intercept attempts to execute "scp", and redirect them to the builtin scp

NOTES

@@ -72,7 +72,6 @@ it uses select(), I'm not sure how I would honor Thread.interrupt() or
 whatever.  It's not guaranteed to interrupt select(), and I'm not keen on
 adding an arbitrary timeout/polling feature to it.
 
-XXX - scp
 XXX - zlib
 XXX - rsync
 

dropbear/dbutil.c

@@ -574,10 +574,27 @@ int spawn_command(void(*exec_fn)(void *user_data), void *exec_data,
  * re-enabled SIGPIPE. If cmd is NULL, will run a login shell.
  */
 void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell) {
-	char * argv[4];
+	char * argv[100];
 	char * baseshell = NULL;
 	unsigned int i;
 
+	/* Re-enable SIGPIPE for the executed process */
+	if (signal(SIGPIPE, SIG_DFL) == SIG_ERR) {
+		dropbear_exit("signal() error");
+	}
+
+	/* close file descriptors except stdin/stdout/stderr
+	 * Need to be sure FDs are closed here to avoid reading files as root */
+	for (i = 3; i <= maxfd; i++) {
+		m_close(i);
+	}
+
+	if (cmd && !strncmp(cmd, "scp ", 4)) {
+		int argc = split_cmd(cmd, argv, sizeof argv/sizeof argv[0]);
+		scp_main(argc, argv);
+		exit(0);
+	}
+
 	baseshell = basename(usershell);
 
 	if (cmd != NULL) {
@@ -598,17 +615,6 @@ void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell) {
 		argv[1] = NULL;
 	}
 
-	/* Re-enable SIGPIPE for the executed process */
-	if (signal(SIGPIPE, SIG_DFL) == SIG_ERR) {
-		dropbear_exit("signal() error");
-	}
-
-	/* close file descriptors except stdin/stdout/stderr
-	 * Need to be sure FDs are closed here to avoid reading files as root */
-	for (i = 3; i <= maxfd; i++) {
-		m_close(i);
-	}
-
 	execv(usershell, argv);
 }
 

dropbear/options.h

@@ -267,7 +267,7 @@ much traffic. */
 
 /* This is used by the scp binary when used as a client binary. If you're
  * not using the Dropbear client, you'll need to change it */
-#undef _PATH_SSH_PROGRAM
+#define _PATH_SSH_PROGRAM "/dev/null"
 
 /* Whether to log commands executed by a client. This only logs the 
  * (single) command sent to the server, not what a user did in a 

jni/Android.mk

@@ -449,6 +449,8 @@ DROPBEAR_SRCS := $(DROPBEAR_PATH)/atomicio.c \
 	$(DROPBEAR_PATH)/progressmeter.c \
 	$(DROPBEAR_PATH)/queue.c \
 	$(DROPBEAR_PATH)/rsa.c \
+	$(DROPBEAR_PATH)/scp.c \
+	$(DROPBEAR_PATH)/scpmisc.c \
 	$(DROPBEAR_PATH)/signkey.c \
 	$(DROPBEAR_PATH)/sshpty.c \
 	$(DROPBEAR_PATH)/svr-agentfwd.c \

jni/config.h

@@ -15,6 +15,7 @@
 #define HAVE_GETADDRINFO 1
 #define HAVE_FREEADDRINFO 1
 #define HAVE_GETNAMEINFO 1
+#define HAVE_FORK 1
 
 #define HAVE_BASENAME 1
 #define HAVE_NETINET_TCP_H 1
@@ -26,13 +27,17 @@
 
 #define DROPBEAR_SERVER 1
 #define DBMULTI_dropbear 1
+#define DBMULTI_scp 1
 #define DROPBEAR_MULTI 1
 
 
-extern const char *conf_path_file(const char *fn);	/* in jni/interface.c */
+/* in jni/interface.c: */
 extern const char *conf_path;
 extern const char *conf_shell;
 extern const char *conf_home;
+const char *conf_path_file(const char *fn);
+int split_cmd(const char *in, char **argv, int max_argc);
+
 
 
 #endif /* __CONFIG_H__ */

jni/interface.c

@@ -54,8 +54,8 @@ jni_init(JNIEnv *env_)
 }
 
 /* split str into argv entries, honoring " and \ (but nothing else) */
-static int
+int
-process_extra(const char *in, char **argv, int max_argc)
+split_cmd(const char *in, char **argv, int max_argc)
 {
 	char curr[1000];
 	int curr_len = 0;
@@ -63,6 +63,7 @@ process_extra(const char *in, char **argv, int max_argc)
 	int argc = 0;
 
 	if (!in) {
+		argv[argc] = NULL;
 		return 0;
 	}
 	while (1) {
@@ -71,7 +72,7 @@ process_extra(const char *in, char **argv, int max_argc)
 		    (!in_quotes && isspace(c))) {
 			if (curr_len) {
 				curr[curr_len] = 0;
-				if (argc+1 >= max_argc) {
+				if (argc+2 >= max_argc) {
 					break;
 				}
 				argv[argc++] = strdup(curr);
@@ -96,6 +97,7 @@ process_extra(const char *in, char **argv, int max_argc)
 			curr[curr_len++] = c;
 		}
 	}
+	argv[argc] = NULL;
 	return argc;
 }
 
@@ -158,7 +160,7 @@ Java_org_galexander_sshd_SimpleSSHDService_start_1sshd(JNIEnv *env_,
 			sprintf(argv[argc], "%d", (int)port);
 			argc++;
 		}
-		argc += process_extra(extra, &argv[argc],
+		argc += split_cmd(extra, &argv[argc],
 				(sizeof argv / sizeof *argv) - argc);
 		fprintf(stderr, "starting dropbear\n");
 		retval = dropbear_main(argc, argv);