Added reverse proxy support from Kim Holviala. His comments regarding

this addition follow:

  The patch implements a simple reverse proxy (with one funky extra
  feature). It has all the regular features: mapping remote servers to local
  namespace (ReversePath), disabling forward proxying (ReverseOnly) and HTTP
  redirect rewriting (ReverseBaseURL).

  The funky feature is this: You map Google to /google/ and the Google front
  page opens up fine. Type in stuff and click "Google Search" and you'll get
  an error from tinyproxy. Reason for this is that Google's form submits to
  "/search" which unfortunately bypasses our /google/ mapping (if they'd
  submit to "search" without the slash it would have worked ok). Turn on
  ReverseMagic and it starts working....

  ReverseMagic "hijacks" one cookie which it sends to the client browser.
  This cookie contains the current reverse proxy path mapping (in the above
  case /google/) so that even if the site uses absolute links the reverse
  proxy still knows where to map the request.

  And yes, it works. No, I've never seen this done before - I couldn't find
  _any_ working OSS reverse proxies, and the commercial ones I've seen try
  to parse the page and fix all links (in the above case changing "/search"
  to "/google/search"). The problem with modifying the html is that it might
  not be parsable (very common) or it might be encoded so that the proxy
  can't read it (mod_gzip or likes).

  Hope you like that patch. One caveat - I haven't coded with C in like
  three years so my code might be a bit messy.... There shouldn't be any
  security problems thou, but you never know. I did all the stuff out of my
  memory without reading any RFC's, but I tested everything with Moz, Konq,
  IE6, Links and Lynx and they all worked fine.

8 files changed, 279 insertions, 30 deletions

diff --git a/src/conns.c b/src/conns.c
index 6a320ac..4420721 100644
--- a/src/conns.c
+++ b/src/conns.c
@@ -1,4 +1,4 @@
-/* $Id: conns.c,v 1.19 2003-08-01 00:14:34 rjkaes Exp $
+/* $Id: conns.c,v 1.20 2004-01-26 19:11:51 rjkaes Exp $
  *
  * Create and free the connection structure. One day there could be
  * other connection related tasks put here, but for now the header
@@ -76,6 +76,10 @@ initialize_conn(int client_fd, const char* ipaddr, const char* string_addr)
 
 	update_stats(STAT_OPEN);
 
+#ifdef REVERSE_SUPPORT
+	connptr->reversepath = NULL;
+#endif
+
 	return connptr;
 
 error_exit:
@@ -123,6 +127,11 @@ destroy_conn(struct conn_s *connptr)
 	if (connptr->client_string_addr)
 		safefree(connptr->client_string_addr);
 
+#ifdef REVERSE_SUPPORT
+	if (connptr->reversepath)
+		safefree(connptr->reversepath);
+#endif
+
 	safefree(connptr);
 
 	update_stats(STAT_CLOSE);
diff --git a/src/conns.h b/src/conns.h
index c5ad9a7..5d0422a 100644
--- a/src/conns.h
+++ b/src/conns.h
@@ -1,4 +1,4 @@
-/* $Id: conns.h,v 1.15 2003-08-01 00:14:34 rjkaes Exp $
+/* $Id: conns.h,v 1.16 2004-01-26 19:11:51 rjkaes Exp $
  *
  * See 'conns.c' for a detailed description.
  *
@@ -66,6 +66,13 @@ struct conn_s {
 		unsigned int major;
 		unsigned int minor;
 	} protocol;
+
+#ifdef REVERSE_SUPPORT
+	/*
+	 * Place to store the current per-connection reverse proxy path
+	 */
+	char* reversepath;
+#endif
 };
 
