Documentation Source Text

/*
** A small, simple HTTP server.
**
** Features:
**
**     * Launched from inetd/xinetd/stunnel4, or as a stand-alone server
**     * One process per request
**     * Deliver static content or run CGI
**     * Virtual sites based on the "Host:" property of the HTTP header
**     * Runs in a chroot jail
**     * Unified log file in a CSV format
**     * Small code base (this 1 file) to facilitate security auditing
**     * Simple setup - no configuration files to misconfigure
** 
** This file implements a small and simple but secure and effective web
................................................................................
**        RFC-5785 to allow letsencrypt or certbot to generate a TSL cert
**        using webroot.
**
**    (4) Characters other than [0-9a-zA-Z,-./:_~] and any %HH characters
**        escapes in the filename are all translated into "_".  This is
**        a defense against cross-site scripting attacks and other mischief.
**
**    (5) Executable files are run as CGI.  All other files are delivered
**        as is.
**
**    (6) For SSL support use stunnel and add the -https 1 option on the
**        httpd command-line.
**
**    (7) If a file named "-auth" exists in the same directory as the file to
**        be run as CGI or to be delivered, then it contains information
**        for HTTP Basic authorization.  See file format details below.
................................................................................
**
**    (8) To run as a stand-alone server, simply add the "-port N" command-line
**        option to define which TCP port to listen on.
**
**    (9) For static content, the mimetype is determined by the file suffix
**        using a table built into the source code below.  If you have
**        unusual content files, you might need to extend this table.




**
** Command-line Options:
**
**  --root DIR       Defines the directory that contains the various
**                   $HOST.website subdirectories, each containing web content 
**                   for a single virtual host.  If launched as root and if
**                   "--user USER" also appears on the command-line and if
................................................................................
};


/*
** Double any double-quote characters in a string.
*/
static char *Escape(char *z){
  int i, j;
  int n;
  char c;
  char *zOut;
  for(i=0; (c=z[i])!=0 && c!='"'; i++){}
  if( c==0 ) return z;
  n = 1;
  for(i++; (c=z[i])!=0; i++){ if( c=='"' ) n++; }
  zOut = malloc( i+n+1 );
................................................................................
  }
  statusSent = 0;
}

/*
** Allocate memory safely
*/
static char *SafeMalloc( int size ){
  char *p;

  p = (char*)malloc(size);
  if( p==0 ){
    strcpy(zReplyStatus, "998");
    MakeLogEntry(1,100);  /* LOG: Malloc() failed */
    exit(1);
................................................................................
}

/*
** Set the value of environment variable zVar to zValue.
*/
static void SetEnv(const char *zVar, const char *zValue){
  char *z;
  int len;
  if( zValue==0 ) zValue="";
  /* Disable an attempted bashdoor attack */
  if( strncmp(zValue,"() {",4)==0 ) zValue = "";
  len = strlen(zVar) + strlen(zValue) + 2;
  z = SafeMalloc(len);
  sprintf(z,"%s=%s",zVar,zValue);
  putenv(z);
................................................................................
}

/*
** Make a copy of a string into memory obtained from malloc.
*/
static char *StrDup(const char *zSrc){
  char *zDest;
  int size;

  if( zSrc==0 ) return 0;
  size = strlen(zSrc) + 1;
  zDest = (char*)SafeMalloc( size );
  strcpy(zDest,zSrc);
  return zDest;
}
static char *StrAppend(char *zPrior, const char *zSep, const char *zSrc){
  char *zDest;
  int size;
  int n1, n2;

  if( zSrc==0 ) return 0;
  if( zPrior==0 ) return StrDup(zSrc);
  size = (n1=strlen(zSrc)) + (n2=strlen(zSep)) + strlen(zPrior) + 1;
  zDest = (char*)SafeMalloc( size );
  strcpy(zDest,zPrior);
................................................................................
** A CGI or SCGI script has run and is sending its reply back across
** the channel "in".  Process this reply into an appropriate HTTP reply.
** Close the "in" channel when done.
*/
static void CgiHandleReply(FILE *in){
  int seenContentLength = 0;   /* True if Content-length: header seen */
  int contentLength = 0;       /* The content length */
  int nRes = 0;                /* Bytes of payload */
  int nMalloc = 0;             /* Bytes of space allocated to aRes */
  char *aRes = 0;              /* Payload */
  int c;                       /* Next character from in */
  char *z;                     /* Pointer to something inside of zLine */
  char zLine[1000];            /* One line of reply from the CGI script */

  if( useTimeout ) alarm(15);
  while( fgets(zLine,sizeof(zLine),in) && !isspace(zLine[0]) ){
................................................................................
        if( aRes==0 ){
           Malfunction(610, "Out of memory: %d bytes", nMalloc);
        }
      }
      aRes[nRes++] = c;
    }
    aRes[nRes] = 0;
    nOut += printf("Content-length: %d\r\n\r\n%s", nRes, aRes);
    free(aRes);
  }
  fclose(in);
}

