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108 lines
3.3 KiB
108 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0 |
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#include <stdio.h> |
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#include <assert.h> |
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#include <unistd.h> |
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#include <bpf/bpf.h> |
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#include <bpf/libbpf.h> |
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#include <sys/socket.h> |
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#include <netinet/in.h> |
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#include <arpa/inet.h> |
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int main(int ac, char **argv) |
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{ |
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struct sockaddr_in *serv_addr_in, *mapped_addr_in, *tmp_addr_in; |
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struct sockaddr serv_addr, mapped_addr, tmp_addr; |
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int serverfd, serverconnfd, clientfd, map_fd; |
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struct bpf_link *link = NULL; |
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struct bpf_program *prog; |
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struct bpf_object *obj; |
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socklen_t sockaddr_len; |
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char filename[256]; |
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char *ip; |
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serv_addr_in = (struct sockaddr_in *)&serv_addr; |
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mapped_addr_in = (struct sockaddr_in *)&mapped_addr; |
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tmp_addr_in = (struct sockaddr_in *)&tmp_addr; |
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); |
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obj = bpf_object__open_file(filename, NULL); |
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if (libbpf_get_error(obj)) { |
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fprintf(stderr, "ERROR: opening BPF object file failed\n"); |
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return 0; |
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} |
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prog = bpf_object__find_program_by_name(obj, "bpf_prog1"); |
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if (libbpf_get_error(prog)) { |
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fprintf(stderr, "ERROR: finding a prog in obj file failed\n"); |
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goto cleanup; |
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} |
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/* load BPF program */ |
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if (bpf_object__load(obj)) { |
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fprintf(stderr, "ERROR: loading BPF object file failed\n"); |
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goto cleanup; |
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} |
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map_fd = bpf_object__find_map_fd_by_name(obj, "dnat_map"); |
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if (map_fd < 0) { |
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fprintf(stderr, "ERROR: finding a map in obj file failed\n"); |
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goto cleanup; |
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} |
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link = bpf_program__attach(prog); |
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if (libbpf_get_error(link)) { |
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fprintf(stderr, "ERROR: bpf_program__attach failed\n"); |
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link = NULL; |
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goto cleanup; |
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} |
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assert((serverfd = socket(AF_INET, SOCK_STREAM, 0)) > 0); |
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assert((clientfd = socket(AF_INET, SOCK_STREAM, 0)) > 0); |
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/* Bind server to ephemeral port on lo */ |
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memset(&serv_addr, 0, sizeof(serv_addr)); |
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serv_addr_in->sin_family = AF_INET; |
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serv_addr_in->sin_port = 0; |
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serv_addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); |
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assert(bind(serverfd, &serv_addr, sizeof(serv_addr)) == 0); |
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sockaddr_len = sizeof(serv_addr); |
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assert(getsockname(serverfd, &serv_addr, &sockaddr_len) == 0); |
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ip = inet_ntoa(serv_addr_in->sin_addr); |
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printf("Server bound to: %s:%d\n", ip, ntohs(serv_addr_in->sin_port)); |
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memset(&mapped_addr, 0, sizeof(mapped_addr)); |
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mapped_addr_in->sin_family = AF_INET; |
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mapped_addr_in->sin_port = htons(5555); |
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mapped_addr_in->sin_addr.s_addr = inet_addr("255.255.255.255"); |
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assert(!bpf_map_update_elem(map_fd, &mapped_addr, &serv_addr, BPF_ANY)); |
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assert(listen(serverfd, 5) == 0); |
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ip = inet_ntoa(mapped_addr_in->sin_addr); |
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printf("Client connecting to: %s:%d\n", |
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ip, ntohs(mapped_addr_in->sin_port)); |
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assert(connect(clientfd, &mapped_addr, sizeof(mapped_addr)) == 0); |
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sockaddr_len = sizeof(tmp_addr); |
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ip = inet_ntoa(tmp_addr_in->sin_addr); |
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assert((serverconnfd = accept(serverfd, &tmp_addr, &sockaddr_len)) > 0); |
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printf("Server received connection from: %s:%d\n", |
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ip, ntohs(tmp_addr_in->sin_port)); |
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sockaddr_len = sizeof(tmp_addr); |
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assert(getpeername(clientfd, &tmp_addr, &sockaddr_len) == 0); |
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ip = inet_ntoa(tmp_addr_in->sin_addr); |
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printf("Client's peer address: %s:%d\n", |
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ip, ntohs(tmp_addr_in->sin_port)); |
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/* Is the server's getsockname = the socket getpeername */ |
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assert(memcmp(&serv_addr, &tmp_addr, sizeof(struct sockaddr_in)) == 0); |
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cleanup: |
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bpf_link__destroy(link); |
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bpf_object__close(obj); |
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return 0; |
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}
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