--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/lib/rtsp.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,822 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#ifndef CURL_DISABLE_RTSP
+
+#include "urldata.h"
+#include <curl/curl.h>
+#include "transfer.h"
+#include "sendf.h"
+#include "multiif.h"
+#include "http.h"
+#include "url.h"
+#include "progress.h"
+#include "rtsp.h"
+#include "strcase.h"
+#include "select.h"
+#include "connect.h"
+#include "strdup.h"
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+#define RTP_PKT_CHANNEL(p)   ((int)((unsigned char)((p)[1])))
+
+#define RTP_PKT_LENGTH(p)  ((((int)((unsigned char)((p)[2]))) << 8) | \
+                             ((int)((unsigned char)((p)[3]))))
+
+/* protocol-specific functions set up to be called by the main engine */
+static CURLcode rtsp_do(struct connectdata *conn, bool *done);
+static CURLcode rtsp_done(struct connectdata *conn, CURLcode, bool premature);
+static CURLcode rtsp_connect(struct connectdata *conn, bool *done);
+static CURLcode rtsp_disconnect(struct connectdata *conn, bool dead);
+static int rtsp_getsock_do(struct connectdata *conn, curl_socket_t *socks);
+
+/*
+ * Parse and write out any available RTP data.
+ *
+ * nread: amount of data left after k->str. will be modified if RTP
+ *        data is parsed and k->str is moved up
+ * readmore: whether or not the RTP parser needs more data right away
+ */
+static CURLcode rtsp_rtp_readwrite(struct Curl_easy *data,
+                                   struct connectdata *conn,
+                                   ssize_t *nread,
+                                   bool *readmore);
+
+static CURLcode rtsp_setup_connection(struct connectdata *conn);
+static unsigned int rtsp_conncheck(struct connectdata *check,
+                                   unsigned int checks_to_perform);
+
+/* this returns the socket to wait for in the DO and DOING state for the multi
+   interface and then we're always _sending_ a request and thus we wait for
+   the single socket to become writable only */
+static int rtsp_getsock_do(struct connectdata *conn,
+                           curl_socket_t *socks)
+{
+  /* write mode */
+  socks[0] = conn->sock[FIRSTSOCKET];
+  return GETSOCK_WRITESOCK(0);
+}
+
+static
+CURLcode rtp_client_write(struct connectdata *conn, char *ptr, size_t len);
+
+
+/*
+ * RTSP handler interface.
+ */
+const struct Curl_handler Curl_handler_rtsp = {
+  "RTSP",                               /* scheme */
+  rtsp_setup_connection,                /* setup_connection */
+  rtsp_do,                              /* do_it */
+  rtsp_done,                            /* done */
+  ZERO_NULL,                            /* do_more */
+  rtsp_connect,                         /* connect_it */
+  ZERO_NULL,                            /* connecting */
+  ZERO_NULL,                            /* doing */
+  ZERO_NULL,                            /* proto_getsock */
+  rtsp_getsock_do,                      /* doing_getsock */
+  ZERO_NULL,                            /* domore_getsock */
+  ZERO_NULL,                            /* perform_getsock */
+  rtsp_disconnect,                      /* disconnect */
+  rtsp_rtp_readwrite,                   /* readwrite */
+  rtsp_conncheck,                       /* connection_check */
+  PORT_RTSP,                            /* defport */
+  CURLPROTO_RTSP,                       /* protocol */
+  PROTOPT_NONE                          /* flags */
+};
+
+
+static CURLcode rtsp_setup_connection(struct connectdata *conn)
+{
+  struct RTSP *rtsp;
+
+  conn->data->req.protop = rtsp = calloc(1, sizeof(struct RTSP));
+  if(!rtsp)
+    return CURLE_OUT_OF_MEMORY;
+
+  return CURLE_OK;
+}
+
+
+/*
+ * The server may send us RTP data at any point, and RTSPREQ_RECEIVE does not
+ * want to block the application forever while receiving a stream. Therefore,
+ * we cannot assume that an RTSP socket is dead just because it is readable.
+ *
+ * Instead, if it is readable, run Curl_connalive() to peek at the socket
+ * and distinguish between closed and data.
