banners

#include "proto-banner1.h"

#include "smack.h"

#include <ctype.h>

enum {

    HTTPFIELD_INCOMPLETE,

    HTTPFIELD_SERVER,

    HTTPFIELD_UNKNOWN,

    HTTPFIELD_NEWLINE,

};

struct Patterns http_fields[] = {

    {"Server:",     7, HTTPFIELD_SERVER, SMACK_ANCHOR_BEGIN},

    {":",           1, HTTPFIELD_UNKNOWN, 0},

    {"\n",          1, HTTPFIELD_NEWLINE, 0}, 

    {0,0,0,0}

};

/***************************************************************************

 * BIZARRE CODE ALERT!

 *

 * This uses a "byte-by-byte state-machine" to parse the response HTTP

 * header. This is standard practice for high-performance network

 * devices, but is probably unfamiliar to the average network engineer.

 *

 * The way this works is that each byte of input causes a transition to

 * the next state. That means we can parse the response from a server

 * without having to buffer packets. The server can send the response

 * one byte at a time (one packet for each byte) or in one entire packet.

 * Either way, we don't. We don't need to buffer the entire response

 * header waiting for the final packet to arrive, but handle each packet

 * individually.

 * 

 * This is especially useful with our custom TCP stack, which simply

 * rejects out-of-order packets.

 ***************************************************************************/

unsigned

banner_http(  struct Banner1 *banner1,

        unsigned state,

        const unsigned char *px, size_t length,

        char *banner, unsigned *banner_offset, size_t banner_max)

{

    unsigned i;

    unsigned state2;

    size_t id;

    enum {

        FIELD_START = 9,

        FIELD_NAME,

        FIELD_COLON,

        FIELD_VALUE,

    };

    state2 = (state>>16) & 0xFFFF;

    id = (state>>8) & 0xFF;

    state = (state>>0) & 0xFF;

    for (i=0; i<length; i++)

    switch (state) {

    case 0: case 1: case 2: case 3: case 4:

        if (toupper(px[i]) != "HTTP/"[state])

            state = STATE_DONE;

        else

            state++;

        break;

    case 5:

        if (px[i] == '.')

            state++;

        else if (!isdigit(px[i]))

            state = STATE_DONE;

        break;

    case 6:

        if (isspace(px[i]))

            state++;

        else if (!isdigit(px[i]))

            state = STATE_DONE;

        break;

    case 7:

        /* TODO: look for 1xx response code */

        if (px[i] == '\n')

            state = FIELD_START;

        break;

    case FIELD_START:

        if (px[i] == '\r')

            break;

        else if (px[i] == '\n') {

            state = STATE_DONE;

            break;

        } else {

            state2 = 0;

            state = FIELD_NAME;

            /* drop down */

        }

    case FIELD_NAME:

        if (px[i] == '\r')

            break;

        id = smack_search_next(

                        banner1->http_fields,

                        &state2, 

                        px, &i, (unsigned)length);

        if (id == HTTPFIELD_NEWLINE) {

            state2 = 0;

            state = FIELD_START;

        } else if (id == SMACK_NOT_FOUND)

            ; /* continue here */

        else if (id == HTTPFIELD_UNKNOWN) {

            size_t id2;

            id2 = smack_next_match(banner1->http_fields, &state2);

            if (id2 != SMACK_NOT_FOUND)

                id = id2;

            state = FIELD_COLON;

        } else

            state = STATE_DONE;

        break;

    case FIELD_COLON:

        if (px[i] == '\n') {

            state = FIELD_START;

            break;

        } else if (isspace(px[i])) {

            break;

        } else {

            state = FIELD_VALUE;

            /* drop down */

        }

    case FIELD_VALUE:

        if (px[i] == '\r')

            break;

        else if (px[i] == '\n') {

            state = FIELD_START;

            break;

        }

        if (id == HTTPFIELD_SERVER) {

            if (*banner_offset < banner_max) {

                banner[(*banner_offset)++] = px[i];

            }

        }

        break;

    case STATE_DONE:

    default:

        i = (unsigned)length;

        break;

    }

    if (state == STATE_DONE)

        return state;

    else

        return (state2 & 0xFFFF) << 16

                | (id & 0xFF) << 8

                | (state & 0xFF);

}

#ifndef PROTO_HTTP_H

#define PROTO_HTTP_H

#include "proto-banner1.h"

extern struct Patterns http_fields[];

unsigned

banner_http(  struct Banner1 *banner1,

        unsigned state,

        const unsigned char *px, size_t length,

        char *banner, unsigned *banner_offset, size_t banner_max);

#endif

#include "proto-ssh.h"

#include "proto-banner1.h"

#include <ctype.h>

/***************************************************************************

 ***************************************************************************/

unsigned

banner_ssh(  struct Banner1 *banner1,

        unsigned state,

        const unsigned char *px, size_t length,

        char *banner, unsigned *banner_offset, size_t banner_max)

{

    unsigned i;

    banner1=banner1;

    for (i=0; i<length; i++)

    switch (state) {

    case 0:

        if (px[i] == '\r')

            continue;

        if (px[i] == '\n' || px[i] == '\0' || !isprint(px[i])) {

            state = STATE_DONE;

            continue;

        }

        if (*banner_offset < banner_max)

            banner[(*banner_offset)++] = px[i];

        break;

    default:

        i = (unsigned)length;

        break;

    }

    return state;

}

#ifndef PROTO_SSH_H

#define PROTO_SSH_H

struct Banner1;

unsigned

banner_ssh(  struct Banner1 *banner1,

        unsigned state,

        const unsigned char *px, size_t length,

        char *banner, unsigned *banner_offset, size_t banner_max);

#endif