From 75e95789179b2efac88fd0f8d6555722695e3f94 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Mon, 26 Mar 2018 18:21:03 +0200
Subject: prepare for different payload dissectors

---
 utils.c | 129 +++++++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 88 insertions(+), 41 deletions(-)

(limited to 'utils.c')

diff --git a/utils.c b/utils.c
index 0c763bc..55499af 100644
--- a/utils.c
+++ b/utils.c
@@ -3,36 +3,77 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <string.h>
 
 #include "utils.h"
 
 #define MAX_UNIX_FDS	32
 
-#define LOG(fmt, args ...) \
-	fprintf(stderr, ">>> UDTRACE: " fmt, ## args)
-
 /***********************************************************************
  * Utility functions
  ***********************************************************************/
 
-static int unix_fds[MAX_UNIX_FDS];
+/* taken from libosmocore */
+static char hexd_buff[4096];
+static const char hex_chars[] = "0123456789abcdef";
+static char *hexdump(const unsigned char *buf, int len, char *delim)
+{
+	int i;
+	char *cur = hexd_buff;
 
-__attribute__ ((constructor)) static void udtrace_init(void) {
+	hexd_buff[0] = 0;
+	for (i = 0; i < len; i++) {
+		const char *delimp = delim;
+		int len_remain = sizeof(hexd_buff) - (cur - hexd_buff);
+		if (len_remain < 3)
+			break;
+
+		*cur++ = hex_chars[buf[i] >> 4];
+		*cur++ = hex_chars[buf[i] & 0xf];
+
+		while (len_remain > 1 && *delimp) {
+			*cur++ = *delimp++;
+			len_remain--;
+		}
+
+		*cur = 0;
+	}
+	hexd_buff[sizeof(hexd_buff)-1] = 0;
+	return hexd_buff;
+}
+
+typedef void (*udtrace_dissector)(int fd, bool is_out, const char *fn, const uint8_t *data, unsigned int len);
+
+static void default_dissector(int fd, bool is_out, const char *fn, const uint8_t *data, unsigned int len)
+{
+	fprintf(stderr, "%d %s %c %s\n", fd, fn, is_out ? 'W' : 'R', hexdump(data, len, ""));
+}
+
+struct sock_state {
+	int fd;
+	const char *path;
+	udtrace_dissector dissector;
+};
+
+static struct sock_state unix_fds[MAX_UNIX_FDS];
+
+__attribute__ ((constructor)) static void udtrace_init(void)
+{
 	int i;
 	LOG("Unix Domain Socket Trace initialized\n");
 	for (i = 0; i < ARRAY_SIZE(unix_fds); i++) {
-		unix_fds[i] = -1;
+		unix_fds[i] = (struct sock_state) { -1, NULL, NULL };
 	}
 }
 
 /* add a file descriptor from the list of to-be-traced ones */
-void add_fd(int fd)
+void udtrace_add_fd(int fd)
 {
 	int i;
 	for (i = 0; i < ARRAY_SIZE(unix_fds); i++) {
-		if (unix_fds[i] == -1) {
+		if (unix_fds[i].fd == -1) {
 			LOG("Adding FD %d\n", fd);
-			unix_fds[i] = fd;
+			unix_fds[i].fd = fd;
 			return;
 		}
 	}
@@ -40,56 +81,62 @@ void add_fd(int fd)
 }
 
 /* delete a file descriptor from the list of to-be-traced ones */
-void del_fd(int fd)
+void udtrace_del_fd(int fd)
 {
 	int i;
 	for (i = 0; i < ARRAY_SIZE(unix_fds); i++) {
-		if (unix_fds[i] == fd) {
+		if (unix_fds[i].fd == fd) {
 			LOG("Removing FD %d\n", fd);
-			unix_fds[i] = -1;
+			free((void *) unix_fds[i].path);
+			unix_fds[i] = (struct sock_state) { -1, NULL, NULL };
 			return;
 		}
 	}
 	LOG("Couldn't delete UNIX FD %d (no such FD)\n", fd);
 }
 
-/* is the given file descriptor part of the to-be-traced unix domain fd's? */
-bool is_unix_socket(int fd)
+static void udtrace_resolve_dissector(struct sock_state *ss)
+{
+	/* FIXME: actual useful dissectors resovled by path */
+	ss->dissector = &default_dissector;
+}
+
+/* set the path of a given fd */
+void udtrace_fd_set_path(int fd, const char *path)
 {
 	int i;
 	for (i = 0; i < ARRAY_SIZE(unix_fds); i++) {
-		if (unix_fds[i] == fd)
-			return true;
+		if (unix_fds[i].fd == fd) {
+			unix_fds[i].path = strdup(path);
+			udtrace_resolve_dissector(&unix_fds[i]);
+			return;
+		}
 	}
-	return false;
 }
 
-
-/* taken from libosmocore */
-static char hexd_buff[4096];
-static const char hex_chars[] = "0123456789abcdef";
-char *udtrace_hexdump(const unsigned char *buf, int len, char *delim)
+const struct sock_state *udtrace_sstate_by_fd(int fd)
 {
 	int i;
-	char *cur = hexd_buff;
-
-	hexd_buff[0] = 0;
-	for (i = 0; i < len; i++) {
-		const char *delimp = delim;
-		int len_remain = sizeof(hexd_buff) - (cur - hexd_buff);
-		if (len_remain < 3)
-			break;
-
-		*cur++ = hex_chars[buf[i] >> 4];
-		*cur++ = hex_chars[buf[i] & 0xf];
+	for (i = 0; i < ARRAY_SIZE(unix_fds); i++) {
+		if (unix_fds[i].fd == fd)
+			return &unix_fds[i];
+	}
+	return NULL;
+}
 
-		while (len_remain > 1 && *delimp) {
-			*cur++ = *delimp++;
-			len_remain--;
-		}
+/* is the given file descriptor part of the to-be-traced unix domain fd's? */
+bool is_unix_socket(int fd)
+{
+	if (udtrace_sstate_by_fd(fd))
+		return true;
+	else
+		return false;
+}
 
-		*cur = 0;
-	}
-	hexd_buff[sizeof(hexd_buff)-1] = 0;
-	return hexd_buff;
+void udtrace_data(int fd, bool is_out, const char *fn, const uint8_t *data, unsigned int len)
+{
+	const struct sock_state *ss = udtrace_sstate_by_fd(fd);
+	if (!data || !len || !ss)
+		return;
+	ss->dissector(fd, is_out, fn, data, len);
 }
-- 
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