+ */
+static bool rtsp_connisdead(struct connectdata *check)
+{
+  int sval;
+  bool ret_val = TRUE;
+
+  sval = SOCKET_READABLE(check->sock[FIRSTSOCKET], 0);
+  if(sval == 0) {
+    /* timeout */
+    ret_val = FALSE;
+  }
+  else if(sval & CURL_CSELECT_ERR) {
+    /* socket is in an error state */
+    ret_val = TRUE;
+  }
+  else if(sval & CURL_CSELECT_IN) {
+    /* readable with no error. could still be closed */
+    ret_val = !Curl_connalive(check);
+  }
+
+  return ret_val;
+}
+
+/*
+ * Function to check on various aspects of a connection.
+ */
+static unsigned int rtsp_conncheck(struct connectdata *check,
+                                   unsigned int checks_to_perform)
+{
+  unsigned int ret_val = CONNRESULT_NONE;
+
+  if(checks_to_perform & CONNCHECK_ISDEAD) {
+    if(rtsp_connisdead(check))
+      ret_val |= CONNRESULT_DEAD;
+  }
+
+  return ret_val;
+}
+
+
+static CURLcode rtsp_connect(struct connectdata *conn, bool *done)
+{
+  CURLcode httpStatus;
+  struct Curl_easy *data = conn->data;
+
+  httpStatus = Curl_http_connect(conn, done);
+
+  /* Initialize the CSeq if not already done */
+  if(data->state.rtsp_next_client_CSeq == 0)
+    data->state.rtsp_next_client_CSeq = 1;
+  if(data->state.rtsp_next_server_CSeq == 0)
+    data->state.rtsp_next_server_CSeq = 1;
+
+  conn->proto.rtspc.rtp_channel = -1;
+
+  return httpStatus;
+}
+
+static CURLcode rtsp_disconnect(struct connectdata *conn, bool dead)
+{
+  (void) dead;
+  Curl_safefree(conn->proto.rtspc.rtp_buf);
+  return CURLE_OK;
+}
+
+
+static CURLcode rtsp_done(struct connectdata *conn,
+                          CURLcode status, bool premature)
+{
+  struct Curl_easy *data = conn->data;
+  struct RTSP *rtsp = data->req.protop;
+  CURLcode httpStatus;
+
+  /* Bypass HTTP empty-reply checks on receive */
+  if(data->set.rtspreq == RTSPREQ_RECEIVE)
+    premature = TRUE;
+
+  httpStatus = Curl_http_done(conn, status, premature);
+
+  if(rtsp) {
+    /* Check the sequence numbers */
+    long CSeq_sent = rtsp->CSeq_sent;
+    long CSeq_recv = rtsp->CSeq_recv;
+    if((data->set.rtspreq != RTSPREQ_RECEIVE) && (CSeq_sent != CSeq_recv)) {
+      failf(data,
+            "The CSeq of this request %ld did not match the response %ld",
+            CSeq_sent, CSeq_recv);
+      return CURLE_RTSP_CSEQ_ERROR;
+    }
+    if(data->set.rtspreq == RTSPREQ_RECEIVE &&
+            (conn->proto.rtspc.rtp_channel == -1)) {
+      infof(data, "Got an RTP Receive with a CSeq of %ld\n", CSeq_recv);
+    }
+  }
+
+  return httpStatus;
+}
+
+static CURLcode rtsp_do(struct connectdata *conn, bool *done)
+{
+  struct Curl_easy *data = conn->data;
+  CURLcode result = CURLE_OK;
+  Curl_RtspReq rtspreq = data->set.rtspreq;
+  struct RTSP *rtsp = data->req.protop;
+  Curl_send_buffer *req_buffer;
+  curl_off_t postsize = 0; /* for ANNOUNCE and SET_PARAMETER */
+  curl_off_t putsize = 0; /* for ANNOUNCE and SET_PARAMETER */
+
+  const char *p_request = NULL;
+  const char *p_session_id = NULL;
+  const char *p_accept = NULL;
+  const char *p_accept_encoding = NULL;
+  const char *p_range = NULL;
+  const char *p_referrer = NULL;
+  const char *p_stream_uri = NULL;
+  const char *p_transport = NULL;
+  const char *p_uagent = NULL;
+  const char *p_proxyuserpwd = NULL;
+  const char *p_userpwd = NULL;
+
+  *done = TRUE;
+
+  rtsp->CSeq_sent = data->state.rtsp_next_client_CSeq;
+  rtsp->CSeq_recv = 0;
+
+  /* Setup the 'p_request' pointer to the proper p_request string
+   * Since all RTSP requests are included here, there is no need to
+   * support custom requests like HTTP.
