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