feat(server): Add support for -o option argument in server example

Allow passing server configuration options via the -o flag and expose
ssh_bind_config_parse_string() as a public API.

Signed-off-by: Francesco <eferollo@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

examples/ssh_server.c

@@ -107,6 +107,14 @@ static struct argp_option options[] = {
         .doc   = "Set the authorized keys file.",
         .group = 0
     },
+    {
+        .name  = "option",
+        .key   = 'o',
+        .arg   = "OPTION",
+        .flags = 0,
+        .doc   = "Set server configuration option [-o OptionName=Value]",
+        .group = 0
+    },
     {
         .name  = "user",
         .key   = 'u',
@@ -158,6 +166,9 @@ parse_opt(int key, char *arg, struct argp_state *state)
     case 'a':
         strncpy(authorizedkeys, arg, DEF_STR_SIZE - 1);
         break;
+    case 'o':
+        ssh_bind_config_parse_string(sshbind, arg);
+        break;
     case 'u':
         strncpy(username, arg, sizeof(username) - 1);
         break;
@@ -194,7 +205,7 @@ parse_opt(int argc, char **argv, ssh_bind sshbind)
 {
     int key;
 
-    while((key = getopt(argc, argv, "a:e:k:p:P:r:u:v")) != -1) {
+    while((key = getopt(argc, argv, "a:e:k:o:p:P:r:u:v")) != -1) {
         if (key == 'p') {
             ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDPORT_STR, optarg);
         } else if (key == 'k') {
@@ -205,6 +216,8 @@ parse_opt(int argc, char **argv, ssh_bind sshbind)
             ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_HOSTKEY, optarg);
         } else if (key == 'a') {
             strncpy(authorizedkeys, optarg, DEF_STR_SIZE-1);
+        } else if (key == 'o') {
+            ssh_bind_config_parse_string(sshbind, optarg);
         } else if (key == 'u') {
             strncpy(username, optarg, sizeof(username) - 1);
         } else if (key == 'P') {
@@ -222,6 +235,7 @@ parse_opt(int argc, char **argv, ssh_bind sshbind)
                "libssh %s -- a Secure Shell protocol implementation\n"
                "\n"
                "  -a, --authorizedkeys=FILE  Set the authorized keys file.\n"
+               "  -o, --option=OPTION        Set server configuration option (e.g., -o OptionName=Value).\n"
                "  -e, --ecdsakey=FILE        Set the ecdsa key (deprecated alias for 'k').\n"
                "  -k, --hostkey=FILE         Set a host key.  Can be used multiple times.\n"
                "                             Implies no default keys.\n"

include/libssh/bind_config.h

@@ -66,16 +66,6 @@ enum ssh_bind_config_opcode_e {
  */
 int ssh_bind_config_parse_file(ssh_bind sshbind, const char *filename);
 
-/* @brief Parse configuration string and set the options to the given bind session
- *
- * @params[in] bind      The ssh bind session
- * @params[in] input     Null terminated string containing the configuration
- *
- * @returns    SSH_OK on successful parsing the configuration string,
- *             SSH_ERROR on error
- */
-int ssh_bind_config_parse_string(ssh_bind bind, const char *input);
-
 #ifdef __cplusplus
 }
 #endif

include/libssh/server.h

@@ -102,6 +102,8 @@ LIBSSH_API int ssh_bind_options_set(ssh_bind sshbind,
 LIBSSH_API int ssh_bind_options_parse_config(ssh_bind sshbind,
     const char *filename);
 
+LIBSSH_API int ssh_bind_config_parse_string(ssh_bind bind, const char *input);
+
 /**
  * @brief Start listening to the socket.
  *

src/bind_config.c

@@ -676,7 +676,9 @@ int ssh_bind_config_parse_file(ssh_bind bind, const char *filename)
     return 0;
 }
 
-/* @brief Parse configuration string and set the options to the given bind session
+/**
+ * @brief Parse configuration string and set the options to the given bind
+ * session
  *
  * @params[in] bind      The ssh bind session
  * @params[in] input     Null terminated string containing the configuration
@@ -713,21 +715,29 @@ int ssh_bind_config_parse_string(ssh_bind bind, const char *input)
         }
         if (c == NULL) {
             /* should not happen, would mean a string without trailing '\0' */
-            SSH_LOG(SSH_LOG_WARN, "No trailing '\\0' in config string");
+            ssh_set_error(bind,
+                          SSH_FATAL,
+                          "No trailing '\\0' in config string");
             return SSH_ERROR;
         }
         line_len = c - line_start;
         if (line_len > MAX_LINE_SIZE - 1) {
-            SSH_LOG(SSH_LOG_WARN,
+            ssh_set_error(bind,
-                    "Line %u too long: %zu characters",
+                          SSH_FATAL,
-                    line_num,
+                          "Line %u too long: %zu characters",
-                    line_len);
+                          line_num,
+                          line_len);
             return SSH_ERROR;
         }
         memcpy(line, line_start, line_len);
         line[line_len] = '\0';
         SSH_LOG(SSH_LOG_DEBUG, "Line %u: %s", line_num, line);
-        rv = ssh_bind_config_parse_line(bind, line, line_num, &parser_flags, seen, 0);
+        rv = ssh_bind_config_parse_line(bind,
+                                        line,
+                                        line_num,
+                                        &parser_flags,
+                                        seen,
+                                        0);
         if (rv < 0) {
             return SSH_ERROR;
         }

src/libssh.map

@@ -507,3 +507,9 @@ LIBSSH_4_11_0    # Released
         sshsig_verify;
 } LIBSSH_4_10_0;
 
+LIBSSH_AFTER_4_11_0
+{
+    global:
+        ssh_bind_config_parse_string;
+} LIBSSH_4_11_0;
+