 /*
diff --git a/src/grammar.y b/src/grammar.y
index 00596dd..9f3a74c 100644
--- a/src/grammar.y
+++ b/src/grammar.y
@@ -1,4 +1,4 @@
-/* $Id: grammar.y,v 1.23 2003-06-26 18:17:09 rjkaes Exp $
+/* $Id: grammar.y,v 1.24 2004-01-26 19:11:51 rjkaes Exp $
  *
  * This is the grammar for tinyproxy's configuration file. It needs to be
  * in sync with scanner.l. If you know more about yacc and lex than I do
@@ -50,6 +50,7 @@ int yylex(void);
 %token KW_FILTER KW_FILTERURLS KW_FILTEREXTENDED KW_FILTER_DEFAULT_DENY
 %token KW_FILTER_CASESENSITIVE
 %token KW_UPSTREAM
+%token KW_REVERSEPATH KW_REVERSEONLY KW_REVERSEMAGIC KW_REVERSEBASEURL
 %token KW_CONNECTPORT KW_BIND
 %token KW_STATHOST
 %token KW_ALLOW KW_DENY
@@ -167,6 +168,46 @@ statement
 		  log_message(LOG_WARNING, "X-Tinyproxy header support was not compiled in.");
 #endif
 	   }
+	| KW_REVERSEPATH string
+	   {
+#ifdef REVERSE_SUPPORT
+		  reversepath_add(NULL, $2);
+#else
+		  log_message(LOG_WARNING, "Reverse proxy support was not compiled in.");
+#endif
+	   }
+	| KW_REVERSEPATH string string
+	   {
+#ifdef REVERSE_SUPPORT
+		  reversepath_add($2, $3);
+#else
+		  log_message(LOG_WARNING, "Reverse proxy support was not compiled in.");
+#endif
+	   }
+	| KW_REVERSEONLY yesno
+	   {
+#ifdef REVERSE_SUPPORT
+		  config.reverseonly = $2;
+#else
+		  log_message(LOG_WARNING, "Reverse proxy support was not compiled in.");
+#endif
+	   }
+	| KW_REVERSEMAGIC yesno
+	   {
+#ifdef REVERSE_SUPPORT
+		  config.reversemagic = $2;
+#else
+		  log_message(LOG_WARNING, "Reverse proxy support was not compiled in.");
+#endif
+	   }
+	| KW_REVERSEBASEURL string
+	   {
+#ifdef REVERSE_SUPPORT
+		  config.reversebaseurl = $2;
+#else
+		  log_message(LOG_WARNING, "Reverse proxy support was not compiled in.");
+#endif
+	   }
         | KW_UPSTREAM unique_address ':' NUMBER
           {
 #ifdef UPSTREAM_SUPPORT
diff --git a/src/reqs.c b/src/reqs.c
index 3f33a7f..f00fee9 100644
--- a/src/reqs.c
+++ b/src/reqs.c
@@ -1,4 +1,4 @@
-/* $Id: reqs.c,v 1.108 2003-08-07 16:32:12 rjkaes Exp $
+/* $Id: reqs.c,v 1.109 2004-01-26 19:11:51 rjkaes Exp $
  *
  * This is where all the work in tinyproxy is actually done. Incoming
  * connections have a new child created for them. The child then
@@ -330,7 +330,7 @@ upstream_add(const char *host, int port, const char *domain)
 
 	if (domain == NULL) {
 		if (!host || host[0] == '\0' || port < 1) {
-			log_message(LOG_WARNING, "Nonsence upstream rule: invalid host or port");
+			log_message(LOG_WARNING, "Nonsense upstream rule: invalid host or port");
 			goto upstream_cleanup;
 		}
 
@@ -404,7 +404,7 @@ upstream_add(const char *host, int port, const char *domain)
 
 	return;
 
-      upstream_cleanup:
+upstream_cleanup:
 	safefree(up->host);
 	safefree(up->domain);
 	safefree(up);
@@ -465,6 +465,68 @@ upstream_get(char *host)
 }
 #endif
 
+#ifdef REVERSE_SUPPORT
+/*
+ * Add entry to the reversepath list
+ */
+void
+reversepath_add(const char *path, const char *url)
+{
+	struct reversepath *reverse;
+
+	if (url == NULL) {
+		log_message(LOG_WARNING, "Illegal reverse proxy rule: missing url");
+		return;
+	}
+
+	if (!strstr(url, "://")) {
+		log_message(LOG_WARNING,
+		            "Skipping reverse proxy rule: '%s' is not a valid url", url);
+		return;
+	}
+
+	if (path && *path != '/') {
+		log_message(LOG_WARNING,
+		            "Skipping reverse proxy rule: path '%s' doesn't start with a /", path);
+		return;
+	}
+
+	if (!(reverse = safemalloc(sizeof (struct reversepath)))) {
+		log_message(LOG_ERR, "Unable to allocate memory in reversepath_add()");
+		return;
+	}
+
+	if (!path) reverse->path = safestrdup("/");
+	else reverse->path = safestrdup(path);
+
+	reverse->url = safestrdup(url);
+
+	reverse->next = config.reversepath_list;
+	config.reversepath_list = reverse;
+
+	log_message(LOG_INFO,
+	            "Added reverse proxy rule: %s -> %s", reverse->path, reverse->url);
+}
+
+/*
+ * Check if a request url is in the reversepath list
+ */
+static struct reversepath *
+reversepath_get(char *url)
+{
+	struct reversepath *reverse = config.reversepath_list;
+
+	while (reverse) {
+		if (strstr(url, reverse->path) == url)
+			return reverse;
+
+		reverse = reverse->next;
+	}
+
+	return NULL;
+}
+#endif
+
 /*
  * Create a connection for HTTP connections.
  */
@@ -488,7 +550,7 @@ establish_http_connection(struct conn_s *connptr, struct request_s *request)
 }
 
