From 08c7d67face0e504ae52a021206c3002f991d600 Mon Sep 17 00:00:00 2001
From: Manas Trivedi <manas.trivedi.020@gmail.com>
Date: Tue, 24 Mar 2026 15:26:44 +0000
Subject: [PATCH] examples: replace atoi() with strtol() for safe number
 parsing

Replace all usages on atoi() in examples with strtol() and add validation
for the same.

Signed-off-by: Manas Trivedi <manas.trivedi.020@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
---
 examples/samplesshd-kbdint.c | 12 ++++++------
 examples/sshnetcat.c         | 29 ++++++++++++++++++++++++++---
 2 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/examples/samplesshd-kbdint.c b/examples/samplesshd-kbdint.c
index 919eb338..9d6e0539 100644
--- a/examples/samplesshd-kbdint.c
+++ b/examples/samplesshd-kbdint.c
@@ -40,7 +40,7 @@ clients must be made or how a client should react.
 #endif
 #endif
 
-static int port = 22;
+static const char* port = "22";
 static bool authenticated = false;
 
 #ifdef WITH_PCAP
@@ -139,10 +139,10 @@ static error_t parse_opt (int key, char *arg, struct argp_state *state) {
   ssh_bind sshbind = state->input;
 
   switch (key) {
-    case 'p':
-      ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDPORT_STR, arg);
-      port = atoi(arg);
-      break;
+    case 'p': 
+        ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDPORT_STR, arg);
+        port = arg;
+        break;
     case 'r':
     case 'k':
       ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_HOSTKEY, arg);
@@ -315,7 +315,7 @@ int main(int argc, char **argv)
         printf("Error listening to socket: %s\n", ssh_get_error(sshbind));
         return 1;
     }
-    printf("Started sample libssh sshd on port %d\n", port);
+    printf("Started sample libssh sshd on port %s\n", port);
     printf("You can login as the user %s with the password %s\n", SSHD_USER,
                                                             SSHD_PASSWORD);
     r = ssh_bind_accept(sshbind, session);
diff --git a/examples/sshnetcat.c b/examples/sshnetcat.c
index 3dba51e8..3df7f335 100644
--- a/examples/sshnetcat.c
+++ b/examples/sshnetcat.c
@@ -41,6 +41,7 @@ clients must be made or how a client should react.
 
 char *host = NULL;
 const char *desthost = "localhost";
+static int port_num = 22;
 const char *port = "22";
 
 #ifdef WITH_PCAP
@@ -74,8 +75,23 @@ static int opts(int argc, char **argv)
         host = argv[optind++];
     if (optind < argc)
         desthost = argv[optind++];
-    if (optind < argc)
-        port = argv[optind++];
+    if (optind < argc) {
+        char *endptr = NULL;
+        long tmp;
+
+        errno = 0;
+        tmp = strtol(argv[optind], &endptr, 10);
+
+        if (errno != 0 || endptr == argv[optind] || *endptr != '\0' ||
+            tmp < 0 || tmp > 65535) {
+            fprintf(stderr, "Invalid port: %s\n", argv[optind]);
+            usage();
+        }
+
+        port = argv[optind];
+        port_num = (int)tmp;
+        optind++;
+    }
     if (host == NULL)
         usage();
     return 0;
@@ -192,12 +208,19 @@ static void forwarding(ssh_session session)
 {
     ssh_channel channel;
     int r;
+
     channel = ssh_channel_new(session);
-    r = ssh_channel_open_forward(channel, desthost, atoi(port), "localhost", 22);
+
+    r = ssh_channel_open_forward(channel,
+                                 desthost,
+                                 port_num,
+                                 "localhost",
+                                 22);
     if (r < 0) {
         printf("error forwarding port : %s\n", ssh_get_error(session));
         return;
     }
+
     select_loop(session, channel);
 }