英文:
Not able to attach so_reuseport_cbpf in cpp
问题
以下BPF程序在cpp中绑定到UDP套接字时使用SO_ATTACH_REUSEPORT_CBPF引发错误
struct sock_filter code[] = {
{BPF_LD | BPF_MEM, 0, 0, 0x00000000}, // 将内存加载到累加器中
//{BPF_ALU | BPF_ADD, 0, 0, 0x00000001}, // 添加1
//{BPF_ALU | BPF_MOD, 0, 0, 0x00000003}, // 取模3
//{BPF_ST , 0, 0, 0x00000000}, // 保存到临时内存
//{BPF_RET | BPF_A, 0, 0, 0x00000000}, // 返回累加器中的值
};
但是当我将BPF程序更改为
struct sock_filter code[] = {
{BPF_RET, 0, 0, 0x00000000}
};
我的代码正常运行。
第一个BPF程序有什么问题？
我尝试执行两个BPF程序，期望第一个BPF程序成功附加到我的UDP套接字。
英文:
Below BPF prgram in cpp is throwing error when binding to udp socket using SO_ATTACH_REUSEPORT_CBPF
struct sock_filter code[] = {
{BPF_LD | BPF_MEM, 0, 0, 0x00000000}, // load memory to accumulator
//{BPF_ALU | BPF_ADD, 0, 0, 0x00000001}, // add 1
//{BPF_ALU | BPF_MOD, 0, 0, 0x00000003}, //module 3
//{BPF_ST , 0, 0, 0x00000000}, // save in scratch memory
//{BPF_RET | BPF_A, 0, 0, 0x00000000}, // return value in accumulator
};
But when i am changing bpf program to
struct sock_filter code[] = {
{BPF_RET, 0, 0, 0x00000000}
};
My code is running fine.
What is problem in 1st bpf program??
I tried executing with both bpf program, expecting that first bpf program attach succesfully to my udp socket.
答案1
得分: 0
所有可能的控制流都必须以BPF_RET操作结束。
以下内容也应有效：
struct sock_filter code[] = {
{BPF_LD | BPF_MEM, 0, 0, 0x00000000}, // 将内存加载到累加器
//{BPF_ALU | BPF_ADD, 0, 0, 0x00000001}, // 加1
//{BPF_ALU | BPF_MOD, 0, 0, 0x00000003}, // 取模3
//{BPF_ST , 0, 0, 0x00000000}, // 保存到临时存储器
{BPF_RET | BPF_A, 0, 0, 0x00000000}, // 将累加器中的值返回
};
英文:
All possible control flows must end with a BPF_RET operation.
The following should also be valid:
struct sock_filter code[] = {
{BPF_LD | BPF_MEM, 0, 0, 0x00000000}, // load memory to accumulator
//{BPF_ALU | BPF_ADD, 0, 0, 0x00000001}, // add 1
//{BPF_ALU | BPF_MOD, 0, 0, 0x00000003}, //module 3
//{BPF_ST , 0, 0, 0x00000000}, // save in scratch memory
{BPF_RET | BPF_A, 0, 0, 0x00000000}, // return value in accumulator
};
答案2
得分: 0
Both the BPF program is valid. I made a mistake when declaring struct sock_fprog.
Initially, it was
struct sock_fprog bpf = {
.len = 1,
.filter = code,
};
So that's why the BPF program
struct sock_filter code[] = {
{BPF_RET, 0, 0, 0x00000000}
};
runs correctly as it has only one instruction.
Now I changed the struct code to run for any number of instructions:
struct sock_fprog bpf = {
.len = sizeof(code)/sizeof(code[0]),
.filter = code,
};
英文:
Both the BPF program is valid. I made mistake when declaring struct sock_fprog.
Initially it was
struct sock_fprog bpf = {
.len = 1,
.filter = code,
};
So that's why bpf program
struct sock_filter code[] = {
{BPF_RET, 0, 0, 0x00000000}
};
run correctly as it has only one instruction.
Now i changed the struct code to run for any number of instructions:
struct sock_fprog bpf = {
.len = sizeof(code)/sizeof(code[0]),
.filter = code,
};
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论