// Copyright 2004-2018 Nicholas J. Kain // SPDX-License-Identifier: MIT #include #include #include #include #include #include #include #include #include #include "nk/log.h" #include "nk/io.h" #include "options.h" #include "ndhc.h" #include "dhcp.h" #include "options.h" #include "arp.h" #include "ifchange.h" static struct dhcpmsg cfg_packet; // Copy of the current configuration packet. static int ifcmd_raw(char *buf, size_t buflen, const char *optname, char *optdata, size_t optlen) { if (!optdata) { log_line("%s: (%s) '%s' option has no data", client_config.interface, __func__, optname); return -1; } if (optlen > INT_MAX) { log_line("%s: (%s) '%s' option optlen out of bounds", client_config.interface, __func__, optname); return -1; } if (buflen < strlen(optname) + optlen + 3) { log_line("%s: (%s) '%s' option buf too short", client_config.interface, __func__, optname); return -1; } int ioptlen = (int)optlen; ssize_t olen = snprintf(buf, buflen, "%s:%.*s;", optname, ioptlen, optdata); if (olen < 0 || (size_t)olen > buflen) { log_line("%s: (%s) '%s' option would truncate, so it was dropped.", client_config.interface, __func__, optname); memset(buf, 0, buflen); return -1; } return olen; } static int ifcmd_bytes(char *buf, size_t buflen, const char *optname, uint8_t *optdata, size_t optlen) { return ifcmd_raw(buf, buflen, optname, (char *)optdata, optlen); } static int ifcmd_u8(char *buf, size_t buflen, const char *optname, uint8_t *optdata, size_t optlen) { if (!optdata || optlen < 1) return -1; char numbuf[16]; uint8_t c = optdata[0]; ssize_t olen = snprintf(numbuf, sizeof numbuf, "%c", c); if (olen < 0 || (size_t)olen > sizeof numbuf) return -1; return ifcmd_raw(buf, buflen, optname, numbuf, strlen(numbuf)); } static int ifcmd_u16(char *buf, size_t buflen, const char *optname, uint8_t *optdata, size_t optlen) { if (!optdata || optlen < 2) return -1; char numbuf[16]; uint16_t v; memcpy(&v, optdata, 2); v = ntohs(v); ssize_t olen = snprintf(numbuf, sizeof numbuf, "%hu", v); if (olen < 0 || (size_t)olen > sizeof numbuf) return -1; return ifcmd_raw(buf, buflen, optname, numbuf, strlen(numbuf)); } static int ifcmd_s32(char *buf, size_t buflen, const char *optname, uint8_t *optdata, size_t optlen) { if (!optdata || optlen < 4) return -1; char numbuf[16]; uint32_t v; memcpy(&v, optdata, 4); v = ntohl(v); ssize_t olen = snprintf(numbuf, sizeof numbuf, "%d", v); if (olen < 0 || (size_t)olen > sizeof numbuf) return -1; return ifcmd_raw(buf, buflen, optname, numbuf, strlen(numbuf)); } static int ifcmd_ip(char *buf, size_t buflen, const char *optname, uint8_t *optdata, size_t optlen) { if (!optdata || optlen < 4) return -1; char ipbuf[INET_ADDRSTRLEN]; inet_ntop(AF_INET, optdata, ipbuf, sizeof ipbuf); return ifcmd_raw(buf, buflen, optname, ipbuf, strlen(ipbuf)); } static int ifcmd_iplist(char *out, size_t outlen, const char *optname, uint8_t *optdata, size_t optlen) { char buf[2048]; char ipbuf[INET_ADDRSTRLEN]; size_t bufoff = 0; size_t optoff = 0; if (!optdata || optlen < 4) return -1; inet_ntop(AF_INET, optdata + optoff, ipbuf, sizeof ipbuf); ssize_t wc = snprintf(buf + bufoff, sizeof buf, "%s", ipbuf); if (wc < 0 || (size_t)wc > sizeof buf) return -1; optoff += 4; bufoff += (size_t)wc; while (optlen >= 4 + optoff) { inet_ntop(AF_INET, optdata + optoff, ipbuf, sizeof ipbuf); wc = snprintf(buf + bufoff, sizeof buf, ",%s", ipbuf); if (wc < 0 || (size_t)wc > sizeof buf) return -1; optoff += 4; bufoff += (size_t)wc; } return ifcmd_raw(out, outlen, optname, buf, strlen(buf)); } static int ifchd_cmd(char *b, size_t bl, uint8_t *od, size_t ol, uint8_t code) { switch (code) { case DCODE_ROUTER: return ifcmd_ip(b, bl, "routr", od, ol); case DCODE_DNS: return ifcmd_iplist(b, bl, "dns", od, ol); case DCODE_LPRSVR: return ifcmd_iplist(b, bl, "lpr", od, ol); case DCODE_NTPSVR: return ifcmd_iplist(b, bl, "ntp", od, ol); case DCODE_WINS: return ifcmd_iplist(b, bl, "wins", od, ol); case DCODE_HOSTNAME: return ifcmd_bytes(b, bl, "host", od, ol); case DCODE_DOMAIN: return ifcmd_bytes(b, bl, "dom", od, ol); case DCODE_TIMEZONE: return ifcmd_s32(b, bl, "tzone", od, ol); case DCODE_MTU: return ifcmd_u16(b, bl, "mtu", od, ol); case DCODE_IPTTL: return ifcmd_u8(b, bl, "ipttl", od, ol); default: break; } log_line("%s: Invalid option code (%c) for ifchd