source: lib/http_client.c @ b447d2b

  /********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2013 Wilmer van der Gaast and others                *
  \********************************************************************/

/* HTTP(S) module                                                       */

/*
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  Suite 330, Boston, MA  02111-1307  USA
*/

#include <string.h>
#include <stdio.h>

#include "http_client.h"
#include "url.h"
#include "sock.h"


static gboolean http_connected( gpointer data, int source, b_input_condition cond );
static gboolean http_ssl_connected( gpointer data, int returncode, void *source, b_input_condition cond );
static gboolean http_incoming_data( gpointer data, int source, b_input_condition cond );
static void http_free( struct http_request *req );


struct http_request *http_dorequest( char *host, int port, int ssl, char *request, http_input_function func, gpointer data )
{
        struct http_request *req;
        int error = 0;
        
        req = g_new0( struct http_request, 1 );
        
        if( ssl )
        {
                req->ssl = ssl_connect( host, port, TRUE, http_ssl_connected, req );
                if( req->ssl == NULL )
                        error = 1;
        }
        else
        {
                req->fd = proxy_connect( host, port, http_connected, req );
                if( req->fd < 0 )
                        error = 1;
        }
        
        if( error )
        {
                http_free( req );
                return NULL;
        }
        
        req->func = func;
        req->data = data;
        req->request = g_strdup( request );
        req->request_length = strlen( request );
        req->redir_ttl = 3;
        req->content_length = -1;
        
        if( getenv( "BITLBEE_DEBUG" ) )
                printf( "About to send HTTP request:\n%s\n", req->request );
        
        return req;
}

struct http_request *http_dorequest_url( char *url_string, http_input_function func, gpointer data )
{
        url_t *url = g_new0( url_t, 1 );
        char *request;
        void *ret;
        
        if( !url_set( url, url_string ) )
        {
                g_free( url );
                return NULL;
        }
        
        if( url->proto != PROTO_HTTP && url->proto != PROTO_HTTPS )
        {
                g_free( url );
                return NULL;
        }
        
        request = g_strdup_printf( "GET %s HTTP/1.0\r\n"
                                   "Host: %s\r\n"
                                   "User-Agent: BitlBee " BITLBEE_VERSION " " ARCH "/" CPU "\r\n"
                                   "\r\n", url->file, url->host );
        
        ret = http_dorequest( url->host, url->port,
                              url->proto == PROTO_HTTPS, request, func, data );
        
        g_free( url );
        g_free( request );
        return ret;
}

/* This one is actually pretty simple... Might get more calls if we can't write 
   the whole request at once. */
static gboolean http_connected( gpointer data, int source, b_input_condition cond )
{
        struct http_request *req = data;
        int st;
        
        if( source < 0 )
                goto error;
        
        if( req->inpa > 0 )
                b_event_remove( req->inpa );
        
        sock_make_nonblocking( req->fd );
        
        if( req->ssl )
        {
                st = ssl_write( req->ssl, req->request + req->bytes_written,
                                req->request_length - req->bytes_written );
                if( st < 0 )
                {
                        if( ssl_errno != SSL_AGAIN )
                        {
                                ssl_disconnect( req->ssl );
                                goto error;
                        }
                }
        }
        else
        {
                st = write( source, req->request + req->bytes_written,
                                    req->request_length - req->bytes_written );
                if( st < 0 )
                {
                        if( !sockerr_again() )
                        {
                                closesocket( req->fd );
                                goto error;
                        }
                }
        }
        
        if( st > 0 )
                req->bytes_written += st;
        
        if( req->bytes_written < req->request_length )
                req->inpa = b_input_add( source,
                                         req->ssl ? ssl_getdirection( req->ssl ) : B_EV_IO_WRITE,
                                         http_connected, req );
        else
                req->inpa = b_input_add( source, B_EV_IO_READ, http_incoming_data, req );
        
        return FALSE;
        
error:
        if( req->status_string == NULL )
                req->status_string = g_strdup( "Error while writing HTTP request" );
        
        req->func( req );
        http_free( req );
        return FALSE;
}

static gboolean http_ssl_connected( gpointer data, int returncode, void *source, b_input_condition cond )
{
        struct http_request *req = data;
        