 /*
- * These two defines are for the SSL tunneling.
+ * These two defines are for the SSL tunnelling.
  */
 #define SSL_CONNECTION_RESPONSE "HTTP/1.0 200 Connection established"
 #define PROXY_AGENT "Proxy-agent: " PACKAGE "/" VERSION
@@ -517,6 +579,13 @@ process_request(struct conn_s *connptr, hashmap_t hashofheaders)
 	char *url;
 	struct request_s *request;
 
+#ifdef REVERSE_SUPPORT
+	char *rewrite_url = NULL;
+	char *cookie = NULL;
+	char *cookieval;
+	struct reversepath *reverse;
+#endif
+
 	int ret;
 
 	size_t request_len;
@@ -577,6 +646,66 @@ process_request(struct conn_s *connptr, hashmap_t hashofheaders)
 		return NULL;
 	}
 
+#ifdef REVERSE_SUPPORT
+	/*
+	 * Reverse proxy URL rewriting.
+	 */
+	if (config.reversepath_list != NULL) {
+		/* Reverse requests always start with a slash */
+		if (*url == '/') {
+			/* First try locating the reverse mapping by request url */
+			reverse = reversepath_get(url);
+			if (reverse) {
+				rewrite_url = safemalloc(strlen(url) +
+				              strlen(reverse->url) + 1);
+				strcpy(rewrite_url, reverse->url);
+				strcat(rewrite_url, url + strlen(reverse->path));
+			} else if (config.reversemagic &&
+			         hashmap_entry_by_key(hashofheaders, "cookie",
+			                              (void **)&cookie) > 0) {
+
+				/* No match - try the magical tracking cookie next */
+				if ((cookieval = strstr(cookie, REVERSE_COOKIE "=")) &&
+				    (reverse = reversepath_get(cookieval +
+				                               strlen(REVERSE_COOKIE) + 1))) {
+
+					rewrite_url = safemalloc(strlen(url) +
+					                         strlen(reverse->url) + 1);
+					strcpy(rewrite_url, reverse->url);
+					strcat(rewrite_url, url + 1);
+
+					log_message(LOG_INFO,
+					            "Magical tracking cookie says: %s",
+					            reverse->path);
+				}
+			}
+		}
+
+		/* Forward proxy support off and no reverse path match found */
+		if (config.reverseonly && !rewrite_url) {
+			log_message(LOG_ERR, "Bad request");
+			indicate_http_error(connptr, 400, "Bad Request",
+					    "detail", "Request has an invalid URL",
+					    "url", url,
+					    NULL);
+
+			safefree(url);
+			free_request_struct(request);
+
+			return NULL;
+		}
+
+		log_message(LOG_CONN, "Rewriting URL: %s -> %s",
+			    url, rewrite_url);
+
+		safefree(url);
+		url = rewrite_url;
+
+		/* Store reverse path so that the magical tracking cookie can be set */
+		if (config.reversemagic) connptr->reversepath = safestrdup(reverse->path);
+	}
+#endif
+
 	if (strncasecmp(url, "http://", 7) == 0
 	    || (UPSTREAM_CONFIGURED() && strncasecmp(url, "ftp://", 6) == 0)) {
 		char *skipped_type = strstr(url, "//") + 2;
@@ -726,7 +855,7 @@ process_request(struct conn_s *connptr, hashmap_t hashofheaders)
 					    request->host);
 
 			indicate_http_error(connptr, 403, "Filtered",
-					    "detail", "The request you made has been filted",
+					    "detail", "The request you made has been filtered",
 					    "url", url,
 					    NULL);
 
@@ -1178,6 +1307,10 @@ process_server_headers(struct conn_s *connptr)
 	int i;
 	int ret;
 
+#ifdef REVERSE_SUPPORT
+	struct reversepath *reverse = config.reversepath_list;
+#endif
+
 	/* FIXME: Remember to handle a "simple_req" type */
 