+   **/
+  data->set.opt_no_body = TRUE; /* most requests don't contain a body */
+  switch(rtspreq) {
+  default:
+    failf(data, "Got invalid RTSP request");
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+  case RTSPREQ_OPTIONS:
+    p_request = "OPTIONS";
+    break;
+  case RTSPREQ_DESCRIBE:
+    p_request = "DESCRIBE";
+    data->set.opt_no_body = FALSE;
+    break;
+  case RTSPREQ_ANNOUNCE:
+    p_request = "ANNOUNCE";
+    break;
+  case RTSPREQ_SETUP:
+    p_request = "SETUP";
+    break;
+  case RTSPREQ_PLAY:
+    p_request = "PLAY";
+    break;
+  case RTSPREQ_PAUSE:
+    p_request = "PAUSE";
+    break;
+  case RTSPREQ_TEARDOWN:
+    p_request = "TEARDOWN";
+    break;
+  case RTSPREQ_GET_PARAMETER:
+    /* GET_PARAMETER's no_body status is determined later */
+    p_request = "GET_PARAMETER";
+    data->set.opt_no_body = FALSE;
+    break;
+  case RTSPREQ_SET_PARAMETER:
+    p_request = "SET_PARAMETER";
+    break;
+  case RTSPREQ_RECORD:
+    p_request = "RECORD";
+    break;
+  case RTSPREQ_RECEIVE:
+    p_request = "";
+    /* Treat interleaved RTP as body*/
+    data->set.opt_no_body = FALSE;
+    break;
+  case RTSPREQ_LAST:
+    failf(data, "Got invalid RTSP request: RTSPREQ_LAST");
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+  }
+
+  if(rtspreq == RTSPREQ_RECEIVE) {
+    Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, -1);
+
+    return result;
+  }
+
+  p_session_id = data->set.str[STRING_RTSP_SESSION_ID];
+  if(!p_session_id &&
+     (rtspreq & ~(RTSPREQ_OPTIONS | RTSPREQ_DESCRIBE | RTSPREQ_SETUP))) {
+    failf(data, "Refusing to issue an RTSP request [%s] without a session ID.",
+          p_request);
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+  }
+
+  /* Stream URI. Default to server '*' if not specified */
+  if(data->set.str[STRING_RTSP_STREAM_URI]) {
+    p_stream_uri = data->set.str[STRING_RTSP_STREAM_URI];
+  }
+  else {
+    p_stream_uri = "*";
+  }
+
+  /* Transport Header for SETUP requests */
+  p_transport = Curl_checkheaders(conn, "Transport");
+  if(rtspreq == RTSPREQ_SETUP && !p_transport) {
+    /* New Transport: setting? */
+    if(data->set.str[STRING_RTSP_TRANSPORT]) {
+      Curl_safefree(conn->allocptr.rtsp_transport);
+
+      conn->allocptr.rtsp_transport =
+        aprintf("Transport: %s\r\n",
+                data->set.str[STRING_RTSP_TRANSPORT]);
+      if(!conn->allocptr.rtsp_transport)
+        return CURLE_OUT_OF_MEMORY;
+    }
+    else {
+      failf(data,
+            "Refusing to issue an RTSP SETUP without a Transport: header.");
+      return CURLE_BAD_FUNCTION_ARGUMENT;
+    }
+
+    p_transport = conn->allocptr.rtsp_transport;
+  }
+
+  /* Accept Headers for DESCRIBE requests */
+  if(rtspreq == RTSPREQ_DESCRIBE) {
+    /* Accept Header */
+    p_accept = Curl_checkheaders(conn, "Accept")?