cmd.", client_config.interface, code); return -1; } static int ifchwrite(const char *buf, size_t count) { ssize_t r = safe_write(ifchSock[0], buf, count); if (r < 0 || (size_t)r != count) { log_line("%s: (%s) write failed: %zd", client_config.interface, __func__, r); return -1; } char data[256], control[256]; struct iovec iov = { .iov_base = data, .iov_len = sizeof data - 1, }; struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1, .msg_control = control, .msg_controllen = sizeof control }; r = safe_recvmsg(ifchSock[0], &msg, 0); if (r == 0) { // Remote end hung up. exit(EXIT_SUCCESS); } else if (r < 0) { suicide("%s: (%s) recvmsg failed: %s", client_config.interface, __func__, strerror(errno)); } data[iov.iov_len] = '\0'; if (r == 1 && data[0] == '+') return 0; return -1; } bool ifchange_carrier_isup(void) { char buf[256]; snprintf(buf, sizeof buf, "carrier:;"); return ifchwrite(buf, strlen(buf)) == 0; } int ifchange_deconfig(struct client_state_t *cs) { char buf[256]; int ret = -1; if (cs->ifDeconfig) return 0; snprintf(buf, sizeof buf, "ip4:0.0.0.0,255.255.255.255;"); log_line("%s: Resetting IP configuration.", client_config.interface); ret = ifchwrite(buf, strlen(buf)); if (ret >= 0) { cs->ifDeconfig = 1; memset(&cfg_packet, 0, sizeof cfg_packet); } return ret; } static size_t send_client_ip(char *out, size_t olen, struct dhcpmsg *packet) { uint8_t optdata[MAX_DOPT_SIZE], olddata[MAX_DOPT_SIZE]; char ip[INET_ADDRSTRLEN], sn[INET_ADDRSTRLEN], bc[INET_ADDRSTRLEN]; size_t optlen, oldlen; bool change_ipaddr = false; bool have_subnet = false; bool change_subnet = false; bool have_bcast = false; bool change_bcast = false; if (memcmp(&packet->yiaddr, &cfg_packet.yiaddr, sizeof packet->yiaddr)) change_ipaddr = true; inet_ntop(AF_INET, &packet->yiaddr, ip, sizeof ip); optlen = get_dhcp_opt(packet, DCODE_SUBNET, optdata, sizeof optdata); if (optlen >= 4) { have_subnet = true; inet_ntop(AF_INET, optdata, sn, sizeof sn); oldlen = get_dhcp_opt(&cfg_packet, DCODE_SUBNET, olddata, sizeof olddata); if (oldlen != optlen || memcmp(optdata, olddata, optlen)) change_subnet = true; } optlen = get_dhcp_opt(packet, DCODE_BROADCAST, optdata, sizeof optdata); if (optlen >= 4) { have_bcast = true; inet_ntop(AF_INET, optdata, bc, sizeof bc); oldlen = get_dhcp_opt(&cfg_packet, DCODE_BROADCAST, olddata, sizeof olddata); if (oldlen != optlen || memcmp(optdata, olddata, optlen)) change_bcast = true; } // Nothing to change. if (!change_ipaddr && !change_subnet && !change_bcast) return 0; if (!have_subnet) { static char snClassC[] = "255.255.255.0"; log_line("%s: Server did not send a subnet mask. Assuming 255.255.255.0.", client_config.interface); memcpy(sn, snClassC, sizeof snClassC); } int snlen; if (have_bcast) { snlen = snprintf(out, olen, "ip4:%s,%s,%s;", ip, sn, bc); } else { snlen = snprintf(out, olen, "ip4:%s,%s;", ip, sn); } if (snlen < 0 || (size_t)snlen > olen) { log_line("%s: (%s) ip4 command would truncate so it was dropped.", client_config.interface, __func__); memset(out, 0, olen); return 0; } return (size_t)snlen; } static size_t send_cmd(char *out, size_t olen, struct dhcpmsg *packet, uint8_t code) { uint8_t optdata[MAX_DOPT_SIZE], olddata[MAX_DOPT_SIZE]; size_t optlen, oldlen; optlen = get_dhcp_opt(packet, code, optdata, sizeof optdata); if (!optlen) return 0; oldlen = get_dhcp_opt(&cfg_packet, code, olddata, sizeof olddata); if (oldlen == optlen && !memcmp(optdata, olddata, optlen)) return 0; int r = ifchd_cmd(out, olen, optdata, optlen, code); return r > 0 ? (size_t)r : 0; } int ifchange_bind(struct client_state_t *cs, struct dhcpmsg *packet) { char buf[2048]; size_t bo; int ret = -1; memset(buf, 0, sizeof buf); bo = send_client_ip(buf, sizeof buf, packet); bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_ROUTER); bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_DNS); bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_HOSTNAME); bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_DOMAIN); bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_MTU); bo += send_cmd(buf + bo, sizeof buf - bo, packet, DCODE_WINS); if (bo) { log_line("%s: bind command: '%s'", client_config.interface, buf); ret = ifchwrite(buf, bo); } if (ret >= 0) { cs->ifDeconfig = 0; memcpy(&cfg_packet, packet, sizeof cfg_packet); } return ret; }