hexagram/src/pcapng.c

#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <hexagram/pcapng.h>

static ssize_t handle_option(hexagram_pcapng_stream *stream,
                             hexagram_pcapng_block_header *header,
                             uint16_t code,
                             uint16_t len) {
    ssize_t readlen;
    uint8_t data[65535];

    if ((readlen = read(stream->fd, data, (size_t)len)) < 0) {
        goto error_io;
    }

    if (header->type == HEXAGRAM_PCAPNG_BLOCK_IF) {
        if (code == HEXAGRAM_PCAPNG_OPTION_IF_TSRESOL) {
            stream->if_tsresol = data[0];
        }
    }

    stream->error = HEXAGRAM_PCAPNG_ERROR_OK;

    return readlen;

error_io:
    stream->error = HEXAGRAM_PCAPNG_ERROR_IO;

    return -1;
}

static ssize_t read_options(hexagram_pcapng_stream *stream,
                            hexagram_pcapng_block_header *header,
                            hexagram_pcapng_option_handler *handler,
                            size_t len) {
    hexagram_pcapng_option option;
    ssize_t total = 0;

    while (total < len) {
        ssize_t readlen;

        if ((readlen = read(stream->fd, &option, sizeof(option))) < 0) {
            stream->error = HEXAGRAM_PCAPNG_ERROR_IO;

            goto error_io;
        } else {
            total += readlen;
        }

        if ((readlen = handler(stream, header, option.code, option.length)) < 0) {
            goto error_io;
        } else if (readlen < option.length) {
            stream->error = HEXAGRAM_PCAPNG_ERROR_TRUNCATED;

            goto error_io;
        } else {
            total += readlen;
        }

        if ((readlen = lseek(stream->fd, option.length % sizeof(uint32_t), SEEK_CUR)) < 0) {
            goto error_io;
        } else {
            total += readlen;
        }
    }

    stream->error = HEXAGRAM_PCAPNG_ERROR_OK;

    return total;

error_io:
    return -1;
}

hexagram_pcapng_stream *hexagram_pcapng_stream_open_fd(int fd) {
    hexagram_pcapng_stream *stream;

    if ((stream = malloc(sizeof(*stream))) == NULL) {
        goto error_malloc_stream;
    }

    stream->fd         = fd;
    stream->error      = HEXAGRAM_PCAPNG_ERROR_OK;
    stream->if_tsresol = 0;

    return stream;

error_malloc_stream:
    return NULL;
}

void hexagram_pcapng_stream_destroy(hexagram_pcapng_stream *stream) {
    memset(stream, '\0', sizeof(*stream));

    free(stream);
}

ssize_t hexagram_pcapng_stream_read(hexagram_pcapng_stream *stream,
                                    hexagram_pcapng_block_handler *handler) {
    hexagram_pcapng_block_header header;
    hexagram_pcapng_block_footer footer;
    ssize_t total = 0;

    while (1) {
        size_t expected;
        ssize_t readlen;

        if ((readlen = read(stream->fd, &header, sizeof(header))) < 0) {
            stream->error = HEXAGRAM_PCAPNG_ERROR_IO;

            goto error_io;
        } else if (readlen == 0) {
            goto done;
        } else if (readlen < sizeof(header)) {
            stream->error = HEXAGRAM_PCAPNG_ERROR_TRUNCATED;

            goto error_io;
        } else {
            total += readlen;
        }

        expected = header.length - sizeof(header) - sizeof(footer);

        if ((readlen = handler(stream, header.type, expected)) < 0) {
            goto error_io;
        } else {
            total += readlen;
        }

        if ((readlen = read(stream->fd, &footer, sizeof(footer))) < 0) {
            stream->error = HEXAGRAM_PCAPNG_ERROR_IO;

            goto error_io;
        } else if (readlen == 0) {
            goto done;
        } else if (readlen < sizeof(footer)) {
            stream->error = HEXAGRAM_PCAPNG_ERROR_TRUNCATED;

            goto error_io;
        } else if (footer.length != header.length) {
            stream->error = HEXAGRAM_PCAPNG_ERROR_FORMAT;

            goto error_io;
        } else {
            total += readlen;
        }
    }

done:
    stream->error = HEXAGRAM_PCAPNG_ERROR_OK;

    return total;

error_io:
    return -1;
}