server-cors-proxy.h

#pragma once

#include "common.h"
#include "http.h"

#include <string>
#include <unordered_set>
#include <list>
#include <map>
#include <algorithm>
#include <cctype>

#include "server-http.h"

static std::string proxy_header_to_lower(std::string header) {
    std::transform(header.begin(), header.end(), header.begin(), [](unsigned char c) {
        return std::tolower(c);
    });
    return header;
}

static server_http_res_ptr proxy_request(const server_http_req & req, std::string method) {
    std::string target_url = req.get_param("url");
    common_http_url parsed_url = common_http_parse_url(target_url);

    if (parsed_url.host.empty()) {
        throw std::runtime_error("invalid target URL: missing host");
    }

    if (parsed_url.path.empty()) {
        parsed_url.path = "/";
    }

    if (!parsed_url.password.empty()) {
        throw std::runtime_error("authentication in target URL is not supported");
    }

    if (parsed_url.scheme != "http" && parsed_url.scheme != "https") {
        throw std::runtime_error("unsupported URL scheme in target URL: " + parsed_url.scheme);
    }

    SRV_INF("proxying %s request to %s://%s:%i%s\n", method.c_str(), parsed_url.scheme.c_str(), parsed_url.host.c_str(), parsed_url.port, parsed_url.path.c_str());

    std::map<std::string, std::string> headers;
    const std::string proxy_header_prefix = "x-llama-server-proxy-header-";
    for (auto [key, value] : req.headers) {
        const std::string lowered_key = proxy_header_to_lower(key);
        if (!string_starts_with(lowered_key, proxy_header_prefix)) {
            continue;
        }

        auto new_key = key.substr(proxy_header_prefix.size());
        if (new_key.empty()) {
            continue;
        }

        headers[new_key] = value;
    }

    auto proxy = std::make_unique<server_http_proxy>(
            method,
            parsed_url.scheme,
            parsed_url.host,
            parsed_url.port,
            parsed_url.path,
            headers,
            req.body,
            req.files,
            req.should_stop,
            600, // timeout_read (default to 10 minutes)
            600  // timeout_write (default to 10 minutes)
            );

    return proxy;
}

static server_http_context::handler_t proxy_handler_post = [](const server_http_req & req) -> server_http_res_ptr {
    return proxy_request(req, "POST");
};

static server_http_context::handler_t proxy_handler_get = [](const server_http_req & req) -> server_http_res_ptr {
    return proxy_request(req, "GET");
};