wget: URL-decode user:password before base64-encoding it into auth hdr. Closes 3625.

function                                             old     new   delta
percent_decode_in_place                                -     152    +152
parse_url                                            304     317     +13
handle_incoming_and_exit                            2795    2798      +3
httpd_main                                           763     760      -3
decodeString                                         152       -    -152
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 2/1 up/down: 168/-155)           Total: 13 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 86 insertions, 81 deletions

diff --git a/include/libbb.h b/include/libbb.h
index d0c7ace22..21cbe1cac 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1578,6 +1578,15 @@ int starts_with_cpu(const char *str) FAST_FUNC;
 unsigned get_cpu_count(void) FAST_FUNC;
 
 
+/* Use strict=1 if you process input from untrusted source:
+ * it will return NULL on invalid %xx (bad hex chars)
+ * and str + 1 if decoded char is / or NUL.
+ * In non-strict mode, it always succeeds (returns str),
+ * and also it additionally decoded '+' to space.
+ */
+char *percent_decode_in_place(char *str, int strict) FAST_FUNC;
+
+
 extern const char bb_uuenc_tbl_base64[];
 extern const char bb_uuenc_tbl_std[];
 void bb_uuencode(char *store, const void *s, int length, const char *tbl) FAST_FUNC;
diff --git a/libbb/percent_decode.c b/libbb/percent_decode.c
new file mode 100644
index 000000000..9a9d80c4a
--- /dev/null
+++ b/libbb/percent_decode.c
@@ -0,0 +1,69 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+
+//kbuild:lib-y += percent_decode.o
+
+#include "libbb.h"
+
+static unsigned hex_to_bin(unsigned char c)
+{
+	unsigned v;
+
+	v = c - '0';
+	if (v <= 9)
+		return v;
+	/* c | 0x20: letters to lower case, non-letters
+	 * to (potentially different) non-letters */
+	v = (unsigned)(c | 0x20) - 'a';
+	if (v <= 5)
+		return v + 10;
+	return ~0;
+/* For testing:
+void t(char c) { printf("'%c'(%u) %u\n", c, c, hex_to_bin(c)); }
+int main() { t(0x10); t(0x20); t('0'); t('9'); t('A'); t('F'); t('a'); t('f');
+t('0'-1); t('9'+1); t('A'-1); t('F'+1); t('a'-1); t('f'+1); return 0; }
+*/
+}
+
+char* FAST_FUNC percent_decode_in_place(char *str, int strict)
+{
+	/* note that decoded string is always shorter than original */
+	char *src = str;
+	char *dst = str;
+	char c;
+
+	while ((c = *src++) != '\0') {
+		unsigned v;
+
+		if (!strict && c == '+') {
+			*dst++ = ' ';
+			continue;
+		}
+		if (c != '%') {
+			*dst++ = c;
+			continue;
+		}
+		v = hex_to_bin(src[0]);
+		if (v > 15) {
+ bad_hex:
+			if (strict)
+				return NULL;
+			*dst++ = '%';
+			continue;
+		}
+		v = (v * 16) | hex_to_bin(src[1]);
+		if (v > 255)
+			goto bad_hex;
+		if (strict && (v == '/' || v == '\0')) {
+			/* caller takes it as indication of invalid
+			 * (dangerous wrt exploits) chars */
+			return str + 1;
+		}
+		*dst++ = v;
+		src += 2;
+	}
+	*dst = '\0';
+	return str;
+}
diff --git a/networking/httpd.c b/networking/httpd.c
index ba5eebad5..24482fe52 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -820,78 +820,6 @@ static char *encodeString(const char *string)
 }
 #endif
 
