Interpret the \i and \x escape sequences to insert the IP of the

requesting host

tftpd/remap.c

@@ -43,7 +43,8 @@ struct rule {
 };
 
 /* Do \-substitution.  Call with string == NULL to get length only. */
-static int genmatchstring(char *string, const char *pattern, const char *input, const regmatch_t *pmatch)
+static int genmatchstring(char *string, const char *pattern, const char *input,
+			  const regmatch_t *pmatch, match_pattern_callback macrosub)
 {
   int len = 0;
   int n, mlen;
@@ -60,11 +61,8 @@ static int genmatchstring(char *string, const char *pattern, const char *input,
   /* Transform matched section */
   while ( *pattern ) {
     if ( *pattern == '\\' && pattern[1] != '\0' ) {
-      if ( pattern[1] < '0' || pattern[1] > '9' ) {
-	len++;
-	if ( string )
-	  *string++ = pattern[1];
-      } else {
+      char macro = pattern[1];
+      if ( macro >= '0' && macro <= '9' ) {
 	n = pattern[1] - '0';
 	
 	if ( pmatch[n].rm_so != -1 ) {
@@ -75,6 +73,16 @@ static int genmatchstring(char *string, const char *pattern, const char *input,
 	    string += mlen;
 	  }
 	}
+      } else {
+	int sublen;
+	if ( macrosub &&
+	     (sublen = macrosub(macro, string)) >= 0 ) {
+	  len += sublen;
+	} else {
+	  len++;
+	  if ( string )
+	    *string++ = pattern[1];
+	}
       }
       pattern += 2;
     } else {
@@ -257,7 +265,8 @@ void freerules(struct rule *r)
 }
 
 /* Execute a rule set on a string; returns a malloc'd new string. */
-char *rewrite_string(const char *input, const struct rule *rules, int is_put)
+char *rewrite_string(const char *input, const struct rule *rules,
+		     int is_put, match_pattern_callback macrosub)
 {
   char *current = tfstrdup(input);
   char *newstr;
@@ -299,9 +308,11 @@ char *rewrite_string(const char *input, const struct rule *rules, int is_put)
 	}
 	
 	if ( ruleptr->rule_flags & RULE_REWRITE ) {
-	  len = genmatchstring(NULL, ruleptr->pattern, current, pmatch);
+	  len = genmatchstring(NULL, ruleptr->pattern, current,
+			       pmatch, macrosub);
 	  newstr = tfmalloc(len+1);
-	  genmatchstring(newstr, ruleptr->pattern, current, pmatch);
+	  genmatchstring(newstr, ruleptr->pattern, current,
+			 pmatch, macrosub);
 	  free(current);
 	  current = newstr;
 	  if ( verbosity >= 3 ) {

tftpd/remap.h

@@ -18,15 +18,17 @@
 #ifndef TFTPD_REMAP_H
 #define TFTPD_REMAP_H
 
-#include <stdlib.h>
-#include <stdio.h>
-#include "../config.h"
-
 /* Opaque type */
 struct rule;
 
 #ifdef WITH_REGEX
 
+/* This is called when we encounter a substitution like \i.  The
+   macro character is passed as the first argument; the output buffer,
+   if any, is passed as the second argument.  The function should return
+   the number of characters output, or -1 on failure. */
+typedef int (*match_pattern_callback)(char, char *);
+
 /* Read a rule file */
 struct rule *parserulefile(FILE *);
 
@@ -34,7 +36,8 @@ struct rule *parserulefile(FILE *);
 void freerules(struct rule *);
 
 /* Execute a rule set on a string; returns a malloc'd new string. */
-char *rewrite_string(const char *, const struct rule *, int);
+char *rewrite_string(const char *, const struct rule *, int,
+		     match_pattern_callback);
 
 #endif /* WITH_REGEX */
 #endif /* TFTPD_REMAP_H */

tftpd/tftpd.8

@@ -177,12 +177,7 @@ Replace the substring matched by
 .I regex
 by the
 .IR "replacement pattern" .
-The escape sequence
-\\0
-can be used to copy the entire matched string, and the sequences
-\\1 to \\9
-copies parenthesized subexpressions.  To specify a backslash, white
-space or hash mark, you need to \\-escape it.
+The replacement pattern may contain escape sequences; see below.
 .TP
 .B g
 Repeat this rule until it no longer matches.  This is always used with
@@ -210,6 +205,35 @@ This rule applies to GET (RRQ) requests only.
 .B P
 This rule applies to PUT (WRQ) requests only.
 .PP
+The following escape sequences are recognized as part of the
+.IR "replacement pattern" :
+.TP
+\fB\\0\fP
+The entire string matched by the
+.IR regex .
+.TP
+\fB\\1\fP to \fB\\9\fP
+Match the first nine parentensized subexpressions, \\( ... \\) of the
+.I regex
+pattern.
+.TP
+\fB\\i\fP
+The IP address of the requesting host, in dotted-quad notation
+(e.g. 192.0.2.169).
+.TP
+\fB\\x\fP
+The IP address of the requesting host, in hexadecimal notation
+(e.g. C00002A9).
+.TP
+\fB\\\fP
+Literal backslash.
+.TP
+\fB\\\fP\fIwhitespace\fP
+Literal whitespace.
+.TP
+\fB\\#\fI
+Literal hash mark.
+.PP
 If the mapping file is changed, you need to send
 .B SIGHUP
 to any outstanding

tftpd/tftpd.c

@@ -779,23 +779,64 @@ do_opt(char *opt, char *val, char **ap)
   return;
 }
 
+#ifdef WITH_REGEX
+
+/*
+ * This is called by the remap engine when it encounters macros such
+ * as \i.  It should write the output in "output" if non-NULL, and
+ * return the length of the output (generated or not).
+ *
+ * Return -1 on failure.
+ */
+int
+rewrite_macros(char macro, char *output);
+
+int
+rewrite_macros(char macro, char *output)
+{
+  char *p;
+
+  switch (macro) {
+  case 'i':
+    p = inet_ntoa(from.sin_addr);
+    if ( output )
+      strcpy(output, p);
+    return strlen(p);
+    
+  case 'x':
+    if ( output )
+      sprintf(output, "%08X",
+	      ntohl(from.sin_addr.s_addr));
+    return 8;
+
+  default:
+    return -1;
+  }
+}
+
 /*
  * Modify the filename, if applicable.  If it returns NULL, deny the access.
  */
 char *
 rewrite_access(char *filename, int mode)
 {
-#ifdef WITH_REGEX
   if ( rewrite_rules ) {
-    char *newname = rewrite_string(filename, rewrite_rules, mode != RRQ);
+    char *newname = rewrite_string(filename, rewrite_rules,
+				   mode != RRQ, rewrite_macros);
     filename = newname;
   }
-#else
-  (void)mode;			/* Suppress unused warning */
-#endif
   return filename;
 }
 
+#else
+char *
+rewrite_access(char *filename, int mode)
+{
+  (void)mode;			/* Avoid warning */
+  return filename;
+}
+#endif
+
 FILE *file;
 /*
  * Validate file access.  Since we