/*
** Send an SCGI request to a host identified by zFile and process the
................................................................................
  char *zPort = 0;
  int rc;
  int iSocket = -1;
  struct addrinfo hints;
  struct addrinfo *ai = 0;
  struct addrinfo *p;
  char *zHdr;
  int nHdr = 0;
  int nHdrAlloc;
  int i;
  char zLine[1000];
  in = fopen(zFile, "rb");
  if( in==0 ){
    Malfunction(700, "cannot open \"%s\"\n", zFile);
  }
  if( fgets(zLine, sizeof(zLine)-1, in)==0 ){
................................................................................
  if( s==0 ){
    Malfunction(706, "could not turn the socket into a FILE\n");
  }

  nHdrAlloc = 0;
  zHdr = 0;
  if( zContentLength==0 ) zContentLength = "0";
  for(i=0; i<sizeof(cgienv)/sizeof(cgienv[0]); i++){
    int n1, n2;
    if( cgienv[i].pzEnvValue[0]==0 ) continue;
    n1 = (int)strlen(cgienv[i].zEnvName);
    n2 = (int)strlen(*cgienv[i].pzEnvValue);
    if( n1+n2+2+nHdr >= nHdrAlloc ){
      nHdrAlloc = nHdr + n1 + n2 + 1000;
      zHdr = realloc(zHdr, nHdrAlloc);
................................................................................
    memcpy(zHdr+nHdr, cgienv[i].zEnvName, n1);
    nHdr += n1;
    zHdr[nHdr++] = 0;
    memcpy(zHdr+nHdr, *cgienv[i].pzEnvValue, n2);
    nHdr += n2;
    zHdr[nHdr++] = 0;
  }
  fprintf(s,"%d:",nHdr);
  fwrite(zHdr, 1, nHdr, s);
  fprintf(s,",");
  free(zHdr);
  if( zMethod[0]=='P'
   && atoi(zContentLength)>0 
   && (in = fopen(zTmpNam,"r"))!=0 ){
    size_t n;
................................................................................

  /* Create a file to hold the POST query data, if any.  We have to
  ** do it this way.  We can't just pass the file descriptor down to
  ** the child process because the fgets() function may have already
  ** read part of the POST data into its internal buffer.
  */
  if( zMethod[0]=='P' && zContentLength!=0 ){
    int len = atoi(zContentLength);
    FILE *out;
    char *zBuf;
    int n;

    if( len>MAX_CONTENT_LENGTH ){
      StartResponse("500 Request too large");
      nOut += printf(

/*
** A small, simple HTTP server.
**
** Features:
**
**     * Launched from inetd/xinetd/stunnel4, or as a stand-alone server
**     * One process per request
**     * Deliver static content or run CGI or SCGI
**     * Virtual sites based on the "Host:" property of the HTTP header
**     * Runs in a chroot jail
**     * Unified log file in a CSV format
**     * Small code base (this 1 file) to facilitate security auditing
**     * Simple setup - no configuration files to misconfigure
** 
** This file implements a small and simple but secure and effective web
................................................................................
**        RFC-5785 to allow letsencrypt or certbot to generate a TSL cert
**        using webroot.
**
**    (4) Characters other than [0-9a-zA-Z,-./:_~] and any %HH characters
**        escapes in the filename are all translated into "_".  This is
**        a defense against cross-site scripting attacks and other mischief.
**
**    (5) Executable files are run as CGI.  Files whose name ends with ".scgi"****        trigger and SCGI request (see item 10 below).  All other files
**        are delivered as is.
**
**    (6) For SSL support use stunnel and add the -https 1 option on the
**        httpd command-line.
**
**    (7) If a file named "-auth" exists in the same directory as the file to
**        be run as CGI or to be delivered, then it contains information
**        for HTTP Basic authorization.  See file format details below.
................................................................................
**
**    (8) To run as a stand-alone server, simply add the "-port N" command-line
**        option to define which TCP port to listen on.
**
**    (9) For static content, the mimetype is determined by the file suffix
**        using a table built into the source code below.  If you have
**        unusual content files, you might need to extend this table.
**
**   (10) Content files that end with ".scgi" and that contain text of the
**        form "SCGI hostname port" will format an SCGI request and send it
**        to hostname:port, the relay back the reply.
**
** Command-line Options:
**
**  --root DIR       Defines the directory that contains the various
**                   $HOST.website subdirectories, each containing web content 
**                   for a single virtual host.  If launched as root and if
**                   "--user USER" also appears on the command-line and if
................................................................................
};


/*
** Double any double-quote characters in a string.
*/
static char *Escape(char *z){
  size_t i, j;
  size_t n;
  char c;
  char *zOut;
  for(i=0; (c=z[i])!=0 && c!='"'; i++){}
  if( c==0 ) return z;
  n = 1;
  for(i++; (c=z[i])!=0; i++){ if( c=='"' ) n++; }
  zOut = malloc( i+n+1 );
................................................................................
  }
  statusSent = 0;
}

/*
** Allocate memory safely
*/
static char *SafeMalloc( size_t size ){
  char *p;

  p = (char*)malloc(size);
  if( p==0 ){
    strcpy(zReplyStatus, "998");
    MakeLogEntry(1,100);  /* LOG: Malloc() failed */
    exit(1);
................................................................................
}