        if( source == NULL )
        {
                if( returncode != 0 )
                {
                        char *err = ssl_verify_strerror( returncode );
                        req->status_string = g_strdup_printf(
                                "Certificate verification problem 0x%x: %s",
                                returncode, err ? err : "Unknown" );
                        g_free( err );
                }
                return http_connected( data, -1, cond );
        }
        
        req->fd = ssl_getfd( source );
        
        return http_connected( data, req->fd, cond );
}

typedef enum {
        CR_OK,
        CR_EOF,
        CR_ERROR,
        CR_ABORT,
} http_ret_t;

static gboolean http_handle_headers( struct http_request *req );
static http_ret_t http_process_chunked_data( struct http_request *req, const char *buffer, int len );
static http_ret_t http_process_data( struct http_request *req, const char *buffer, int len );

static gboolean http_incoming_data( gpointer data, int source, b_input_condition cond )
{
        struct http_request *req = data;
        char buffer[4096];
        int st;
        
        if( req->inpa > 0 )
                b_event_remove( req->inpa );
        
        if( req->ssl )
        {
                st = ssl_read( req->ssl, buffer, sizeof( buffer ) );
                if( st < 0 )
                {
                        if( ssl_errno != SSL_AGAIN )
                        {
                                /* goto cleanup; */
                                
                                /* YAY! We have to deal with crappy Microsoft
                                   servers that LOVE to send invalid TLS
                                   packets that abort connections! \o/ */
                                
                                goto eof;
                        }
                }
                else if( st == 0 )
                {
                        goto eof;
                }
        }
        else
        {
                st = read( req->fd, buffer, sizeof( buffer ) );
                if( st < 0 )
                {
                        if( !sockerr_again() )
                        {
                                req->status_string = g_strdup( strerror( errno ) );
                                goto cleanup;
                        }
                }
                else if( st == 0 )
                {
                        goto eof;
                }
        }
        
        if( st > 0 )
        {
                http_ret_t c;
                
                if( req->flags & HTTPC_CHUNKED )
                        c = http_process_chunked_data( req, buffer, st );
                else
                        c = http_process_data( req, buffer, st );
                
                if( c == CR_EOF )
                        goto eof;
                else if( c == CR_ERROR || c == CR_ABORT )
                        return FALSE;
        }
        
        if( req->content_length != -1 &&
            req->body_size >= req->content_length )
                goto eof;
        
        if( ssl_pending( req->ssl ) )
                return http_incoming_data( data, source, cond );
        
        /* There will be more! */
        req->inpa = b_input_add( req->fd,
                                 req->ssl ? ssl_getdirection( req->ssl ) : B_EV_IO_READ,
                                 http_incoming_data, req );
        
        return FALSE;

eof:
        req->flags |= HTTPC_EOF;
        
        /* Maybe if the webserver is overloaded, or when there's bad SSL
           support... */
        if( req->bytes_read == 0 )
        {
                req->status_string = g_strdup( "Empty HTTP reply" );
                goto cleanup;
        }

cleanup:
        if( req->ssl )
                ssl_disconnect( req->ssl );
        else
                closesocket( req->fd );
        
        if( req->body_size < req->content_length )
        {
                req->status_code = -1;
                g_free( req->status_string );
                req->status_string = g_strdup( "Response truncated" );
        }
        
        if( getenv( "BITLBEE_DEBUG" ) && req )
                printf( "Finishing HTTP request with status: %s\n",
                        req->status_string ? req->status_string : "NULL" );
        
        req->func( req );
        http_free( req );
        return FALSE;
}

static http_ret_t http_process_chunked_data( struct http_request *req, const char *buffer, int len )
{
        char *chunk, *eos, *s;
        
        if( len < 0 )
                return TRUE;
        
        if( len > 0 )
        {
                req->cbuf = g_realloc( req->cbuf, req->cblen + len + 1 );
                memcpy( req->cbuf + req->cblen, buffer, len );
                req->cblen += len;
                req->cbuf[req->cblen] = '\0';
        }
        