+      NULL:"Accept: application/sdp\r\n";
+
+    /* Accept-Encoding header */
+    if(!Curl_checkheaders(conn, "Accept-Encoding") &&
+       data->set.str[STRING_ENCODING]) {
+      Curl_safefree(conn->allocptr.accept_encoding);
+      conn->allocptr.accept_encoding =
+        aprintf("Accept-Encoding: %s\r\n", data->set.str[STRING_ENCODING]);
+
+      if(!conn->allocptr.accept_encoding)
+        return CURLE_OUT_OF_MEMORY;
+
+      p_accept_encoding = conn->allocptr.accept_encoding;
+    }
+  }
+
+  /* The User-Agent string might have been allocated in url.c already, because
+     it might have been used in the proxy connect, but if we have got a header
+     with the user-agent string specified, we erase the previously made string
+     here. */
+  if(Curl_checkheaders(conn, "User-Agent") && conn->allocptr.uagent) {
+    Curl_safefree(conn->allocptr.uagent);
+    conn->allocptr.uagent = NULL;
+  }
+  else if(!Curl_checkheaders(conn, "User-Agent") &&
+          data->set.str[STRING_USERAGENT]) {
+    p_uagent = conn->allocptr.uagent;
+  }
+
+  /* setup the authentication headers */
+  result = Curl_http_output_auth(conn, p_request, p_stream_uri, FALSE);
+  if(result)
+    return result;
+
+  p_proxyuserpwd = conn->allocptr.proxyuserpwd;
+  p_userpwd = conn->allocptr.userpwd;
+
+  /* Referrer */
+  Curl_safefree(conn->allocptr.ref);
+  if(data->change.referer && !Curl_checkheaders(conn, "Referer"))
+    conn->allocptr.ref = aprintf("Referer: %s\r\n", data->change.referer);
+  else
+    conn->allocptr.ref = NULL;
+
+  p_referrer = conn->allocptr.ref;
+
+  /*
+   * Range Header
+   * Only applies to PLAY, PAUSE, RECORD
+   *
+   * Go ahead and use the Range stuff supplied for HTTP
+   */
+  if(data->state.use_range &&
+     (rtspreq  & (RTSPREQ_PLAY | RTSPREQ_PAUSE | RTSPREQ_RECORD))) {
+
+    /* Check to see if there is a range set in the custom headers */
+    if(!Curl_checkheaders(conn, "Range") && data->state.range) {
+      Curl_safefree(conn->allocptr.rangeline);
+      conn->allocptr.rangeline = aprintf("Range: %s\r\n", data->state.range);
+      p_range = conn->allocptr.rangeline;
+    }
+  }
+
+  /*
+   * Sanity check the custom headers
+   */
+  if(Curl_checkheaders(conn, "CSeq")) {
+    failf(data, "CSeq cannot be set as a custom header.");
+    return CURLE_RTSP_CSEQ_ERROR;
+  }
+  if(Curl_checkheaders(conn, "Session")) {
+    failf(data, "Session ID cannot be set as a custom header.");
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+  }
+
+  /* Initialize a dynamic send buffer */
+  req_buffer = Curl_add_buffer_init();
+
+  if(!req_buffer)
+    return CURLE_OUT_OF_MEMORY;
+
+  result =
+    Curl_add_bufferf(&req_buffer,
+                     "%s %s RTSP/1.0\r\n" /* Request Stream-URI RTSP/1.0 */
+                     "CSeq: %ld\r\n", /* CSeq */
+                     p_request, p_stream_uri, rtsp->CSeq_sent);
+  if(result)
+    return result;
+
+  /*
+   * Rather than do a normal alloc line, keep the session_id unformatted
+   * to make comparison easier
+   */
+  if(p_session_id) {
+    result = Curl_add_bufferf(&req_buffer, "Session: %s\r\n", p_session_id);
+    if(result)
+      return result;
+  }
+
+  /*
+   * Shared HTTP-like options
+   */
+  result = Curl_add_bufferf(&req_buffer,
+                            "%s" /* transport */
+                            "%s" /* accept */
+                            "%s" /* accept-encoding */
+                            "%s" /* range */
+                            "%s" /* referrer */
+                            "%s" /* user-agent */
+                            "%s" /* proxyuserpwd */
+                            "%s" /* userpwd */
+                            ,
+                            p_transport ? p_transport : "",
+                            p_accept ? p_accept : "",
+                            p_accept_encoding ? p_accept_encoding : "",
+                            p_range ? p_range : "",
+                            p_referrer ? p_referrer : "",
+                            p_uagent ? p_uagent : "",
+                            p_proxyuserpwd ? p_proxyuserpwd : "",
+                            p_userpwd ? p_userpwd : "");
+
+  /*
+   * Free userpwd now --- cannot reuse this for Negotiate and possibly NTLM
+   * with basic and digest, it will be freed anyway by the next request
+   */
+  Curl_safefree(conn->allocptr.userpwd);
+  conn->allocptr.userpwd = NULL;
+
+  if(result)
+    return result;
+
+  if((rtspreq == RTSPREQ_SETUP) || (rtspreq == RTSPREQ_DESCRIBE)) {
+    result = Curl_add_timecondition(conn, req_buffer);
+    if(result)
+      return result;
+  }
+
+  result = Curl_add_custom_headers(conn, FALSE, req_buffer);
+  if(result)
+    return result;
+
+  if(rtspreq == RTSPREQ_ANNOUNCE ||
+     rtspreq == RTSPREQ_SET_PARAMETER ||
+     rtspreq == RTSPREQ_GET_PARAMETER) {
+
+    if(data->set.upload) {
+      putsize = data->state.infilesize;
+      data->set.httpreq = HTTPREQ_PUT;
+
+    }
+    else {
+      postsize = (data->state.infilesize != -1)?
