dhcp.zip_dhcp原理

#include <assert.h> #include "dhcp.h" #include "global.h" #include "utils.h" net_config netconfig = { 0x00 }; char *IfName = DEFAULT_IFNAME; int IfName_len = DEFAULT_IFNAME_LEN; //void *(*currState)() = &dhcpReboot; int DebugFlag = 1; unsigned int lease_time; unsigned LeaseTime = DEFAULT_LEASETIME; time_t TimeOut = DEFAULT_TIMEOUT; int magic_cookie = 0; unsigned short dhcpMsgSize = 0; unsigned nleaseTime = 0; int error_l = 0; // contain error_l number accur in state machine static int dhcpSocket = -1; unsigned short ip_id; static short int narpCheck = 0; dhcpOptions DhcpOptions; dhcpInterface DhcpIface; udpipMessage UdpIpMsgSend, UdpIpMsgRecv; unsigned char ClientHwAddr[ETH_ALEN]; struct ip *ipSend = (struct ip *)((struct udpiphdr *)UdpIpMsgSend.udpipmsg)->ip; struct ip *ipRecv = (struct ip *)((struct udpiphdr *)UdpIpMsgRecv.udpipmsg)->ip; dhcpMessage *DhcpMsgSend = (dhcpMessage *)&UdpIpMsgSend.udpipmsg[sizeof(udpiphdr)]; dhcpMessage *DhcpMsgRecv = (dhcpMessage *)&UdpIpMsgRecv.udpipmsg[sizeof(udpiphdr)]; struct timeval stStart,stCurtime; unsigned char dhcp_success = 0; pthread_t g_timeoutcheck_thread = 0; static void *dhcptimeoutcheck_thread(void) { unsigned int diff = 0; prctl(PR_SET_NAME, "#DHCP_LEASE", 0,0,0); pthread_detach(pthread_self()); while(1) { usleep(100000); if (dhcp_success == 1) { gettimeofday(&stCurtime,NULL); diff = (unsigned int)(stCurtime.tv_sec - stStart.tv_sec); if (diff > lease_time-lease_time/2) { dhcp_success = 0; dhcpReBound(); } } } g_timeoutcheck_thread = 0; return NULL; } int dhcp_run(int iWiFi ) { // Reset status dhcp_success = 0; memset(&netconfig, 0x00, sizeof(netconfig)); // End if(iWiFi == 1) { IfName = WIFI_IFNAME; IfName_len = WIFI_IFNAME_LEN; } else { IfName = DEFAULT_IFNAME; IfName_len = DEFAULT_IFNAME_LEN; } void *(*currState)(void) = &dhcpReboot; if (getuid()) { zPrintf(DEBUG_eErr,"%s(%d):not a superuser\n", __FILE__, __LINE__); return ERR_NOROOT; } memset(&DhcpOptions, 0, sizeof(dhcpOptions)); magic_cookie = htonl(MAGIC_COOKIE); dhcpMsgSize = htons(sizeof(dhcpMessage)); nleaseTime = htonl(LeaseTime); do { if ((currState=(void *(*)(void))currState()) == NULL) { zPrintf(DEBUG_eWrn,"dhcp run return error!\n"); return error_l; } } while (currState != &dhcpBound); dhcpBound(); dhcpStop(); return 0; // success } void *dhcpStart() { int o = 1, i=0; struct ifreq ifr; struct sockaddr_pkt sap; short int saved_if_flags; memset(&ifr,0,sizeof(struct ifreq)); memcpy(ifr.ifr_name,IfName,IfName_len); if (dhcpSocket != -1) { close(dhcpSocket); dhcpSocket = -1; } dhcpSocket = socket(AF_PACKET,SOCK_PACKET,htons(ETH_P_ALL)); if (dhcpSocket == -1) { zPrintf(DEBUG_eErr,"%s(%d):dhcpStart:socket:%s\n", __FILE__, __LINE__, strerror(errno)); error_l = ERR_SOCKET; return NULL; } do { i++; if ( i>1 ) zPrintf(DEBUG_eMsg,"dhcpStart: retrying MAC address request " "(returned %02x:%02x:%02x:%02x:%02x:%02x)", ClientHwAddr[0],ClientHwAddr[1],ClientHwAddr[2], ClientHwAddr[3],ClientHwAddr[4],ClientHwAddr[5]); if (ioctl(dhcpSocket,SIOCGIFHWADDR,&ifr) < 0) { zPrintf(DEBUG_eErr,"%s(%d):dhcpStart:ioctl:%s\n", __FILE__, __LINE__, strerror(errno)); error_l = ERR_SOCKET; close(dhcpSocket); dhcpSocket = -1; return NULL; } if (ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER && ifr.ifr_hwaddr.sa_family != ARPHRD_IEEE802) { zPrintf(DEBUG_eErr,"%s(%d):dhcpStart: interface %s is not Ethernet or 802.2 Token Ring\n", __FILE__, __LINE__, ifr.ifr_name); error_l = ERR_SOCKET; close(dhcpSocket); dhcpSocket = -1; return NULL; } //added by Snoopy 2006-1-16, hold timeout struct timeval timeout; timeout.tv_sec = 1; timeout.tv_usec = 0;//100000;//20ms if (setsockopt(dhcpSocket, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof timeout) < 0) { close(dhcpSocket); dhcpSocket = -1; return NULL; } if (setsockopt(dhcpSocket, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof timeout) < 0) { close(dhcpSocket); dhcpSocket = -1; return NULL; } //end if (setsockopt(dhcpSocket,SOL_SOCKET,SO_BROADCAST,&o,sizeof(o)) < -1) { zPrintf(DEBUG_eErr,"%s(%d):dhcpStart:setsockopt:%s\n", __FILE__, __LINE__, strerror(errno)); error_l = ERR_SOCKET; close(dhcpSocket); dhcpSocket = -1; return NULL; } if (ioctl(dhcpSocket,SIOCGIFFLAGS,&ifr) < 0) { zPrintf(DEBUG_eErr,"%s(%d):dhcpStart:ioctl:%s\n", __FILE__, __LINE__, strerror(errno)); error_l = ERR_SOCKET; close(dhcpSocket); dhcpSocket = -1; return NULL; } saved_if_flags = ifr.ifr_flags; ifr.ifr_flags = saved_if_flags | IFF_UP | IFF_BROADCAST | IFF_NOTRAILERS | IFF_RUNNING; if (ioctl(dhcpSocket,SIOCSIFFLAGS,&ifr)) { zPrintf(DEBUG_eErr,"%s(%d):dhcpStart:ioctl:%s\n", __FILE__, __LINE__, strerror(errno)); error_l = ERR_SOCKET; close(dhcpSocket); dhcpSocket = -1; return NULL; } memset(&sap,0,sizeof(sap)); sap.spkt_protocol = htons(ETH_P_ALL); memcpy(sap.spkt_device,IfName,IfName_len); sap.spkt_family = AF_PACKET; if (bind(dhcpSocket,(struct sockaddr*)&sap,sizeof(struct sockaddr)) == -1) zPrintf(DEBUG_eErr,"%s(%d):dhcpStart:bind:%s\n", __FILE__, __LINE__, strerror(errno)); memcpy(ClientHwAddr,ifr.ifr_hwaddr.sa_data,ETH_ALEN); if (DebugFlag) zPrintf(DEBUG_eMsg,"dhcpcd: MAC address = %02x:%02x:%02x:%02x:%02x:%02x\n", ClientHwAddr[0], ClientHwAddr[1], ClientHwAddr[2], ClientHwAddr[3], ClientHwAddr[4], ClientHwAddr[5]); } while (!ClientHwAddr[0] && !ClientHwAddr[1] && !ClientHwAddr[2] && !ClientHwAddr[3] && !ClientHwAddr[4] && !ClientHwAddr[5] && i<HWADDR_TRIES ); ip_id = time(NULL)&0xffff; srandom(ip_id); // seed for random() return (void*)&dhcpInit; } void *dhcpReboot() { struct ifreq ifr; struct sockaddr_in *p = (struct sockaddr_in *)&(ifr.ifr_addr); if (dhcpStart() == NULL) return NULL; memset(&DhcpOptions,0,sizeof(DhcpOptions)); memset(&DhcpIface,0,sizeof(dhcpInterface)); memset(&DhcpIface,0,sizeof(dhcpInterface)); memset(&ifr,0,sizeof(struct ifreq)); memcpy(ifr.ifr_name,IfName,IfName_len); p->sin_family = AF_INET; if (ioctl(dhcpSocket,SIOCGIFADDR,&ifr) == 0) DhcpIface.ciaddr=p->sin_addr.s_addr; classIDsetup(); clientIDsetup(); return (void*)&dhcpInit; } void *dhcpInit() { releaseDhcpOptions(); #ifdef DEBUG zPrintf(DEBUG_eErr,"ClassID = \"%s\"\n", DhcpIface.class_id); zPrintf(DEBUG_eErr,"ClientID = \"%u.%u.%u.%02X.%02X.%02X.%02X.%02X.%02X\"\n", DhcpIface.client_id[0],DhcpIface.client_id[1],DhcpIface.client_id[2], DhcpIface.client_id[3],DhcpIface.client_id[4],DhcpIface.client_id[5], DhcpIface.client_id[6],DhcpIface.client_id[7],DhcpIface.client_id[8]); #endif if (DebugFlag) zPrint