Diff: src/libxively/http_layer_parser.c

Revision:

0:82702e998d3f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/libxively/http_layer_parser.c	Wed Jun 26 10:40:43 2013 +0000
@@ -0,0 +1,196 @@
+// Copyright (c) 2003-2013, LogMeIn, Inc. All rights reserved.
+// This is part of Xively C library, it is under the BSD 3-Clause license.
+
+/**
+ * \file    http_layer_parser.c
+ * \author  Olgierd Humenczuk
+ * \brief   Our simple HTTP parser [see http_layer_parser.h]
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "xively.h"
+#include "xi_macros.h"
+#include "http_consts.h"
+#include "http_layer_parser.h"
+#include "xi_debug.h"
+#include "xi_err.h"
+
+static const char XI_HTTP_STATUS_PATTERN[] =
+    "HTTP/%d.%d %d %" XI_STR(XI_HTTP_STATUS_STRING_SIZE) "[^\r\n]\r\n"; //!< the match pattern
+
+#define SET_HTTP_STATUS_PATTERN(a,b,c,d) XI_HTTP_STATUS_PATTERN, &a, &b, &c, d
+
+static const char XI_HTTP_TOKEN_NAMES[ XI_HTTP_HEADERS_COUNT ][ XI_HTTP_HEADER_NAME_MAX_SIZE ] =
+    {
+          "date"            // XI_HTTP_HEADER_DATE
+        , "content-type"    // XI_HTTP_HEADER_CONTENT_TYPE
+        , "content-length"  // XI_HTTP_HEADER_CONTENT_LENGTH
+        , "connection"      // XI_HTTP_HEADER_CONNECTION
+        , "x-request-id"    // XI_HTTP_HEADER_X_REQUEST_ID
+        , "cache-control"   // XI_HTTP_HEADER_CACHE_CONTROL
+        , "age"             // XI_HTTP_HEADER_AGE
+        , "vary"            // XI_HTTP_HEADER_VARY
+        , "unknown"         // XI_HTTP_HEADER_UNKNOWN, //!< !!!! this must be always on the last position
+    };
+
+static inline http_header_type_t classify_header( const char* header )
+{
+    for( unsigned short i = 0; i < XI_HTTP_HEADER_COUNT - 1; ++i )
+    {
+        if( strcasecmp( header, XI_HTTP_TOKEN_NAMES[ i ] ) == 0 )
+            return ( http_header_type_t ) i;
+    }
+
+    return XI_HTTP_HEADER_UNKNOWN;
+}
+
+const char* parse_http_status( http_response_t* response, const char* content )
+{
+    // variables
+    int c = 0;
+
+    // find the first occurrence of CRLF
+    const char* header_end_ptr = strstr( content, XI_HTTP_CRLF );
+
+    // check continuation condition
+    XI_CHECK_ZERO( header_end_ptr, XI_HTTP_STATUS_PARSE_ERROR );
+
+    // update the pointer
+    header_end_ptr += 2;
+
+    // parse
+    c = sscanf( content
+        , SET_HTTP_STATUS_PATTERN(
+              response->http_version1
+            , response->http_version2
+            , response->http_status
+            , response->http_status_string ) );
+
+    // check if all arguments found
+    XI_CHECK_CND( c != 4, XI_HTTP_STATUS_PARSE_ERROR );
+
+    // return updated ptr
+    return header_end_ptr;
+
+err_handling:
+    return 0;
+}
+
+const char* parse_http_header( http_response_t* response
+    , const char* content )
+{
+    // find the first occurrence of CRLF
+    const char* header_end_ptr      = strstr( content, XI_HTTP_CRLF );
+    const char* header_name_end_ptr = strstr( content, ":" );
+
+    // check continuation condition
+    XI_CHECK_ZERO( header_end_ptr, XI_HTTP_HEADER_PARSE_ERROR );
+    XI_CHECK_ZERO( header_name_end_ptr, XI_HTTP_HEADER_PARSE_ERROR );
+    XI_CHECK_CND( header_name_end_ptr > header_end_ptr, XI_HTTP_HEADER_PARSE_ERROR );
+
+    {
+        int size = sizeof( response->http_headers[ response->http_headers_size ].name );
+