        /* Turns out writing a proper chunked-encoding state machine is not
           that simple. :-( I've tested this one feeding it byte by byte so
           I hope it's solid now. */
        chunk = req->cbuf;
        eos = req->cbuf + req->cblen;
        while( TRUE )
        {
                int clen = 0;
                
                /* Might be a \r\n from the last chunk. */
                s = chunk;
                while( isspace( *s ) )
                        s ++;
                /* Chunk length. Might be incomplete. */
                if( s < eos && sscanf( s, "%x", &clen ) != 1 )
                        return CR_ERROR;
                while( isxdigit( *s ) )
                        s ++;
                
                /* If we read anything here, it *must* be \r\n. */
                if( strncmp( s, "\r\n", MIN( 2, eos - s ) ) != 0 )
                        return CR_ERROR;
                s += 2;
                
                if( s >= eos )
                        break;
                
                /* 0-length chunk means end of response. */     
                if( clen == 0 )
                        return CR_EOF;
                
                /* Wait for the whole chunk to arrive. */
                if( s + clen > eos )
                        break;
                if( http_process_data( req, s, clen ) != CR_OK )
                        return CR_ABORT;
                
                chunk = s + clen;
        }
        
        if( chunk != req->cbuf )
        {
                req->cblen = eos - chunk;
                s = g_memdup( chunk, req->cblen + 1 );
                g_free( req->cbuf );
                req->cbuf = s;
        }
        
        return CR_OK;
}

static http_ret_t http_process_data( struct http_request *req, const char *buffer, int len )
{
        if( len <= 0 )
                return CR_OK;
        
        if( !req->reply_body )
        {
                req->reply_headers = g_realloc( req->reply_headers, req->bytes_read + len + 1 );
                memcpy( req->reply_headers + req->bytes_read, buffer, len );
                req->bytes_read += len;
                req->reply_headers[req->bytes_read] = '\0';
                
                if( strstr( req->reply_headers, "\r\n\r\n" ) ||
                    strstr( req->reply_headers, "\n\n" ) )
                {
                        /* We've now received all headers. Look for something
                           interesting. */
                        if( !http_handle_headers( req ) )
                                return CR_ABORT;
                        
                        /* Start parsing the body as chunked if required. */
                        if( req->flags & HTTPC_CHUNKED )
                                return http_process_chunked_data( req, NULL, 0 );
                }
        }
        else
        {
                int pos = req->reply_body - req->sbuf;
                req->sbuf = g_realloc( req->sbuf, req->sblen + len + 1 );
                memcpy( req->sbuf + req->sblen, buffer, len );
                req->bytes_read += len;
                req->sblen += len;
                req->sbuf[req->sblen] = '\0';
                req->reply_body = req->sbuf + pos;
                req->body_size = req->sblen - pos;
        }
        
        if( ( req->flags & HTTPC_STREAMING ) && req->reply_body )
                req->func( req );
        
        return CR_OK;
}

/* Splits headers and body. Checks result code, in case of 300s it'll handle
   redirects. If this returns FALSE, don't call any callbacks! */
static gboolean http_handle_headers( struct http_request *req )
{
        char *end1, *end2, *s;
        int evil_server = 0;
        
        /* Zero termination is very convenient. */
        req->reply_headers[req->bytes_read] = '\0';
        
        /* Find the separation between headers and body, and keep stupid
           webservers in mind. */
        end1 = strstr( req->reply_headers, "\r\n\r\n" );
        end2 = strstr( req->reply_headers, "\n\n" );
        
        if( end2 && end2 < end1 )
        {
                end1 = end2 + 1;
                evil_server = 1;
        }
        else if( end1 )
        {
                end1 += 2;
        }
        else
        {
                req->status_string = g_strdup( "Malformed HTTP reply" );
                return TRUE;
        }
        
        *end1 = '\0';
        
        if( getenv( "BITLBEE_DEBUG" ) )
                printf( "HTTP response headers:\n%s\n", req->reply_headers );
        
        if( evil_server )
                req->reply_body = end1 + 1;
        else
                req->reply_body = end1 + 2;
        
