Nginx 字符串设计

  • 用一个简单结构表示，字符串长度和指向字符串首地址的指针
  • 用宏来创建、设置字符串结构体
  • 创建都是用的字符串常量，其存放在数据段，生命期和整个程序一致
  • 如果要在结构体成员中使用，则需要手动设置长度和数据指针

Nginx 字符串结构

typedef struct {
    size_t      len;
    u_char     *data;
} ngx_str_t;

Nginx 字符串初始化

  • ngx_string 被大量使用，一般直接在程序中使用 ngx_string("xxx")
  • 空字符串用 ngx_null_string 初始化
  • 后两个操作分别设置一个 ngx_str_t 变量的值
#define ngx_string(str)     { sizeof(str) - 1, (u_char *) str }
#define ngx_null_string     { 0, NULL }
#define ngx_str_set(str, text)                                               \
    (str)->len = sizeof(text) - 1; (str)->data = (u_char *) text
#define ngx_str_null(str)   (str)->len = 0; (str)->data = NULL

Nginx 字符串相关操作

使用内存池分配一块内存，其内容和给定的字符串内容一致

u_char *
ngx_pstrdup(ngx_pool_t *pool, ngx_str_t *src)
{
    u_char  *dst;

    dst = ngx_pnalloc(pool, src->len);
    if (dst == NULL) {
        return NULL;
    }

    ngx_memcpy(dst, src->data, src->len);

    return dst;
}

base64 加密字符串或URL

void
ngx_encode_base64(ngx_str_t *dst, ngx_str_t *src)
{
    static u_char   basis64[] =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    ngx_encode_base64_internal(dst, src, basis64, 1);
}


void
ngx_encode_base64url(ngx_str_t *dst, ngx_str_t *src)
{
    static u_char   basis64[] =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";

    ngx_encode_base64_internal(dst, src, basis64, 0);
}


static void
ngx_encode_base64_internal(ngx_str_t *dst, ngx_str_t *src, const u_char *basis,
    ngx_uint_t padding)
{
    u_char         *d, *s;
    size_t          len;

    len = src->len;
    s = src->data;
    d = dst->data;

    while (len > 2) {
        *d++ = basis[(s[0] >> 2) & 0x3f];
        *d++ = basis[((s[0] & 3) << 4) | (s[1] >> 4)];
        *d++ = basis[((s[1] & 0x0f) << 2) | (s[2] >> 6)];
        *d++ = basis[s[2] & 0x3f];

        s += 3;
        len -= 3;
    }

    if (len) {
        *d++ = basis[(s[0] >> 2) & 0x3f];

        if (len == 1) {
            *d++ = basis[(s[0] & 3) << 4];
            if (padding) {
                *d++ = '=';
            }

        } else {
            *d++ = basis[((s[0] & 3) << 4) | (s[1] >> 4)];
            *d++ = basis[(s[1] & 0x0f) << 2];
        }

        if (padding) {
            *d++ = '=';
        }
    }

    dst->len = d - dst->data;
}

base64 解密字符串或URL

ngx_int_t
ngx_decode_base64(ngx_str_t *dst, ngx_str_t *src)
{
    static u_char   basis64[] = {
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 62, 77, 77, 77, 63,
        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 77, 77, 77, 77, 77, 77,
        77,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 77, 77, 77, 77, 77,
        77, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
        41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 77, 77, 77, 77, 77,

        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77
    };

    return ngx_decode_base64_internal(dst, src, basis64);
}


ngx_int_t
ngx_decode_base64url(ngx_str_t *dst, ngx_str_t *src)
{
    static u_char   basis64[] = {
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 62, 77, 77,
        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 77, 77, 77, 77, 77, 77,
        77,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 77, 77, 77, 77, 63,
        77, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
        41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 77, 77, 77, 77, 77,

        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77,
        77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77, 77
    };

    return ngx_decode_base64_internal(dst, src, basis64);
}


static ngx_int_t
ngx_decode_base64_internal(ngx_str_t *dst, ngx_str_t *src, const u_char *basis)
{
    size_t          len;
    u_char         *d, *s;

    for (len = 0; len < src->len; len++) {
        if (src->data[len] == '=') {
            break;
        }

        if (basis[src->data[len]] == 77) {
            return NGX_ERROR;
        }
    }

    if (len % 4 == 1) {
        return NGX_ERROR;
    }

    s = src->data;
    d = dst->data;

    while (len > 3) {
        *d++ = (u_char) (basis[s[0]] << 2 | basis[s[1]] >> 4);
        *d++ = (u_char) (basis[s[1]] << 4 | basis[s[2]] >> 2);
        *d++ = (u_char) (basis[s[2]] << 6 | basis[s[3]]);

        s += 4;
        len -= 4;
    }

    if (len > 1) {
        *d++ = (u_char) (basis[s[0]] << 2 | basis[s[1]] >> 4);
    }

    if (len > 2) {
        *d++ = (u_char) (basis[s[1]] << 4 | basis[s[2]] >> 2);
    }

    dst->len = d - dst->data;

    return NGX_OK;
}