redis protocol parsing code and test.

redis-proto-test.cc

#include    <stdio.h>
#include    <stdlib.h>
#include    <stdint.h>
#include    <ctype.h>
#include    <string.h>

#define     CR      '\r'
#define     LF      '\n'

class message {
public:
    int state;
    char *pos;
    int narg;
    int ret;
    int rlen;
    int rexpectedlen;
    int needsplit;
};

void parse(char *buffer, int buf_size, message *msg) {
    enum {
        START,
        NARG,
        NARG_LF,
        ARGN_LEN_MARK,
        ARGN_LEN,
        ARGN_LEN_LF,
        ARGN,
        ARGN_LF,
    };

    int state = msg->state;
    char *pos = msg->pos;
    char *end = buffer + buf_size;
    char ch;
    int len;

    for ( ;pos < end; pos++) {
        ch = *pos;
        switch(state) {
        case START:
            if (ch != '*') {
                goto error;
            }
            state = NARG;
            msg->narg = 0;
            msg->rlen = 0;
            msg->rexpectedlen = 0;
            break;

        case NARG:
            if (isdigit(ch)) {
                msg->narg = msg->narg * 10 + (uint32_t)(ch - '0');
            } else if (ch == CR) {
                if (msg->narg == 0) {
                    printf("ERROR: %d(%s)\n", __LINE__, pos);
                    goto error;
                }
                state = NARG_LF;
            } else {
                printf("ERROR: %d(%s)\n", __LINE__, pos);
                goto error;
            }

            break;
            
        case NARG_LF:
            if (ch != LF) {
                printf("ERROR: %d(%s)\n", __LINE__, pos);
                goto error;
            }

            state = ARGN_LEN_MARK;
            break;

        case ARGN_LEN_MARK:
            if (ch == '$') {
                state = ARGN_LEN;
                msg->rlen = 0;
            } else {
                printf("ERROR: %d(%s)\n", __LINE__, pos);
                goto error;
            }
            break;

        case ARGN_LEN:
            if (isdigit(ch)) {
                msg->rlen = msg->rlen * 10 + (uint32_t)(ch - '0');
            } else if (ch == CR) {
                state = ARGN_LEN_LF;
            } else {
                printf("ERROR: %d(%s)\n", __LINE__, pos);
                goto error;
            }

            break;

        case ARGN_LEN_LF:
            if (ch != LF) {
                printf("ERROR: %d(%s)\n", __LINE__, pos);
                goto error;
            }

            state = ARGN;
            break;

        case ARGN:
            len = msg->rexpectedlen ? msg->rexpectedlen : msg->rlen;
            if (pos + len > end) {
                msg->rexpectedlen = (uint32_t)(pos + len - end);
                pos = end - 1;
            } else {
                if (*(pos + len) != CR) {
                    printf("ERROR: %d(%d:%s)\n", __LINE__, len, pos);
                    goto error;
                }

                pos += len;
                msg->rexpectedlen = 0;
                msg->rlen = 0;
                state = ARGN_LF;
                msg->narg--;
            }

            break;

        case ARGN_LF:
            if (ch != LF) {
                printf("ERROR: %d(%s)\n", __LINE__, pos);
                goto error;
            }

            if (msg->narg == 0) {
                goto done;
            }

            state = ARGN_LEN_MARK;
            break;
        }
    }

    msg->state = state;
    msg->pos = pos;
    //need next packet
    msg->ret = 3;

    return;

error:
    msg->ret = -1;
    return;

done:
    msg->state = START;
    msg->pos = pos + 1;
    msg->ret = 0;
    if (msg->pos != end) {
        msg->needsplit = 1;
    }
    return;

}

int main(int argc, char *argv[]) {
    message msg;
    memset(&msg, 0, sizeof(message));

    char *ptr = (char *)"*3\r\n$3\r\nset\r\n$3\r\nkey\r\n$5\r\nvalue\r\n";
    msg.pos = ptr;
    parse(ptr, strlen(ptr), &msg);
    printf("ret: %d(%d)\n", msg.ret, msg.needsplit);

    memset(&msg, 0, sizeof(message));
    ptr = (char *)"*3\r\n$3\r\nset\r\n$3";
    msg.pos = ptr;
    parse(ptr, strlen(ptr), &msg);
    printf("ret: %d(%d)\n", msg.ret, msg.needsplit);
    ptr = (char *)"\r\nkey\r\n$5\r\nvalue\r\n";
    msg.pos = ptr;
    parse(ptr, strlen(ptr), &msg);
    printf("ret: %d(%d)\n", msg.ret, msg.needsplit);
    memset(&msg, 0, sizeof(message));
    ptr = (char *)"*3\r\n$3\r\nset\r\n$3";
    msg.pos = ptr;
    parse(ptr, strlen(ptr), &msg);
    printf("ret: %d(%d)\n", msg.ret, msg.needsplit);
    ptr = (char *)"\r\nkey\r\n$5\r\nvalue\r\n$ab";
    msg.pos = ptr;
    parse(ptr, strlen(ptr), &msg);
    printf("ret: %d(%d)\n", msg.ret, msg.needsplit);

    parse(msg.pos, 2, &msg);
    printf("ret: %d(%d)\n", msg.ret, msg.needsplit);
    return 0;
}