[PATCH] examples: add public key auth for specific key

[Eric Bentley <ebentley66@xxxxxxxxx>]

There was no example of using a specific key for authentication so I added
one.

Eric Bentley (1):
  examples: add public key auth for specific key

 examples/authentication.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

-- 
2.6.0.GITFrom 044f825eb5480a6f0d32f3f83836230e577589a4 Mon Sep 17 00:00:00 2001
From: Eric Bentley <ebentley66@xxxxxxxxx>
Date: Mon, 27 Nov 2017 12:56:29 -0500
Subject: [PATCH] examples: add public key auth for specific key

Signed-off-by: ebentley66@xxxxxxxxx
---
 examples/authentication.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/examples/authentication.c b/examples/authentication.c
index b9f70f5..89459e4 100644
--- a/examples/authentication.c
+++ b/examples/authentication.c
@@ -99,6 +99,39 @@ int authenticate_kbdint(ssh_session session, const char *password) {
     return err;
 }
 
+static int auth_keyfile(ssh_session session, char* keyfile)
+{
+  ssh_key key = NULL;
+  char pubkey[132]; // +".pub"
+  int rc;
+
+  snprintf(pubkey, 132, "%s.pub", keyfile);
+
+  rc = ssh_pki_import_pubkey_file( pubkey, &key);
+
+  if (rc != SSH_OK)
+    return SSH_AUTH_DENIED;
+
+  rc = ssh_userauth_try_publickey(session, NULL, key);
+
+  ssh_key_free(key);
+
+  if (rc!=SSH_AUTH_SUCCESS)
+    return SSH_AUTH_DENIED;
+
+  rc = ssh_pki_import_privkey_file(keyfile, NULL, NULL, NULL, &key);
+
+  if (rc != SSH_OK)
+    return SSH_AUTH_DENIED;
+
+  rc = ssh_userauth_publickey(session, NULL, key);
+
+  ssh_key_free(key);
+
+  return rc;
+}
+
+
 static void error(ssh_session session){
 	fprintf(stderr,"Authentication failed: %s\n",ssh_get_error(session));
 }
@@ -136,6 +169,34 @@ int authenticate_console(ssh_session session){
       } else if (rc == SSH_AUTH_SUCCESS) {
         break;
       }
+      {
+        char buffer[128] = {0};
+        char *p = NULL;
+
+        printf("auto failed.  Do you want to try a specific key? (y/n)\n");
+        if (fgets(buffer, sizeof(buffer), stdin) == NULL) {
+          break;
+        }
+        if ((buffer[0]=='Y') || (buffer[0]=='y')) {
+          printf("private key filename: ");
+
+          if (fgets(buffer, sizeof(buffer), stdin) == NULL) {
+            return SSH_AUTH_ERROR;
+          }
+
+          buffer[sizeof(buffer) - 1] = '\0';
+          if ((p = strchr(buffer, '\n'))) {
+            *p = '\0';
+          }
+
+          rc = auth_keyfile(session, buffer);
+
+          if(rc == SSH_AUTH_SUCCESS) {
+            break;
+          }
+          fprintf(stderr, "failed with key\n");
+        }
+      }
     }
 
     // Try to authenticate with keyboard interactive";
-- 
2.6.0.GIT