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curl_easy_recv.3 3.7 KB

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  23. .TH curl_easy_recv 3 "29 April 2008" "libcurl 7.18.2" "libcurl Manual"
  24. .SH NAME
  25. curl_easy_recv - receives raw data on an "easy" connection
  26. .SH SYNOPSIS
  27. .B #include <curl/easy.h>
  28. .sp
  29. .BI "CURLcode curl_easy_recv( CURL *" curl ", void *" buffer ","
  30. .BI "size_t " buflen ", size_t *" n ");"
  31. .ad
  32. .SH DESCRIPTION
  33. This function receives raw data from the established connection. You may use
  34. it together with \fIcurl_easy_send(3)\fP to implement custom protocols using
  35. libcurl. This functionality can be particularly useful if you use proxies
  36. and/or SSL encryption: libcurl will take care of proxy negotiation and
  37. connection set-up.
  38. \fBbuffer\fP is a pointer to your buffer that will get the received
  39. data. \fBbuflen\fP is the maximum amount of data you can get in that
  40. buffer. The variable \fBn\fP points to will receive the number of received
  41. bytes.
  42. To establish the connection, set \fICURLOPT_CONNECT_ONLY(3)\fP option before
  43. calling \fIcurl_easy_perform(3)\fP or \fIcurl_multi_perform(3)\fP. Note that
  44. \fIcurl_easy_recv(3)\fP does not work on connections that were created without
  45. this option.
  46. The call will return \fBCURLE_AGAIN\fP if there is no data to read - the
  47. socket is used in non-blocking mode internally. When \fBCURLE_AGAIN\fP is
  48. returned, use your operating system facilities like \fIselect(2)\fP to wait
  49. for data. The socket may be obtained using \fIcurl_easy_getinfo(3)\fP with
  50. \fICURLINFO_ACTIVESOCKET(3)\fP.
  51. Wait on the socket only if \fIcurl_easy_recv(3)\fP returns \fBCURLE_AGAIN\fP.
  52. The reason for this is libcurl or the SSL library may internally cache some
  53. data, therefore you should call \fIcurl_easy_recv(3)\fP until all data is
  54. read which would include any cached data.
  55. Furthermore if you wait on the socket and it tells you there is data to read,
  56. \fIcurl_easy_recv(3)\fP may return \fBCURLE_AGAIN\fP if the only data that was
  57. read was for internal SSL processing, and no other data is available.
  58. .SH AVAILABILITY
  59. Added in 7.18.2.
  60. .SH RETURN VALUE
  61. On success, returns \fBCURLE_OK\fP, stores the received data into
  62. \fBbuffer\fP, and the number of bytes it actually read into \fB*n\fP.
  63. On failure, returns the appropriate error code.
  64. The function may return \fBCURLE_AGAIN\fP. In this case, use your operating
  65. system facilities to wait until data can be read, and retry.
  66. Reading exactly 0 bytes indicates a closed connection.
  67. If there's no socket available to use from the previous transfer, this function
  68. returns \fBCURLE_UNSUPPORTED_PROTOCOL\fP.
  69. .SH EXAMPLE
  70. See \fBsendrecv.c\fP in \fBdocs/examples\fP directory for usage example.
  71. .SH "SEE ALSO"
  72. .BR curl_easy_setopt "(3), " curl_easy_perform "(3), "
  73. .BR curl_easy_getinfo "(3), "
  74. .BR curl_easy_send "(3) "