+        data->state.infilesize:
+        (data->set.postfields? (curl_off_t)strlen(data->set.postfields):0);
+      data->set.httpreq = HTTPREQ_POST;
+    }
+
+    if(putsize > 0 || postsize > 0) {
+      /* As stated in the http comments, it is probably not wise to
+       * actually set a custom Content-Length in the headers */
+      if(!Curl_checkheaders(conn, "Content-Length")) {
+        result =
+          Curl_add_bufferf(&req_buffer,
+                           "Content-Length: %" CURL_FORMAT_CURL_OFF_T"\r\n",
+                           (data->set.upload ? putsize : postsize));
+        if(result)
+          return result;
+      }
+
+      if(rtspreq == RTSPREQ_SET_PARAMETER ||
+         rtspreq == RTSPREQ_GET_PARAMETER) {
+        if(!Curl_checkheaders(conn, "Content-Type")) {
+          result = Curl_add_bufferf(&req_buffer,
+                                    "Content-Type: text/parameters\r\n");
+          if(result)
+            return result;
+        }
+      }
+
+      if(rtspreq == RTSPREQ_ANNOUNCE) {
+        if(!Curl_checkheaders(conn, "Content-Type")) {
+          result = Curl_add_bufferf(&req_buffer,
+                                    "Content-Type: application/sdp\r\n");
+          if(result)
+            return result;
+        }
+      }
+
+      data->state.expect100header = FALSE; /* RTSP posts are simple/small */
+    }
+    else if(rtspreq == RTSPREQ_GET_PARAMETER) {
+      /* Check for an empty GET_PARAMETER (heartbeat) request */
+      data->set.httpreq = HTTPREQ_HEAD;
+      data->set.opt_no_body = TRUE;
+    }
+  }
+
+  /* RTSP never allows chunked transfer */
+  data->req.forbidchunk = TRUE;
+  /* Finish the request buffer */
+  result = Curl_add_buffer(&req_buffer, "\r\n", 2);
+  if(result)
+    return result;
+
+  if(postsize > 0) {
+    result = Curl_add_buffer(&req_buffer, data->set.postfields,
+                             (size_t)postsize);
+    if(result)
+      return result;
+  }
+
+  /* issue the request */
+  result = Curl_add_buffer_send(&req_buffer, conn,
+                                &data->info.request_size, 0, FIRSTSOCKET);
+  if(result) {
+    failf(data, "Failed sending RTSP request");
+    return result;
+  }
+
+  Curl_setup_transfer(data, FIRSTSOCKET, -1, TRUE, putsize?FIRSTSOCKET:-1);
+
+  /* Increment the CSeq on success */
+  data->state.rtsp_next_client_CSeq++;
+
+  if(data->req.writebytecount) {
+    /* if a request-body has been sent off, we make sure this progress is
+       noted properly */
+    Curl_pgrsSetUploadCounter(data, data->req.writebytecount);
+    if(Curl_pgrsUpdate(conn))
+      result = CURLE_ABORTED_BY_CALLBACK;
+  }
+
+  return result;
+}
+
+
+static CURLcode rtsp_rtp_readwrite(struct Curl_easy *data,
+                                   struct connectdata *conn,
+                                   ssize_t *nread,
+                                   bool *readmore) {
+  struct SingleRequest *k = &data->req;
+  struct rtsp_conn *rtspc = &(conn->proto.rtspc);
+
+  char *rtp; /* moving pointer to rtp data */