/*
** Set the value of environment variable zVar to zValue.
*/
static void SetEnv(const char *zVar, const char *zValue){
  char *z;
  size_t len;
  if( zValue==0 ) zValue="";
  /* Disable an attempted bashdoor attack */
  if( strncmp(zValue,"() {",4)==0 ) zValue = "";
  len = strlen(zVar) + strlen(zValue) + 2;
  z = SafeMalloc(len);
  sprintf(z,"%s=%s",zVar,zValue);
  putenv(z);
................................................................................
}

/*
** Make a copy of a string into memory obtained from malloc.
*/
static char *StrDup(const char *zSrc){
  char *zDest;
  size_t size;

  if( zSrc==0 ) return 0;
  size = strlen(zSrc) + 1;
  zDest = (char*)SafeMalloc( size );
  strcpy(zDest,zSrc);
  return zDest;
}
static char *StrAppend(char *zPrior, const char *zSep, const char *zSrc){
  char *zDest;
  size_t size;
  int n1, n2;

  if( zSrc==0 ) return 0;
  if( zPrior==0 ) return StrDup(zSrc);
  size = (n1=strlen(zSrc)) + (n2=strlen(zSep)) + strlen(zPrior) + 1;
  zDest = (char*)SafeMalloc( size );
  strcpy(zDest,zPrior);
................................................................................
** A CGI or SCGI script has run and is sending its reply back across
** the channel "in".  Process this reply into an appropriate HTTP reply.
** Close the "in" channel when done.
*/
static void CgiHandleReply(FILE *in){
  int seenContentLength = 0;   /* True if Content-length: header seen */
  int contentLength = 0;       /* The content length */
  size_t nRes = 0;             /* Bytes of payload */
  size_t nMalloc = 0;          /* Bytes of space allocated to aRes */
  char *aRes = 0;              /* Payload */
  int c;                       /* Next character from in */
  char *z;                     /* Pointer to something inside of zLine */
  char zLine[1000];            /* One line of reply from the CGI script */

  if( useTimeout ) alarm(15);
  while( fgets(zLine,sizeof(zLine),in) && !isspace(zLine[0]) ){
................................................................................
        if( aRes==0 ){
           Malfunction(610, "Out of memory: %d bytes", nMalloc);
        }
      }
      aRes[nRes++] = c;
    }
    aRes[nRes] = 0;
    nOut += printf("Content-length: %d\r\n\r\n%s", (int)nRes, aRes);
    free(aRes);
  }
  fclose(in);
}

/*
** Send an SCGI request to a host identified by zFile and process the
................................................................................
  char *zPort = 0;
  int rc;
  int iSocket = -1;
  struct addrinfo hints;
  struct addrinfo *ai = 0;
  struct addrinfo *p;
  char *zHdr;
  size_t nHdr = 0;
  size_t nHdrAlloc;
  int i;
  char zLine[1000];
  in = fopen(zFile, "rb");
  if( in==0 ){
    Malfunction(700, "cannot open \"%s\"\n", zFile);
  }
  if( fgets(zLine, sizeof(zLine)-1, in)==0 ){
................................................................................
  if( s==0 ){
    Malfunction(706, "could not turn the socket into a FILE\n");
  }

  nHdrAlloc = 0;
  zHdr = 0;
  if( zContentLength==0 ) zContentLength = "0";
  for(i=0; i<(int)(sizeof(cgienv)/sizeof(cgienv[0])); i++){
    int n1, n2;
    if( cgienv[i].pzEnvValue[0]==0 ) continue;
    n1 = (int)strlen(cgienv[i].zEnvName);
    n2 = (int)strlen(*cgienv[i].pzEnvValue);
    if( n1+n2+2+nHdr >= nHdrAlloc ){
      nHdrAlloc = nHdr + n1 + n2 + 1000;
      zHdr = realloc(zHdr, nHdrAlloc);
................................................................................
    memcpy(zHdr+nHdr, cgienv[i].zEnvName, n1);
    nHdr += n1;
    zHdr[nHdr++] = 0;
    memcpy(zHdr+nHdr, *cgienv[i].pzEnvValue, n2);
    nHdr += n2;
    zHdr[nHdr++] = 0;
  }
  fprintf(s,"%d:",(int)nHdr);
  fwrite(zHdr, 1, nHdr, s);
  fprintf(s,",");
  free(zHdr);
  if( zMethod[0]=='P'
   && atoi(zContentLength)>0 
   && (in = fopen(zTmpNam,"r"))!=0 ){
    size_t n;
................................................................................

  /* Create a file to hold the POST query data, if any.  We have to
  ** do it this way.  We can't just pass the file descriptor down to
  ** the child process because the fgets() function may have already
  ** read part of the POST data into its internal buffer.
  */
  if( zMethod[0]=='P' && zContentLength!=0 ){
    size_t len = atoi(zContentLength);
    FILE *out;
    char *zBuf;
    int n;

    if( len>MAX_CONTENT_LENGTH ){
      StartResponse("500 Request too large");
      nOut += printf(