[PATCH 16/16] runopts: Re-introduce the `get_user_name()' function from `scp' development

[Michael Witten]

Date: Sun, 8 Nov 2015 04:15:38 -0000
The command `scp' originally handled user name parsing on its own, including
the retrieval of the current user's name when no user name is specified.

The `get_user_name()' function was developed to retrieve the current user's
name lazily (on demand), so as not to waste cycles when a user name is
*explicitly* specified. Furthermore, there was a warning message (actually,
a fatal error message) produced when it was impossible to retrieve the
current user's name; this message was eventually stripped out because it was
relatively useless and takes up space.

Ultimately, though, all of the `[user@]host' parsing machinery was ripped
out of `scp', because it is already handled by `dropbear/dbclient'. However,
as it turns out, this centralized machinery could also benefit from the same
changes that were made for `scp'; hence, this commit re-introduces the
`get_user_name()' function (albeit for use by `dropbear/dbclient' instead),
including the removal of the relatively useless warning message.

This function has been added to `cli-runopts.c', because the current user's
name represents part of the invocation context (i.e., part of the runtime
options); by including the declaration in `runopts.h', it automatically
becomes visible where it is needed.
---
 cli-main.c       |  2 +-
 cli-runopts.c    | 32 ++++++++++++--------------------
 common-session.c |  1 +
 runopts.h        |  2 +-
 4 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/cli-main.c b/cli-main.c
index c7c9035..a811312 100644
--- a/cli-main.c
+++ b/cli-main.c
@@ -135,7 +135,7 @@ static void exec_proxy_cmd(void *user_data_cmd) {
 static void cli_proxy_cmd(int *sock_in, int *sock_out) {
 	int ret;
 
-	fill_passwd(cli_opts.own_user);
+	fill_passwd(get_user_name());
 
 	ret = spawn_command(exec_proxy_cmd, cli_opts.proxycmd,
 			sock_out, sock_in, NULL, NULL);
diff --git a/cli-runopts.c b/cli-runopts.c
index c4cd12c..34cad00 100644
--- a/cli-runopts.c
+++ b/cli-runopts.c
@@ -36,7 +36,6 @@ cli_runopts cli_opts; /* GLOBAL */
 static void printhelp();
 static void parse_hostname(const char* orighostarg);
 static void parse_multihop_hostname(const char* orighostarg, const char* argv0);
-static void fill_own_user();
 #ifdef ENABLE_CLI_PUBKEY_AUTH
 static void loadidentityfile(const char* filename, int warnfail);
 #endif
@@ -102,6 +101,17 @@ static void printhelp() {
 					
 }
 
+const char *get_user_name() {
+	static const char *user_name = NULL;
+
+	if (user_name == NULL) {
+		struct passwd *pwd = getpwuid(getuid());
+		user_name = pwd ? m_strdup(pwd->pw_name) : "unknown";
+	}
+
+	return user_name;
+}
+
 void cli_getopts(int argc, char ** argv) {
 	unsigned int i, j;
 	char ** next = 0;
@@ -175,8 +185,6 @@ void cli_getopts(int argc, char ** argv) {
 	opts.keepalive_secs = DEFAULT_KEEPALIVE;
 	opts.idle_timeout_secs = DEFAULT_IDLE_TIMEOUT;
 
-	fill_own_user();
-
 	for (i = 1; i < (unsigned int)argc; i++) {
 		/* Handle non-flag arguments such as hostname or commands for the remote host */
 		if (argv[i][0] != '-')
@@ -640,7 +648,7 @@ static void parse_hostname(const char* orighostarg) {
 	}
 
 	if (cli_opts.username == NULL) {
-		cli_opts.username = m_strdup(cli_opts.own_user);
+		cli_opts.username = m_strdup(get_user_name());
 	}
 
 	port = strchr(cli_opts.remotehost, '^');
@@ -695,22 +703,6 @@ fail:
 }
 #endif
 
-static void fill_own_user() {
-	uid_t uid;
-	struct passwd *pw = NULL; 
-
-	uid = getuid();
-
-	pw = getpwuid(uid);
-	if (pw && pw->pw_name != NULL) {
-		cli_opts.own_user = m_strdup(pw->pw_name);
-	} else {
-		dropbear_log(LOG_INFO, "Warning: failed to identify current user. Trying anyway.");
-		cli_opts.own_user = "unknown";
-	}
-
-}
-
 #ifdef ENABLE_CLI_ANYTCPFWD
 /* Turn a "[listenaddr:]listenport:remoteaddr:remoteport" string into into a forwarding
  * set, and add it to the forwarding list */
diff --git a/common-session.c b/common-session.c
index 874d539..dd818b2 100644
--- a/common-session.c
+++ b/common-session.c
@@ -581,6 +581,7 @@ const char* get_user_shell() {
 		return ses.authstate.pw_shell;
 	}
 }
+
 void fill_passwd(const char* username) {
 	struct passwd *pw = NULL;
 	if (ses.authstate.pw_name)
diff --git a/runopts.h b/runopts.h
index 0a97937..654d6d4 100644
--- a/runopts.h
+++ b/runopts.h
@@ -127,7 +127,6 @@ typedef struct cli_runopts {
 	char *remotehost;
 	char *remoteport;
 
-	const char *own_user;
 	char *username;
 
 	char *cmd;
@@ -165,6 +164,7 @@ typedef struct cli_runopts {
 
 extern cli_runopts cli_opts;
 void cli_getopts(int argc, char ** argv);
+const char *get_user_name();
 
 #ifdef ENABLE_USER_ALGO_LIST
 void parse_ciphers_macs();