From 8a61b74ec1eb5cc959cac9e1004545fe4703f035 Mon Sep 17 00:00:00 2001
From: Walter Doekes <walter+github@wjd.nu>
Date: Tue, 23 Apr 2024 11:20:08 +0200
Subject: [PATCH] Band-aid around missing line numbers in XML parse errors

Suggested and reviewed by Michael Stovenour (@mstovenour).
Closes: #721 (along with #725)
---
 include/xp_parser.h |  1 +
 src/scenario.cpp    |  3 ++-
 src/xp_parser.c     | 54 ++++++++++++++++++++++++++++++++++++---------
 3 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/include/xp_parser.h b/include/xp_parser.h
index b9d5bd615..663e08d85 100644
--- a/include/xp_parser.h
+++ b/include/xp_parser.h
@@ -29,6 +29,7 @@ int xp_set_xml_buffer_from_file(const char *filename);
 char* xp_open_element(int index);
 void xp_close_element(void);
 int xp_is_invalid();
+int xp_get_invalid_line();
 const char* xp_get_value(const char *name);
 char* xp_get_cdata(void);
 int xp_get_content_length(const char *P_buffer);
diff --git a/src/scenario.cpp b/src/scenario.cpp
index 0ab5757da..e0e3915b5 100644
--- a/src/scenario.cpp
+++ b/src/scenario.cpp
@@ -1026,7 +1026,8 @@ scenario::scenario(char * filename, int deflt)
     /* Close scenario element */
     xp_close_element();
     if (xp_is_invalid()) {
-        ERROR("Invalid XML in scenario. See: https://github.com/SIPp/sipp/issues/414");
+        ERROR("Invalid XML in scenario near line %d. See: https://github.com/SIPp/sipp/issues/414",
+                xp_get_invalid_line());
     }
 
     str_int_map::iterator label_it = labelMap.find("_unexp.main");
diff --git a/src/xp_parser.c b/src/xp_parser.c
index 0c40d2315..26cb06a75 100644
--- a/src/xp_parser.c
+++ b/src/xp_parser.c
@@ -51,7 +51,7 @@
 static char  xp_file[XP_MAX_FILE_LEN + 1];
 static char *xp_position[XP_MAX_STACK_LEN];
 static int   xp_stack = 0;
-static int   xp_stack_invalid = 0;
+static int   xp_stack_invalid_line = 0;
 
 static char  xp_history[XP_MAX_FILE_LEN + 1];
 static char *xp_history_pos;
@@ -119,6 +119,27 @@ static const char *xp_find_escape(const char *escape, size_t len)
     return NULL;
 }
 
+static int xp_get_lineno(const char *endpos)
+{
+    const char *p = xp_file;
+    int lf_count = 0;
+
+    if (p < xp_file || p > xp_file + sizeof(xp_file)) {
+        return -1;
+    }
+
+    while (p < endpos) {
+        if (*p == '\n') {
+            lf_count += 1;
+        } else if (*p == '\0') {
+            break;
+        }
+        ++p;
+    }
+
+    return lf_count + 1;
+}
+
 #if 0
 static void xp_history_debug() {
     char *p = &xp_history[0];
@@ -280,7 +301,7 @@ int xp_set_xml_buffer_from_string(const char *str)
     }
 
     strcpy(xp_file, str);
-    xp_stack = xp_stack_invalid = 0;
+    xp_stack = xp_stack_invalid_line = 0;
     xp_history_reset();
     xp_position[xp_stack] = xp_file;
 
@@ -310,7 +331,7 @@ int xp_set_xml_buffer_from_file(const char *filename)
         xp_file[index++] = c;
         if (index >= XP_MAX_FILE_LEN) {
             xp_file[index++] = 0;
-            xp_stack = xp_stack_invalid = 0;
+            xp_stack = xp_stack_invalid_line = 0;
             xp_history_reset();
             xp_position[xp_stack] = xp_file;
             fclose(f);
@@ -320,7 +341,7 @@ int xp_set_xml_buffer_from_file(const char *filename)
     xp_file[index++] = 0;
     fclose(f);
 
-    xp_stack = xp_stack_invalid = 0;
+    xp_stack = xp_stack_invalid_line = 0;
     xp_history_reset();
     xp_position[xp_stack] = xp_file;
 
@@ -382,10 +403,10 @@ char *xp_open_element(int index)
                     return NULL;
 
                 xp_history_pop();
-                if (strcmp(xp_history_pos + 1, name) && !xp_stack_invalid) {
-                    xp_stack_invalid = 1;
-                    fprintf(stderr, "Unexpected </%s> (expected </%s>)\n",
-                        name, xp_history_pos + 1);
+                if (strcmp(xp_history_pos + 1, name) && !xp_stack_invalid_line) {
+                    xp_stack_invalid_line = xp_get_lineno(ptr);
+                    fprintf(stderr, "Unexpected </%s> (expected </%s>) near line %d\n",
+                        name, xp_history_pos + 1, xp_stack_invalid_line);
                 }
             } else {
                 char *end = xp_find_start_tag_end(ptr + 1);
@@ -422,7 +443,7 @@ char *xp_open_element(int index)
 void xp_close_element()
 {
     if (!xp_stack) {
-        xp_stack_invalid = 1;
+        xp_stack_invalid_line = -1;
         return;
     }
     xp_stack--;
@@ -431,10 +452,12 @@ void xp_close_element()
 int xp_is_invalid(void)
 {
     const char *elem;
-    if (xp_stack_invalid) {
+    if (xp_stack_invalid_line) {
+        /* Found different closing element */
         return 1;
     }
     if (xp_stack) {
+        /* Does not happen because main parser never goes deep */
         return 1;
     }
     if ((elem = xp_open_element(1))) { /* anything after <scenario>? */
@@ -444,6 +467,17 @@ int xp_is_invalid(void)
     return 0;
 }
 
+int xp_get_invalid_line(void)
+{
+    if (xp_stack_invalid_line) {
+        return xp_stack_invalid_line;
+    } else if (xp_stack == 0) {
+        return xp_get_lineno(xp_position[1]);
+    } else {
+        return -1;
+    }
+}
+
 const char *xp_get_value(const char *name)
 {
     int index = 0;