-/*
- * Given a URL encoded string, convert it to plain ascii.
- * Since decoding always makes strings smaller, the decode is done in-place.
- * Thus, callers should xstrdup() the argument if they do not want the
- * argument modified.  The return is the original pointer, allowing this
- * function to be easily used as arguments to other functions.
- *
- * string    The first string to decode.
- * option_d  1 if called for httpd -d
- *
- * Returns a pointer to the decoded string (same as input).
- */
-static unsigned hex_to_bin(unsigned char c)
-{
-	unsigned v;
-
-	v = c - '0';
-	if (v <= 9)
-		return v;
-	/* c | 0x20: letters to lower case, non-letters
-	 * to (potentially different) non-letters */
-	v = (unsigned)(c | 0x20) - 'a';
-	if (v <= 5)
-		return v + 10;
-	return ~0;
-/* For testing:
-void t(char c) { printf("'%c'(%u) %u\n", c, c, hex_to_bin(c)); }
-int main() { t(0x10); t(0x20); t('0'); t('9'); t('A'); t('F'); t('a'); t('f');
-t('0'-1); t('9'+1); t('A'-1); t('F'+1); t('a'-1); t('f'+1); return 0; }
-*/
-}
-static char *decodeString(char *orig, int option_d)
-{
-	/* note that decoded string is always shorter than original */
-	char *string = orig;
-	char *ptr = string;
-	char c;
-
-	while ((c = *ptr++) != '\0') {
-		unsigned v;
-
-		if (option_d && c == '+') {
-			*string++ = ' ';
-			continue;
-		}
-		if (c != '%') {
-			*string++ = c;
-			continue;
-		}
-		v = hex_to_bin(ptr[0]);
-		if (v > 15) {
- bad_hex:
-			if (!option_d)
-				return NULL;
-			*string++ = '%';
-			continue;
-		}
-		v = (v * 16) | hex_to_bin(ptr[1]);
-		if (v > 255)
-			goto bad_hex;
-		if (!option_d && (v == '/' || v == '\0')) {
-			/* caller takes it as indication of invalid
-			 * (dangerous wrt exploits) chars */
-			return orig + 1;
-		}
-		*string++ = v;
-		ptr += 2;
-	}
-	*string = '\0';
-	return orig;
-}
-
 #if ENABLE_FEATURE_HTTPD_BASIC_AUTH
 /*
  * Decode a base64 data stream as per rfc1521.
@@ -1949,7 +1877,7 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
 	}
 
 	/* Decode URL escape sequences */
-	tptr = decodeString(urlcopy, 0);
+	tptr = percent_decode_in_place(urlcopy, /*strict:*/ 1);
 	if (tptr == NULL)
 		send_headers_and_exit(HTTP_BAD_REQUEST);
 	if (tptr == urlcopy + 1) {
@@ -2408,7 +2336,7 @@ int httpd_main(int argc UNUSED_PARAM, char **argv)
 			, &verbose
 		);
 	if (opt & OPT_DECODE_URL) {
-		fputs(decodeString(url_for_decode, 1), stdout);
+		fputs(percent_decode_in_place(url_for_decode, /*strict:*/ 0), stdout);
 		return 0;
 	}
 #if ENABLE_FEATURE_HTTPD_ENCODE_URL_STR
diff --git a/networking/wget.c b/networking/wget.c
index 6443705fd..94a2f7c3d 100644
--- a/networking/wget.c
+++ b/networking/wget.c
@@ -298,8 +298,13 @@ static void parse_url(const char *src_url, struct host_info *h)
 
 	sp = strrchr(h->host, '@');
 	if (sp != NULL) {
-		h->user = h->host;
+		// URL-decode "user:password" string before base64-encoding:
+		// wget http://test:my%20pass@example.com should send
+		// Authorization: Basic dGVzdDpteSBwYXNz
+		// which decodes to "test:my pass".
+		// Standard wget and curl do this too.
 		*sp = '\0';
+		h->user = percent_decode_in_place(h->host, /*strict:*/ 0);
 		h->host = sp + 1;
 	}
 
@@ -660,12 +665,6 @@ static void download_one_url(const char *url)
 
 #if ENABLE_FEATURE_WGET_AUTHENTICATION
 		if (target.user) {
-//TODO: URL-decode "user:password" string before base64-encoding:
-//wget http://test:my%20pass@example.com should send
-// Authorization: Basic dGVzdDpteSBwYXNz
-//which decodes to "test:my pass", instead of what we send now:
-// Authorization: Basic dGVzdDpteSUyMHBhc3M=
-//Can reuse decodeString() from httpd.c
 			fprintf(sfp, "Proxy-Authorization: Basic %s\r\n"+6,
 				base64enc(target.user));
 		}