_option_buffer); + } + if (!bp) + bp = dhcp_opt_buffer; + memcpy(bp, op, ol); + bp += ol; + } + ol = *p; + op = p + 1; + bl += ol; + } + switch (o) { + case DHO_PAD: + continue; + case DHO_END: + if (overl & 1) { + /* bit 1 set means parse boot file */ + overl &= ~1; + p = dhcp->bootfile; + e = p + sizeof(dhcp->bootfile); + } else if (overl & 2) { + /* bit 2 set means parse server name */ + overl &= ~2; + p = dhcp->servername; + e = p + sizeof(dhcp->servername); + } else + goto exit; + break; + case DHO_OPTIONSOVERLOADED: + /* Ensure we only get this option once */ + if (!overl) + overl = p[1]; + break; + } + l = *p++; + p += l; + } + +exit: + if (valid_length(o, bl, type) == -1) { + errno = EINVAL; + return NULL; + } + if (len) + *len = bl; + if (bp) { + memcpy(bp, op, ol); + return (const uint8_t *)&dhcp_opt_buffer; + } + if (op) + return op; + errno = ENOENT; + return NULL; +} + +int +get_option_addr(uint32_t *a, const struct dhcp_message *dhcp, uint8_t option) +{ + const uint8_t *p = get_option_raw(dhcp, option); + + if (!p) + return -1; + memcpy(a, p, sizeof(*a)); + return 0; +} + +int +get_option_uint32(uint32_t *i, const struct dhcp_message *dhcp, uint8_t option) +{ + uint32_t a; + + if (get_option_addr(&a, dhcp, option) == -1) + return -1; + + *i = ntohl(a); + return 0; +} + +uint32_t +get_netmask(uint32_t addr) +{ + uint32_t dst; + + if (addr == 0) + return 0; + + dst = htonl(addr); + if (IN_CLASSA(dst)) + return ntohl(IN_CLASSA_NET); + if (IN_CLASSB (dst)) + return ntohl(IN_CLASSB_NET); + if (IN_CLASSC (dst)) + return ntohl(IN_CLASSC_NET); + + return 0; +} + +void showlease(struct dhcp_lease *lease) +{ + printf("addr: %s\n", inet_ntoa(lease->addr)); + printf("net: %s\n", inet_ntoa(lease->net)); + printf("leasetime: %d\n", lease->leasetime); + printf("renew: %d\n", lease->renewaltime); + printf("rebind: %d\n", lease->rebindtime); + printf("server: %s\n", inet_ntoa(lease->server)); +} +#define MAX_LEASETIME 2147460 + +int +main(int argc, char *argv[]) +{ + struct dhcp_message *dhcp; + struct dhcp_lease *lease; + char leasefile[PATH_MAX]; + + if (argc < 2) { + fprintf(stderr, "Usage: %s <interface>\n", argv[0]); + exit(1); + } + snprintf(leasefile, PATH_MAX, LEASEFILE, argv[1]); + if ((dhcp = get_lease(leasefile)) == NULL) { + fprintf(stderr, "Couldn't read lease file: %s\n", strerror(errno)); + exit(1); + } + lease = malloc(sizeof(*lease)); + lease->frominfo = 0; + lease->addr.s_addr = dhcp->yiaddr; + + if (get_option_addr(&lease->net.s_addr, dhcp, DHO_SUBNETMASK) == -1) + lease->net.s_addr = get_netmask(dhcp->yiaddr); + if (get_option_uint32(&lease->leasetime, dhcp, DHO_LEASETIME) != 0) + lease->leasetime = DEFAULT_LEASETIME; + get_option_addr(&lease->server.s_addr, dhcp, DHO_SERVERID); + /* Dm: limit lease time value to avoid negative numbers when + converting to milliseconds */ + if ((lease->leasetime != ~0U) && (lease->leasetime > MAX_LEASETIME)) + lease->leasetime = MAX_LEASETIME; + if (get_option_uint32(&lease->renewaltime, dhcp, DHO_RENEWALTIME) != 0) + lease->renewaltime = 0; + if (get_option_uint32(&lease->rebindtime, dhcp, DHO_REBINDTIME) != 0) + lease->rebindtime = 0; + showlease(lease); + free(lease); + return 0; +} |