+  ssize_t rtp_dataleft; /* how much data left to parse in this round */
+  char *scratch;
+  CURLcode result;
+
+  if(rtspc->rtp_buf) {
+    /* There was some leftover data the last time. Merge buffers */
+    char *newptr = Curl_saferealloc(rtspc->rtp_buf,
+                                    rtspc->rtp_bufsize + *nread);
+    if(!newptr) {
+      rtspc->rtp_buf = NULL;
+      rtspc->rtp_bufsize = 0;
+      return CURLE_OUT_OF_MEMORY;
+    }
+    rtspc->rtp_buf = newptr;
+    memcpy(rtspc->rtp_buf + rtspc->rtp_bufsize, k->str, *nread);
+    rtspc->rtp_bufsize += *nread;
+    rtp = rtspc->rtp_buf;
+    rtp_dataleft = rtspc->rtp_bufsize;
+  }
+  else {
+    /* Just parse the request buffer directly */
+    rtp = k->str;
+    rtp_dataleft = *nread;
+  }
+
+  while((rtp_dataleft > 0) &&
+        (rtp[0] == '$')) {
+    if(rtp_dataleft > 4) {
+      int rtp_length;
+
+      /* Parse the header */
+      /* The channel identifier immediately follows and is 1 byte */
+      rtspc->rtp_channel = RTP_PKT_CHANNEL(rtp);
+
+      /* The length is two bytes */
+      rtp_length = RTP_PKT_LENGTH(rtp);
+
+      if(rtp_dataleft < rtp_length + 4) {
+        /* Need more - incomplete payload*/
+        *readmore = TRUE;
+        break;
+      }
+      /* We have the full RTP interleaved packet
+       * Write out the header including the leading '$' */
+      DEBUGF(infof(data, "RTP write channel %d rtp_length %d\n",
+             rtspc->rtp_channel, rtp_length));
+      result = rtp_client_write(conn, &rtp[0], rtp_length + 4);
+      if(result) {
+        failf(data, "Got an error writing an RTP packet");
+        *readmore = FALSE;
+        Curl_safefree(rtspc->rtp_buf);
+        rtspc->rtp_buf = NULL;
+        rtspc->rtp_bufsize = 0;
+        return result;
+      }
+
+      /* Move forward in the buffer */
+      rtp_dataleft -= rtp_length + 4;
+      rtp += rtp_length + 4;
+
+      if(data->set.rtspreq == RTSPREQ_RECEIVE) {
+        /* If we are in a passive receive, give control back
+         * to the app as often as we can.
+         */
+        k->keepon &= ~KEEP_RECV;
+      }
+    }
+    else {
+      /* Need more - incomplete header */
+      *readmore = TRUE;
+      break;
+    }
+  }
+
+  if(rtp_dataleft != 0 && rtp[0] == '$') {
+    DEBUGF(infof(data, "RTP Rewinding %zd %s\n", rtp_dataleft,
+          *readmore ? "(READMORE)" : ""));
+
+    /* Store the incomplete RTP packet for a "rewind" */
+    scratch = malloc(rtp_dataleft);
+    if(!scratch) {
+      Curl_safefree(rtspc->rtp_buf);
+      rtspc->rtp_buf = NULL;
+      rtspc->rtp_bufsize = 0;
+      return CURLE_OUT_OF_MEMORY;
+    }
+    memcpy(scratch, rtp, rtp_dataleft);
+    Curl_safefree(rtspc->rtp_buf);
+    rtspc->rtp_buf = scratch;
+    rtspc->rtp_bufsize = rtp_dataleft;
+
+    /* As far as the transfer is concerned, this data is consumed */
+    *nread = 0;
+    return CURLE_OK;
+  }
+  /* Fix up k->str to point just after the last RTP packet */
+  k->str += *nread - rtp_dataleft;
+
+  /* either all of the data has been read or...
