[FFmpeg-devel] [PATCH] Handling special characters in a URL.

[Senthilnathan Maadasamy]

On Tue, Feb 12, 2013 at 5:12 AM, Stefano Sabatini <stefasab at gmail.com>wrote:

>
> > + * Percent encodes parts of a URL string based on RFC 3986.
>
> Nit:
> Percent encode part of an URL string according to RFC 3986.
>
> The following corrections are subtleties related to internal/global
> consistency/semantics.


I have made the suggested changes in the patch below:

Support for special characters in URL

Signed-off-by: Senthilnathan M <senthilnathan.maadasamy at gmail.com>
---
 libavformat/utils.c |   54
+++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/libavformat/utils.c b/libavformat/utils.c
index 10d2449..a068884 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -3754,6 +3754,40 @@ void av_pkt_dump_log2(void *avcl, int level,
AVPacket *pkt, int dump_payload,
     pkt_dump_internal(avcl, NULL, level, pkt, dump_payload, st->time_base);
 }

+/**
+ * Percent encode part of an URL string according to RFC 3986.
+ *
+ * @param dst destination buffer where the percent-encoded string is
written
+ * @param src portion of an URL (e.g. protocol, hostname, path) to
+ *            percent-encoded
+ * @param allowed string containing the allowed characters which must not
be
+ *                encoded. It may be NULL if there are no such characters.
+ * @param dst_size size in bytes of the dst buffer
+ * @return complete length of the percent-encoded string
+ */
+static size_t ff_url_percent_encode(char *dst, const char *src,
+                                    const char *allowed, size_t dst_size)
+{
+    char c;
+    int enc_len = 0;
+
+    while (c = *src) {
+        if (isalnum(c) || strchr("-._~%", c)
+            || (allowed && strchr(allowed, c))) {
+            if (enc_len+1 < dst_size) dst[enc_len] = c;
+            enc_len++;
+        } else {
+            if (enc_len+3 < dst_size) snprintf(&dst[enc_len], 4, "%%%02x",
c);
+            enc_len += 3;
+        }
+        src++;
+    }
+
+    if (enc_len < dst_size) dst[enc_len] = '\0';
+    enc_len++;
+    return enc_len;
+}
+
 void av_url_split(char *proto, int proto_size,
                   char *authorization, int authorization_size,
                   char *hostname, int hostname_size,
@@ -3762,6 +3796,9 @@ void av_url_split(char *proto, int proto_size,
                   const char *url)
 {
     const char *p, *ls, *ls2, *at, *at2, *col, *brk;
+    char hostname_enc[MAX_URL_SIZE];
+    char path_enc[MAX_URL_SIZE];
+    size_t enc_size;

     if (port_ptr)               *port_ptr = -1;
     if (proto_size > 0)         proto[0] = 0;
@@ -3817,6 +3854,23 @@ void av_url_split(char *proto, int proto_size,
             av_strlcpy(hostname, p,
                        FFMIN(ls + 1 - p, hostname_size));
     }
+
+    enc_size = ff_url_percent_encode(hostname_enc, hostname, NULL,
+                                        hostname_size);
+    if (enc_size <= hostname_size) {
+        av_strlcpy(hostname, hostname_enc, hostname_size);
+    } else {
+        av_log(NULL, AV_LOG_ERROR,
+            "Skipping hostname percent-encoding since buffer is too
small\n");
+    }
+
+    enc_size = ff_url_percent_encode(path_enc, path, "/?", path_size);
+    if (enc_size <= path_size) {
+        av_strlcpy(path, path_enc, path_size);
+    } else {
+        av_log(NULL, AV_LOG_ERROR,
+            "Skipping path percent-encoding since buffer is too small\n");
+    }
 }

 char *ff_data_to_hex(char *buff, const uint8_t *src, int s, int lowercase)
-- 
1.7.9.5