// SPDX-License-Identifier: GPL-2.0 #include <arpa/inet.h> #include <error.h> #include <errno.h> #include <unistd.h> int main(void) { int fd1, fd2, one = 1; struct sockaddr_in6 bind_addr = { .sin6_family = AF_INET6, .sin6_port = htons(20000), .sin6_flowinfo = htonl(0), .sin6_addr = {}, .sin6_scope_id = 0, }; inet_pton(AF_INET6, "::", &bind_addr.sin6_addr); fd1 = socket(AF_INET6, SOCK_STREAM, IPPROTO_IP); if (fd1 < 0) { error(1, errno, "socket fd1"); return -1; } if (setsockopt(fd1, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one))) { error(1, errno, "setsockopt(SO_REUSEADDR) fd1"); goto out_err1; } if (bind(fd1, (struct sockaddr *)&bind_addr, sizeof(bind_addr))) { error(1, errno, "bind fd1"); goto out_err1; } if (listen(fd1, 0)) { error(1, errno, "listen"); goto out_err1; } fd2 = socket(AF_INET6, SOCK_STREAM, IPPROTO_IP); if (fd2 < 0) { error(1, errno, "socket fd2"); goto out_err1; } if (connect(fd2, (struct sockaddr *)&bind_addr, sizeof(bind_addr))) { error(1, errno, "bind fd2"); goto out_err2; } close(fd2); close(fd1); return 0; out_err2: close(fd2); out_err1: close(fd1); return -1; }