        /* Separately allocated space for headers and body. */
        req->sblen = req->body_size = req->reply_headers + req->bytes_read - req->reply_body;
        req->sbuf = req->reply_body = g_memdup( req->reply_body, req->body_size + 1 );
        req->reply_headers = g_realloc( req->reply_headers, end1 - req->reply_headers + 1 );
        
        if( ( end1 = strchr( req->reply_headers, ' ' ) ) != NULL )
        {
                if( sscanf( end1 + 1, "%hd", &req->status_code ) != 1 )
                {
                        req->status_string = g_strdup( "Can't parse status code" );
                        req->status_code = -1;
                }
                else
                {
                        char *eol;
                        
                        if( evil_server )
                                eol = strchr( end1, '\n' );
                        else
                                eol = strchr( end1, '\r' );
                        
                        req->status_string = g_strndup( end1 + 1, eol - end1 - 1 );
                        
                        /* Just to be sure... */
                        if( ( eol = strchr( req->status_string, '\r' ) ) )
                                *eol = 0;
                        if( ( eol = strchr( req->status_string, '\n' ) ) )
                                *eol = 0;
                }
        }
        else
        {
                req->status_string = g_strdup( "Can't locate status code" );
                req->status_code = -1;
        }
        
        if( ( ( req->status_code >= 301 && req->status_code <= 303 ) ||
              req->status_code == 307 ) && req->redir_ttl-- > 0 )
        {
                char *loc, *new_request, *new_host;
                int error = 0, new_port, new_proto;
                
                /* We might fill it again, so let's not leak any memory. */
                g_free( req->status_string );
                req->status_string = NULL;
                
                loc = strstr( req->reply_headers, "\nLocation: " );
                if( loc == NULL ) /* We can't handle this redirect... */
                {
                        req->status_string = g_strdup( "Can't locate Location: header" );
                        return TRUE;
                }
                
                loc += 11;
                while( *loc == ' ' )
                        loc ++;
                
                /* TODO/FIXME: Possibly have to handle relative redirections,
                   and rewrite Host: headers. Not necessary for now, it's
                   enough for passport authentication like this. */
                
                if( *loc == '/' )
                {
                        /* Just a different pathname... */
                        
                        /* Since we don't cache the servername, and since we
                           don't need this yet anyway, I won't implement it. */
                        
                        req->status_string = g_strdup( "Can't handle relative redirects" );
                        
                        return TRUE;
                }
                else
                {
                        /* A whole URL */
                        url_t *url;
                        char *s, *version, *headers;
                        const char *new_method;
                        
                        s = strstr( loc, "\r\n" );
                        if( s == NULL )
                                return TRUE;
                        
                        url = g_new0( url_t, 1 );
                        *s = 0;
                        
                        if( !url_set( url, loc ) )
                        {
                                req->status_string = g_strdup( "Malformed redirect URL" );
                                g_free( url );
                                return TRUE;
                        }
                        
                        /* Find all headers and, if necessary, the POST request contents.
                           Skip the old Host: header though. This crappy code here means
                           anything using this http_client MUST put the Host: header at
                           the top. */
                        if( !( ( s = strstr( req->request, "\r\nHost: " ) ) &&
                               ( s = strstr( s + strlen( "\r\nHost: " ), "\r\n" ) ) ) )
                        {
                                req->status_string = g_strdup( "Error while rebuilding request string" );
                                g_free( url );
                                return TRUE;
                        }
                        headers = s;
                        
                        /* More or less HTTP/1.0 compliant, from my reading of RFC 2616.
                           Always perform a GET request unless we received a 301. 303 was
                           meant for this but it's HTTP/1.1-only and we're specifically
                           speaking HTTP/1.0. ...
                           
