已定义并初始化memcpy上的SegFault以及源和目标
通过复制到初始化指针,我得到了SEGFULT。这是相关代码已定义并初始化memcpy上的SegFault以及源和目标,c,linux,C,Linux,通过复制到初始化指针,我得到了SEGFULT。这是相关代码 *pay = (char *)malloc(sizeof(t1) + 1020 /*1000=payload*/); memset(*pay, 0, sizeof(t1) + 1020); struct ethhdr *eth = (struct ethhdr *) *pay; struct iphdr *ip = (struct iphdr *) (*pay + sizeof(struct ethhdr)); struct tcphd
*pay = (char *)malloc(sizeof(t1) + 1020 /*1000=payload*/);
memset(*pay, 0, sizeof(t1) + 1020);
struct ethhdr *eth = (struct ethhdr *) *pay;
struct iphdr *ip = (struct iphdr *) (*pay + sizeof(struct ethhdr));
struct tcphdr *tcp = (struct tcphdr *) (*pay + sizeof(struct ethhdr) + sizeof(struct iphdr));
我做到了
memcpy(eth->h_dest, p->h_source, sizeof(eth->h_source));
但上面的线路导致了SEG故障。我在另一个线程memcpy((p)->h_-source,received_-packet_-eth->h_-source,sizeof(eth->h_-source))中这样分配h_-source
代码>
h_source
位于structstruct packets*p
这就是我在其他线程中初始化和分配它的定义struct packets*p
。因此,struct packets*p
不是未初始化的指针。我确信当SEGFULT发生时,它会被分配
unsigned char h_source[ETH_ALEN]; /* source ether addr */
谢谢你的帮助
更新这是函数的完整代码
void get_payload_to_send(struct packets *p, char **pay)
{
printf("%s --->>> %s", p->ip_source, p->ip_dest);
int t1;
*pay = (char *)malloc(sizeof(t1) + 1020 /*1000=payload*/);
memset(*pay, 0, sizeof(t1) + 1020);
struct ethhdr *eth = (struct ethhdr *) *pay;
struct iphdr *ip = (struct iphdr *) (*pay + sizeof(struct ethhdr));
struct tcphdr *tcp = (struct tcphdr *) (*pay + sizeof(struct ethhdr) + sizeof(struct iphdr));
//if (p->h_proto == ntohs(p->h_proto) == ETH_P_IP)
{
if (p->syn == 1 && p->ack == 0 && p->fin == 0)
{
///Ethernet
//memcpy(eth->h_dest, p->h_source, sizeof(eth->h_source));
eth->h_proto = htonl(ETH_P_IP);
//memcpy(eth->h_source, p->h_dest, sizeof(eth->h_dest));
////IP
// memcpy(ip->saddr, inet_addr(p->ip_dest), sizeof(ip->saddr));
struct sockaddr_in s1, s2;
s1.sin_family = AF_INET;
s1.sin_port = htons(80);
s1.sin_addr.s_addr = inet_addr(p->ip_source);
s2.sin_family = AF_INET;
s2.sin_port = htons(5009);
s2.sin_addr.s_addr = inet_addr(p->ip_dest);
//ip->saddr = s1.sin_addr.s_addr;
sleep(2);
ip->daddr = s2.sin_addr.s_addr;
char c[20];
memcpy(ip->saddr, inet_addr(p->ip_dest), sizeof(c) - 1);
ip->ihl = 5;
ip->version = 4;
ip->tos = 0;
ip->tot_len = sizeof(t1) + 1020;
srand(1001);
ip->id = htonl(rand());
ip->frag_off = 0;
ip->ttl = 225;
ip->protocol = IPPROTO_TCP;
ip->check = 0;
tcp->syn = 1;
tcp->ack = 1;
memcpy(ip->daddr, inet_addr(p->ip_source), sizeof(c) - 1);
//ip->check = csum((unsigned short *)*pay, ip->tot_len);
}
else if (p->syn == 0 && p->ack == 1)
{
}
}
//printf("%saddr %s -->>", p->ip_source);
//printf("daddr %s\n", p->ip_dest);
//populate eth
}
这是对上述函数进行函数调用的代码
void *task_sender(void *args) {