+   * rtp now points at the next byte to parse
+   */
+  if(rtp_dataleft > 0)
+    DEBUGASSERT(k->str[0] == rtp[0]);
+
+  DEBUGASSERT(rtp_dataleft <= *nread); /* sanity check */
+
+  *nread = rtp_dataleft;
+
+  /* If we get here, we have finished with the leftover/merge buffer */
+  Curl_safefree(rtspc->rtp_buf);
+  rtspc->rtp_buf = NULL;
+  rtspc->rtp_bufsize = 0;
+
+  return CURLE_OK;
+}
+
+static
+CURLcode rtp_client_write(struct connectdata *conn, char *ptr, size_t len)
+{
+  struct Curl_easy *data = conn->data;
+  size_t wrote;
+  curl_write_callback writeit;
+  void *user_ptr;
+
+  if(len == 0) {
+    failf(data, "Cannot write a 0 size RTP packet.");
+    return CURLE_WRITE_ERROR;
+  }
+
+  /* If the user has configured CURLOPT_INTERLEAVEFUNCTION then use that
+     function and any configured CURLOPT_INTERLEAVEDATA to write out the RTP
+     data. Otherwise, use the CURLOPT_WRITEFUNCTION with the CURLOPT_WRITEDATA
+     pointer to write out the RTP data. */
+  if(data->set.fwrite_rtp) {
+    writeit = data->set.fwrite_rtp;
+    user_ptr = data->set.rtp_out;
+  }
+  else {
+    writeit = data->set.fwrite_func;
+    user_ptr = data->set.out;
+  }
+
+  Curl_set_in_callback(data, true);
+  wrote = writeit(ptr, 1, len, user_ptr);
+  Curl_set_in_callback(data, false);
+
+  if(CURL_WRITEFUNC_PAUSE == wrote) {
+    failf(data, "Cannot pause RTP");
+    return CURLE_WRITE_ERROR;
+  }
+
+  if(wrote != len) {
+    failf(data, "Failed writing RTP data");
+    return CURLE_WRITE_ERROR;
+  }
+
+  return CURLE_OK;
+}
+
+CURLcode Curl_rtsp_parseheader(struct connectdata *conn,
+                               char *header)
+{
+  struct Curl_easy *data = conn->data;
+  long CSeq = 0;
+
+  if(checkprefix("CSeq:", header)) {
+    /* Store the received CSeq. Match is verified in rtsp_done */
+    int nc = sscanf(&header[4], ": %ld", &CSeq);
+    if(nc == 1) {
+      struct RTSP *rtsp = data->req.protop;
+      rtsp->CSeq_recv = CSeq; /* mark the request */
+      data->state.rtsp_CSeq_recv = CSeq; /* update the handle */
+    }
+    else {
+      failf(data, "Unable to read the CSeq header: [%s]", header);
+      return CURLE_RTSP_CSEQ_ERROR;
+    }
+  }
+  else if(checkprefix("Session:", header)) {
+    char *start;
+
+    /* Find the first non-space letter */
+    start = header + 8;
+    while(*start && ISSPACE(*start))
+      start++;
+
+    if(!*start) {
+      failf(data, "Got a blank Session ID");
+    }
+    else if(data->set.str[STRING_RTSP_SESSION_ID]) {
+      /* If the Session ID is set, then compare */
+      if(strncmp(start, data->set.str[STRING_RTSP_SESSION_ID],
+                 strlen(data->set.str[STRING_RTSP_SESSION_ID]))  != 0) {
+        failf(data, "Got RTSP Session ID Line [%s], but wanted ID [%s]",
+              start, data->set.str[STRING_RTSP_SESSION_ID]);
+        return CURLE_RTSP_SESSION_ERROR;
+      }
+    }
+    else {
+      /* If the Session ID is not set, and we find it in a response, then set
+       * it.
+       *
+       * Allow any non whitespace content, up to the field separator or end of
+       * line. RFC 2326 isn't 100% clear on the session ID and for example
+       * gstreamer does url-encoded session ID's not covered by the standard.
+       */
+      char *end = start;
+      while(*end && *end != ';' && !ISSPACE(*end))
+        end++;
+
+      /* Copy the id substring into a new buffer */
+      data->set.str[STRING_RTSP_SESSION_ID] = malloc(end - start + 1);
+      if(data->set.str[STRING_RTSP_SESSION_ID] == NULL)
+        return CURLE_OUT_OF_MEMORY;
+      memcpy(data->set.str[STRING_RTSP_SESSION_ID], start, end - start);
+      (data->set.str[STRING_RTSP_SESSION_ID])[end - start] = '\0';
+    }
+  }
+  return CURLE_OK;
+}
+
+#endif /* CURL_DISABLE_RTSP */