                           Well except someone at identi.ca's didn't bother reading any
                           RFCs and just return HTTP/1.1-specific status codes to HTTP/1.0
                           requests. Fuckers. So here we are, handle 301..303,307. */
                        if( strncmp( req->request, "GET", 3 ) == 0 )
                                /* GETs never become POSTs. */
                                new_method = "GET";
                        else if( req->status_code == 302 || req->status_code == 303 )
                                /* 302 de-facto becomes GET, 303 as specified by RFC 2616#10.3.3 */
                                new_method = "GET";
                        else
                                /* 301 de-facto should stay POST, 307 specifally RFC 2616#10.3.8 */
                                new_method = "POST";
                        
                        if( ( version = strstr( req->request, " HTTP/" ) ) &&
                            ( s = strstr( version, "\r\n" ) ) )
                        {
                                version ++;
                                version = g_strndup( version, s - version );
                        }
                        else
                                version = g_strdup( "HTTP/1.0" );
                        
                        /* Okay, this isn't fun! We have to rebuild the request... :-( */
                        new_request = g_strdup_printf( "%s %s %s\r\nHost: %s%s",
                                                       new_method, url->file, version,
                                                       url->host, headers );
                        
                        new_host = g_strdup( url->host );
                        new_port = url->port;
                        new_proto = url->proto;
                        
                        /* If we went from POST to GET, truncate the request content. */
                        if( new_request[0] != req->request[0] && new_request[0] == 'G' &&
                            ( s = strstr( new_request, "\r\n\r\n" ) ) )
                                s[4] = '\0';
                        
                        g_free( url );
                        g_free( version );
                }
                
                if( req->ssl )
                        ssl_disconnect( req->ssl );
                else
                        closesocket( req->fd );
                
                req->fd = -1;
                req->ssl = NULL;
                
                if( getenv( "BITLBEE_DEBUG" ) )
                        printf( "New headers for redirected HTTP request:\n%s\n", new_request );
        
                if( new_proto == PROTO_HTTPS )
                {
                        req->ssl = ssl_connect( new_host, new_port, TRUE, http_ssl_connected, req );
                        if( req->ssl == NULL )
                                error = 1;
                }
                else
                {
                        req->fd = proxy_connect( new_host, new_port, http_connected, req );
                        if( req->fd < 0 )
                                error = 1;
                }
                g_free( new_host );
                
                if( error )
                {
                        req->status_string = g_strdup( "Connection problem during redirect" );
                        g_free( new_request );
                        return TRUE;
                }
                
                g_free( req->request );
                g_free( req->reply_headers );
                g_free( req->sbuf );
                req->request = new_request;
                req->request_length = strlen( new_request );
                req->bytes_read = req->bytes_written = req->inpa = 0;
                req->reply_headers = req->reply_body = NULL;
                req->sbuf = req->cbuf = NULL;
                req->sblen = req->cblen = 0;
                
                return FALSE;
        }

        if( ( s = get_rfc822_header( req->reply_headers, "Content-Length", 0 ) ) &&
            sscanf( s, "%d", &req->content_length ) != 1 )
                req->content_length = -1;
        g_free( s );
        
        if( ( s = get_rfc822_header( req->reply_headers, "Transfer-Encoding", 0 ) ) )
        {
                if( strcasestr( s, "chunked" ) )
                {
                        req->flags |= HTTPC_CHUNKED;
                        req->cbuf = req->sbuf;
                        req->cblen = req->sblen;
                        
                        req->reply_body = req->sbuf = g_strdup( "" );
                        req->body_size = req->sblen = 0;
                }
                g_free( s );
        }
        
        return TRUE;
}

void http_flush_bytes( struct http_request *req, size_t len )
{
        if( len <= 0 || len > req->body_size || !( req->flags & HTTPC_STREAMING ) )
                return;
        
        req->reply_body += len;
        req->body_size -= len;
        
        if( req->reply_body - req->sbuf >= 512 )
        {
                char *new = g_memdup( req->reply_body, req->body_size + 1 );
                g_free( req->sbuf );
                req->reply_body = req->sbuf = new;
                req->sblen = req->body_size;
        }
}

void http_close( struct http_request *req )
{
        if( !req )
                return;
        
        if( req->inpa > 0 )
                b_event_remove( req->inpa );
        
        if( req->ssl )
                ssl_disconnect( req->ssl );
        else
                closesocket( req->fd );
        
        http_free( req );
}

static void http_free( struct http_request *req )
{
        g_free( req->request );
        g_free( req->reply_headers );
        g_free( req->status_string );
        g_free( req->sbuf );
        g_free( req->cbuf );
        g_free( req );
}