struct struct_super_struct *super = (struct struct_super_struct *)args;
struct packets *p = super->p; //(struct packets *)args;
printf("Sender\n");
while (1)
{
//printf("got uppder loop SENDER\n");
pthread_mutex_lock(&mutex);
while (nop == 0)
{
pthread_cond_wait(&cond, &mutex);
//printf("finished waiting in SENDER\n");
}
int i = 0;
printf("NOP is greater than 2 in SENDER %d\n");
while (nop > 0)
{
// check_and_process_connection(super,(p+i));
//if (p == NULL) break;
if (strcmp("192.168.10.25", (p+i)->ip_dest) == 0 && (p+i)->syn == 1 && (p+i)->ack == 0)
{
//sleep(1);
//printf("%s\n", (p+i)->ip_dest);
//if (strcmp((p+i)->ip_dest, "192.168.10.25") == 0)
{
char *pac;
struct packets *pt = (p+i);
get_payload_to_send((p+i), &pac);
struct sockaddr_in temp;
struct ethhdr *eth = (struct ethhdr *)pac;
struct iphdr *ip = (struct iphdr *)(pac + sizeof(struct ethhdr));
struct tcphdr *tcp = (struct tcphdr *)(pac + sizeof(struct ethhdr) + sizeof(struct iphdr));
temp.sin_addr.s_addr = ip->saddr;
char *source = inet_ntoa(temp.sin_addr);
struct sockaddr_in temp1;
temp1.sin_addr.s_addr = ip->daddr;
char *dest = inet_ntoa(temp1.sin_addr);
printf("%s >> %s \n", (p+i)->ip_source, (p+i)->ip_dest);
//if (strcmp("192.168.10.25",dest) == 0 && strcmp("192.168.10.25", source) == 0)
{
///temp1.sin_addr.s_addr = ip->daddr;
printf("should be\n");
printf("frm %s to %s syc:%d ack:%d \n",
inet_ntoa(temp.sin_addr),
inet_ntoa(temp1.sin_addr),
tcp->syn, tcp->ack);
}
/*
printf("__________________________________________________\n");
printf("lastop: %d\n", (p+i)->lastop);
printf("source: %s %d\n", (p+i)->ip_source, (p+i)->tcp_source);
printf("dest: %s %d\n", (p+i)->ip_dest, (p+i)->tcp_dest);
printf("syc: %d\n", (p+i)->syn);
printf("ack: %d\n", (p+i)->ack);
printf("seq: %d\n", (p+i)->seq);
printf("ack seq: %d\n", (p+i)->ack_seq);
(p+i)->lastop = 0;
printf("lastop: %d\n", (p+i)->lastop);
*/
}
//printf("dest port: %d\n", (p+i)->tcp_dest);
}
//else { printf("source ip: %s\n", (p+i)->ip_source); printf("dest ip: %s\n", (p+i)->ip_dest); }
//p++;
nop--;
i++;
//printf("just processed packet SENDER\n");
}
//p = NULL;
pthread_mutex_unlock(&mutex);
nop = 0;
int s = pthread_cond_signal(&cond);
}
}
更新2
struct packets {
int syn;
char payload[1000];
// pthread_mutex_t mutex;
int lastop;
unsigned char h_dest[ETH_ALEN]; /* destination eth addr */
unsigned char h_source[ETH_ALEN]; /* source ether addr */
__be16 h_proto;
char ip_source[20];
char ip_dest[20];
int tcp_source;
int tcp_dest;
int seq;
int ack_seq;
int ack;
int fin;
int rst;
int window;
int nop;
struct ethhdr *eth;
struct iphdr *ip;
struct tcphdr *tcp;
}; // *p=NULL;
注意我发现使用gdb调试的是memcpy(eth->h_dest,p->h_source,sizeof(eth->h_source))代码>行eth->hdest
为NULL
问题在于您没有提供指向memset()的正确指针:
char*pay=(char*)malloc(sizeof(t1)+1020);
memset(*支付,0,大小(t1)+1020);
使用动态分配的数组pay
中的第一个char
作为目标地址清除内存
正确的形式是
char*pay=malloc(sizeof(t1)+1020);
memset(pay,0,sizeof(t1)+1020);
这是因为pay
是指向动态分配数组的指针,而*pay
是指向其第一个元素的值,就像pay[0]
一样
(在C中,不需要从void*显式转换,例如malloc()的返回值。)
同一错误重复了几次:
struct ethhdr*eth=(struct ethhdr*)*支付;
结构iphdr*ip=(结构iphdr*)(*pay+sizeof(结构ethhdr));
struct tcphdr*tcp=(struct tcphdr*)(*pay+sizeof(struct ethhdr)+sizeof(struct iphdr));
它们声明并初始化指向从动态分配数组pay
中的第一个字符派生的地址的指针,而不是相对于数组开头的地址
同样,它们的正确形式是
struct ethhdr*eth=(struct ethhdr*)支付;
结构iphdr*ip=(结构iphdr*)(pay+sizeof(结构ethhdr));
struct tcphdr*tcp=(struct tcphdr*)(pay+sizeof(struct ethhdr)+sizeof(struct iphdr));
因为*pay
指的是pay
数组中第一个元素的值,而pay
指的是数组的地址
显然,实际代码是
char**pay;
*pay=malloc(sizeof(t1)+1020);
memset(*支付,0,大小(t1)+1020);
这缺少两个基本的检查:
pay
不为空
那malloc()
成功了
该代码可能因上述症状中的任一原因而失败。至少在处,将其改写为
断言(pay!=NULL);
*pay=malloc(sizeof(t1)+1020);
断言(*pay!=NULL);
memset(*支付,0,大小(t1)+1020);
由于eth
、ip
和tcp
变量定义保持其原始形式(即*pay
)。问题在于您没有提供指向memset()的正确指针。
:
char*pay=(char*)malloc(sizeof(t1)+1020);
memset(*支付,0,大小(t1)+1020);
使用动态分配的数组pay
中的第一个char
作为目标地址清除内存
正确的形式是
char*pay=malloc(sizeof(t1)+1020);
memset(pay,0,sizeof(t1)+1020);
这是因为pay
是指向动态分配数组的指针,而*pay
是指向其第一个元素的值,就像pay[0]
一样
(在C中,不需要从void*显式转换,例如malloc()的返回值。)
同一错误重复了几次:
struct ethhdr*eth=(struct ethhdr*)*支付;
结构iphdr*ip=(结构iphdr*)(*pay+sizeof(结构ethhdr));
struct tcphdr*tcp=(struct tcphdr*)(*pay+sizeof(struct ethhdr)+sizeof(struct iphdr));
它们声明并初始化指向从动态分配数组pay
中的第一个字符派生的地址的指针,而不是相对于数组开头的地址
同样,它们的正确形式是
struct ethhdr*eth=(struct ethhdr*)支付;
结构iphdr*ip=(结构iphdr*)(pay+sizeof(结构ethhdr));
struct tcphdr*tcp=(struct tcphdr*)(pay+sizeof(struct ethhdr)+sizeof(struct iphdr));
因为*pay
指的是pay
数组中第一个元素的值,而pay
指的是数组的地址
显然,实际代码是
char**pay;
*pay=malloc(sizeof(t1)+1020);
memset(*支付,0,大小(t1)+1020);
这缺少两个基本的检查:
pay
不为空
那malloc()
成功了
该代码可能因上述症状中的任一原因而失败。至少在处,将其改写为
断言(pay!=NULL);
*pay=malloc(sizeof(t1)+1020);
断言(*pay!=NULL);
memset(*支付,0,大小(t1)+1020);
由于eth
、ip
和tcp
变量定义保持其原始形式(即*pay
)。这些行上有两个主要错误:
struct ethhdr *eth = (struct ethhdr *) *pay;
struct iphdr *ip = (struct iphdr *) (*pay + sizeof(struct ethhdr));
struct tcphdr *tcp = (struct tcphdr *) (*pay + sizeof(struct ethhdr) + sizeof(struct iphdr));
pay*
指向的内存是使用一个神奇的数字分配的,ethhdr
、iphdr
和tcphdr
的大小可能是相同的,但我不想继续工作
void get_payload_to_send(struct packets *p,char **pay)
{
printf("%s --->>> %s",p->ip_source,p->ip_dest);
int t1;
*pay=(char *) malloc(sizeof(t1)+1020/*1000=payload*/);
memset (*pay, 0, sizeof(t1)+1020);
struct ethhdr *eth = (struct ethhdr *) *pay;
struct iphdr *ip = (struct iphdr *) (*pay + sizeof(struct ethhdr));
struct tcphdr *tcp = (struct tcphdr *) (*pay + sizeof(struct ethhdr) + sizeof(struct iphdr));
memcpy(eth->h_dest,p->h_source,sizeof(eth->h_source));