example: Add subsystem_netconf.c

This example demonstrates how to use libssh2 to send a request to
the NETCONF subsystem available e.g. in JunOS.

See also http://tools.ietf.org/html/draft-ietf-netconf-ssh-06

example/.gitignore

@@ -25,6 +25,7 @@ libssh2_config.h.in
 stamp-h2
 sftp_append
 ssh2_echo
+subsystem_netconf
 test-scp
 test-sftp_append
 test-sftp_nonblock

example/Makefile.am

@@ -6,7 +6,8 @@ EXTRA_DIST = libssh2_config.h.in
 noinst_PROGRAMS = direct_tcpip ssh2 scp scp_nonblock scp_write		\
  scp_write_nonblock sftp sftp_nonblock sftp_write sftp_write_nonblock	\
  sftp_mkdir sftp_mkdir_nonblock sftp_RW_nonblock sftpdir		\
- sftpdir_nonblock ssh2_exec ssh2_agent ssh2_echo sftp_append
+ sftpdir_nonblock ssh2_exec ssh2_agent ssh2_echo sftp_append		\
+ subsystem_netconf
 
 AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/example
 LDADD = $(top_builddir)/src/libssh2.la

example/subsystem_netconf.c

@@ -0,0 +1,268 @@
+#include "libssh2_config.h"
+#include <libssh2.h>
+
+#ifdef WIN32
+#include <windows.h>
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#else
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/time.h>
+#endif
+
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#ifdef HAVE_SYS_SELECT_H
+#include <sys/select.h>
+#endif
+
+#ifndef INADDR_NONE
+#define INADDR_NONE (in_addr_t)-1
+#endif
+
+const char *keyfile1 = "/home/username/.ssh/id_rsa.pub";
+const char *keyfile2 = "/home/username/.ssh/id_rsa";
+const char *username = "username";
+const char *password = "";
+
+const char *server_ip = "127.0.0.1";
+
+enum {
+    AUTH_NONE = 0,
+    AUTH_PASSWORD,
+    AUTH_PUBLICKEY
+};
+
+int netconf_write(LIBSSH2_CHANNEL *channel, const char *buf, size_t len)
+{
+    int i;
+    ssize_t wr = 0;
+
+    do {
+        i = libssh2_channel_write(channel, buf, len);
+        if (i < 0) {
+            fprintf(stderr, "libssh2_channel_write: %d\n", i);
+            return -1;
+        }
+        wr += i;
+    } while (i > 0 && wr < len);
+
+    return 0;
+}
+
+int netconf_read_until(LIBSSH2_CHANNEL *channel, const char *endtag, char *buf, size_t buflen)
+{
+    ssize_t len, rd = 0;
+    char *endreply, *specialsequence = NULL;
+
+    memset(buf, 0, buflen);
+
+    do {
+        len = libssh2_channel_read(channel, buf + rd, buflen - rd);
+        if (LIBSSH2_ERROR_EAGAIN == len)
+            continue;
+        else if (len < 0) {
+            fprintf(stderr, "libssh2_channel_read: %d", (int)len);
+            return -1;
+        }
+        rd += len;
+
+        /* read more data until we see a rpc-reply closing tag followed by
+         * the special sequence ]]>]]> */
+
+        /* really, this MUST be replaced with proper XML parsing! */
+
+        endreply = strstr(buf, endtag);
+        if (endreply)
+            specialsequence = strstr(endreply, "]]>]]>");
+
+    } while (!endreply || !specialsequence);
+
+    return rd;
+}
+
+int main(int argc, char *argv[])
+{
+    int rc, sock = -1, i, auth = AUTH_NONE;
+    struct sockaddr_in sin;
+    socklen_t sinlen;
+    const char *fingerprint;
+    char *userauthlist;
+    LIBSSH2_SESSION *session;
+    LIBSSH2_CHANNEL *channel = NULL;
+    char buf[1048576]; /* avoid any buffer reallocation for simplicity */
+    ssize_t len;
+
+#ifdef WIN32
+    char sockopt;
+    WSADATA wsadata;
+
+    WSAStartup(MAKEWORD(2,0), &wsadata);
+#else
+    int sockopt;
+#endif
+
+    if (argc > 1)
+        server_ip = argv[1];
+    if (argc > 2)
+        username = argv[2];
+    if (argc > 3)
+        password = argv[3];
+
+    rc = libssh2_init (0);
+    if (rc != 0) {
+        fprintf (stderr, "libssh2 initialization failed (%d)\n", rc);
+        return 1;
+    }
+
+    /* Connect to SSH server */
+    sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+    sin.sin_family = AF_INET;
+    if (INADDR_NONE == (sin.sin_addr.s_addr = inet_addr(server_ip))) {
+        fprintf(stderr, "inet_addr: Invalid IP address \"%s\"\n", server_ip);
+        return -1;
+    }
+    sin.sin_port = htons(830);
+    if (connect(sock, (struct sockaddr*)(&sin),
+                sizeof(struct sockaddr_in)) != 0) {
+        fprintf(stderr, "Failed to connect to %s!\n", inet_ntoa(sin.sin_addr));
+        return -1;
+    }
+
+    /* Create a session instance */
+    session = libssh2_session_init();
+    if(!session) {
+        fprintf(stderr, "Could not initialize SSH session!\n");