 	/* Get the response line from the remote server. */
@@ -1251,6 +1384,41 @@ process_server_headers(struct conn_s *connptr)
 	if (ret < 0)
 		goto ERROR_EXIT;
 
+#ifdef REVERSE_SUPPORT
+	/* Write tracking cookie for the magical reverse proxy path hack */
+	if (config.reversemagic && connptr->reversepath) {
+		ret = write_message(connptr->client_fd,
+				    "Set-Cookie: " REVERSE_COOKIE "=%s; path=/\r\n",
+				    connptr->reversepath);
+		if (ret < 0) goto ERROR_EXIT;
+	}
+
+	/* Rewrite the HTTP redirect if needed */
+	if (config.reversebaseurl &&
+	    hashmap_entry_by_key(hashofheaders, "location", (void **)&header) > 0) {
+
+		/* Look for a matching entry in the reversepath list */
+		while (reverse) {
+			if (strncasecmp(header,
+			                reverse->url,
+			                (len = strlen(reverse->url))) == 0) break;
+			reverse = reverse->next;
+		}
+
+		if (reverse) {
+			ret = write_message(connptr->client_fd, "Location: %s%s%s\r\n",
+			                    config.reversebaseurl, (reverse->path + 1),
+			                    (header + len));
+			if (ret < 0) goto ERROR_EXIT;
+
+			log_message(LOG_INFO,
+			            "Rewriting HTTP redirect: %s -> %s%s%s", header,
+			            config.reversebaseurl, (reverse->path + 1), (header + len));
+			hashmap_remove(hashofheaders, "location");
+		}
+	}
+#endif
+
 	/*
 	 * All right, output all the remaining headers to the client.
 	 */
diff --git a/src/reqs.h b/src/reqs.h
index b324858..d1dac79 100644
--- a/src/reqs.h
+++ b/src/reqs.h
@@ -1,4 +1,4 @@
-/* $Id: reqs.h,v 1.4 2003-05-29 19:43:57 rjkaes Exp $
+/* $Id: reqs.h,v 1.5 2004-01-26 19:11:51 rjkaes Exp $
  *
  * See 'reqs.c' for a detailed description.
  *
@@ -22,5 +22,6 @@
 extern void handle_connection(int fd);
 extern void add_connect_port_allowed(int port);
 extern void upstream_add(const char *host, int port, const char *domain);
+extern void reversepath_add(const char *path, const char *url);
 
 #endif
diff --git a/src/scanner.l b/src/scanner.l
index 54e01a4..8418ca0 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -1,4 +1,4 @@
-/* $Id: scanner.l,v 1.22 2003-06-26 18:26:10 rjkaes Exp $
+/* $Id: scanner.l,v 1.23 2004-01-26 19:11:51 rjkaes Exp $
  *
  * This builds the scanner for the tinyproxy configuration file. This
  * file needs to stay in sync with grammar.y. If someone knows lex and yacc
@@ -24,12 +24,12 @@
 
 struct keyword {
         char *kw_name;
-        int kw_token;
+	int kw_token;
 };
 
 static struct keyword keywords[] = {
-        /* statements */
-        { "port",		 KW_PORT },
+	/* statements */
+	{ "port",		 KW_PORT },
 	{ "logfile",		 KW_LOGFILE },
 	{ "syslog",		 KW_SYSLOG },
 	{ "maxclients",		 KW_MAXCLIENTS },
@@ -44,24 +44,28 @@ static struct keyword keywords[] = {
 	{ "group",		 KW_GROUP },
 	{ "anonymous",		 KW_ANONYMOUS },
 	{ "filter",		 KW_FILTER },
-        { "filterurls",          KW_FILTERURLS },
-        { "filterextended",      KW_FILTEREXTENDED },
-        { "filterdefaultdeny",   KW_FILTER_DEFAULT_DENY },
-        { "filtercasesensitive", KW_FILTER_CASESENSITIVE },
+	{ "filterurls",          KW_FILTERURLS },
+	{ "filterextended",      KW_FILTEREXTENDED },
+	{ "filterdefaultdeny",   KW_FILTER_DEFAULT_DENY },
+	{ "filtercasesensitive", KW_FILTER_CASESENSITIVE },
 	{ "xtinyproxy",		 KW_XTINYPROXY },
-        { "upstream",            KW_UPSTREAM },
+	{ "reversepath",         KW_REVERSEPATH },
+	{ "reverseonly",         KW_REVERSEONLY },
+	{ "reversemagic",        KW_REVERSEMAGIC },
+	{ "reversebaseurl",      KW_REVERSEBASEURL },
+	{ "upstream",            KW_UPSTREAM },
 	{ "allow",		 KW_ALLOW },
-        { "deny",                KW_DENY },
-        { "connectport",         KW_CONNECTPORT },
-        { "bind",                KW_BIND },
-        { "viaproxyname",        KW_VIA_PROXY_NAME },
-        { "stathost",            KW_STATHOST },
+	{ "deny",                KW_DENY },
+	{ "connectport",         KW_CONNECTPORT },
+	{ "bind",                KW_BIND },
+	{ "viaproxyname",        KW_VIA_PROXY_NAME },
+	{ "stathost",            KW_STATHOST },
 	{ "errorfile",	         KW_ERRORPAGE },
 	{ "defaulterrorfile",    KW_DEFAULT_ERRORPAGE },
 	{ "statfile",            KW_STATPAGE },
 
