feat(sockutls): Add initial support for socket helpers

components/sock_utils/src/socketpair.c

@@ -0,0 +1,76 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <fcntl.h>
+#include "lwip/sockets.h"
+#include "socketpair.h"
+#include "esp_check.h"
+
+#define INVALID_SOCKET (-1)
+
+static const char *TAG = "socket_helpers";
+
+int socketpair(int domain, int type, int protocol, int sv[2])
+{
+    if (protocol != 0 || type != SOCK_STREAM || domain != AF_UNIX) {
+        errno = ENOSYS; // not implemented
+        return -1;
+    }
+    struct sockaddr_storage ss;
+    struct sockaddr_in *sa = (struct sockaddr_in *)&ss;
+    socklen_t ss_len = sizeof(struct sockaddr_in);
+    int fd1 = INVALID_SOCKET;
+    int fd2 = INVALID_SOCKET;
+    int listenfd = INVALID_SOCKET;
+    int ret = 0; // Success
+
+    sa->sin_family = AF_INET;
+    sa->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+    sa->sin_port = 0;
+    listenfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+    ESP_GOTO_ON_FALSE(listenfd != INVALID_SOCKET, -1, err, TAG, "Cannot create listening socket");
+    ESP_GOTO_ON_FALSE(listen(listenfd, 1) == 0, -1, err, TAG, "Failed to listen");
+
+    memset(&ss, 0, sizeof(ss));
+    ss_len = sizeof(ss);
+    ESP_GOTO_ON_FALSE(getsockname(listenfd, (struct sockaddr *)&ss, &ss_len) >= 0, -1, err, TAG, "getsockname failed");
+
+    sa->sin_family = AF_INET;
+    sa->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+
+    fd1 = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+    ESP_GOTO_ON_FALSE(fd1 != INVALID_SOCKET, -1, err, TAG, "Cannot create read side socket");
+    ESP_GOTO_ON_FALSE(connect(fd1, (struct sockaddr *)&ss, ss_len) >= 0, -1, err, TAG, "Failed to connect fd1");
+    fd2 = accept(listenfd, NULL, 0);
+    ESP_GOTO_ON_FALSE(fd2 != INVALID_SOCKET, -1, err, TAG, "Failed to accept fd2");
+
+    close(listenfd);
+    sv[0] = fd1;
+    sv[1] = fd2;
+    return ret;
+
+err:
+    if (listenfd != INVALID_SOCKET) {
+        close(listenfd);
+    }
+    if (fd1 != INVALID_SOCKET) {
+        close(fd1);
+    }
+    return ret;
+}
+
+int pipe(int pipefd[2])
+{
+    if (socketpair(AF_UNIX, SOCK_STREAM, 0, pipefd) == -1) {
+        return -1;
+    }
+    // Close the unwanted ends to make it a unidirectional pipe
+    if (shutdown(pipefd[0], SHUT_WR) == -1 || shutdown(pipefd[1], SHUT_RD) == -1) {
+        close(pipefd[0]);
+        close(pipefd[1]);
+        return -1;
+    }
+    return 0;
+}