+        XI_CHECK_CND( header_name_end_ptr - content > size - 1, XI_HTTP_HEADER_PARSE_ERROR );
+
+        memcpy( response->http_headers[ response->http_headers_size ].name
+            , content, XI_MIN( size - 1, header_name_end_ptr - content ) );
+
+        // set the guard
+        XI_GUARD_EOS( response->http_headers[ response->http_headers_size ].name, size );
+    }
+
+    // update the pointer
+    header_name_end_ptr += 2;
+
+    {
+        int size = sizeof( response->http_headers[ response->http_headers_size ].value );
+
+        XI_CHECK_CND( header_end_ptr - header_name_end_ptr > size - 1, XI_HTTP_HEADER_PARSE_ERROR );
+
+        memcpy( response->http_headers[ response->http_headers_size ].value
+            , header_name_end_ptr, XI_MIN( size - 1, header_end_ptr - header_name_end_ptr ) );
+
+        // set the guard
+        XI_GUARD_EOS( response->http_headers[ response->http_headers_size ].value, size );
+    }
+
+    // @TODO change the complexity of the classify header
+    // implementation now it's O( n*m ) it can be done in O( n )
+    // using some sort of simple DFA
+    // I'm working on a very simple Python DFA generator for C
+    // but still this is a w.i.p. at the moment
+
+    // parse the header name
+    {
+        http_header_type_t ht = classify_header(
+            response->http_headers[ response->http_headers_size ].name );
+
+        // accept headers that differs from unknown
+        if( ht != XI_HTTP_HEADER_UNKNOWN )
+        {
+            response->http_headers_checklist[ ht ] =
+                &response->http_headers[ response->http_headers_size ];
+        }
+
+        // set header type
+        response->http_headers[ response->http_headers_size ].header_type = ht;
+
+        // increment headers size and check if it's okay
+        response->http_headers_size += 1;
+
+        XI_CHECK_CND( response->http_headers_size >= XI_HTTP_MAX_HEADERS
+            , XI_HTTP_HEADER_PARSE_ERROR );
+
+        // update the pointer
+        header_end_ptr += sizeof( XI_HTTP_CRLF ) - 1;
+    }
+
+    return header_end_ptr;
+
+err_handling:
+    return 0;
+}
+
+http_response_t* parse_http( http_response_t* response, const char* content )
+{
+    memset( response, 0, sizeof( http_response_t ) );
+
+    // remember where is the end of header section
+    const char* ptr_to_headers_end = strstr( content, XI_HTTP_CRLFX2 );
+
+    // check the continuation condition
+    XI_CHECK_ZERO( ptr_to_headers_end, XI_HTTP_PARSE_ERROR );
+
+    // update the pointer
+    ptr_to_headers_end += sizeof( XI_HTTP_CRLF ) - 1;
+
+    const char* payload_begin = ptr_to_headers_end + sizeof( XI_HTTP_CRLF ) - 1;
+
+    XI_CHECK_ZERO( payload_begin, XI_HTTP_PARSE_ERROR );
+
+    // parse status
+    const char* ptr = parse_http_status( response, content );
+
+    // check the continuation condition
+    XI_CHECK_ZERO( ptr, XI_HTTP_PARSE_ERROR );
+
+    // read the headers
+    while( ( ptr = parse_http_header( response, ptr ) ) != '\0'
+        && ptr != ptr_to_headers_end );
+
+    // if there was an error, forward it
+    xi_err_t e = xi_get_last_error();
+    XI_CHECK_CND( e != XI_NO_ERR, e );
+
+    // just copy the content
+    strncpy( response->http_content, payload_begin, sizeof( response->http_content ) );
+
+    return response;
+
+err_handling:
+    return 0;
+}