+        return -1;
+    }
+
+    /* ... start it up. This will trade welcome banners, exchange keys,
+     * and setup crypto, compression, and MAC layers
+     */
+    rc = libssh2_session_startup(session, sock);
+    if(rc) {
+        fprintf(stderr, "Error when starting up SSH session: %d\n", rc);
+        return -1;
+    }
+
+    /* At this point we havn't yet authenticated.  The first thing to do
+     * is check the hostkey's fingerprint against our known hosts Your app
+     * may have it hard coded, may go to a file, may present it to the
+     * user, that's your call
+     */
+    fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
+    fprintf(stderr, "Fingerprint: ");
+    for(i = 0; i < 20; i++)
+        fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
+    fprintf(stderr, "\n");
+
+    /* check what authentication methods are available */
+    userauthlist = libssh2_userauth_list(session, username, strlen(username));
+    printf("Authentication methods: %s\n", userauthlist);
+    if (strstr(userauthlist, "password"))
+        auth |= AUTH_PASSWORD;
+    if (strstr(userauthlist, "publickey"))
+        auth |= AUTH_PUBLICKEY;
+
+    /* check for options */
+    if(argc > 4) {
+        if ((auth & AUTH_PASSWORD) && !strcasecmp(argv[4], "-p"))
+            auth = AUTH_PASSWORD;
+        if ((auth & AUTH_PUBLICKEY) && !strcasecmp(argv[4], "-k"))
+            auth = AUTH_PUBLICKEY;
+    }
+
+    if (auth & AUTH_PASSWORD) {
+        if (libssh2_userauth_password(session, username, password)) {
+            fprintf(stderr, "Authentication by password failed.\n");
+            goto shutdown;
+        }
+    } else if (auth & AUTH_PUBLICKEY) {
+        if (libssh2_userauth_publickey_fromfile(session, username, keyfile1,
+                                                keyfile2, password)) {
+            printf("Authentication by public key failed!\n");
+            goto shutdown;
+        }
+        printf("Authentication by public key succeeded.\n");
+    } else {
+        printf("No supported authentication methods found!\n");
+        goto shutdown;
+    }
+
+    /* open a channel */
+    channel = libssh2_channel_open_session(session);
+    if (!channel) {
+        fprintf(stderr, "Could not open the channel!\n"
+                "(Note that this can be a problem at the server!"
+                " Please review the server logs.)\n");
+        goto shutdown;
+    }
+
+    /* execute the subsystem on our channel */
+    if (libssh2_channel_subsystem(channel, "netconf")) {
+        fprintf(stderr, "Could not execute the \"netconf\" subsystem!\n"
+                "(Note that this can be a problem at the server!"
+                " Please review the server logs.)\n");
+        goto shutdown;
+    }
+
+    /* NETCONF: http://tools.ietf.org/html/draft-ietf-netconf-ssh-06 */
+
+    printf("Sending NETCONF client <hello>\n");
+    snprintf(buf, sizeof(buf),
+      "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+      "<hello>"
+      "<capabilities>"
+      "<capability>urn:ietf:params:xml:ns:netconf:base:1.0</capability>"
+      "</capabilities>"
+      "</hello>\n"
+      "]]>]]>\n%n", &len);
+    if (-1 == netconf_write(channel, buf, len))
+        goto shutdown;
+
+    printf("Reading NETCONF server <hello>\n");
+    if (-1 == netconf_read_until(channel, "</hello>", buf, sizeof(buf)))
+        goto shutdown;
+
+    printf("Got %d bytes:\n----------------------\n%s", len, buf);
+
+    printf("Sending NETCONF <rpc>\n");
+    snprintf(buf, sizeof(buf),
+      "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+      "<rpc xmlns=\"urn:ietf:params:xml:ns:netconf:base:1.0\">"
+      "<get-interface-information><terse/></get-interface-information>"
+      "</rpc>\n"
+      "]]>]]>\n%n", &len);
+    if (-1 == netconf_write(channel, buf, len))
+        goto shutdown;
+
+    printf("Reading NETCONF <rpc-reply>\n");
+    len = netconf_read_until(channel, "</rpc-reply>", buf, sizeof(buf));
+    if (-1 == len)
+        goto shutdown;
+
+    printf("Got %d bytes:\n----------------------\n%s", len, buf);
+
+shutdown:
+    if (channel)
+        libssh2_channel_free(channel);
+    libssh2_session_disconnect(session, "Client disconnecting normally");
+    libssh2_session_free(session);
+
+#ifdef WIN32
+    closesocket(sock);
+#else
+    close(sock);
+#endif
+
+    libssh2_exit();
+
+    return 0;
+}