-        /* loglevel and the settings */
-        { "loglevel",            KW_LOGLEVEL },
+	/* loglevel and the settings */
+	{ "loglevel",            KW_LOGLEVEL },
 	{ "critical",		 KW_LOG_CRITICAL },
 	{ "error",		 KW_LOG_ERROR },
 	{ "warning",		 KW_LOG_WARNING },
diff --git a/src/tinyproxy.c b/src/tinyproxy.c
index 76ff993..578a10a 100644
--- a/src/tinyproxy.c
+++ b/src/tinyproxy.c
@@ -1,4 +1,4 @@
-/* $Id: tinyproxy.c,v 1.46 2003-03-17 04:24:19 rjkaes Exp $
+/* $Id: tinyproxy.c,v 1.47 2004-01-26 19:11:51 rjkaes Exp $
  *
  * The initialize routine. Basically sets up all the initial stuff (logfile,
  * listening socket, config options, etc.) and then sits there and loops
@@ -130,9 +130,9 @@ Options:\n\
   -v            Display the version number.\n");
 
 	/* Display the modes compiled into tinyproxy */
-	printf("\nFeatures Compiled In:\n");
+	printf("\nFeatures compiled in:\n");
 #ifdef XTINYPROXY_ENABLE
-	printf("    XTinyproxy Header\n");
+	printf("    XTinyproxy header\n");
 #endif				/* XTINYPROXY */
 #ifdef FILTER_ENABLE
 	printf("    Filtering\n");
@@ -141,8 +141,11 @@ Options:\n\
 	printf("    Debugging code\n");
 #endif				/* NDEBUG */
 #ifdef TRANSPARENT_PROXY
-	printf("    Transparent Proxy Support\n");
+	printf("    Transparent proxy support\n");
 #endif                          /* TRANSPARENT_PROXY */
+#ifdef REVERSE_SUPPORT
+	printf("    Reverse proxy support\n");
+#endif				/* REVERSE_SUPPORT */
 }
 
 int
diff --git a/src/tinyproxy.h b/src/tinyproxy.h
index 0c4e461..ad02120 100644
--- a/src/tinyproxy.h
+++ b/src/tinyproxy.h
@@ -1,4 +1,4 @@
-/* $Id: tinyproxy.h,v 1.42 2003-08-01 00:14:34 rjkaes Exp $
+/* $Id: tinyproxy.h,v 1.43 2004-01-26 19:11:51 rjkaes Exp $
  *
  * See 'tinyproxy.c' for a detailed description.
  *
@@ -36,6 +36,16 @@ struct upstream {
 };
 #endif
 
+#ifdef REVERSE_SUPPORT
+struct reversepath {
+	struct reversepath *next;
+	char *path;
+	char *url;
+};
+
+#define REVERSE_COOKIE "yummy_magical_cookie"
+#endif
+
 /*
  * Hold all the configuration time information.
  */
@@ -58,6 +68,12 @@ struct config_s {
 #ifdef XTINYPROXY_ENABLE
 	char *my_domain;
 #endif
+#ifdef REVERSE_SUPPORT
+	struct reversepath *reversepath_list;
+	unsigned int reverseonly; /* boolean */
+	unsigned int reversemagic; /* boolean */
+	char *reversebaseurl;
+#endif
 #ifdef UPSTREAM_SUPPORT
 	struct upstream *upstream_list;
 #endif				/* UPSTREAM_SUPPORT */