rtmp: add functions for reading AMF values

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavformat/rtmppkt.c

@@ -71,6 +71,51 @@ void ff_amf_write_object_end(uint8_t **dst)
     bytestream_put_be24(dst, AMF_DATA_TYPE_OBJECT_END);
 }
 
+int ff_amf_read_bool(GetByteContext *bc, int *val)
+{
+    if (bytestream2_get_byte(bc) != AMF_DATA_TYPE_BOOL)
+        return AVERROR_INVALIDDATA;
+    *val = bytestream2_get_byte(bc);
+    return 0;
+}
+
+int ff_amf_read_number(GetByteContext *bc, double *val)
+{
+    uint64_t read;
+    if (bytestream2_get_byte(bc) != AMF_DATA_TYPE_NUMBER)
+        return AVERROR_INVALIDDATA;
+    read = bytestream2_get_be64(bc);
+    *val = av_int2double(read);
+    return 0;
+}
+
+int ff_amf_read_string(GetByteContext *bc, uint8_t *str,
+                       int strsize, int *length)
+{
+    int stringlen = 0;
+    int readsize;
+    if (bytestream2_get_byte(bc) != AMF_DATA_TYPE_STRING)
+        return AVERROR_INVALIDDATA;
+    stringlen = bytestream2_get_be16(bc);
+    if (stringlen + 1 > strsize)
+        return AVERROR(EINVAL);
+    readsize = bytestream2_get_buffer(bc, str, stringlen);
+    if (readsize != stringlen) {
+        av_log(NULL, AV_LOG_WARNING,
+               "Unable to read as many bytes as AMF string signaled\n");
+    }
+    str[readsize] = '\0';
+    *length = FFMIN(stringlen, readsize);
+    return 0;
+}
+
+int ff_amf_read_null(GetByteContext *bc)
+{
+    if (bytestream2_get_byte(bc) != AMF_DATA_TYPE_NULL)
+        return AVERROR_INVALIDDATA;
+    return 0;
+}
+
 int ff_rtmp_packet_read(URLContext *h, RTMPPacket *p,
                         int chunk_size, RTMPPacket *prev_pkt)
 {

libavformat/rtmppkt.h

@@ -231,6 +231,48 @@ void ff_amf_write_field_name(uint8_t **dst, const char *str);
  */
 void ff_amf_write_object_end(uint8_t **dst);
 
+/**
+ * Read AMF boolean value.
+ *
+ *@param[in,out] gbc GetByteContext initialized with AMF-formatted data
+ *@param[out]    val 0 or 1
+ *@return 0 on success or an AVERROR code on failure
+*/
+int ff_amf_read_bool(GetByteContext *gbc, int *val);
+
+/**
+ * Read AMF number value.
+ *
+ *@param[in,out] gbc GetByteContext initialized with AMF-formatted data
+ *@param[out]    val read value
+ *@return 0 on success or an AVERROR code on failure
+*/
+int ff_amf_read_number(GetByteContext *gbc, double *val);
+
+/**
+ * Read AMF string value.
+ *
+ * Appends a trailing \0 to output string in order to
+ * ease later parsing.
+ *
+ *@param[in,out] gbc     GetByteContext initialized with AMF-formatted data
+ *@param[out]    str     read string
+ *@param[in]     strsize buffer size available to store the read string
+ *@param[out]    length  read string length
+ *@return 0 on success or an AVERROR code on failure
+*/
+int ff_amf_read_string(GetByteContext *gbc, uint8_t *str,
+                       int strsize, int *length);
+
+/**
+ * Read AMF NULL value.
+ *
+ *@param[in,out] gbc GetByteContext initialized with AMF-formatted data
+ *@return 0 on success or an AVERROR code on failure
+*/
+int ff_amf_read_null(GetByteContext *gbc);
+
+
 /** @} */ // AMF funcs
 
 #endif /* AVFORMAT_RTMPPKT_H */