EEPW论坛

[color=#006400]在dot1x客户端的发包代码中定义了以下的结构。[/color]/** Ethernet Header */ typedef struct eapol_ether_header_s { uchar_t ether_dhost[MY_ETHER_ADDR_LEN]; uchar_t ether_shost[MY_ETHER_ADDR_LEN]; ushort_t ether_type; }eapol_ether_header_t; /** EAPOL Header */ typedef struct eapol_hdr_s { uchar_t version; /* EAPOL proto version */ uchar_t eaptype; /* EAPOL Packet type */ ushort_t len; /* Packet body length */ }eapol_hdr_t ; /* EAP Private patch */ typedef struct eap_private_field_s{ uchar_t linkageId[8]; /* string "linkage" */ ushort_t version; /* version number */ ushort_t build; /* build number */ ulong_t msgType; /* message type */ }eap_private_field_t; [color=#DC143C]这里是组包代码[/color] void eapol_create_start_stop_frame(DOT1X_T *client, char *buffer, char stst) { eapol_ether_header_t *eather_hdr; eapol_hdr_t *eapol_hdr; eap_private_field_t *eap_private_field; eather_hdr = (eapol_ether_header_t *)buffer; eapol_hdr = (eapol_hdr_t *)(buffer + sizeof(eapol_ether_header_t)); eap_private_field = (eap_private_field_t *)(buffer + sizeof(eapol_ether_header_t) + sizeof(eapol_hdr_t)); /* copy eather header to packet */ memcpy(eather_hdr->ether_dhost, eapol_dst, sizeof(eather_hdr->ether_dhost)); memcpy(eather_hdr->ether_shost, client->srcMac, sizeof(eather_hdr->ether_shost)); eather_hdr->ether_type = ntohs(PAE_ETHER_TYPE); /* copy eapol header to packet */ eapol_hdr->version = PAE_PROTOCOL_V1; eapol_hdr->eaptype = stst; eapol_hdr->len = 0; /* copy linkage private field to packet */ memset(eap_private_field->linkageId, 0, sizeof(eap_private_field->linkageId)); memcpy(eap_private_field->linkageId, EAP_LINKAGE_IDENTIFIER, strlen(EAP_LINKAGE_IDENTIFIER)); eap_private_field->version = htons(EAP_LINKAGE_VERSION); eap_private_field->build = htons(EAP_LINKAGE_BUILD); [color=#DC143C]eap_private_field->msgType = 0x12345678;[/color] [color=#006400]/* 用Tornado跟踪调试发现这句代码运行完后msgType值仍为0x00000000，用下面的eapol_debug函数dump出内存也是msgType字段为0。后来经人点拨发现是字节对齐问题（这种问题终于被我撞到了），在eap_private_field_t结构中加入了__attribute__ ((packed))便好了，但还是有老大的疑惑，这是dot1x客户端的代码，在认证端（另一个设备）也有相同的eap_private_field_t结构，为什么那个组包就好好的？既然在客户端出现了字节对齐的问题，是不是在另一个设备迟早也会出这个问题的？各位达人说说你们怎么避免这个问题的。另：客户端用的是ARM芯片，认证端用的是PPC。 */[/color] eapol_debug("eapol_create_start_stop_frame", buffer, DEFAULT_PACKET_LEN, NULL); return; }